Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason why
you disagree
that would account for any differences in sound quality.

Go ahead Robert, get technical, I'm sure I can find someone to translate if
it gets to technical for what you think is my lack of brainpower.

On Thu, 20 Oct 2005 07:39:07 GMT, "
wrote:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason why
you disagree
that would account for any differences in sound quality.

Go ahead Robert, get technical, I'm sure I can find someone to translate if
it gets to technical for what you think is my lack of brainpower.

As a staunch objectivist, don't you consider your own statement pretty
absurd?

Please tell us how you can make a statement about difference between
these two components without a dbt?

"dave weil" wrote in message
news
On Thu, 20 Oct 2005 07:39:07 GMT, "
wrote:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason
why
you disagree
that would account for any differences in sound quality.

Go ahead Robert, get technical, I'm sure I can find someone to translate
if
it gets to technical for what you think is my lack of brainpower.

As a staunch objectivist, don't you consider your own statement pretty
absurd?


What's absurd is bad mouthing a brand of amps without any kind of
comparison.

Please tell us how you can make a statement about difference between
these two components without a dbt?

I don't think you honestly do that for any amp, yet people do it here all
the time.

I do think it would be a great test to do, since the cost of the QSC is not
out of reach for someone with a bit of discipline, the way a Krell is, and
you don't have to hire a forklift to move the QSC which is made for touring
and therefore ruggedly built and has twice the power, there's no reason at
all to assume it wouldn't be as transparent as the Krell.

On Thu, 20 Oct 2005 16:26:57 GMT, "
wrote:


"dave weil" wrote in message
news
On Thu, 20 Oct 2005 07:39:07 GMT, "
wrote:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason
why
you disagree
that would account for any differences in sound quality.

Go ahead Robert, get technical, I'm sure I can find someone to translate
if
it gets to technical for what you think is my lack of brainpower.

As a staunch objectivist, don't you consider your own statement pretty
absurd?


What's absurd is bad mouthing a brand of amps without any kind of
comparison.

So, you think that his statement means that the world is free to make
comments on sound quality without even listening to the products in
question? Making value judgments on sound based solely on a short spec
sheet? Does his statement give you a free pass to make the same sort
of error?

Please tell us how you can make a statement about difference between
these two components without a dbt?

I don't think you honestly do that for any amp, yet people do it here all
the time.

So, as my mom would have said, "If your friend jumps off the top of a
building, you're going to do the same"?

I do think it would be a great test to do, since the cost of the QSC is not
out of reach for someone with a bit of discipline, the way a Krell is, and
you don't have to hire a forklift to move the QSC which is made for touring
and therefore ruggedly built and has twice the power, there's no reason at
all to assume it wouldn't be as transparent as the Krell.

Maybe you should talk to Stewart, who claims to have done such testing
with his Krell and other amps.

Still, you have fallen into the same trap that you accuse OTHERS of
making. But because you think you're on the "right side of the
angels", it's OK for you to do so.

Bad form.

"dave weil" wrote in message
...
On Thu, 20 Oct 2005 16:26:57 GMT, "
wrote:


"dave weil" wrote in message
news
On Thu, 20 Oct 2005 07:39:07 GMT, "
wrote:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason
why
you disagree
that would account for any differences in sound quality.

Go ahead Robert, get technical, I'm sure I can find someone to translate
if
it gets to technical for what you think is my lack of brainpower.

As a staunch objectivist, don't you consider your own statement pretty
absurd?


What's absurd is bad mouthing a brand of amps without any kind of
comparison.

So, you think that his statement means that the world is free to make
comments on sound quality without even listening to the products in
question? Making value judgments on sound based solely on a short spec
sheet? Does his statement give you a free pass to make the same sort
of error?

Please tell us how you can make a statement about difference between
these two components without a dbt?

I don't think you honestly do that for any amp, yet people do it here all
the time.

So, as my mom would have said, "If your friend jumps off the top of a
building, you're going to do the same"?


I think sometimes it good to illustrate absurdity by being a bit absurd.

I do think it would be a great test to do, since the cost of the QSC is
not
out of reach for someone with a bit of discipline, the way a Krell is, and
you don't have to hire a forklift to move the QSC which is made for
touring
and therefore ruggedly built and has twice the power, there's no reason at
all to assume it wouldn't be as transparent as the Krell.

Maybe you should talk to Stewart, who claims to have done such testing
with his Krell and other amps.

I have seen his posts about comaparing other amps to his own Krell.

Still, you have fallen into the same trap that you accuse OTHERS of
making. But because you think you're on the "right side of the
angels", it's OK for you to do so.

Bad form.

I think I'm on the side that has the best most reliable evidence and that
does not as a habit make personal attacks on those who disagree with
alternate viewpoints.

The bad form is from those who make such posts personal, and who while
knowing that a certain test protocol is widely accepted by those doing
genuine scientific research into audio differences, still claim it is an
unproven protocol. Then there are those who trash a peice of gear without
any sort of bias controlled listening comparisons, and those who claim to
defend preference trashing one they don't agree with.

I simply posted some figures to see if anyone could give a hint of why they
might not think it could compete with a well known and well respected piece
of equipment from an audiophile approved manufacturer.

So far no one has given any intelligent reason why this QSC amp couldn't go
head to head with any audiophile amp ever made. It is a very high power amp
with low noise and low distortion that used in a normal listening
environment should be as good or better than any other SS amp.

As I said, it would be very interesting to do a blind comparison of the QSC
amp against a Krell or any other amp approved for home listening. I doubt
that there will be any way someone will be offering up a Krell or something
in that price range for comparison, but there are other amps that are
reputed to sound great which don't cost Krell kind of money that might be
used for such a comparison.

I just like the idea of being able to get the most bang for one's buck, and
using a pro amp that has a very low price and very high power compared to
any similar powered audiophile amp would be one way to enlighten consumers
as to how they can do that.

" said:


As I said, it would be very interesting to do a blind comparison of the QSC
amp against a Krell or any other amp approved for home listening. I doubt
that there will be any way someone will be offering up a Krell or something
in that price range for comparison, but there are other amps that are
reputed to sound great which don't cost Krell kind of money that might be
used for such a comparison.

I just like the idea of being able to get the most bang for one's buck, and
using a pro amp that has a very low price and very high power compared to
any similar powered audiophile amp would be one way to enlighten consumers
as to how they can do that.


If you can agree to split the shipping costs, I can send you one of
mine to try.
The component cost is about ‚¬800, when everything is bought new -
(assuming one *can* buy the 2SK135/2SJ50 anywhere today. I have a
stash of them reserved for future projects, hah!).

It is not a Krell, but it has some current reserve (which, if I'm
informed correctly, should be of no consequence for the comparison to,
say, a Pioneer receiver or even a QSC ampplifier).

It would probably be a nice idea to compare it to your Acoustat, since
that amp most likely uses the same output devices, but in a different
configuration.

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

" wrote in message
link.net...


Snip...

So far no one has given any intelligent reason why this QSC amp couldn't
go head to head with any audiophile amp ever made. It is a very high
power amp with low noise and low distortion that used in a normal
listening environment should be as good or better than any other SS amp.

How about the noise from the fan? I sold a Hafler 500 years ago because I
found the noise from the fan to be bothersome in my quiet listening room.


As I said, it would be very interesting to do a blind comparison of the
QSC amp against a Krell or any other amp approved for home listening. I
doubt that there will be any way someone will be offering up a Krell or
something in that price range for comparison, but there are other amps
that are reputed to sound great which don't cost Krell kind of money that
might be used for such a comparison.

I just like the idea of being able to get the most bang for one's buck,

Whatever floats your boat.

and using a pro amp that has a very low price and very high power compared
to any similar powered audiophile amp would be one way to enlighten
consumers as to how they can do that.

Just curious, do you own the QSC amp or have you even listened to one in a
home environment? If not, you are recommending an amp based strictly on
specs which I don't think "enlightens" anyone.

John

On Sat, 22 Oct 2005 20:00:40 GMT, "
wrote:

I don't think you honestly do that for any amp, yet people do it here all
the time.

So, as my mom would have said, "If your friend jumps off the top of a
building, you're going to do the same"?


I think sometimes it good to illustrate absurdity by being a bit absurd.

So, we shouldn't take your comments that started this whole thread
seriously at all then. You were just wasting everyone's time...

" wrote in message
ink.net...
Krell 350 Watt monoblocks @ $17,500.00 per pair
QSC PLX 3402 Stereo amp $1200.00

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00

Ever heard of opportunity cost? It is obvious that you have none but there
are folks who will make more than $15K in the time it takes to fiddle with
their amp. Even worse they'll be left with no warranty and if the amp ever,
for any reason, starts a fire and burns down the building, chances are that
insurance won't cover it. These are real choices for some people, just not
for you.

"Margaret von B."
wrote in message

" wrote in
message

ink.net...
Krell 350 Watt monoblocks @ $17,500.00 per pair
QSC PLX 3402 Stereo amp $1200.00

I figure you get the QSC and either modify it by adding
heat sinks or replacing the fans with very quiet ones,
and still have saved around $15,000.00

Neither are required. QSC amp fans aren't *that* noisy, and
if they are a problem its easier just to put them out of ear
shot. Since they aren't $15k amps, the *need* to put them on
display is vastly reduced. Of course this shoots the $#@!!
out of what $15k amps are *really* about, and that's
bragging rights.

Ever heard of opportunity cost? It is obvious that you
have none but there are folks who will make more than
$15K in the time it takes to fiddle with their amp.

Good thing that there's no need to fiddle with QSC amps.

Arny Krueger wrote:
snip
(spray monitor with FDS before continuing)

Ever heard of opportunity cost? It is obvious that you
have none but there are folks who will make more than
$15K in the time it takes to fiddle with their amp.

Good thing that there's no need to fiddle with QSC amps.

Better we should ask, Why does QSC not simply make a variant of their
existing amp in a more cosmetically attractive case with bigger, much
bigger, heatsink, and sell it under a badge engineered name to the high
end market?

Probably they thought about it and realized no one will buy it.

The QSC amp is economically and reliably designed to give good service
at high sustained power levels. Any home installation that uses
sustained power levels in these regions means either you have a very
big house, very inefficient speakers, or are or will shortly be turning
hearing-impaired.

"Bret Ludwig" wrote in message
oups.com...

Arny Krueger wrote:
snip
(spray monitor with FDS before continuing)

Ever heard of opportunity cost? It is obvious that you
have none but there are folks who will make more than
$15K in the time it takes to fiddle with their amp.

Good thing that there's no need to fiddle with QSC amps.

Better we should ask, Why does QSC not simply make a variant of their
existing amp in a more cosmetically attractive case with bigger, much
bigger, heatsink, and sell it under a badge engineered name to the high
end market?

You'd have to ask them. They used to make the USA line that had no fan and
were perfectly fine for home use also. Maybe they just don't want to have
to deal with the whacko contingent.



Probably they thought about it and realized no one will buy it.

Probalbly they have thought about and with a business that is sound and
thriving after 30 years, they don't need to. I've seen tehir facility in
Orange County and it's huge. By comnparison, Sumo when it was in business,
occupied just a small area in an industrial strip, as does Hsu subvwoofers
the last time I saw their faciltiy.

The QSC amp is economically and reliably designed to give good service
at high sustained power levels. Any home installation that uses
sustained power levels in these regions means either you have a very
big house, very inefficient speakers, or are or will shortly be turning
hearing-impaired.

Or just want to have an econmical amp that can drive any speaker you might
ever wish to own and still have tons of reserve power, to help insure you
never clip. Some tranisents when listening at live levels can require
enourmous amounts of reserve power.
Something like the PLX I mentioned has that in abundance. I also have seen
IB subwoofers that use such amps to drive 3,4,5,as many as 24 drivers to get
real bass down to 8 HZ. Real audiohiles know how to get bass and what sort
of power that requires.

"Bret Ludwig" wrote in message
oups.com
Arny Krueger wrote:
snip
(spray monitor with FDS before continuing)

Ever heard of opportunity cost? It is obvious that you
have none but there are folks who will make more than
$15K in the time it takes to fiddle with their amp.

Good thing that there's no need to fiddle with QSC amps.

Better we should ask, Why does QSC not simply make a
variant of their existing amp in a more cosmetically
attractive case with bigger, much bigger, heatsink, and
sell it under a badge engineered name to the high end
market?

Good question. BTW their competitor Behringer already does:

http://www.behringer.com/A500/index.cfm?lang=ENG

Probably they thought about it and realized no one will
buy it.

I get this feeling that Behringer's product will sell
briskly.

The QSC amp is economically and reliably designed to give
good service at high sustained power levels. Any home
installation that uses sustained power levels in these
regions means either you have a very big house, very
inefficient speakers, or are or will shortly be turning
hearing-impaired.

QSC makes smaller amps, you know.

On Sun, 23 Oct 2005 07:05:21 -0400, "Arny Krueger"
wrote:

Better we should ask, Why does QSC not simply make a
variant of their existing amp in a more cosmetically
attractive case with bigger, much bigger, heatsink, and
sell it under a badge engineered name to the high end
market?

Good question. BTW their competitor Behringer already does:

http://www.behringer.com/A500/index.cfm?lang=ENG

Probably they thought about it and realized no one will
buy it.

I get this feeling that Behringer's product will sell
briskly.

Well, at $229 ex shipping and customs, it probably should.

Odd that you think it's being marketed to the high end market.

"Arny Krueger" wrote in message
...
"Bret Ludwig" wrote in message
oups.com
Arny Krueger wrote:
snip
(spray monitor with FDS before continuing)

Ever heard of opportunity cost? It is obvious that you
have none but there are folks who will make more than
$15K in the time it takes to fiddle with their amp.

Good thing that there's no need to fiddle with QSC amps.

Better we should ask, Why does QSC not simply make a
variant of their existing amp in a more cosmetically
attractive case with bigger, much bigger, heatsink, and
sell it under a badge engineered name to the high end
market?

Good question. BTW their competitor Behringer already does:

http://www.behringer.com/A500/index.cfm?lang=ENG

Probably they thought about it and realized no one will
buy it.

I get this feeling that Behringer's product will sell briskly.

I'm tremendously impressed. Behringer has made an excellent amplifier at an
extremely low price. 50 cents/watt for a fully packaged design is dirt
cheap.

I'm ready to buy!

Norm Strong

"Margaret von B." wrote in message
...

" wrote in message
ink.net...
Krell 350 Watt monoblocks @ $17,500.00 per pair
QSC PLX 3402 Stereo amp $1200.00

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00

Ever heard of opportunity cost?

I must admit I've not heard that phrase. Explain please.

It is obvious that you have none but there
are folks who will make more than $15K in the time it takes to fiddle with
their amp.

How smart do you need to be to connect an amp to a preamp?

Even worse they'll be left with no warranty and if the amp ever,
for any reason, starts a fire and burns down the building, chances are
that insurance won't cover it. These are real choices for some people,
just not for you.

The QSC has a 6 year warranty, their products have been favored by pros for
30 years, so I doubt that a fire is a very real consideration. What kind of
cheap ass insurance company would not cover such an event?

Mikey wrote:

Maggie wrote:

Ever heard of opportunity cost?

I must admit I've not heard that phrase. Explain please.

Yes, Mags, do explain the concept of "opportunity cost"
and after that, please expound on "utility theory" and then
wrap things up with "Schumpeterian profits."

For an encore, dazzle us with an analogousness of "Gresham's
Law" as applicable to rao.


Cheers,

GeoSynch

I wrote:

Mikey wrote:

Maggie wrote:

Ever heard of opportunity cost?

I must admit I've not heard that phrase. Explain please.

Yes, Mags, do explain the concept of "opportunity cost"
and after that, please expound on "utility theory" and then
wrap things up with "Schumpeterian profits."

For an encore, dazzle us with an analogousness of "Gresham's
Law" as applicable to rao.

Lack of response indicative Mag's economic capabilities are as
substantive as cotton candy.


GeoSynch

" wrote in message
nk.net...

"Margaret von B." wrote in message
...

" wrote in message
ink.net...
Krell 350 Watt monoblocks @ $17,500.00 per pair
QSC PLX 3402 Stereo amp $1200.00

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00

Ever heard of opportunity cost?

I must admit I've not heard that phrase. Explain please.


Mine was a rhetorical question and I actually cannot believe you'd be *that*
ignorant. The only parallel I can think of would be Geoeunuch in a
whorehouse. LOL!

It is obvious that you have none but there
are folks who will make more than $15K in the time it takes to fiddle
with their amp.

How smart do you need to be to connect an amp to a preamp?


Instant memory loss? Go up 10 lines, read your own drivel, and try again.

Even worse they'll be left with no warranty and if the amp ever,
for any reason, starts a fire and burns down the building, chances are
that insurance won't cover it. These are real choices for some people,
just not for you.

The QSC has a 6 year warranty, their products have been favored by pros
for 30 years, so I doubt that a fire is a very real consideration. What
kind of cheap ass insurance company would not cover such an event?

Major companies won't cover damages caused by hacked equipment. Call your
rep if you got one.


Cheers,

Margaret

Maggie the Fleahole vamped:

Mine was a rhetorical question and I actually cannot believe you'd be *that*
ignorant. The only parallel I can think of would be Geoeunuch in a whorehouse.
LOL!

If you were the only whore in the house, old girl, the eunuchs would breathe
a sigh of relief.


GeoSynch

wrote:
Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason why
you disagree
that would account for any differences in sound quality.


6K ohm input impedance isn't ideal and may cause problems with many a
source. One will have to be careful in selecting a preamp to insure
compatibility and probably will need to avoid any passives or
autoformer types. This excessive input load may also lead to... gasp...
interconnect cable type sensitivity if the source is load sensitive.

But most disconcerting is the very strange input sensitivity spec.
1.9V @ 8 ohms? Are they implying that input sensitivity varies with
output load impedance? That will cause FR variance with any speaker
having a non-flat impedance curve (virtually all but active speakers).


So that begs the question already raised... why isn't FR specified?

ScottW

"ScottW" wrote in message
ups.com


Origional document reference:

http://www.qscaudio.com/products/amps/plx/plx.htm

6K ohm input impedance isn't ideal and may cause problems
with many a source.

Other than older vacuum tubed preamps, its hard to think of
any. Most modern (less than 20 year old) vacuum tube and SS
preamps will handle 2 volts into a 6 K ohm just fine. Most
will put out upwards of 10 volts into a 10K load, for
example.


But most disconcerting is the very strange input
sensitivity spec. 1.9V @ 8 ohms?


Are they implying that input sensitivity
varies with output load impedance? That will cause FR
variance with any speaker having a non-flat impedance
curve (virtually all but active speakers).


What they are saying that this is the input sensivitity for
rated output with a 4 ohm load.

The rated output power varies with load impedance, and the
rest follows.


So that begs the question already raised... why isn't FR
specified?

It is, in a part of the original document that Mike didn't
post.

"ScottW" wrote in message
ups.com...

wrote:
Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason
why
you disagree
that would account for any differences in sound quality.


6K ohm input impedance isn't ideal and may cause problems with many a
source. One will have to be careful in selecting a preamp to insure
compatibility and probably will need to avoid any passives or
autoformer types. This excessive input load may also lead to... gasp...
interconnect cable type sensitivity if the source is load sensitive.

But most disconcerting is the very strange input sensitivity spec.
1.9V @ 8 ohms? Are they implying that input sensitivity varies with
output load impedance? That will cause FR variance with any speaker
having a non-flat impedance curve (virtually all but active speakers).

I'll bet that's a typo. Either that or it represents the voltage necessary
at the input to drive the amplifier to its rated output when connected to an
8 ohm load. That's a perfectly logical interpretation, although I would
have made it clear if I had written the spec sheet.

In truth, it's the Krell input sensitivity spec that needs fixing. They
should have stated that 2.6v is required to supply 350W into an 8 ohm load
(which is the case.)

Norm Strong

"ScottW" wrote in message
ups.com...

wrote:
Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db

I figure you get the QSC and either modify it by adding heat sinks or
replacing the fans with very quiet ones,
and still have saved around $15,000.00 and not be able to hear any
difference.

If you have a difference of opinion, please provide the technical reason
why
you disagree
that would account for any differences in sound quality.


6K ohm input impedance isn't ideal and may cause problems with many a
source. One will have to be careful in selecting a preamp to insure
compatibility and probably will need to avoid any passives or
autoformer types. This excessive input load may also lead to... gasp...
interconnect cable type sensitivity if the source is load sensitive.

But most disconcerting is the very strange input sensitivity spec.
1.9V @ 8 ohms? Are they implying that input sensitivity varies with
output load impedance? That will cause FR variance with any speaker
having a non-flat impedance curve (virtually all but active speakers).


So that begs the question already raised... why isn't FR specified?

ScottW

Because I was late and it was tired. As you can see I posted the web
address where it could be found, and later the entire spec list for their
PLX line. The FR is typical of any decent amp.

" said:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db


One of the things that I noticed immediately is the ability of the
Krell to deliver twice the power (meaning current) in half the load,
up to 2 ohms.
I suspect that even in 1 ohm the figure would be close to the required
2800W, be it for a brief period of time.
The QSC has only marginally more power into 2 ohms (not that those
insanely high wattages have any meaningful use, you will note).
Also, the current doesn't double with half the load.
This means the Krell has a stiffer power supply, despite the lower
average wattage. It is a true constant voltage source.

The input impedance of the QSC amp is rather low, something to keep in
mind when driving it directly from an opamp's output.

The input sensitivity should have nothing to do with the output load
impedance, is this a typo, a mistake or does the amp use such a high
amount of global feedback that the load has influence on the input?
In the latter case, problems might arise with strongly reactive loads,
and this may make for a different sounding amplifier.
I also noticed the DF isn't specified.

There are more issues to discuss, but that would require more
information about both amps, and, preferably, the schematics.

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

"Sander deWaal" wrote in message

" said:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db


One of the things that I noticed immediately is the
ability of the Krell to deliver twice the power (meaning
current) in half the load, up to 2 ohms.
I suspect that even in 1 ohm the figure would be close to
the required 2800W, be it for a brief period of time.
The QSC has only marginally more power into 2 ohms (not
that those insanely high wattages have any meaningful
use, you will note).
Also, the current doesn't double with half the load.
This means the Krell has a stiffer power supply, despite
the lower average wattage. It is a true constant voltage
source.

Just shows that Sander is easily snowed by raw specsmanship.

It's pretty well known in the industry that the Krell
ratings sheet has been juggled by Krell. The 8 ohm power
rating was backed off, to create the impression that it is
an ideal amp and puts out twice the power into 4 ohms. If
the Krell amp were rated more conventionally based on those
tests that Sander's buddy Middius hates, there would be a
different story.

The input impedance of the QSC amp is rather low,
something to keep in mind when driving it directly from
an opamp's output.

Most conventional audio-grade opamps have absolutely no
problem driving a 1K load to 5 volts rms, let alone just 2.
Ditto for modern preamps, whether vacuum tube or SS.

The input sensitivity should have nothing to do with the
output load impedance, is this a typo, a mistake or does
the amp use such a high amount of global feedback that
the load has influence on the input? In the latter case,
problems might arise with strongly reactive loads, and
this may make for a different sounding amplifier.
I also noticed the DF isn't specified.

Shows that Sander can't see that the amps input sensitivity
is scaled to its output ratings into various load
impedances.

There are more issues to discuss, but that would require
more information about both amps, and, preferably, the
schematics.

Looks like having Sander comment on power amps is like
engaging the proverbial loose cannon.

Taking technical comments about SS amps at face value from a
tube advocate like Sander is very risky.

Arny Krueger wrote:
"Sander deWaal" wrote in message

" said:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db


One of the things that I noticed immediately is the
ability of the Krell to deliver twice the power (meaning
current) in half the load, up to 2 ohms.
I suspect that even in 1 ohm the figure would be close to
the required 2800W, be it for a brief period of time.
The QSC has only marginally more power into 2 ohms (not
that those insanely high wattages have any meaningful
use, you will note).
Also, the current doesn't double with half the load.
This means the Krell has a stiffer power supply, despite
the lower average wattage. It is a true constant voltage
source.

Just shows that Sander is easily snowed by raw specsmanship.

It's pretty well known in the industry that the Krell
ratings sheet has been juggled by Krell. The 8 ohm power
rating was backed off, to create the impression that it is
an ideal amp and puts out twice the power into 4 ohms. If
the Krell amp were rated more conventionally based on those
tests that Sander's buddy Middius hates, there would be a
different story.

The input impedance of the QSC amp is rather low,
something to keep in mind when driving it directly from
an opamp's output.

Most conventional audio-grade opamps have absolutely no
problem driving a 1K load to 5 volts rms,

What good is that if 1.7 V will drive the QSC to clipping
into a 4 ohm load?

let alone just 2.
Ditto for modern preamps, whether vacuum tube or SS.

But not all. I have a CD that didn't like it. As I said before
(and Arny snipped cuz he couldn't address it), that low input
impedance probably leaves the
passive attenuator pres out.


The input sensitivity should have nothing to do with the
output load impedance, is this a typo, a mistake or does
the amp use such a high amount of global feedback that
the load has influence on the input? In the latter case,
problems might arise with strongly reactive loads, and
this may make for a different sounding amplifier.
I also noticed the DF isn't specified.

Shows that Sander can't see that the amps input sensitivity
is scaled to its output ratings into various load
impedances.

BS... Sander's right and only cheap ass amps whose max output
voltage diminishes as a function of load need do this.

You say Krell underrates their 8 ohm capability...
I say QSC overrates theirs.

Which would you prefer.. an underrated amp or an overrated amp?

ScottW

On 20 Oct 2005 15:00:13 -0700, "ScottW" wrote:

BS... Sander's right

No, he's not.

and only cheap ass amps whose max output
voltage diminishes as a function of load need do this.

What a moron. Essentially ALL audio power amps do that, since
essentially NONE of them have regulated high-voltage rails. It's only
a question of "how much" does the output voltage droop.

You say Krell underrates their 8 ohm capability...

You're wrong. Have you ever seen a review of a Krell when their power
output is actually measured? Sheesh, the ignorance!

I say QSC overrates theirs.

What an idiot like you says means nothing.

Which would you prefer.. an underrated amp or an overrated amp?

We should not be surprised you'd ask such a stupid question.

"dizzy" wrote in message
...
On 20 Oct 2005 15:00:13 -0700, "ScottW" wrote:

BS... Sander's right

No, he's not.

and only cheap ass amps whose max output
voltage diminishes as a function of load need do this.

What a moron. Essentially ALL audio power amps do that, since
essentially NONE of them have regulated high-voltage rails. It's only
a question of "how much" does the output voltage droop.

If the output droops the amp will have more than power problems.
I think you mean DC supply droops... yet the KSA (the Krell I am
most familiar with) has plenty of current reserve to prevent this.


You say Krell underrates their 8 ohm capability...

You're wrong. Have you ever seen a review of a Krell when their power
output is actually measured? Sheesh, the ignorance!

Provide a reference Arny... I mean Dizzy.


I say QSC overrates theirs.

What an idiot like you says means nothing.

Which would you prefer.. an underrated amp or an overrated amp?

We should not be surprised you'd ask such a stupid question.

and you provide no answers... just noise.

ScottW

"dizzy" wrote in message

On 20 Oct 2005 15:00:13 -0700, "ScottW"
wrote:

BS... Sander's right

No, he's not.

and only cheap ass amps whose max output
voltage diminishes as a function of load need do this.

What a moron.

You forgot the bull-headed part.

Essentially ALL audio power amps do that,
since essentially NONE of them have regulated
high-voltage rails. It's only a question of "how much"
does the output voltage droop.

Exactly.

You say Krell underrates their 8 ohm capability...

You're wrong. Have you ever seen a review of a Krell
when their power output is actually measured? Sheesh,
the ignorance!

You heard that old statement "Ignorance is Bliss"? Scotty
should be very happy!

I've been trying to educate Scotty about audio for years,
and its like trying to teach a pig to sing. All I did is
**** off the pig.

I say QSC overrates theirs.

What an idiot like you says means nothing.

I think Scotty is a software guy. It seems like he saved up
his sheckels and paid too much for some pretty good
speakers, and now he thinks he's John Atkinson.

Which would you prefer.. an underrated amp or an
overrated amp?

We should not be surprised you'd ask such a stupid
question.

Again agreed. What we want is amps that get the job done for
a price we want to pay. Sometimes you have to spend a little
money - that QSC PLX isn't exactly cheap.

But the Krell is not about good audio, its about bragging
rights for the new rich.

"Arny Krueger" said:


It's pretty well known in the industry that the Krell
ratings sheet has been juggled by Krell. The 8 ohm power
rating was backed off, to create the impression that it is
an ideal amp and puts out twice the power into 4 ohms. If
the Krell amp were rated more conventionally based on those
tests that Sander's buddy Middius hates, there would be a
different story.


You're forgetting that the Krell also doubles current in 2 ohms.
The 8 ohms power ratings must be way, way underrated then.


The input impedance of the QSC amp is rather low,
something to keep in mind when driving it directly from
an opamp's output.

Most conventional audio-grade opamps have absolutely no
problem driving a 1K load to 5 volts rms, let alone just 2.
Ditto for modern preamps, whether vacuum tube or SS.


Then why does e.g. Sony advise to load their CD players with at least
50 kohms? Their output capacitors are at least 47 uF, so a low
frequency rollof wouldn't be a problem (for the math challenged, the
-3 dB frequency is then around 0.5 Hz).


The input sensitivity should have nothing to do with the
output load impedance, is this a typo, a mistake or does
the amp use such a high amount of global feedback that
the load has influence on the input? In the latter case,
problems might arise with strongly reactive loads, and
this may make for a different sounding amplifier.
I also noticed the DF isn't specified.


Shows that Sander can't see that the amps input sensitivity
is scaled to its output ratings into various load
impedances.


********.
A good amp is a constant voltage source, regardless the load.
That means the load should be of no consequence to the input level.
If there is influence, it's a bad design. Simple as that.


There are more issues to discuss, but that would require
more information about both amps, and, preferably, the
schematics.

Looks like having Sander comment on power amps is like
engaging the proverbial loose cannon.


You think the specs Mike gave are enough to determine whether these
amps will sound the same in a DBT, regardless the load?

Don't make me laugh.


Taking technical comments about SS amps at face value from a
tube advocate like Sander is very risky.


Taking technical comments about anything regarding audio on an Usenet
forum is very risky, no matter who the source is.

But given © that you seem to think of yourself as the "bearer of
Light" on audio newsgroups, I don't expect you to adhere to this view.


Party on, dude.

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

"Sander deWaal" wrote in message

"Arny Krueger" said:


It's pretty well known in the industry that the Krell
ratings sheet has been juggled by Krell. The 8 ohm power
rating was backed off, to create the impression that it
is an ideal amp and puts out twice the power into 4
ohms. If the Krell amp were rated more conventionally
based on those tests that Sander's buddy Middius hates,
there would be a different story.

You're forgetting that the Krell also doubles current in
2 ohms.

The point is that what doubles is not the amps maximum
current output but the amps spec.

The 8 ohms power ratings must be way, way underrated then.

Yup. If you derated the QSC in a similar fashion, it would
still be more powerful by far.

The input impedance of the QSC amp is rather low,
something to keep in mind when driving it directly from
an opamp's output.

Most conventional audio-grade opamps have absolutely no
problem driving a 1K load to 5 volts rms, let alone just
2. Ditto for modern preamps, whether vacuum tube or SS.

Then why does e.g. Sony advise to load their CD players
with at least 50 kohms?

They like to use small output coupling caps?

Real men use the digital outputs of optical players, anyway.

Their output capacitors are at
least 47 uF, so a low frequency rollof wouldn't be a
problem (for the math challenged, the -3 dB frequency is
then around 0.5 Hz).

I seem to recall that the output caps of my Sony CD player
were 47 uF, for maybe the first year... ;-)

The input sensitivity should have nothing to do with the
output load impedance, is this a typo, a mistake or does
the amp use such a high amount of global feedback that
the load has influence on the input? In the latter case,
problems might arise with strongly reactive loads, and
this may make for a different sounding amplifier.
I also noticed the DF isn't specified.

Shows that Sander can't see that the amps input
sensitivity is scaled to its output ratings into various
load impedances.

********.

Do the math.

A good amp is a constant voltage source, regardless the
load.

Agreed, as is the QSC.

That means the load should be of no consequence to the
input level. If there is influence, it's a bad design.
Simple as that.

You're misinterpreting the spec.

There are more issues to discuss, but that would require
more information about both amps, and, preferably, the
schematics.

Looks like having Sander comment on power amps is like
engaging the proverbial loose cannon.

You think the specs Mike gave are enough to determine
whether these amps will sound the same in a DBT,
regardless the load?

Nope, but I've measured enough QSC amps to know how the
unspecified performance areas are.

Don't make me laugh.

Well Sander, I can't get you to even do simple math....

On Fri, 21 Oct 2005 18:21:35 +0200, Sander deWaal
wrote:

A good amp is a constant voltage source, regardless the load.
That means the load should be of no consequence to the input level.
If there is influence, it's a bad design. Simple as that.

You are without a clue. Simple as that.

No amp can do that, unless the high-voltage rails to the output stage
are regulated. Essentially none do that, because it would be STUPID
to do so. It would reduce the peak output voltage/power for no
purpose AT ALL other than to satisfy idiots who think that amplifiers
should be a "constant voltage source regardless of load".

"dizzy" wrote in message


On Fri, 21 Oct 2005 18:21:35 +0200, Sander deWaal
wrote:

A good amp is a constant voltage source, regardless the
load.
That means the load should be of no consequence to the
input level. If there is influence, it's a bad design.
Simple as that.

You are without a clue. Simple as that.

Let's put it this way - Sander is a vacuum tube uber alles
proponent and a friend of Ge0rge Middius.

No amp can do that, unless the high-voltage rails to the
output stage are regulated.

Even that extreme design feature would not ensure that the
amp was a constant voltage source on the bench, because as
the output current goes up, the voltage drop across various
components in series with the load go up.

Essentially none do that,
because it would be STUPID to do so.

The regulator would cause some loss of power all by itself.

It would reduce the
peak output voltage/power for no purpose AT ALL other
than to satisfy idiots who think that amplifiers should
be a "constant voltage source regardless of load".

Agreed.

dizzy said:


A good amp is a constant voltage source, regardless the load.
That means the load should be of no consequence to the input level.
If there is influence, it's a bad design. Simple as that.

You are without a clue. Simple as that.


Really?
I'm sure I'll stay up worrying this night, son.


No amp can do that, unless the high-voltage rails to the output stage
are regulated. Essentially none do that, because it would be STUPID
to do so. It would reduce the peak output voltage/power for no
purpose AT ALL other than to satisfy idiots who think that amplifiers
should be a "constant voltage source regardless of load".


So you're using current sources to drive your speakers?
Interesting.

Be sure to brief everyone at the next AES meeting and be ready to
receive a design award.

BTW think of the consequences: pentode amps withouf GNFB could be used
without worrying about silly old dogmas like damping factor.
One of the major concerns with tube amps wiped away, just like that!
500 watt amplifiers fed by 9 V batteries in series, driving Apogee
Duettas.
Oh, the opportunities!

It's a pity you chose to post here anonymously, I bet your real name
is Michaelson or De Paravicini or something :-)

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

"Sander deWaal" wrote in message
...
" said:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db


One of the things that I noticed immediately is the ability of the
Krell to deliver twice the power (meaning current) in half the load,
up to 2 ohms.
I suspect that even in 1 ohm the figure would be close to the required
2800W, be it for a brief period of time.
The QSC has only marginally more power into 2 ohms (not that those
insanely high wattages have any meaningful use, you will note).
Also, the current doesn't double with half the load.
This means the Krell has a stiffer power supply, despite the lower
average wattage. It is a true constant voltage source.

You've jumped to a conclusion that's not borne out by the figures. The
power output into a variety of load impedances is simply part of the spec.
It does not mean that the power output of the Krell will double just by
changing the load from 8 to 4 ohms. In other words, it has nothing to do
with the "stiffness" of the power supply.

What it DOES mean, on the other hand, is that the Krell is a 1400W amplifier
designed for optimum performance into a load of 2 ohms or less. Since the
output is voltage limited, it's an inefficient amplifier choice for an 8 ohm
speaker.

Norm Strong

wrote:
"Sander deWaal" wrote in message
...
" said:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db


One of the things that I noticed immediately is the ability of the
Krell to deliver twice the power (meaning current) in half the load,
up to 2 ohms.
I suspect that even in 1 ohm the figure would be close to the required
2800W, be it for a brief period of time.
The QSC has only marginally more power into 2 ohms (not that those
insanely high wattages have any meaningful use, you will note).
Also, the current doesn't double with half the load.
This means the Krell has a stiffer power supply, despite the lower
average wattage. It is a true constant voltage source.

You've jumped to a conclusion that's not borne out by the figures. The
power output into a variety of load impedances is simply part of the spec.
It does not mean that the power output of the Krell will double just by
changing the load from 8 to 4 ohms.



BS. Power output is either current limited or voltage limited.
Obviously into an 8 ohm load the amp is voltage limited. The QSC is
also voltage limited into 8 ohms but becomes current limited into 4
ohms.
IF the QSC is driven to max output into 8 ohms with 1.9 V rms input it
will suddenly find itself current clipping if that load is increased to
4 ohms. The max input is now only 1.7 V rms. Since the gain is the
same the useful dynamic range of the amp is reduced.

In other words, it has nothing to do
with the "stiffness" of the power supply.

I guess we differ on the meaning of "stiffness". In my opinion...
the power (current and voltage) capability of an amp is very dependent
on its power supply.


What it DOES mean, on the other hand, is that the Krell is a 1400W amplifier
designed for optimum performance into a load of 2 ohms or less. Since the
output is voltage limited, it's an inefficient amplifier choice for an 8 ohm
speaker.

Excess current capacity may bother you, I like it. It makes the amp
more versatile and acceptable for use with virtually any speaker. The
QSC suffers degraded dynamic range with load and the specs also show it
suffer increased THD into 4 ohm loads as well.

ScottW

"ScottW" wrote in message
oups.com...

wrote:
"Sander deWaal" wrote in message
...
" said:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db


One of the things that I noticed immediately is the ability of the
Krell to deliver twice the power (meaning current) in half the load,
up to 2 ohms.
I suspect that even in 1 ohm the figure would be close to the required
2800W, be it for a brief period of time.
The QSC has only marginally more power into 2 ohms (not that those
insanely high wattages have any meaningful use, you will note).
Also, the current doesn't double with half the load.
This means the Krell has a stiffer power supply, despite the lower
average wattage. It is a true constant voltage source.

You've jumped to a conclusion that's not borne out by the figures. The
power output into a variety of load impedances is simply part of the
spec.
It does not mean that the power output of the Krell will double just by
changing the load from 8 to 4 ohms.



BS. Power output is either current limited or voltage limited.
Obviously into an 8 ohm load the amp is voltage limited. The QSC is
also voltage limited into 8 ohms but becomes current limited into 4
ohms.
IF the QSC is driven to max output into 8 ohms with 1.9 V rms input it
will suddenly find itself current clipping if that load is increased to
4 ohms. The max input is now only 1.7 V rms. Since the gain is the
same the useful dynamic range of the amp is reduced.

In other words, it has nothing to do
with the "stiffness" of the power supply.

I guess we differ on the meaning of "stiffness". In my opinion...
the power (current and voltage) capability of an amp is very dependent
on its power supply.


What it DOES mean, on the other hand, is that the Krell is a 1400W
amplifier
designed for optimum performance into a load of 2 ohms or less. Since
the
output is voltage limited, it's an inefficient amplifier choice for an 8
ohm
speaker.

Excess current capacity may bother you, I like it. It makes the amp
more versatile and acceptable for use with virtually any speaker. The
QSC suffers degraded dynamic range with load and the specs also show it
suffer increased THD into 4 ohm loads as well.

ScottW

Here's the whole list.


8 ohms 20 Hz-20 kHz 0.03% THD 200W 300W 425W 550W 700W
4 ohms 20 Hz-20 kHz 0.05% THD 325W 500W 700W 900W 1100W
2 ohms 1 kHz 1% THD 600W 800W 1200W 1500W 1700W
BRIDGE MONO MODE
16 ohms 20 Hz-20 kHz 0.1% THD 400W 600W 850W 1100W 1400W
8 ohms 20 Hz-20 kHz 0.1% THD 700W 1100W 1500W 2000W 2200W
4 ohms 1 kHz 1% THD 1200W 1600W 2400W 3000W 3400W
Signal to Noise (20 Hz-20 kHz) -106 dB -107 dB -108 dB -107 dB
-107 dB
Input Sensitivity @ 8 ohms 1.0Vrms 1.2Vrms 1.5Vrms 1.7Vrms 1.9Vrms
Input Sensitivity @ 4 ohms 0.9Vrms 1.1Vrms 1.3Vrms 1.5Vrms 1.7Vrms
Voltage Gain 40x (32 dB) 40x (32 dB) 40x (32 dB) 40x (32 dB) 40x
(32 dB)
Output Circuitry AB AB 2-Step Class H 2-Step Class H 2-Step Class H
Power Requirements
(1/8 Power Pink Noise @ 4 Ohm) 6A 10A 8A 10A 12A
ALL MODELS
Distortion (SMPTE-IM) Less than 0.01%
Distortion (Typical)
20 Hz-20 kHz: 10 dB below rated power
1.0 kHz and below: full rated power
Less than 0.01% THD
Less than 0.01% THD
Frequency Response 20 Hz-20 kHz, +/- 0.2 dB / 8 Hz-50 kHz, +0, -3 dB
Damping Factor Greater than 500
Input Impedance 6 k ohms unbalanced, 12 k ohms balanced
Input Clipping 10 Vrms (+22 dB)
Cooling Variable-speed fan, rear-to-front air flow
Connectors, each channel Input: 3-pin XLR & 1/4" TRS balanced
Output: Neutrik Speakon(TM) and touch-proof binding posts
Amplifier Protection Full short circuit, open circuit, thermal,
ultrasonic, and RF protection
Stable into reactive or mismatched loads
Load Protection On/off muting, DC-fault power supply shutdown
Dimensions 19" (48.3 cm) rack mounting, 3.5" (8.9 cm) tall (2 rack
spaces)
13.25" (33.7 cm) deep (from front mounting rails)
Gain 40x (32 dB)
Weight 21 lb (9.5 kg) net, 27 lb (12.3 kg) shipping

"ScottW" wrote in message
oups.com

You've jumped to a conclusion that's not borne out by
the figures. The power output into a variety of load
impedances is simply part of the spec. It does not mean
that the power output of the Krell will double just by
changing the load from 8 to 4 ohms.


BS. Power output is either current limited or voltage
limited.

You're one young naive puppy, Scotty.

When you're talking spec sheet power output, the operative
limit is in the mind of the guy writing the spec sheed.

Obviously into an 8 ohm load the amp is voltage
limited.

If you put them on the bench, you'll no doubt find that they
are spec sheet limited.

*every* power amp I've ever tested in the past 10 years beat
its specs on the test bench.

The QSC is also voltage limited into 8 ohms but
becomes current limited into 4 ohms.

If you're talking about what happens on the test bench then
yes, that could be said. OTOH, if you want to be pedantic,
the power amp is voltage limited in both cases. It's just
that with the lower load impedance, the voltage limit is
lower because the power supply puts out less voltage when
more current is drawn from it. The amp is still clipping
because the output stage is attempting to exceed an internal
voltage limit. IOW, the output transistors are saturating
because their VCE is too low.

This is actually a real-world distinction because power amps
typically have some kind of current limiting. With 4 and 8
ohm loads its exceedingly rare for the current limiting to
come into play. The chances that the QSC's current limiters
are being activated in a standard bench test at rated power
with a 4 ohm resistive load is approximately zero. Its only
slightly more probable that current limiting is being
activated with a 2 ohm load.

IF the QSC is driven to max output into 8 ohms with 1.9 V
rms input it will suddenly find itself current clipping
if that load is increased to 4 ohms.

Exactly. Thus, the input voltage required to drive the amp
to a lower rated output voltage is lower. Get it now?

The max input is now only 1.7 V rms. Since the gain
is the same the
useful dynamic range of the amp is reduced.

Depends on how you talk about dynamic range. The usual
convention is to rate the dynamic range of a power amp based
on power output into the stated load. Since the amp can put
out more undistorted power into the lower load impeance,
most people would say it has more dynamic range.

In other words, it has nothing to do
with the "stiffness" of the power supply.

I guess we differ on the meaning of "stiffness". In my
opinion... the power (current and voltage) capability of
an amp is very dependent on its power supply.

Not always. Since you mentioned current limiting, we've got
to remember that current limiting circuits operate pretty
much independent of the power supply.

What it DOES mean, on the other hand, is that the Krell
is a 1400W amplifier designed for optimum performance
into a load of 2 ohms or less.

More correctly, its designed for acceptable performance into
a load of 2 ohms or less.

Since the output is
voltage limited, it's an inefficient amplifier choice
for an 8 ohm speaker.

Compared to what? All good amps are generally voltage
limited.


Excess current capacity may bother you, I like it. It
makes the amp more versatile and acceptable for use with
virtually any speaker.

The QSC is rated to put out more current into low impedance
loads than the Krell because, because of its higher power
rating - 1700 watts versus 1400 watts. I suspect that on
the bench the same ordering continues.

The QSC suffers degraded dynamic
range with load and the specs also show it suffer
increased THD into 4 ohm loads as well.

Actually there's no evidence to base this conclusion on. Any
comparison of the two spec sheets is a comparison of the
fantasies or marketing guys. You'd have to measure them
yourself to know whats *really* happening.

Arny Krueger wrote:
"ScottW" wrote in message
oups.com

You've jumped to a conclusion that's not borne out by
the figures. The power output into a variety of load
impedances is simply part of the spec. It does not mean
that the power output of the Krell will double just by
changing the load from 8 to 4 ohms.


BS. Power output is either current limited or voltage
limited.

You're one young naive puppy, Scotty.

When you're talking spec sheet power output, the operative
limit is in the mind of the guy writing the spec sheed.

Obviously into an 8 ohm load the amp is voltage
limited.

If you put them on the bench, you'll no doubt find that they
are spec sheet limited.

*every* power amp I've ever tested in the past 10 years beat
its specs on the test bench.

Its called margin.


The QSC is also voltage limited into 8 ohms but
becomes current limited into 4 ohms.

If you're talking about what happens on the test bench then
yes, that could be said. OTOH, if you want to be pedantic,
the power amp is voltage limited in both cases. It's just
that with the lower load impedance, the voltage limit is
lower because the power supply puts out less voltage when
more current is drawn from it.

BS... this doesn't happen until you have exceeded its current
capacity.

The amp is still clipping
because the output stage is attempting to exceed an internal
voltage limit. IOW, the output transistors are saturating
because their VCE is too low.

This is actually a real-world distinction because power amps
typically have some kind of current limiting. With 4 and 8
ohm loads its exceedingly rare for the current limiting to
come into play. The chances that the QSC's current limiters
are being activated in a standard bench test at rated power
with a 4 ohm resistive load is approximately zero.

Then you have no valid explanation for the reduced sensitivity or
less than double 8 ohm load power output.

You just keep spinning yourself into a hole.

Its only
slightly more probable that current limiting is being
activated with a 2 ohm load.

IF the QSC is driven to max output into 8 ohms with 1.9 V
rms input it will suddenly find itself current clipping
if that load is increased to 4 ohms.

Exactly. Thus, the input voltage required to drive the amp
to a lower rated output voltage is lower. Get it now?

Yeah.. I got it. and effective dynamic range is also reduced as the
noise floor is probably relatively fixed.


The max input is now only 1.7 V rms. Since the gain
is the same the
useful dynamic range of the amp is reduced.

Depends on how you talk about dynamic range. The usual
convention is to rate the dynamic range of a power amp based
on power output into the stated load. Since the amp can put
out more undistorted power into the lower load impeance,
most people would say it has more dynamic range.

You measuring noise floor in power? I don't think so.


In other words, it has nothing to do
with the "stiffness" of the power supply.

I guess we differ on the meaning of "stiffness". In my
opinion... the power (current and voltage) capability of
an amp is very dependent on its power supply.

Not always. Since you mentioned current limiting, we've got
to remember that current limiting circuits operate pretty
much independent of the power supply.

So much for the drooping bandwagon you jumped on.


What it DOES mean, on the other hand, is that the Krell
is a 1400W amplifier designed for optimum performance
into a load of 2 ohms or less.

More correctly, its designed for acceptable performance into
a load of 2 ohms or less.

Since the output is
voltage limited, it's an inefficient amplifier choice
for an 8 ohm speaker.

Compared to what? All good amps are generally voltage
limited.

Lost track of who you're responding to again I see.



Excess current capacity may bother you, I like it. It
makes the amp more versatile and acceptable for use with
virtually any speaker.

The QSC is rated to put out more current into low impedance
loads than the Krell because, because of its higher power
rating - 1700 watts versus 1400 watts. I suspect that on
the bench the same ordering continues.

The QSC suffers degraded dynamic
range with load and the specs also show it suffer
increased THD into 4 ohm loads as well.

Actually there's no evidence to base this conclusion on. Any
comparison of the two spec sheets is a comparison of the
fantasies or marketing guys. You'd have to measure them
yourself to know whats *really* happening.

and you'd have a sample of 1. I'm sure QSC isn't report increased THD
into 4 ohm loads because they think it sounds cool.

ScottW