I've noticed that if you set the gains too high on an amp, you loose a
great deal of bass response, but when you turn the gains down, the bass
sounds more full and rich. Why is this? I keep reading that the gain
control is actually a volume control, but I don't really believe it.
Setting the gains too high seem to make the music sound awful...

On Fri, 22 Jul 2005 20:53:09 GMT, JC wrote:

I've noticed that if you set the gains too high on an amp, you loose a
great deal of bass response, but when you turn the gains down, the bass
sounds more full and rich. Why is this? I keep reading that the gain
control is actually a volume control, but I don't really believe it.
Setting the gains too high seem to make the music sound awful...

Well, setting the gains too high will make it easier to drive the amp
into clipping, which DOES sound awful, but as long as you're operating
the amp within its proper limits, the bass response shouldn't vary
with gain position.

It may be that with the gains way up, you're clipping the amp and
getting distortion. Perhaps you're hearing the distortion in the
lower frequencies more than in the higher frequencies.

Adjusting the gains is just a way to match the amplifier to the head
unit. You want to set the gains so that when you have the head unit
turned up to about 85% of maximum volume, the amplifier is putting out
its maximum power possible without clipping.

If you have a head unit with a high pre-out voltage, like 8V, you'll
have to turn the gains down on the amp to make everything match up.

If you later switched to a head unit with 2V pre-outs, you'd have to
turn the gains back up on the amp to make everything match up.

In both cases, you're still able to get the maximum clean power
possible out of the amp, you just need the gains so that maximum power
for the amp occurs when you're nearly at maximum volume on the head
unit.


--
Scott Gardner

"Landing on the ship during the daytime is like sex, it's either good or it's great. Landing on the ship at night is like a trip to the dentist, you may get away with no pain, but you just don't feel comfortable." (LCDR Thomas Quinn, USN)

I've noticed that if you set the gains too high on an amp, you loose a
great deal of bass response, but when you turn the gains down, the bass
sounds more full and rich. Why is this?

Your amp is broken or you're driving it into clipping when you set the gains
too high.

I keep reading that the gain
control is actually a volume control, but I don't really believe it.

Have you ever looked at the circuit? There's no reason for you to take it
as faith. Pick up an electronics book (I highly recommend Horowitz and
Hill), read the first couple chapters - at least to the part where it gets
to transistors and op amps, and then order the schematics from the
manufacturer of your choice. That's the only way you'll ever convince
yourself one way or the other.

On Fri, 22 Jul 2005 21:41:51 GMT, "MZ"
wrote:

Your amp is broken or you're driving it into clipping when you set
the gains too high.

I doubt three amps are/were broken. I've noted this with every amp (3)
I've ever owned over the years. And when I said that the music sounded
awful with the gains set high, I didn't mean awful with clipping or
distortion, but because there was a lack of bass...

Your amp is broken or you're driving it into clipping when you set
the gains too high.

I doubt three amps are/were broken. I've noted this with every amp (3)
I've ever owned over the years. And when I said that the music sounded
awful with the gains set high, I didn't mean awful with clipping or
distortion, but because there was a lack of bass...

That could have resulted from clipping, actually. Most people don't
understand how easily it is to drive your amp into clipping, and how much
distortion we tolerate without noticing. When I say that 95% of the people
in here with "sophisticated" audio systems are driving their amplifiers into
clipping to some degree, I'm not exaggerating. Most estimates of the ratio
between peak and average levels for most music tend to come in around 10-20
dB, maybe as low as 6dB for highly compressed recordings (do a google search
for "crest factor"). In other words, if you're operating your 100 watt amp
at full tilt but not driving it into clipping, the average power content of
the recording will be well under 10 watts. This analysis is a bit
oversimplified for a number of reasons, but it should illustrate just how
much power is needed to avoid clipping.

So how would this reduce bass response? Technically, it wouldn't. The
increase in power output that comes with driving an amp into clipping is of
a higher frequency than the frequency that brought you into clipping. By
that, I mean the harmonics generated when clipping will result in an
increase in power at higher frequencies, while the low frequencies maintain
roughly their same output. [this is why clipping an amplifier can sometimes
be dangerous for high frequency drivers that are already being pushed near
their limits, but subs may be left unaffected] Anyway, this might explain
what seems like a diminished bass response.

The other possibility is that something is wrong with the amplifiers or
perhaps even the source unit(s). Or that it was such an exotic (read:
cheap) design specific to that amplifier type, though I have a hard time
imagining how they could screw that circuit up.

If you're driving multiple drivers (such as a component set) running off the
same gain setting, or if you're increasing the gain settings for all of your
amplifiers, then another possibility is that your bass drivers are
experiencing a greater degree of power compression at an earlier onset than
the other speakers, or maybe even that the frequency response of the speaker
is changing favoring higher frequencies at higher power levels. Just
another possibility.

A properly functioning gain adjustment will not have deleterious effects.
The circuit is incredibly simple, and is usually nothing more than a couple
passive components and an op amp [the op amp probably has a far better
frequency response than the rest of the amplifier]. I've seen some designs
where this circuit has a gain 1, but most designs I've encountered and
most that I've heard people in this newsgroup and elsewhere speak of have
gain 1, meaning the gain adjustment is nothing more than an attenuator.

Actually, that brings up a question I have for some of the repair folks who
frequent this newsgroup... Have any of you come across an amplifier, either
car or home audio, that uses as a gain adjustment one of the resistors in
the voltage divider tied to the global NFB loop? Seems to me like that
would eliminate the need for an extra buffer. Though I'd bet putting the
circuit before the input stage is superior, because I can imagine all kinds
of noise being introduced by routing the global NFB signal out through to
the pot...

ok, since you seem to know quite a bit here (not patronizing even though it
sounds that way) how do i set the gain on my amp to avoid clipping? I mean
you're saying i probably won't notice it, and i don't know what to listen
for so i almost guarantee "I" won't notice it. For now i've just set mine
so that it hits about as hard i need. what settings cause clipping and how
can i recognize it?


"MZ" wrote in message
...
Your amp is broken or you're driving it into clipping when you set
the gains too high.

I doubt three amps are/were broken. I've noted this with every amp (3)
I've ever owned over the years. And when I said that the music sounded
awful with the gains set high, I didn't mean awful with clipping or
distortion, but because there was a lack of bass...

That could have resulted from clipping, actually. Most people don't
understand how easily it is to drive your amp into clipping, and how much
distortion we tolerate without noticing. When I say that 95% of the
people
in here with "sophisticated" audio systems are driving their amplifiers
into
clipping to some degree, I'm not exaggerating. Most estimates of the
ratio
between peak and average levels for most music tend to come in around
10-20
dB, maybe as low as 6dB for highly compressed recordings (do a google
search
for "crest factor"). In other words, if you're operating your 100 watt
amp
at full tilt but not driving it into clipping, the average power content
of
the recording will be well under 10 watts. This analysis is a bit
oversimplified for a number of reasons, but it should illustrate just how
much power is needed to avoid clipping.

So how would this reduce bass response? Technically, it wouldn't. The
increase in power output that comes with driving an amp into clipping is
of
a higher frequency than the frequency that brought you into clipping. By
that, I mean the harmonics generated when clipping will result in an
increase in power at higher frequencies, while the low frequencies
maintain
roughly their same output. [this is why clipping an amplifier can
sometimes
be dangerous for high frequency drivers that are already being pushed near
their limits, but subs may be left unaffected] Anyway, this might explain
what seems like a diminished bass response.

The other possibility is that something is wrong with the amplifiers or
perhaps even the source unit(s). Or that it was such an exotic (read:
cheap) design specific to that amplifier type, though I have a hard time
imagining how they could screw that circuit up.

If you're driving multiple drivers (such as a component set) running off
the
same gain setting, or if you're increasing the gain settings for all of
your
amplifiers, then another possibility is that your bass drivers are
experiencing a greater degree of power compression at an earlier onset
than
the other speakers, or maybe even that the frequency response of the
speaker
is changing favoring higher frequencies at higher power levels. Just
another possibility.

A properly functioning gain adjustment will not have deleterious effects.
The circuit is incredibly simple, and is usually nothing more than a
couple
passive components and an op amp [the op amp probably has a far better
frequency response than the rest of the amplifier]. I've seen some
designs
where this circuit has a gain 1, but most designs I've encountered and
most that I've heard people in this newsgroup and elsewhere speak of have
gain 1, meaning the gain adjustment is nothing more than an attenuator.

Actually, that brings up a question I have for some of the repair folks
who
frequent this newsgroup... Have any of you come across an amplifier,
either
car or home audio, that uses as a gain adjustment one of the resistors in
the voltage divider tied to the global NFB loop? Seems to me like that
would eliminate the need for an extra buffer. Though I'd bet putting the
circuit before the input stage is superior, because I can imagine all
kinds
of noise being introduced by routing the global NFB signal out through to
the pot...

Eddie sums it up at www.installer.com/tech/gains.html [I think that's the
right URL]. In short, clipping occurs when you try to get more power out
of the amplifier than it can deliver. It tends to be one of the easiest
forms of distortion to detect (second perhaps to crossover distortion,
which isn't present at a great enough quantity in very many amps anyway).

On Sat, 23 Jul 2005, Chris Mullins wrote:

ok, since you seem to know quite a bit here (not patronizing even though it
sounds that way) how do i set the gain on my amp to avoid clipping? I mean
you're saying i probably won't notice it, and i don't know what to listen
for so i almost guarantee "I" won't notice it. For now i've just set mine
so that it hits about as hard i need. what settings cause clipping and how
can i recognize it?


"MZ" wrote in message
...
Your amp is broken or you're driving it into clipping when you set
the gains too high.

I doubt three amps are/were broken. I've noted this with every amp (3)
I've ever owned over the years. And when I said that the music sounded
awful with the gains set high, I didn't mean awful with clipping or
distortion, but because there was a lack of bass...

That could have resulted from clipping, actually. Most people don't
understand how easily it is to drive your amp into clipping, and how much
distortion we tolerate without noticing. When I say that 95% of the
people
in here with "sophisticated" audio systems are driving their amplifiers
into
clipping to some degree, I'm not exaggerating. Most estimates of the
ratio
between peak and average levels for most music tend to come in around
10-20
dB, maybe as low as 6dB for highly compressed recordings (do a google
search
for "crest factor"). In other words, if you're operating your 100 watt
amp
at full tilt but not driving it into clipping, the average power content
of
the recording will be well under 10 watts. This analysis is a bit
oversimplified for a number of reasons, but it should illustrate just how
much power is needed to avoid clipping.

So how would this reduce bass response? Technically, it wouldn't. The
increase in power output that comes with driving an amp into clipping is
of
a higher frequency than the frequency that brought you into clipping. By
that, I mean the harmonics generated when clipping will result in an
increase in power at higher frequencies, while the low frequencies
maintain
roughly their same output. [this is why clipping an amplifier can
sometimes
be dangerous for high frequency drivers that are already being pushed near
their limits, but subs may be left unaffected] Anyway, this might explain
what seems like a diminished bass response.

The other possibility is that something is wrong with the amplifiers or
perhaps even the source unit(s). Or that it was such an exotic (read:
cheap) design specific to that amplifier type, though I have a hard time
imagining how they could screw that circuit up.

If you're driving multiple drivers (such as a component set) running off
the
same gain setting, or if you're increasing the gain settings for all of
your
amplifiers, then another possibility is that your bass drivers are
experiencing a greater degree of power compression at an earlier onset
than
the other speakers, or maybe even that the frequency response of the
speaker
is changing favoring higher frequencies at higher power levels. Just
another possibility.

A properly functioning gain adjustment will not have deleterious effects.
The circuit is incredibly simple, and is usually nothing more than a
couple
passive components and an op amp [the op amp probably has a far better
frequency response than the rest of the amplifier]. I've seen some
designs
where this circuit has a gain 1, but most designs I've encountered and
most that I've heard people in this newsgroup and elsewhere speak of have
gain 1, meaning the gain adjustment is nothing more than an attenuator.

Actually, that brings up a question I have for some of the repair folks
who
frequent this newsgroup... Have any of you come across an amplifier,
either
car or home audio, that uses as a gain adjustment one of the resistors in
the voltage divider tied to the global NFB loop? Seems to me like that
would eliminate the need for an extra buffer. Though I'd bet putting the
circuit before the input stage is superior, because I can imagine all
kinds
of noise being introduced by routing the global NFB signal out through to
the pot...

"Chris Mullins" wrote in message
...
ok, since you seem to know quite a bit here (not patronizing even though
it sounds that way) how do i set the gain on my amp to avoid clipping? I
mean you're saying i probably won't notice it, and i don't know what to
listen for so i almost guarantee "I" won't notice it. For now i've just
set mine so that it hits about as hard i need. what settings cause
clipping and how can i recognize it?

with a o-scope of course.





"MZ" wrote in message
...
Your amp is broken or you're driving it into clipping when you set
the gains too high.

I doubt three amps are/were broken. I've noted this with every amp (3)
I've ever owned over the years. And when I said that the music sounded
awful with the gains set high, I didn't mean awful with clipping or
distortion, but because there was a lack of bass...

That could have resulted from clipping, actually. Most people don't
understand how easily it is to drive your amp into clipping, and how much
distortion we tolerate without noticing. When I say that 95% of the
people
in here with "sophisticated" audio systems are driving their amplifiers
into
clipping to some degree, I'm not exaggerating. Most estimates of the
ratio
between peak and average levels for most music tend to come in around
10-20
dB, maybe as low as 6dB for highly compressed recordings (do a google
search
for "crest factor"). In other words, if you're operating your 100 watt
amp
at full tilt but not driving it into clipping, the average power content
of
the recording will be well under 10 watts. This analysis is a bit
oversimplified for a number of reasons, but it should illustrate just how
much power is needed to avoid clipping.

So how would this reduce bass response? Technically, it wouldn't. The
increase in power output that comes with driving an amp into clipping is
of
a higher frequency than the frequency that brought you into clipping. By
that, I mean the harmonics generated when clipping will result in an
increase in power at higher frequencies, while the low frequencies
maintain
roughly their same output. [this is why clipping an amplifier can
sometimes
be dangerous for high frequency drivers that are already being pushed
near
their limits, but subs may be left unaffected] Anyway, this might
explain
what seems like a diminished bass response.

The other possibility is that something is wrong with the amplifiers or
perhaps even the source unit(s). Or that it was such an exotic (read:
cheap) design specific to that amplifier type, though I have a hard time
imagining how they could screw that circuit up.

If you're driving multiple drivers (such as a component set) running off
the
same gain setting, or if you're increasing the gain settings for all of
your
amplifiers, then another possibility is that your bass drivers are
experiencing a greater degree of power compression at an earlier onset
than
the other speakers, or maybe even that the frequency response of the
speaker
is changing favoring higher frequencies at higher power levels. Just
another possibility.

A properly functioning gain adjustment will not have deleterious effects.
The circuit is incredibly simple, and is usually nothing more than a
couple
passive components and an op amp [the op amp probably has a far better
frequency response than the rest of the amplifier]. I've seen some
designs
where this circuit has a gain 1, but most designs I've encountered and
most that I've heard people in this newsgroup and elsewhere speak of have
gain 1, meaning the gain adjustment is nothing more than an attenuator.

Actually, that brings up a question I have for some of the repair folks
who
frequent this newsgroup... Have any of you come across an amplifier,
either
car or home audio, that uses as a gain adjustment one of the resistors in
the voltage divider tied to the global NFB loop? Seems to me like that
would eliminate the need for an extra buffer. Though I'd bet putting the
circuit before the input stage is superior, because I can imagine all
kinds
of noise being introduced by routing the global NFB signal out through to
the pot...

ok, since you seem to know quite a bit here (not patronizing even though
it sounds that way) how do i set the gain on my amp to avoid clipping? I
mean you're saying i probably won't notice it, and i don't know what to
listen for so i almost guarantee "I" won't notice it. For now i've just
set mine so that it hits about as hard i need. what settings cause
clipping and how can i recognize it?

with a o-scope of course.

I hope you're being facetious...