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[email protected] howie.stone@btinternet.com is offline
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Default Amplifier for passive subwoofers

I use Gradient subwoofers with Quad ESL 63 electrostatic speakers.=20

Can anyone recommend an amp which is particularly good for this job? One th=
at is safe to use (ie with DC protection built in.)=20

And in theory available in the UK for a second hand price around =C2=A3500

http://www.regonaudio.com/Gradient%2...Subwoofer.html
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Peter Wieck[_2_] Peter Wieck[_2_] is offline
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Default Amplifier for passive subwoofers

On Friday, August 10, 2018 at 4:28:14 PM UTC-4, Howard Stone wrote:
I use Gradient subwoofers with Quad ESL 63 electrostatic speakers.

Can anyone recommend an amp which is particularly good for this job? One that is safe to use (ie with DC protection built in.)

And in theory available in the UK for a second hand price around £500

http://www.regonaudio.com/Gradient%2...Subwoofer.html


With respect, that is a hard question to answer other than "about anything will do". So, a few questions first:

a) Efficiency of the sub-woofer?
b) Tube or solid-state?
c) Generally, on the spectrum between Heavy Metal and Full Classical Orchestra, where do you fall?
d) New, used, or vintage?

Keep in mind that amplification is the least complicated part of your (any) system, and about any reasonably well designed device will work fine. Variations on that theme will depend on speaker efficiency, type of music you (mostly) listen to, and whether you want tube or solid-state. Note that tube amps using output transformers have DC protection automagically.


Peter Wieck
Melrose Park, PA

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~misfit~[_3_] ~misfit~[_3_] is offline
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Default Amplifier for passive subwoofers

Once upon a time on usenet Peter Wieck wrote:
On Friday, August 10, 2018 at 4:28:14 PM UTC-4, Howard Stone wrote:
I use Gradient subwoofers with Quad ESL 63 electrostatic speakers.

Can anyone recommend an amp which is particularly good for this job?
One that is safe to use (ie with DC protection built in.)

And in theory available in the UK for a second hand price around 500

http://www.regonaudio.com/Gradient%2...Subwoofer.html


With respect, that is a hard question to answer other than "about
anything will do". So, a few questions first:

a) Efficiency of the sub-woofer?
b) Tube or solid-state?
c) Generally, on the spectrum between Heavy Metal and Full Classical
Orchestra, where do you fall?
d) New, used, or vintage?

Keep in mind that amplification is the least complicated part of your
(any) system, and about any reasonably well designed device will work
fine. Variations on that theme will depend on speaker efficiency,
type of music you (mostly) listen to, and whether you want tube or
solid-state. Note that tube amps using output transformers have DC
protection automagically.


Peter Wieck
Melrose Park, PA


Hi Peter, a quick question if I may? I bought four second-hand ex-shopping
centre rack mount 100w PA amps cheaply a while back, mainly for the J49/K135
output devices. They use output transformers of a similar size to the main
PS transformers. (Turns out I actually like the way the whole amplifier sans
output transformer sounds so am using those in a project.) I tried to find
out a bit about how this sort of system works but had no luck. Can you offer
any help?

I was wondering if there was any way I could re-use or re-purpose the output
transformers. They're a big hunk of silicone steel and copper, seems a waste
to just throw them in landfill.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)


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Peter Wieck[_2_] Peter Wieck[_2_] is offline
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Default Amplifier for passive subwoofers

On Tuesday, August 14, 2018 at 11:15:25 AM UTC-4, ~misfit~ wrote:
Once upon a time on usenet Peter Wieck wrote:


Hi Peter, a quick question if I may? I bought four second-hand ex-shopping
centre rack mount 100w PA amps cheaply a while back, mainly for the J49/K135
output devices. They use output transformers of a similar size to the main
PS transformers. (Turns out I actually like the way the whole amplifier sans
output transformer sounds so am using those in a project.) I tried to find
out a bit about how this sort of system works but had no luck. Can you offer
any help?

I was wondering if there was any way I could re-use or re-purpose the output
transformers. They're a big hunk of silicone steel and copper, seems a waste
to just throw them in landfill.

Cheers,


Sean:

Likely those are more properly a line-matching transformer designed to operate (typically) at a constant voltage (70.7 - 100 VAC), variable current system. The typical (tube) OPT operates at full B+ voltage (350 VAC+ in many systems, as compared to the 70.7 V (or so) in a solid-state PA system. The amp feeds the primary side (4-8 ohms) and the secondary is a constant-voltage (70-100V).

As above, what you have are, again most likely, the step-up transformers used at the amplifier to raise the voltage into the hundreds-of-feet of distribution wiring to the speakers. There is a similar but much smaller transformer at each speaker to drop-and-match the output to the particular speaker (4-8 ohms). Look at it as similar to what happens when AC power is sent up to a transmission line, then dropped for the individual consumer via a series of transformers.

However, as they are typically fully isolated, they will provide the same level of DC protection as a conventional OPT.

https://www.electronics-tutorials.ws...er/trans70.gif

Shows you the sequence-of-events.

Now, as to re-purposing: There is very, very little current on the primary side of the typical output transformer. If you have a Variac and a VOM, you could try bringing the *SECONDARY* side (70-100V side) up to the limits of the Variac (140 VAC or so) and see what you measure on the primary side. That will give you the (approximate) turns-ratio.

Now, of course, you could also put your amps 100 yards from the speakers, and feed them from the amp by putting the appropriate transformer at either end.

https://adn.harmanpro.com/site_eleme...s_original.pdf

Here is a white-paper on how it all works.

Peter Wieck
Melrose Park, PA
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~misfit~[_3_] ~misfit~[_3_] is offline
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Default Amplifier for passive subwoofers

Once upon a time on usenet Peter Wieck wrote:
On Tuesday, August 14, 2018 at 11:15:25 AM UTC-4, ~misfit~ wrote:
Once upon a time on usenet Peter Wieck wrote:


Hi Peter, a quick question if I may? I bought four second-hand
ex-shopping centre rack mount 100w PA amps cheaply a while back,
mainly for the J49/K135 output devices. They use output transformers
of a similar size to the main PS transformers. (Turns out I actually
like the way the whole amplifier sans output transformer sounds so
am using those in a project.) I tried to find out a bit about how
this sort of system works but had no luck. Can you offer any help?

I was wondering if there was any way I could re-use or re-purpose
the output transformers. They're a big hunk of silicone steel and
copper, seems a waste to just throw them in landfill.

Cheers,


Sean:

Likely those are more properly a line-matching transformer designed
to operate (typically) at a constant voltage (70.7 - 100 VAC),
variable current system. The typical (tube) OPT operates at full B+
voltage (350 VAC+ in many systems, as compared to the 70.7 V (or so)
in a solid-state PA system. The amp feeds the primary side (4-8 ohms)
and the secondary is a constant-voltage (70-100V).

As above, what you have are, again most likely, the step-up
transformers used at the amplifier to raise the voltage into the
hundreds-of-feet of distribution wiring to the speakers. There is a
similar but much smaller transformer at each speaker to
drop-and-match the output to the particular speaker (4-8 ohms). Look
at it as similar to what happens when AC power is sent up to a
transmission line, then dropped for the individual consumer via a
series of transformers.

However, as they are typically fully isolated, they will provide the
same level of DC protection as a conventional OPT.

https://www.electronics-tutorials.ws...er/trans70.gif

Shows you the sequence-of-events.

Now, as to re-purposing: There is very, very little current on the
primary side of the typical output transformer. If you have a Variac
and a VOM, you could try bringing the *SECONDARY* side (70-100V side)
up to the limits of the Variac (140 VAC or so) and see what you
measure on the primary side. That will give you the (approximate)
turns-ratio.

Now, of course, you could also put your amps 100 yards from the
speakers, and feed them from the amp by putting the appropriate
transformer at either end.

https://adn.harmanpro.com/site_eleme...s_original.pdf

Here is a white-paper on how it all works.

Peter Wieck
Melrose Park, PA


Thank you kindly for that pdf - it explains everything I was curious about.
Unfortunately I don't have a Variac - I keep looking for one at the right
price but no luck so far. So the 4 x output transformers are useless to me
and will be thrown in the rubbish if I can't find a recycler who'll take
them.

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)




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Howard Stone Howard Stone is offline
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Default Amplifier for passive subwoofers

a) Efficiency of the sub-woofer?
b) Tube or solid-state?
c) Generally, on the spectrum between Heavy Metal and Full Classical Orchestra, where do you fall?
d) New, used, or vintage?

(a) The Subwoofers are rated at 250W at 8 ohms and has a basic sensitivitv of 86dBW at the 16ohm setting. Heres some more technical data

Inside the speaker box is a pair of 260mm pressed-steel-chassis bass units, pulp coned and fitted with low hysteresis half-roll surrounds of foam polyurethane. Placed side by side on the open baffle, one faces forward and the other back, providing some balancing of linearity.
The Gradient employs two low-frequency drivers in each cabinet, arranged as an open-baffle linear array to give dipole operation. 6dB per octave boost needs to be applied throughout the low frequency range to offset the falling open baffle response, and the bass units used need a linear, high excursion capability; ± 12mm is quoted. Before overload is reached, the degree of boost must be limited and this sets the degree of bass extension available. In this sense the SW63 is not a true sub-woofer in that it does not go that final 10Hz down to 20Hz. However, it does extend the power response of the Quad by almost an octave, whilst simultaneously increasing the dynamic range and linearity of the main system.

(b) Solid state

(c) I listen to organ, harpsichord, small vocal ensemble

(d) used or vintage
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Howard Stone Howard Stone is offline
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Default Amplifier for passive subwoofers

What I think I need is a powerful transistor amp with exceptional bass. I was very tempted to buy a Crown DC-300A because it has such a good reputation for bass, it's affordable and available in the UK. However it turns out to have a very bad reputation for doing DC and frying speakers -- so no!
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Peter Wieck[_2_] Peter Wieck[_2_] is offline
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Default Amplifier for passive subwoofers

On Wednesday, August 15, 2018 at 1:04:38 PM UTC-4, Howard Stone wrote:

(a) The Subwoofers are rated at 250W at 8 ohms and has a basic sensitivitv of 86dBW at the 16ohm setting. Heres some more technical data

Inside the speaker box is a pair of 260mm pressed-steel-chassis bass units, pulp coned and fitted with low hysteresis half-roll surrounds of foam polyurethane. Placed side by side on the open baffle, one faces forward and the other back, providing some balancing of linearity.
The Gradient employs two low-frequency drivers in each cabinet, arranged as an open-baffle linear array to give dipole operation. 6dB per octave boost needs to be applied throughout the low frequency range to offset the falling open baffle response, and the bass units used need a linear, high excursion capability; ± 12mm is quoted. Before overload is reached, the degree of boost must be limited and this sets the degree of bass extension available. In this sense the SW63 is not a true sub-woofer in that it does not go that final 10Hz down to 20Hz. However, it does extend the power response of the Quad by almost an octave, whilst simultaneously increasing the dynamic range and linearity of the main system.

(b) Solid state

(c) I listen to organ, harpsichord, small vocal ensemble

(d) used or vintage


Thank you for that level of detail! And your listening spectrum, while exacting is not terribly difficult.

Creek, Cambridge Audio and B&W come immediately to mind as being readily available on the used/vintage scene in GB, have decent reputations and are also reasonably well made.

https://www.ebay.co.uk/itm/B-W-Bower...AOSwX05bbGW O

Or

https://www.ebay.co.uk/itm/Cambridge...AOSwuc1baWW 2

Will have ample power for your application and not even threaten to clip.

https://www.ebay.co.uk/itm/CREEK-EVO...AOSwQrJbYdB E

Maybe.

Peter Wieck
Melrose Park, PA
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Howard Stone Howard Stone is offline
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Default Amplifier for passive subwoofers

On Wednesday, 15 August 2018 21:43:22 UTC+1, Peter Wieck wrote:
On Wednesday, August 15, 2018 at 1:04:38 PM UTC-4, Howard Stone wrote:
=20
(a) The Subwoofers are rated at 250W at 8 ohms and has a basic sensitiv=

itv of 86dBW at the 16ohm setting. Here=E2=80=99s some more technical data
=20
=E2=80=9CInside the speaker box is a pair of 260mm pressed-steel-chassi=

s bass units, pulp coned and fitted with low hysteresis half-roll surrounds=
of foam polyurethane. Placed side by side on the open baffle, one faces fo=
rward and the other back, providing some balancing of linearity.
The Gradient employs two low-frequency drivers in each cabinet, arrange=

d as an open-baffle linear array to give dipole operation. 6dB per octave b=
oost needs to be applied throughout the low frequency range to offset the f=
alling open baffle response, and the bass units used need a linear, high ex=
cursion capability; =C2=B1 12mm is quoted. Before overload is reached, the =
degree of boost must be limited and this sets the degree of bass extension =
available. In this sense the SW63 is not a true sub-woofer in that it does =
not go that final 10Hz down to 20Hz. However, it does extend the power resp=
onse of the Quad by almost an octave, whilst simultaneously increasing the =
dynamic range and linearity of the main system.=E2=80=9D
=20
(b) Solid state
=20
(c) I listen to organ, harpsichord, small vocal ensemble =20
=20
(d) used or vintage

=20
Thank you for that level of detail! And your listening spectrum, while ex=

acting is not terribly difficult.=20
=20
Creek, Cambridge Audio and B&W come immediately to mind as being readily =

available on the used/vintage scene in GB, have decent reputations and are =
also reasonably well made.=20
=20
https://www.ebay.co.uk/itm/B-W-Bower...-VA100-II-Int=

egrated-Amplifier/292674421961?hash=3Ditem4424c144c9:g:VHIAAOSwX05bb GWO =
=20
=20
Or
=20
https://www.ebay.co.uk/itm/Cambridge...o-Integrated-=

Amplifier/192619789579?hash=3Ditem2cd908bd0b:g:xK8AAOSwuc1ba WW2 =20
=20
Will have ample power for your application and not even threaten to clip=

..=20
=20
https://www.ebay.co.uk/itm/CREEK-EVO...CONDITION-WIT=

H-MANUAL/123313128754?hash=3Ditem1cb6090532:g:6DcAAOSwQrJbY dBE =20
=20
Maybe.=20
=20
Peter Wieck
Melrose Park, PA


Thank you
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Peter Wieck[_2_] Peter Wieck[_2_] is offline
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Posts: 137
Default Amplifier for passive subwoofers

On Wednesday, August 15, 2018 at 4:43:13 PM UTC-4, Howard Stone wrote:
What I think I need is a powerful transistor amp with exceptional bass. I=

was very tempted to buy a Crown DC-300A because it has such a good reputat=
ion for bass, it's affordable and available in the UK. However it turns out=
to have a very bad reputation for doing DC and frying speakers -- so no!

Crown: Purchase an industrial blender. Purchase two bottles of decent beer=
.. Drink the beer. Break the bottles. Insert in Blender - run blender. Crown=
Amp. Good move, avoiding same.=20

You don't need a huge amount of power to run subs. But, I agree that to get=
those bombard pipes properly, you will need 100-watt transient capacity, a=
t least. If you had 100-watt rms capacity, you would get anywhere up to 500=
+ watts of transient capacity - and your speakers would handle that just fi=
ne, and a lot more as a transient.=20

Peter Wieck=20
Melrose Park, PA
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