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boosting amplifier output

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Anonymous
November 19, 2004 3:09:42 PM

Archived from groups: rec.audio.tech (More info?)

I have a Bryston 3B powering my DIY transmission-line woofers that I use for
the 50 to 160 watt range, I use the old AcoustatX 100watt ESL for my my
midrange-lower treble.. The woofers became progressively more power hungry
as the dacron stuffing settled down. At present they are no match for the
Acoustats.
I have Behringer digital equaliser tied to my woofers,
Against the warnings of people who know more about electronic than I do I
tried to lift the overall bass range by 4db. with additional adjusments up
to 8db on some frequencies.
On testing with the Stereophile freqoency range test record and Radio Shack
SPL meter and playing music I can hear no distortion ( I use 1000Hz as my
base volume level).
Am I doing something wrong pushing the amp power that hard?
Should I desist and save for a bigger Bryston instead of boosting the 3B?
If my system sounds complicated that is because it is. It just
grew over many years. I put a lot of work in it and replacing it with an
equivalent quality system would be too expensive. (I use 9 speakers and 6
amps in my surround system).

Thanks for your opinions and advice.
Ludovic Mirabel
Anonymous
November 19, 2004 6:34:17 PM

Archived from groups: rec.audio.tech (More info?)

"ludovic mirabel" <elmir2m @pacificcoast.net> wrote in message
news:10psko9g6r11ib9@corp.supernews.com

> I have a Bryston 3B powering my DIY transmission-line woofers that I
> use for the 50 to 160 watt range, I use the old AcoustatX 100watt ESL
> for my my midrange-lower treble..

Without more details, its hard to position the woofers.

Secondly, despite the traditional mystique that may surround them, there's
really very little about TL enclosures to recommend them over more
conventional designs.

> The woofers became progressively
> more power hungry as the dacron stuffing settled down.

The two things may have happened in the same time frame, but I've got my
doubts about any actual technical connection. Rule of thumb is that you
can't really stuff an enclosure too tightly. As you stuff an enclosure, it
gets acoustically a little larger. The audible effects of this should not
show up as efficiency.

> At present
> they are no match for the Acoustats.

In what sense? Power handling capacity? Directivity matching at the
crossover point?

????

> I have Behringer digital equaliser tied to my woofers,

Good way to overcome enclosure and room matching issues.

> Against the warnings of people who know more about electronic than I
> do I tried to lift the overall bass range by 4db. with additional
> adjusments up to 8db on some frequencies.

This can work.

> On testing with the Stereophile freqoency range test record and Radio
> Shack SPL meter and playing music I can hear no distortion ( I use
> 1000Hz as my base volume level).

Doubling and tripling on sine waves is pretty noticable if you test speakers
by playing a tone and ramping the volume up and down. If the character of
the tone does not change, but it only gets louder or softer, then you aren't
exceeding the dynamic range limits of the woofers.

> Am I doing something wrong pushing the amp power that hard?

If the speakers don't audibly double or triple, and the voice coils don't
cook and start rubbing, then there is probably not a lot that is seriously
wrong.

> Should I desist and save for a bigger Bryston instead of boosting
> the 3B?

Why not measure the voltage across the voice coil of the woofer(s) and see
how it fits with the maximum voltage output capacity of the Bryston. Your
big worry is clipping, and clipping is a very non-subtle effect. It
generally is rough and harsh-sounding.
Anonymous
November 21, 2004 12:12:12 AM

Archived from groups: rec.audio.tech (More info?)

In <10psko9g6r11ib9@corp.supernews.com>, on 11/19/04
at 12:09 PM, "ludovic mirabel" <elmir2m @pacificcoast.net> said:

[ ... ]

>On testing with the Stereophile freqoency range test record and Radio
>Shack SPL meter and playing music I can hear no distortion ( I use
>1000Hz as my base volume level).

Make sure you test the system using frequencies of interest. (testing
the woofers at frequencies that are not normally routed to them, won't
accomplish anything.) I like to use swept tones rather than steps
because the steps may not excite problem areas.

> Am I doing something wrong pushing the amp power that hard?
> Should I desist and save for a bigger Bryston instead of boosting
>the 3B?

Unless the clip light comes on, the 3B is happy. I worry more about
damaging the speakers.

[ ... ]

I think the real question to ask is: "how does it sound"? Is there
something that the system is not doing that you wish it would? Do you
want to feel the bass?

If you've never done any reading about acoustics, here are a few cheap
shots that will, hopefully, expand your curiousity.

The room situation has a profound effect at base frequencies. Moving
the speakers or your listening position a few inches this way or that
will change the sound. An easy way to empirically explore the issues is
to play music with a thumpy bass line and move around the room while
listening. Pop or Jazz usually works best for me. The only real
requirement is that the bass is pronounced and active. Be sure to move
toward the walls, especially the corners. You may want to carry some
markers with you as you move around the room. When you find a spot
where the bass seems much louder or quieter than average, mark that
spot with a "+" or "-". Try moving your listening position or the
woofers to one of the "+" spots. Do some spots warrant a "++"?

You can repeat the above with your test disc. This will be more
rigerous and time consuming. Try different frequencies and mark your
tags with the frequency. Be warned that you may find some "+++" or
"---" spots and things in the room, inside the walls or your speakers
that rattle. You may learn too much. Try turning your head while
listening to single frequency tones.

-----------------------------------------------------------
spam: uce@ftc.gov
wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------
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Anonymous
November 21, 2004 1:04:58 PM

Archived from groups: rec.audio.tech (More info?)

"Barry Mann" <zzzz@zzzz.zzz> wrote in message
news:41a002a8$1$avgroveq$mr2ice@wcnews.cyberonic.com...
> In <10psko9g6r11ib9@corp.supernews.com>, on 11/19/04
> at 12:09 PM, "ludovic mirabel" <elmir2m @pacificcoast.net> said:
>
> [ ... ]
>
>>On testing with the Stereophile freqoency range test record and Radio
>>Shack SPL meter and playing music I can hear no distortion ( I use
>>1000Hz as my base volume level).
>
> Make sure you test the system using frequencies of interest. (testing
> the woofers at frequencies that are not normally routed to them, won't
> accomplish anything.) I like to use swept tones rather than steps
> because the steps may not excite problem areas.
>
I did not make my testing procedure clear: 1) The RS meter is set at 80db.
2) I play the 1000Hz signal through the left side speakers and adjust the
preamp. volume till the meter reads 0 3) I run through all the frequencies
on the test record and try to get all of them to read 0 or near to it.
>> Am I doing something wrong pushing the amp power that hard?
>> Should I desist and save for a bigger Bryston instead of boosting
>>the 3B?
>
> Unless the clip light comes on, the 3B is happy. I worry more about
> damaging the speakers.
>

I'm not too worried about my woofers. They were custom made for me combining
Electrovoice and Altec Lansing frames and magnet-voice coils. I have yet to
hear them strain. I was more concerned about provoking distortion at higher
volumes
> [ ... ]
>
> I think the real question to ask is: "how does it sound"? Is there
> something that the system is not doing that you wish it would? Do you
> want to feel the bass?
>
> If you've never done any reading about acoustics, here are a few cheap
> shots that will, hopefully, expand your curiousity.
>
> The room situation has a profound effect at base frequencies. Moving
> the speakers or your listening position a few inches this way or that
> will change the sound. An easy way to empirically explore the issues is
> to play music with a thumpy bass line and move around the room while
> listening. Pop or Jazz usually works best for me. The only real
> requirement is that the bass is pronounced and active. Be sure to move
> toward the walls, especially the corners. You may want to carry some
> markers with you as you move around the room. When you find a spot
> where the bass seems much louder or quieter than average, mark that
> spot with a "+" or "-". Try moving your listening position or the
> woofers to one of the "+" spots. Do some spots warrant a "++"?
>
> You can repeat the above with your test disc. This will be more
> rigerous and time consuming. Try different frequencies and mark your
> tags with the frequency. Be warned that you may find some "+++" or
> "---" spots and things in the room, inside the walls or your speakers
> that rattle. You may learn too much. Try turning your head while
> listening to single frequency tones.
>
I 'm well aware of the room effects and use them to position my auxiliary 8"
speakers and my Velodyne subwoofer to get the best readings at the
frequencies they serve.
As for my own seating position with 7 large speakers in the system my
possibilities are sevrely restricted.
Many thanks for taking time to write helpful comments.
Ludovic Mirabel
> -----------------------------------------------------------
> spam: uce@ftc.gov
> wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
> 13> (Barry Mann)
> [sorry about the puzzle, spammers are ruining my mailbox]
> -----------------------------------------------------------
>
Anonymous
November 21, 2004 1:24:33 PM

Archived from groups: rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in message
news:R6Odnb85oNRUxQPcRVn-sQ@comcast.com...
> "ludovic mirabel" <elmir2m @pacificcoast.net> wrote in message
> news:10psko9g6r11ib9@corp.supernews.com
>
>> I have a Bryston 3B powering my DIY transmission-line woofers that I
>> use for the 50 to 160 watt range, I use the old AcoustatX 100watt ESL
>> for my my midrange-lower treble..
>
> Without more details, its hard to position the woofers.
>
I tried moving my cylindrical woofer enclosures but found little difference
in RS meter readings, (placed in my listening position). These particular
speakers seem not to be too sensitive to placement
> Secondly, despite the traditional mystique that may surround them, there's
> really very little about TL enclosures to recommend them over more
> conventional designs.
>
I found them pleasanter to listen to- less boomy- than my previous Maganat
closed boxes. Purely subjective, of course
>> The woofers became progressively
>> more power hungry as the dacron stuffing settled down.
>
> The two things may have happened in the same time frame, but I've got my
> doubts about any actual technical connection. Rule of thumb is that you
> can't really stuff an enclosure too tightly. As you stuff an enclosure, it
> gets acoustically a little larger. The audible effects of this should not
> show up as efficiency.
I lack knowledge to dispute this scientifically. All I can say is that the
output at 100 hz through to 40 as meaasured by the meter was progressively
less. I attributed it to the stuffing settling downwards but may have be
completely wrong (the batteries were O.K. and other frequencies did not
change)
>
>> At present
>> they are no match for the Acoustats.
>
> In what sense? Power handling capacity? Directivity matching at the
> crossover point?
>
> ????
In power output at the speaker end as read by the meter.
>> I have Behringer digital equaliser tied to my woofers,
>
> Good way to overcome enclosure and room matching issues.
>
>> Against the warnings of people who know more about electronic than I
>> do I tried to lift the overall bass range by 4db. with additional
>> adjusments up to 8db on some frequencies.
>
> This can work.
>
>> On testing with the Stereophile freqoency range test record and Radio
>> Shack SPL meter and playing music I can hear no distortion ( I use
>> 1000Hz as my base volume level).
>
> Doubling and tripling on sine waves is pretty noticable if you test
> speakers by playing a tone and ramping the volume up and down. If the
> character of the tone does not change, but it only gets louder or softer,
> then you aren't exceeding the dynamic range limits of the woofers.
>
Thank you for reassurance. A bug was put into my brain by a recordist who
said that exceeding a 3 db boost on the equaliser will increase the demands
on the amplifier to a point where it will distort. I can hear no distortion
though but am in search of reassurance from a professional.

>> Am I doing something wrong pushing the amp power that hard?
>
> If the speakers don't audibly double or triple, and the voice coils don't
> cook and start rubbing, then there is probably not a lot that is seriously
> wrong.
>
Thanks again.
>> Should I desist and save for a bigger Bryston instead of boosting
>> the 3B?
>
> Why not measure the voltage across the voice coil of the woofer(s) and see
> how it fits with the maximum voltage output capacity of the Bryston. Your
> big worry is clipping, and clipping is a very non-subtle effect. It
> generally is rough and harsh-sounding.
>
>
>
Anonymous
November 22, 2004 9:11:39 PM

Archived from groups: rec.audio.tech (More info?)

"ludovic mirabel" <elmir2m @pacificcoast.net> wrote in message
>>
> Thank you for reassurance. A bug was put into my brain by a recordist who
> said that exceeding a 3 db boost on the equaliser will increase the
> demands on the amplifier to a point where it will distort. I can hear no
> distortion though but am in search of reassurance from a professional.

It your amp outputs full power without the eq , a 3dB boost at a particular
frequency may indeed ask you amp to deliver approx twice the power that it
can.

geoff
Anonymous
November 22, 2004 9:11:40 PM

Archived from groups: rec.audio.tech (More info?)

On Mon, 22 Nov 2004 18:11:39 +1300, Geoff Wood <geoff@paf.co.nz-nospam> wrote:

>"ludovic mirabel" <elmir2m @pacificcoast.net> wrote in message
>>>
>> Thank you for reassurance. A bug was put into my brain by a recordist who
>> said that exceeding a 3 db boost on the equaliser will increase the
>> demands on the amplifier to a point where it will distort. I can hear no
>> distortion though but am in search of reassurance from a professional.

>It your amp outputs full power without the eq , a 3dB boost at a particular
>frequency may indeed ask you amp to deliver approx twice the power that it
>can.

Asuming all you listen to is white noise.
Anonymous
November 22, 2004 9:11:40 PM

Archived from groups: rec.audio.tech (More info?)

On Mon, 22 Nov 2004 18:11:39 +1300, "Geoff Wood"
<geoff@paf.co.nz-nospam> wrote:

>
>"ludovic mirabel" <elmir2m @pacificcoast.net> wrote in message
>>>
>> Thank you for reassurance. A bug was put into my brain by a recordist who
>> said that exceeding a 3 db boost on the equaliser will increase the
>> demands on the amplifier to a point where it will distort. I can hear no
>> distortion though but am in search of reassurance from a professional.
>
>It your amp outputs full power without the eq , a 3dB boost at a particular
>frequency may indeed ask you amp to deliver approx twice the power that it
>can.

OTOH, I use 9dB of boost between 20 and 60Hz on my TV sound system (to
provide a 'faux subwoofer' effect on my Tannoy 633s), and I've never
heard my Audiolab 8000P clip, even on the usual 'blockbuster' action
movies. To be fair, these are 90dB/w/m speakers, so reasonably
sensitive, but still, it shows that large amounts of EQ boost aren't a
guaranteed problem.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
Anonymous
November 22, 2004 9:11:41 PM

Archived from groups: rec.audio.tech (More info?)

"TCS" <The-Central-Scrutinizer@p.o.b.o.x.com> wrote in message
news:slrncq2vf3.r3e.The-Central-Scrutinizer@linux.client.comcast.net...
> On Mon, 22 Nov 2004 18:11:39 +1300, Geoff Wood <geoff@paf.co.nz-nospam>
wrote:
> >It your amp outputs full power without the eq , a 3dB boost at a
particular
> >frequency may indeed ask you amp to deliver approx twice the power that
it
> >can.

> Asuming all you listen to is white noise.

No, assuming the signal that is boosted was already peaking at maximum
power, regardless of what it is.
The only way the amp would not overload is if there was NO spectral content
in the band being boosted.
Assuming overall gain is not reduced. Which can, and should be in this case.

TonyP.
Anonymous
November 22, 2004 9:11:41 PM

Archived from groups: rec.audio.tech (More info?)

"Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
news:km33q01radaa2g81fc32sbov1q9vhkkgd4@4ax.com...

<snip>

>>It your amp outputs full power without the eq , a 3dB boost at a
>>particular
>>frequency may indeed ask you amp to deliver approx twice the power that it
>>can.
>
> OTOH, I use 9dB of boost between 20 and 60Hz on my TV sound system (to
> provide a 'faux subwoofer' effect on my Tannoy 633s), and I've never
> heard my Audiolab 8000P clip, even on the usual 'blockbuster' action
> movies. To be fair, these are 90dB/w/m speakers, so reasonably
> sensitive, but still, it shows that large amounts of EQ boost aren't a
> guaranteed problem.
> --
>
> Stewart Pinkerton | Music is Art - Audio is Engineering


Certainly not a problem when applied by a professional. This accounts for
perhaps .01% of the population at least. Unfortunately many of our friends,
relatives, customers, newsgroup posters etc happen to occupy the other
99.99% of the general population. Although their "smiley face" approach to
equalizers may indeed lighten our spirits and provide us with extra income,
I still prefer Mr. Pinkertons' approach. :) 


Mark Z.
Anonymous
November 23, 2004 3:52:33 AM

Archived from groups: rec.audio.tech (More info?)

In <10q1nb7djth281d@corp.supernews.com>, on 11/21/04
at 10:24 AM, "ludovic mirabel" <elmir2m @pacificcoast.net> said:

[ ... ]

>> The two things may have happened in the same time frame, but I've got my
>> doubts about any actual technical connection. Rule of thumb is that you
>> can't really stuff an enclosure too tightly. As you stuff an enclosure, it
>> gets acoustically a little larger. The audible effects of this should not
>> show up as efficiency.
>I lack knowledge to dispute this scientifically. All I can say is that
>the output at 100 hz through to 40 as meaasured by the meter was
>progressively less. I attributed it to the stuffing settling
>downwards but may have be completely wrong (the batteries were O.K.
>and other frequencies did not change)

Measuring and making sense of sound pressure levels in a small room is
very difficult.


[ ... ]

>> Doubling and tripling on sine waves is pretty noticable if you test
>> speakers by playing a tone and ramping the volume up and down. If the
>> character of the tone does not change, but it only gets louder or softer,
>> then you aren't exceeding the dynamic range limits of the woofers.
>>
>Thank you for reassurance. A bug was put into my brain by a recordist
>who said that exceeding a 3 db boost on the equaliser will increase
>the demands on the amplifier to a point where it will distort. I can
>hear no distortion though but am in search of reassurance from a
>professional.

The amount of boost is not the issue. As long as you are below the
rated power of the amplifier after the boost, there is no problem. The
argument that distortion rises at the upper end of the amplifier's
power range is common, however, for most transistor amplifiers, percent
distortion actually decreases as one approaches the amplifier's power
limit. Distortion increases dramatically *VERY* near the upper limit.
In your 3B, the clip light will come on when you cross this threshold.

-----------------------------------------------------------
spam: uce@ftc.gov
wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------
Anonymous
November 23, 2004 7:16:45 PM

Archived from groups: rec.audio.tech (More info?)

"TCS" <The-Central-Scrutinizer@p.o.b.o.x.com> wrote in message
news:slrncq2vf3.r3e.The-Central-Scrutinizer@linux.client.comcast.net...
> On Mon, 22 Nov 2004 18:11:39 +1300, Geoff Wood <geoff@paf.co.nz-nospam>
> wrote:
>
>>"ludovic mirabel" <elmir2m @pacificcoast.net> wrote in message
>>>>
>>> Thank you for reassurance. A bug was put into my brain by a recordist
>>> who
>>> said that exceeding a 3 db boost on the equaliser will increase the
>>> demands on the amplifier to a point where it will distort. I can hear no
>>> distortion though but am in search of reassurance from a professional.
>
>>It your amp outputs full power without the eq , a 3dB boost at a
>>particular
>>frequency may indeed ask you amp to deliver approx twice the power that it
>>can.
>
> Asuming all you listen to is white noise.


Or music - and the boost is at a predominant frequency, like loud heavy
bass. Boost the bass 3dB and you may wello'load the amp.

I did say "may" the first time too.

geoff
Anonymous
November 24, 2004 12:54:58 PM

Archived from groups: rec.audio.tech (More info?)

Thank you for your very helpful reply and thanks to Barry Mann and
others who helped.
Ludovic M.
"Arny Krueger" <arnyk@hotpop.com> wrote in message
news:R6Odnb85oNRUxQPcRVn-sQ@comcast.com...
> "ludovic mirabel" <elmir2m @pacificcoast.net> wrote in message
> news:10psko9g6r11ib9@corp.supernews.com
>
>> I have a Bryston 3B powering my DIY transmission-line woofers that I
>> use for the 50 to 160 watt range, I use the old AcoustatX 100watt ESL
>> for my my midrange-lower treble..
>
> Without more details, its hard to position the woofers.
>
> Secondly, despite the traditional mystique that may surround them, there's
> really very little about TL enclosures to recommend them over more
> conventional designs.
>
>> The woofers became progressively
>> more power hungry as the dacron stuffing settled down.
>
> The two things may have happened in the same time frame, but I've got my
> doubts about any actual technical connection. Rule of thumb is that you
> can't really stuff an enclosure too tightly. As you stuff an enclosure, it
> gets acoustically a little larger. The audible effects of this should not
> show up as efficiency.
>
>> At present
>> they are no match for the Acoustats.
>
> In what sense? Power handling capacity? Directivity matching at the
> crossover point?
>
> ????
>
>> I have Behringer digital equaliser tied to my woofers,
>
> Good way to overcome enclosure and room matching issues.
>
>> Against the warnings of people who know more about electronic than I
>> do I tried to lift the overall bass range by 4db. with additional
>> adjusments up to 8db on some frequencies.
>
> This can work.
>
>> On testing with the Stereophile freqoency range test record and Radio
>> Shack SPL meter and playing music I can hear no distortion ( I use
>> 1000Hz as my base volume level).
>
> Doubling and tripling on sine waves is pretty noticable if you test
> speakers by playing a tone and ramping the volume up and down. If the
> character of the tone does not change, but it only gets louder or softer,
> then you aren't exceeding the dynamic range limits of the woofers.
>
>> Am I doing something wrong pushing the amp power that hard?
>
> If the speakers don't audibly double or triple, and the voice coils don't
> cook and start rubbing, then there is probably not a lot that is seriously
> wrong.
>
>> Should I desist and save for a bigger Bryston instead of boosting
>> the 3B?
>
> Why not measure the voltage across the voice coil of the woofer(s) and see
> how it fits with the maximum voltage output capacity of the Bryston. Your
> big worry is clipping, and clipping is a very non-subtle effect. It
> generally is rough and harsh-sounding.
>
>
>
!