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[email protected] dscottp1@yahoo.com is offline
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Default Bose 901 EQ distortion

Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.

My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krawl, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help
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Mark D. Zacharias[_2_] Mark D. Zacharias[_2_] is offline
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Posts: 89
Default Bose 901 EQ distortion


wrote in message
...
Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.

My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krawl, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Many recent vintage CD's are mastered LOUD and compressed. May be a maxxed
out, clipped signal being fed to the EQ, or the EQ may be running out of
headroom, again because of the nature of the signal itself. One would need
to look at the signal with an oscilloscope at the input of the EQ, at
various points inside (at the output pins of the various op-amps inside for
example) and at the output of the EQ itself.

If the signal is reaching the box that way, you may need a different source
unit since the clipping may be occurring there or for that matter might be
coming out of your CD player that way.


Mark Z.


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Serge Auckland Serge Auckland is offline
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Default Bose 901 EQ distortion

"Mark D. Zacharias" wrote in message
. net...

wrote in message
...
Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.

My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krawl, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Many recent vintage CD's are mastered LOUD and compressed. May be a maxxed
out, clipped signal being fed to the EQ, or the EQ may be running out of
headroom, again because of the nature of the signal itself. One would need
to look at the signal with an oscilloscope at the input of the EQ, at
various points inside (at the output pins of the various op-amps inside
for example) and at the output of the EQ itself.

If the signal is reaching the box that way, you may need a different
source unit since the clipping may be occurring there or for that matter
might be coming out of your CD player that way.


Mark Z.

Indeed. I have known some early CD players that would clip by 0dBFS. This
wasn't that much of an issue in the early days of CD when mastering actually
left some headroom, but with recent CDs which hit 0dBFS pretty frequently,
this could be what you're hearing. I have checked one or two of my Diana
Krall CDs and they *are* taken to 0dBFS frequently.

Recent CD players shouldn't do this, but then again, they might.

S.
--
http://audiopages.googlepages.com



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Bob Woodward Bob Woodward is offline
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Default Bose 901 EQ distortion

wrote:
Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's.


Bose ?
no flaming ?
No comment !

Robert


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[email protected] dscottp1@yahoo.com is offline
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Default Bose 901 EQ distortion

On Dec 5, 2:22 pm, Chris Morriss wrote:
In message
,
writes

Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.


My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krall, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Perhaps the high output signal is overloading the input on the
equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors
in an 'L' network for each channel)? This may drop the signal enough.
What is the input spec for the equaliser? Modern highly-compressed CDs
may be putting out 2V rms or so and that may be the problem.
--
Chris Morriss


Thanks for the help folks. Yes the problem seems to be on both
channels and I have tryed it on two different systems. I was
thinking to try attenuation as well. I have tried different CD
players and even drove the eq's input off of a portable cd deck
headphone jack with varied volume output and could detect the
distortion at very low levels. Does the RMS voltage value remain
constant on a headphone channel?

I don't know the input spec on the bose Eq but would apprecieate it
anyone has that information or a link to a service manual.

I can't belive that I am the only person haveing these issues or that
I have aquired two systems with the same problem.
A call to Bose says they will check out the EQ for 60 dollars. I
assume new systems they are selling have upgraded EQs. What are they
doing or changing?

Love the "hat" comment. I deserve it.
Thanks again,
Any other comments?
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Arny Krueger Arny Krueger is offline
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Default Bose 901 EQ distortion

wrote in message

On Dec 5, 2:22 pm, Chris Morriss
wrote:
In message
,
writes

Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and
one pair of series VI, both with the matching Bose EQ.


My problem is that some CD,s and even some passages on
soother CD's cause distortion when using the EQ. This
can be at any volume level. I have only had this
problem with recent CDs. (Diana Krall, Chris Botti) All
my older CD's and the radio plays fine and loud. I
have tried different recievers, CD decks and even
replaced all the caps in one of the EQs. Anyone else
having issues or know where I can find a service manual
for these EQ's?
Really appreciate the help


Perhaps the high output signal is overloading the input
on the equaliser. Can you make up a simple 6dB pad (a
couple of 10k resistors in an 'L' network for each
channel)? This may drop the signal enough. What is the
input spec for the equaliser? Modern highly-compressed
CDs may be putting out 2V rms or so and that may be the
problem. --
Chris Morriss


Thanks for the help folks. Yes the problem seems to be
on both channels and I have tryed it on two different
systems. I was thinking to try attenuation as well. I
have tried different CD players and even drove the eq's
input off of a portable cd deck headphone jack with
varied volume output and could detect the distortion at
very low levels.


Distortion at low levels could be due to corroded contacts.

Does the RMS voltage value remain
constant on a headphone channel?


No. The sound level in your earphones changes, right?

I don't know the input spec on the bose Eq but would
apprecieate it anyone has that information or a link to a
service manual.


It is probable that your equipment isn't meeting spec. IOW, it has failed to
operate properly.

I can't belive that I am the only person haveing these
issues or that I have aquired two systems with the same
problem.


Both samples could be failing the same if it is due to something like
electrolytic caps failing, or problems with a common power supply...



A call to Bose says they will check out the EQ for 60
dollars.


Typical.

I assume new systems they are selling have
upgraded EQs. What are they doing or changing?



The eqs are designed to match the speakers, and newer models of the speakers
no doubt need different eq. There will also be some changes due parts from
the old eqs no longer being available.



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GregS[_3_] GregS[_3_] is offline
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Posts: 664
Default Bose 901 EQ distortion

In article , wrote:
On Dec 5, 2:22 pm, Chris Morriss wrote:
In message
,
writes

Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.


My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krall, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Perhaps the high output signal is overloading the input on the
equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors
in an 'L' network for each channel)? This may drop the signal enough.
What is the input spec for the equaliser? Modern highly-compressed CDs
may be putting out 2V rms or so and that may be the problem.
--
Chris Morriss


Thanks for the help folks. Yes the problem seems to be on both
channels and I have tryed it on two different systems. I was
thinking to try attenuation as well. I have tried different CD
players and even drove the eq's input off of a portable cd deck
headphone jack with varied volume output and could detect the
distortion at very low levels. Does the RMS voltage value remain
constant on a headphone channel?

I don't know the input spec on the bose Eq but would apprecieate it
anyone has that information or a link to a service manual.

I can't belive that I am the only person haveing these issues or that
I have aquired two systems with the same problem.
A call to Bose says they will check out the EQ for 60 dollars. I
assume new systems they are selling have upgraded EQs. What are they
doing or changing?

Love the "hat" comment. I deserve it.
Thanks again,
Any other comments?


I would check the supply on the opamp pins. You need a diagram of the specific
chip. The should be at least 15 volts minimum between plus and minus up
to about 30 volts which is normally used. If you have a scope look for ripple.

I have seen a couple of models of the equalizer. Some seem outlandish
in their opperation. One, I could not reduce the treble enough.
The orginal model came out and the second model, a fully transistorized
unit had a little more selection than the first. After that they were chip opamps,
typically using TLO74's or TLO72's, can't remember. The first models escentially
mimicked the orginal, with even more boost selection, some uncontrolable.
After that, it seemed they were less concerned with the boost, but added
a type of midrange control. If you suck out the low mids, it would appear
to do the same thing as boost the treble and bass. Bose always says
they make improvements, like over a hundred improvements, more
like 100 cost saving features.

greg



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[email protected] dscottp1@yahoo.com is offline
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Default Bose 901 EQ distortion

On Dec 6, 12:24 pm, (GregS) wrote:
In article , wrote:





On Dec 5, 2:22 pm, Chris Morriss wrote:
In message
,
writes


Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.


My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krall, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Perhaps the high output signal is overloading the input on the
equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors
in an 'L' network for each channel)? This may drop the signal enough.
What is the input spec for the equaliser? Modern highly-compressed CDs
may be putting out 2V rms or so and that may be the problem.
--
Chris Morriss


Thanks for the help folks. Yes the problem seems to be on both
channels and I have tryed it on two different systems. I was
thinking to try attenuation as well. I have tried different CD
players and even drove the eq's input off of a portable cd deck
headphone jack with varied volume output and could detect the
distortion at very low levels. Does the RMS voltage value remain
constant on a headphone channel?


I don't know the input spec on the bose Eq but would apprecieate it
anyone has that information or a link to a service manual.


I can't belive that I am the only person haveing these issues or that
I have aquired two systems with the same problem.
A call to Bose says they will check out the EQ for 60 dollars. I
assume new systems they are selling have upgraded EQs. What are they
doing or changing?


Love the "hat" comment. I deserve it.
Thanks again,
Any other comments?


I would check the supply on the opamp pins. You need a diagram of the specific
chip. The should be at least 15 volts minimum between plus and minus up
to about 30 volts which is normally used. If you have a scope look for ripple.


If I recall the series 3 EQ I replaced the caps in it had opamps,
don't remember which chip. I will check the voltage available on the
plus pins


I have seen a couple of models of the equalizer. Some seem outlandish
in their opperation. One, I could not reduce the treble enough.
The orginal model came out and the second model, a fully transistorized
unit had a little more selection than the first. After that they were chip opamps,
typically using TLO74's or TLO72's, can't remember. The first models escentially
mimicked the orginal, with even more boost selection, some uncontrolable.
After that, it seemed they were less concerned with the boost, but added
a type of midrange control. If you suck out the low mids, it would appear
to do the same thing as boost the treble and bass. Bose always says
they make improvements, like over a hundred improvements, more
like 100 cost saving features.

greg- Hide quoted text -

- Show quoted text -


Still looking. Anyone else have this experience? Bose is playing
ignorant "never heard of anything like that before". Two totally
different systems with the same problem.
Thanks for the help.

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GregS[_3_] GregS[_3_] is offline
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Default Bose 901 EQ distortion

In article , wrote:
On Dec 6, 12:24 pm, (GregS) wrote:
In article

,
wrote:





On Dec 5, 2:22 pm, Chris Morriss wrote:
In message
,
writes


Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.


My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krall, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Perhaps the high output signal is overloading the input on the
equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors
in an 'L' network for each channel)? This may drop the signal enough.
What is the input spec for the equaliser? Modern highly-compressed CDs
may be putting out 2V rms or so and that may be the problem.
--
Chris Morriss


Thanks for the help folks. Yes the problem seems to be on both
channels and I have tryed it on two different systems. I was
thinking to try attenuation as well. I have tried different CD
players and even drove the eq's input off of a portable cd deck
headphone jack with varied volume output and could detect the
distortion at very low levels. Does the RMS voltage value remain
constant on a headphone channel?


I don't know the input spec on the bose Eq but would apprecieate it
anyone has that information or a link to a service manual.


I can't belive that I am the only person haveing these issues or that
I have aquired two systems with the same problem.
A call to Bose says they will check out the EQ for 60 dollars. I
assume new systems they are selling have upgraded EQs. What are they
doing or changing?


Love the "hat" comment. I deserve it.
Thanks again,
Any other comments?


I would check the supply on the opamp pins. You need a diagram of the

specific
chip. The should be at least 15 volts minimum between plus and minus up
to about 30 volts which is normally used. If you have a scope look for

ripple.

If I recall the series 3 EQ I replaced the caps in it had opamps,
don't remember which chip. I will check the voltage available on the
plus pins


I have seen a couple of models of the equalizer. Some seem outlandish
in their opperation. One, I could not reduce the treble enough.
The orginal model came out and the second model, a fully transistorized
unit had a little more selection than the first. After that they were chip

opamps,
typically using TLO74's or TLO72's, can't remember. The first models

escentially
mimicked the orginal, with even more boost selection, some uncontrolable.
After that, it seemed they were less concerned with the boost, but added
a type of midrange control. If you suck out the low mids, it would appear
to do the same thing as boost the treble and bass. Bose always says
they make improvements, like over a hundred improvements, more
like 100 cost saving features.

greg- Hide quoted text -

- Show quoted text -


Still looking. Anyone else have this experience? Bose is playing
ignorant "never heard of anything like that before". Two totally
different systems with the same problem.
Thanks for the help.


Input could be as high as 2 volts RMS. or 5.6 volts pp.
With 12 dB treble boost output jumps up to 19.6 vpp.
or 22.4 vpp for 18 dB bass boost.

Try bypassing the EQ, and or try putting something with a variable gain
in front of the EQ.

greg
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Arny Krueger Arny Krueger is offline
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Default Bose 901 EQ distortion

wrote in message


Still looking. Anyone else have this experience? Bose
is playing ignorant "never heard of anything like that
before".


Maybe the person you're talking to is a new hire.

Two totally different systems with the same
problem.


Here's a radical solution - get two channels of parametric equalizer and
dial in the frequency response of your dreams.


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[email protected] dscottp1@yahoo.com is offline
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Default Bose 901 EQ distortion

On Dec 6, 7:54 pm, "Arny Krueger" wrote:
wrote in message



Still looking. Anyone else have this experience? Bose
is playing ignorant "never heard of anything like that
before".


Maybe the person you're talking to is a new hire.

Two totally different systems with the same
problem.


Here's a radical solution - get two channels of parametric equalizer and
dial in the frequency response of your dreams.


Called Bose agan. Got a different guy who said to send the eq back
and they will have a look gratis. (Still says they have never heard of
anything like this. The price is right so it's going back.
Thanks to all

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Peter Larsen[_2_] Peter Larsen[_2_] is offline
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Default Bose 901 EQ distortion

Arny Krueger wrote:

Here's a radical solution - get two channels of parametric equalizer
and dial in the frequency response of your dreams.


Wasn't it the DEQ 2496 that was mentioned in a similar context in a nearby
newsgroup?


Kind regards

Peter Larsen





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Arny Krueger Arny Krueger is offline
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Default Bose 901 EQ distortion

"Peter Larsen" wrote in message

Arny Krueger wrote:

Here's a radical solution - get two channels of
parametric equalizer and dial in the frequency response
of your dreams.


Wasn't it the DEQ 2496 that was mentioned in a similar
context in a nearby newsgroup?


Could be. I've never had one to play with, but lots of people seem to like
'em.

A digital parametric like the DEQ is a better choice for eq newbies if it
has a real-time frequency response display. Helps people match up what they
are doing with what they are hearing.


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Richard Crowley Richard Crowley is offline
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Default Bose 901 EQ distortion

"Arny Krueger" wrote ...
"Peter Larsen" wrote
Arny Krueger wrote:

Here's a radical solution - get two channels of
parametric equalizer and dial in the frequency response
of your dreams.


Wasn't it the DEQ 2496 that was mentioned in a similar
context in a nearby newsgroup?


Could be. I've never had one to play with, but lots of people seem to like
'em.

A digital parametric like the DEQ is a better choice for eq newbies if it
has a real-time frequency response display. Helps people match up what
they are doing with what they are hearing.


Is the curve of the Bose EQ box published anywhere?


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GregS[_3_] GregS[_3_] is offline
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Default Bose 901 EQ distortion

In article , "Richard Crowley" wrote:
"Arny Krueger" wrote ...
"Peter Larsen" wrote
Arny Krueger wrote:

Here's a radical solution - get two channels of
parametric equalizer and dial in the frequency response
of your dreams.

Wasn't it the DEQ 2496 that was mentioned in a similar
context in a nearby newsgroup?


Could be. I've never had one to play with, but lots of people seem to like
'em.

A digital parametric like the DEQ is a better choice for eq newbies if it
has a real-time frequency response display. Helps people match up what
they are doing with what they are hearing.


Is the curve of the Bose EQ box published anywhere?


I think I saw it on the patent.

Anyway, its flat from 100 to about 2 kHz. There is up to an 18 dB peak at 30 Hz,
and a 12 dB peak at 12 kHz. Essentially, most everything is lost above 12 kHz.

greg
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Richard Crowley Richard Crowley is offline
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Default Bose 901 EQ distortion

"GregS" wrote...
"Richard Crowley" wrote:
Is the curve of the Bose EQ box published anywhere?


I think I saw it on the patent.

Anyway, its flat from 100 to about 2 kHz. There is up to an 18 dB peak
at 30 Hz,
and a 12 dB peak at 12 kHz. Essentially, most everything is lost above
12 kHz.


That would make a bullhorn or a telephone sound good! :-)

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Peter Larsen[_2_] Peter Larsen[_2_] is offline
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Default Bose 901 EQ distortion

Richard Crowley wrote:

Is the curve of the Bose EQ box published anywhere?


It looks like the image of a gletcher valley cross-section ...

Someone over in a.a.p.l-s linked to an image of an analysis of it, i have it
somewhere on some harddisk, mostly I think it was about the 802's ... but in
case of the deq one just needs a measuring microphone and to aim for the b&k
living room reference curve, the simplified version is flat up to 200 Hz and
then drops smoothly to -6 dB at 20 kHz, aiming for perfection at the
extremes is folly.

The OP should remember that while there are many frequency analysis displays
that can be used with a pc most of them display white noise as a horisontal
line and pink noise as a line that slopes with -3 dB pr. octave. It may be
unwise to measure loudspeakers with white noise .... I haven't got a DEQ,
but I think it has measurement analysis built in, other folks know a lot
more about it.

The extra AD-DA conversion may be unattracive .... but it may also be
avoidable, depending on actual context.


Kind regards

Peter Larsen




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Default Bose 901 EQ distortion

Richard Crowley wrote:

"GregS" wrote...


"Richard Crowley" wrote:


Is the curve of the Bose EQ box published anywhere?


I think I saw it on the patent.


Anyway, its flat from 100 to about 2 kHz. There is up to an 18 dB
peak at 30 Hz,
and a 12 dB peak at 12 kHz. Essentially, most everything is lost
above 12 kHz.


Studio sound mentioned 22 dB of eq, which lead to it being impossible for
Hugh Ford to measure on the eq version they tested because 1 volt input at
20 kHz caused clipping. I can't get into detail, the paper the print was on
has been recycled long time ago.

That would make a bullhorn or a telephone sound good! :-)


We have to take this in stages, first we teach him what a good EQ is, next
he begins to wonder - like everybody else - about the wisdom of using
midrange units for full range audio. It is no good to just flame the
boseaholics, they need to be taught. It is of course cheaper to just replace
the loudspeakers without getting another eq or getting the broken one fixed,
except that Bose reportedly will take a look on the actual eq box and fix it
if broken.

In the real life, outside the world of the brochures, many loudspeaker-room
combinations will benefit from eq, but as a general guideline something is
broken or ill applied if more than 6 dB boost is relevant, narrow 8 db cuts
may be very relevant in the low range in rooms that have no low range
acoustics regulation, ie. bass traps.


Kind regards

Peter Larsen


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Chris Kidd[_2_] Chris Kidd[_2_] is offline
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Default Bose 901 EQ distortion

I have 33 Bose 102 ceiling speakers installed as under-balcony delay in the
theater where I work. It had a 102 system processor and analog eq/delay
units when originally installed. When the processing was replaced with a BSS
minidrive, the guy who eventually RTA'ed the room said he took a sample of
the 102's EQ pattern by sending a pink noise signal through it and analyzed
the output signal to see what kind of curve the processor provided and used
this as the basis for the minidrives programming "flatline" and then
correcting for room response with the rta. Could you take a new "DSP box"
and analyzer and make your own "901 EQ"?

Chris


"Peter Larsen" wrote in message
...
Richard Crowley wrote:

Is the curve of the Bose EQ box published anywhere?


It looks like the image of a gletcher valley cross-section ...

Someone over in a.a.p.l-s linked to an image of an analysis of it, i have
it somewhere on some harddisk, mostly I think it was about the 802's ...
but in case of the deq one just needs a measuring microphone and to aim
for the b&k living room reference curve, the simplified version is flat up
to 200 Hz and then drops smoothly to -6 dB at 20 kHz, aiming for
perfection at the extremes is folly.

The OP should remember that while there are many frequency analysis
displays that can be used with a pc most of them display white noise as a
horisontal line and pink noise as a line that slopes with -3 dB pr.
octave. It may be unwise to measure loudspeakers with white noise .... I
haven't got a DEQ, but I think it has measurement analysis built in, other
folks know a lot more about it.

The extra AD-DA conversion may be unattracive .... but it may also be
avoidable, depending on actual context.


Kind regards

Peter Larsen



  #23   Report Post  
Posted to rec.audio.tech
Richard Crowley Richard Crowley is offline
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Default Bose 901 EQ distortion

"Chris Kidd" wrote in ...
I have 33 Bose 102 ceiling speakers installed as under-balcony delay in
the theater where I work. It had a 102 system processor and analog
eq/delay units when originally installed. When the processing was
replaced with a BSS minidrive, the guy who eventually RTA'ed the room
said he took a sample of the 102's EQ pattern by sending a pink noise
signal through it and analyzed the output signal to see what kind of
curve the processor provided and used this as the basis for the
minidrives programming "flatline" and then correcting for room response
with the rta. Could you take a new "DSP box" and analyzer and make your
own "901 EQ"?


Dunno why not. A speaker is a speaker, whether it says Bose on
it or not. The bottom line is what it sounds like in the audience
area, so RTA'ing the room may be a good solution to dealing with
whatever wierdness of Bose drivers.

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Steven Sullivan Steven Sullivan is offline
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Posts: 1,268
Default Bose 901 EQ distortion

wrote:
On Dec 5, 2:22 pm, Chris Morriss wrote:
In message
,
writes

Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.


My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krall, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Perhaps the high output signal is overloading the input on the
equaliser. Can you make up a simple 6dB pad (a couple of 10k resistors
in an 'L' network for each channel)? This may drop the signal enough.
What is the input spec for the equaliser? Modern highly-compressed CDs
may be putting out 2V rms or so and that may be the problem.
--
Chris Morriss


Thanks for the help folks. Yes the problem seems to be on both
channels and I have tryed it on two different systems. I was
thinking to try attenuation as well. I have tried different CD
players and even drove the eq's input off of a portable cd deck
headphone jack with varied volume output and could detect the
distortion at very low levels. Does the RMS voltage value remain
constant on a headphone channel?


Something's odd here.

Are Diana Krall's CDs noted for being mastered at high levels?

The loudness wars have been raging since before hte mid-90's,
so I'm surprised these are the only two CDs that show this
effect with your Bose EQs.



___
-S
"As human beings, we understand the world through simile, analogy,
metaphor, narrative and, sometimes, claymation." - B. Mason


  #26   Report Post  
mariarayan mariarayan is offline
Junior Member
 
Posts: 8
Default

Quote:
Originally Posted by Serge Auckland View Post
"Mark D. Zacharias" wrote in message
. net...

wrote in message
...
Hello all,
First, I like my 901s regardless so no flaming please.
I need help with this condition:
I have two sets of 901's. One pair of series IV and one pair of
series VI, both with the matching Bose EQ.

My problem is that some CD,s and even some passages on soother CD's
cause distortion when using the EQ. This can be at any volume level.
I have only had this problem with recent CDs. (Diana Krawl, Chris
Botti) All my older CD's and the radio plays fine and loud. I have
tried different recievers, CD decks and even replaced all the caps in
one of the EQs. Anyone else having issues or know where I can find a
service manual for these EQ's?
Really appreciate the help


Many recent vintage CD's are mastered LOUD and compressed. May be a maxxed
out, clipped signal being fed to the EQ, or the EQ may be running out of
headroom, again because of the nature of the signal itself. One would need
to look at the signal with an oscilloscope at the input of the EQ, at
various points inside (at the output pins of the various op-amps inside
for example) and at the output of the EQ itself.

If the signal is reaching the box that way, you may need a different
source unit since the clipping may be occurring there or for that matter
might be coming out of your CD player that way.


Mark Z.

Indeed. I have known some early CD players that would clip by 0dBFS. This
wasn't that much of an issue in the early days of CD when mastering actually
left some headroom, but with recent CDs which hit 0dBFS pretty frequently,
this could be what you're hearing. I have checked one or two of my Diana
Krall CDs and they *are* taken to 0dBFS frequently.

Recent CD players shouldn't do this, but then again, they might.

S.
--
http://audiopages.googlepages.com

I got bad issues because of that, yeah you are right i think new CD players shouldn't do this
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