Intro to bi-/tri-amping

[Ryan Lantzy]

Re: Intro to bi-/tri-amping

Camcos have a feature that actually turns down the input so that the amp itself will not create more than 1% THD.

The amp gain is input level dependent?

The amp has three Gain settings....26dB, 32dB and 1.4Volts sensitivity.



Rather than having a basic peak limiter like other amps have it has a speaker/amplifier protection circuit where in when you push the amp really hard, the circuit will reduce the input level of the amp to keep the amp from having more than 1% ''non-linear'' distortions. It actually compares the input signal to the output signal to do this.



I use this feature on the amp which probably keeps me from getting every single little volt possible out of the amp but If you read Nexo literature they will tell you to NOT use this feature because the NX processors take care of all the processing for you.

Ryan,



I think pretty much every modern amp made that has a "limiter" uses this method. It's nothing that is all that novel.

 

[RYAN LOUDMUSIC JENKINS]

Re: Intro to bi-/tri-amping

Show me any other amp that turns down the input signal to limit the distortion level. I know of none although I haven't read about all of the Powersofts and newer Labs but I don't know of any that are doing it the same way as the Camcos. Keep in mind that when you disable this feature on the Camco it will behave just like your ''Modern'' amps.

 

[Ryan Lantzy]

Re: Intro to bi-/tri-amping

Show me any other amp that turns down the input signal to limit the distortion level. I know of none although I haven't read about all of the Powersofts and newer Labs but I don't know of any that are doing it the same way as the Camcos. Keep in mind that when you disable this feature on the Camco it will behave just like your ''Modern'' amps.

While difficult to "show" you on the internet, this is exactly what my Yorkville amps do, I've seen it on a scope.



When driven into clipping with the limiter engaged, the waveform never flat-tops. The crest factor of the signal is lowered as the average level continues to rise (if one continues to raise the input level). The effectiveness and audibility of this is largely dependent on the attack and release times chosen.



Also, I think this is how Peavey DDT works... CS1400 manual, page 13.



http://www.peavey.com/assets/literature/manuals/00511000.pdf

 

[Robert Burns]

Re: Intro to bi-/tri-amping

RE: ''Clipped Waveform''

Here is an example:

http://www.ajaudio.co.uk/CONQUEST_4.JPG

 

[RYAN LOUDMUSIC JENKINS]

Re: Intro to bi-/tri-amping

Ryan, I just read about the AP amps and the CS amps and neither seem to work in the same way that the Camco does. I don't know if we are really helping the OP with this info but it might and it might be important to others in the future.



The Camco amps have a microprocessor that controls the input level rather than just compressing it.



The CS amp does seem to use some amount of clipping to start the gain reduction of the compression.



According to the Yorkville website, with the AP amplifiers you can get appro 2-3 dB more output on subs by defeating their clip limiter. They do not mention the monitoring of waveforms or distortion to start the limiting function. It may be a basic VCA limiter but they don't really explain it in their manual as quoted below.



Limiter Switch

With the internal limiters activated, the AP6040's gain is continuously adjusted to fit the signal within the available dynamic range. Occasional clipping is permitted. The limiters will not only help to protect your system's horns and tweeters, but will automatically make the best use of the available dynamic headroom. With the limiters activated, all you need to do is turn up the signal level until you start to see some clipping. The limiters will make sure that you are getting the maximum clean power output at all times. Setting the switch to the IN position completely disables both limiters.



I wouldn't expect to find all of the exact same types of features in amps that cost a fraction of the Camcos such as the CS or AP amplifiers. I still haven't read up on the Lab Gruppens or Powersofts but they may have similar protection devices. I'll have to look those up inthe next couple days.

 

[Ryan Lantzy]

Ryan, I just read about the AP amps and the CS amps and neither seem to work in the same way that the Camco does. I don't know if we are really helping the OP with this info but it might and it might be important to others in the future.

The Camco amps have a microprocessor that controls the input level rather than just compressing it.

Regardless of what the Camco's use to do, if you think about it for a while you'll understand that it's essentially the same result.

If you have a device that lowers the gain of the input based on some threshold (arbitrary level, comparison of distortion, etc) you essentially have some compression going on. Sure, the attack, release, and hold may be different for all these brands of amps, but what the Camco's are doing is neither special nor novel.

I wouldn't expect to find all of the exact same types of features in amps that cost a fraction of the Camcos such as the CS or AP amplifiers. I still haven't read up on the Lab Gruppens or Powersofts but they may have similar protection devices. I'll have to look those up inthe next couple days.

You can use that expectation to help justify the cost, but personally I wouldn't pay a premium for good clip limiters (unless they are of the kind that are in the iTechs). I don't have Camco clip limiters and I've never lost a driver due to overpowering it through some occasional clipping.