Looking for a good clipping circuit for 1000 watt audio amp.

[Modat22]

I have a couple home grown audio amps laying about 250 watt, 500
watt and 1000 watt none have clipping circuits or speaker cut outs.
Does anyone have a schematic for one that takes the rail voltage as
the reference voltage for clipping?

 

[Harry Conover]

Modat22 <modat22@yahoo.com> wrote in message news:<dja5009741j0iqbngdb8uenjv9o4piteua@4ax.com>...

I have a couple home grown audio amps laying about 250 watt, 500
watt and 1000 watt none have clipping circuits or speaker cut outs.
Does anyone have a schematic for one that takes the rail voltage as
the reference voltage for clipping?

Huh? Why would you want to do that?

Wouldn't it make a great deal more sense to clip at one of your
low-level audio stages, where it is relatively easy to implement a
variable clipping level adjustment, such as those commonly used in
radio and TV broadcasting applications.

Perhaps I'm missing something.

Harry C.

 

[Switch]

"Harry Conover" <hhc314@yahoo.com> wrote in message
news:7ce4e226.0401121117.7bc97b2e@posting.google.com...

Modat22 <modat22@yahoo.com> wrote in message
news:<dja5009741j0iqbngdb8uenjv9o4piteua@4ax.com>...
I have a couple home grown audio amps laying about 250 watt, 500
watt and 1000 watt none have clipping circuits or speaker cut outs.
Does anyone have a schematic for one that takes the rail voltage as
the reference voltage for clipping?

Huh? Why would you want to do that?

Wouldn't it make a great deal more sense to clip at one of your
low-level audio stages, where it is relatively easy to implement a
variable clipping level adjustment, such as those commonly used in
radio and TV broadcasting applications.

Perhaps I'm missing something.

Harry C.

Yes Harry, you are missing something. You'd never want to clip the signal source, how
would you deliver clean power to an amp otherwise?!?

First off to the OP, you can't implement such 'protection', it isn't that bad when an
amplifier clips. The top and bottom of the waveform literally get clipped, and until you
get into gross clipping that is audible, the setbacks are not noticable.

You want PEAK transients to get through, and often enough, these peak transients clip the
power supply.

A clipping circuit is usually a indicator (LED) telling you that the amplifier is
clipping. Protection on the output is another story. You don't want it to unlatch the
outputs like that, if there is hardly any protection, your amp may not even have open load
protection!?!?

Put the amp on a circuit capable of running the amp at full power, apply a test signal
1khz lets say, then turn up the gain and observe the output on a scope while it is
connected to a resistor load capable of dissapating the power. Once you see the waveform
clip, you can set this as a reference lets say to a LED VU meter (ie: Dorrough Loudness
Monitor Type 40-A).

Or you can monitor the voltage on the output, and then design a circuit to light a LED
when the AC V gets to that point, however, this won't be entirely accurate.

check out www.ramaudio.com and see how a professional amplifier mutes the input when a
total short across the output occurs, and how it actually eliminates clipping without
loosing the peak transients from coming through.

hope that helps.

 

[Harry Conover]

"Switch" <clubkidd_toronto@hotmail.com> wrote in message news:<8iGMb.73$XZ.4317@news20.bellglobal.com>...

"Harry Conover" <hhc314@yahoo.com> wrote in message
news:7ce4e226.0401121117.7bc97b2e@posting.google.com...
Modat22 <modat22@yahoo.com> wrote in message
news:<dja5009741j0iqbngdb8uenjv9o4piteua@4ax.com>...
I have a couple home grown audio amps laying about 250 watt, 500
watt and 1000 watt none have clipping circuits or speaker cut outs.
Does anyone have a schematic for one that takes the rail voltage as
the reference voltage for clipping?

Huh? Why would you want to do that?

Wouldn't it make a great deal more sense to clip at one of your
low-level audio stages, where it is relatively easy to implement a
variable clipping level adjustment, such as those commonly used in
radio and TV broadcasting applications.

Perhaps I'm missing something.

Harry C.

Yes Harry, you are missing something. You'd never want to clip the signal source, how
would you deliver clean power to an amp otherwise?!?

Right, me bad! I used the term "clipping" rather than the proper term
"limiting".

We do this in broadcasting simply because if you don't you will
overmodulate and splatter crap all over the airwave spectrum, and in
response the FCC will hit you with a stiff fine.

In audio work it really doesn't make much difference, because when the
amplifier and speakers are driven to their clipping or cut-off limits
and distortion artifacts result occur, today's listners don't even
notice it, since it's so much a part of today's sounds!

I really don't look forward to the days when audio amplifier designers
begin to imprelement the audio signal processing utilities that have
been standard equipment in the radio broadcasters repotoire for the
past 30 years, since that would invite a "wall of sound" that would
abolutely negate any posibility of a relaxing drink and seductive
conversation with an attractive female, at least at most places I
know.

The normal equipment line up at the transmitter of a typical rock
station consists of (brand name or generic equivalent) a GE "Stay
Level" amplifier feeding into an RCA Peak Limiter/Clipper amp, likely
followed by a Gates Absolute Clipper. This lineup with keep you at
between 92 and 99% modulation all of the time while safe from the FCC.
Of course your audio signal sounds like crap, but today who cares in
view of the crap that it is being receive in! Right?

Harry C.

 

[Modat22]

First off to the OP, you can't implement such 'protection', it isn't that bad when an
amplifier clips. The top and bottom of the waveform literally get clipped, and until you
get into gross clipping that is audible, the setbacks are not noticable.

You want PEAK transients to get through, and often enough, these peak transients clip the
power supply.

A clipping circuit is usually a indicator (LED) telling you that the amplifier is
clipping. Protection on the output is another story. You don't want it to unlatch the
outputs like that, if there is hardly any protection, your amp may not even have open load
protection!?!?

Put the amp on a circuit capable of running the amp at full power, apply a test signal
1khz lets say, then turn up the gain and observe the output on a scope while it is
connected to a resistor load capable of dissapating the power. Once you see the waveform
clip, you can set this as a reference lets say to a LED VU meter (ie: Dorrough Loudness
Monitor Type 40-A).

Or you can monitor the voltage on the output, and then design a circuit to light a LED
when the AC V gets to that point, however, this won't be entirely accurate.

check out www.ramaudio.com and see how a professional amplifier mutes the input when a
total short across the output occurs, and how it actually eliminates clipping without
loosing the peak transients from coming through.

hope that helps.

Thanks for the information, currently I have no speaker protection in
my amps at all. They are very stable at the moment but I figure I'm
asking for trouble. I probably asked the wrong question, I really need
some sort of speaker protection that I can easily incorporate in to my
current amps.
Thanks

 

[Myron Samila]

"Modat22" <modat22@yahoo.com> wrote in message
news:rq080050tfm9rfg7f4u52jdvei2qrcp67i@4ax.com...

Thanks for the information, currently I have no speaker protection in
my amps at all. They are very stable at the moment but I figure I'm
asking for trouble. I probably asked the wrong question, I really need
some sort of speaker protection that I can easily incorporate in to my
current amps.
Thanks

My Bryston 3B has no protection on the output, it is a high current amplifier a true
workhorse.

To eliminate problems at the output stage, you can use an outboard
compressor/limiter/expander on the input.

I wouldn't put in any type of protection on the output stage of an amp, the more passive
components on the output, the more chance you will hear it.

Ideally, a decent amp with a high damping factor and well damped speakers (high mechanical
Q) will be able to shake off just about anything your amp sends it. AS LONG as it isn't
DC!! That is a whole other type of protection, once an amp goes DC, it will literally fry
everything after it.

Being in the professional audio industry for so long, I've only blown one woofer (18") and
it was because it was severely fatigued (like I am at the moment!).

What type of amps do you have?