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Old 28th October 2012, 05:19 PM   #31
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Quote:
Originally Posted by Esperado View Post
But, once again, if for some reason, i had to respond at that kind of technical requirement (increase the average level with not excessive distortion), i will look limiters side.
Right on!! Thank you very much!!! I have just now realized my error and have finally understood Sreten's warning.
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Old 28th October 2012, 05:33 PM   #32
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Quote:
Originally Posted by sreten View Post
Hi, A thread that starts with a load of misinformation about "palatable clipping" and ignores the general principles of the way dynamic range management is usually done in subs, AV kit and PC speakers is somewhat doomed. (Also the way its done for film, TV and radio, as well as music mastering). Assuming circuits are a fix to a problem and describing them in those terms doesn't cover what they really do and don't do, and thus will mislead a lot. rgds, sreten.
Thank you for this warning.
I have finally understood that the layman's terms of tube/valve amp soft clipping are not done with a typical soft clipper. The layman's language and engineer's language are almost opposites. And I have finally understood that typical soft clippers may be quiet protectors but aren't desirable audio effects. I will again attempt something better for the thread's intro.
Quote:
Originally Posted by AndrewT View Post
Could Baker Clamps be termed a soft clipper? Cordell shows a soft clipper, he called it Klever Klipper.
Thank you for this post!
It is a light shining in the darkness.

Apparently Bob's re-spelling of Klipper is useful for describing a non-typical clipper (I'm surprised to discover that a clipper that benefits audio is not typical), and the re-spelling has some humor content that I wasn't aware of until now. Now, that name "Klever Klipper" would have been quite funny if I'd learned the meaning of it a bit earlier.

Thanks again for the excellent point of reference. I am quite grateful. Thank you for the headroom information too. That was an excellent clue.
The point at which I'd like to cause clipping is 4v input to a power amp--a non-audio signal. And, I wish to gently squeeze (compress?) but not clip audio signals.
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Old 29th October 2012, 01:54 AM   #33
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Tube amps use very high tension rails. Audio signal peak voltages are far from them.
The distortion increases slowly and with a regular curve as the level increase. In fact there is no clipping.
Same thing with an analog magnetic tape.
An analog mixing desk has 24db of headroom, a professional digital recorder 15 or 18db.That is to protect the signal from any clipping during recording and mixing processes.

But, during mastering, all undesirable peaks are limited carefully, with less sound degradation as possible. Those peaks you wanted to get rid off by a soft clipper.
After that, the result of a soft clipper will be: more average distortion at high levels, less disagreeable than natural clipping. Chose your poison.
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Old 29th October 2012, 09:39 AM   #34
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Default Need to find a little diode.

This is going much better. Thanks!
Quote:
Originally Posted by Esperado View Post
After that, the result of a soft clipper will be: more average distortion at high levels, less disagreeable than natural clipping. Chose your poison.
Less disagreeable than natural clipping would be a non-standard soft clipper circuit or a standard compressor. We can do both: compress it before hit it. And for the purpose of this thread, that's what I'm looking for.
Much like this:
(a) An ineffective soft clipper followed by,
(b) an ineffective soft clipper followed by,
(c) a regular soft clipper.
Code:
(c)            -    
(b)          /   \  
(a)         /     \ 
(a)  \     /       
(b)   \   /        
(c)     -
Parts problem, capacitance and voltage:
At line level, it may be possible use 1n5819 0.15v rectifier schottky but that could be coarse. Where can we find the low capacitance 0.1v current reliant diode? Does 1n5819 have a baby sister (smaller, lower capacitance)?
.
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Old 29th October 2012, 10:21 AM   #35
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Cordell's "Klever Klipper" works like a charm. Properly adjusted (tracking rails etc), it kicks in just below output stage clipping to exactly avoid that clipping which tends to be "sticky" (amp takes quite some time to recover from clipping) and sounds much more annoying than a briefly compressed, then "chopped off" peak but still properly amplified.

Key point is that the amp never ever opens its feedback loop -- with the exception of current overload "clipping" which is a different animal, much harder to tame.

One can adjust the "softness" of the clipper by letting it work at lower (large transition) or higher signal amplitudes.
Soundwise, any soft-clipper will steal some volts of undistorted headroom but I found Cordell's pretty well sounding for clipped LF (<500Hz) signals, sort of like the speaker itself is running out of steam, not the amplifier, unless you punish it with gross input overload. With occasional short HF (>2kHz) overload spikes the clipping was effectivly undetectable to my ears.
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Old 29th October 2012, 12:32 PM   #36
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Quote:
Originally Posted by KSTR View Post
Cordell's "Klever Klipper" works like a charm. Properly adjusted (tracking rails etc), it kicks in just below output stage clipping to exactly avoid that clipping which tends to be "sticky" (amp takes quite some time to recover from clipping) and sounds much more annoying than a briefly compressed, then "chopped off" peak but still properly amplified.

Key point is that the amp never ever opens its feedback loop -- with the exception of current overload "clipping" which is a different animal, much harder to tame.

One can adjust the "softness" of the clipper by letting it work at lower (large transition) or higher signal amplitudes.
Soundwise, any soft-clipper will steal some volts of undistorted headroom but I found Cordell's pretty well sounding for clipped LF (<500Hz) signals, sort of like the speaker itself is running out of steam, not the amplifier, unless you punish it with gross input overload. With occasional short HF (>2kHz) overload spikes the clipping was effectively undetectable to my ears.
Thank you sir!!! Awesome!!!

I'm trying to figure out the circuit locations of all of the audio effect.

Comparison:
A slow attack compressor (clipnipper in my signature line) can't stop bass impact; however, a fast soft clip circuit does remove biggest signal first, as quickly as possible. They can be used together if level frequency response is desired.

Either changes power supply workload.

Speculation guesswork at the power circuit effect:
The slow attack compressor decreases the duration of workload and allows the power supply reservoir to recharge faster so the amplifier's time spent defenseless is reduced. The fast soft clipper prevents peaks from discharging the power supply, and gives one the chance of buying a transformer big enough to prevent discharge so that amplifier is never defenseless (true if there's umbilical cable or diode or capmulti, operating the amplifier board somewhat lower voltage than power board). Lastly, the possible combination of compressor and soft clipper first reduces workload duration and then also blocks peak discharge.

Very Klever resource management!! But some of what we hear is surely power circuit effect.

Assumptions:
By putting the sensor at amplifier input, and by reducing power supply workload duration and peaks, maybe (maybe) usable headroom for music is not reduced. A current reliant diode sensor might make a circuit that guesses reasonably, in which case there's no need to connect power noise to amplifier input. Details: Zener, Bat, and 1n4148 are useful for voltage precision; however, the curve of current reliant 1n5819, MR and LED are more attractive for compressor effect.

I'd like to try for a no op-amp, no opto, simplified solution at line level.

Symmetric versus Dual Asymmetric:
And we can do "forced symmetry" which is good for a little boost. While researching the Volumax type compressors, a radio station transmitter headroom boost (also works on audio power amp), I also read that the major flaw was the necessity of selecting announcers and DJ's with more symmetrical voices, but DJ's with asymmetrical voices were fired or paid much less (because too quiet). Later on, the asymmetrical voice guys got their jobs back when forced symmetry compressor circuits (Dual Asymmetric, one for upswing another for downswing) were added at the mic preamps. After that, it was quickly discovered that normal music is an asymmetrical signal.

But someone forgot. . .
On checking out the waveforms of quite a few tracks with the computer wav editor, it shows that most of the tracks have asymmetric peaks.

Given the typical recording studio output (containing asymmetric clips), I propose to "upgrade" our project to dual-asymmetric sensor/detector, so that it is unnecessary to harm both sides of the waveform every time. The upgrade is one detector for upswing and a second detector for downswing. In my observation, it is unlikely that both detectors will activate at precisely the same time during normal music signal playback. If the circuit is fast enough, dual asymmetric looks doable.

Question:
Is Bob Cordell's compress+soft-clip circuit a Symmetric or Dual Asymmetric?
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Last edited by danielwritesbac; 29th October 2012 at 12:44 PM.
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Old 23rd November 2012, 10:31 AM   #37
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Default Much closer

The BAT85, BAT86 has low capacitance for low noise. On researching headphone amp clippers, the 1N34A and LED have mainly 2nd order harmonic like a tube clip.

For experiment, I used:
1k5 series loss at input to help form the voltage divider.
10k-BAT86clipper-680n as the main shunt.
10k-BAT86clipper-BAT86clipper added shunt.
This successfully constrained the TV to reasonable output.
I'm looking forward to trying out some 1N34A germanium.
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Last edited by danielwritesbac; 23rd November 2012 at 10:34 AM.
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