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Any Delay In A Compressor?

#4
Not generally. There are a few ways of doing it, but the envelope follower is not in the signal path, so any delay on it doesn't change the signal time.

What a comp has is a variable gain stage that is controlled by the amplitude of your signal. Any delay in the envelope follower would just delay the time it takes for the compression to start. Simply put, it's like a guy turning a volume knob. The louder the signal, the more he turns it down. If he takes awhile to notice and turn it down, that just means it's louder for a bit before getting compressed.

Of course, depending on the gain stage, there may be changes in phase or possibly a minor unnoticeable delay (~1ms at most); however, that's something that could happen in anything with a gain stage (basically every effect, preamp, amp, etc out there).

Bongo can probably explain this better than I can. Hope this helps explain it though.
 
#5
SurferJoe46 said:
Since a compressor prolly requires some time to achieve it's job of limiting or compressing sound, does that add a little delay or cause the signal to be late in exiting the compressor?
Click to expand...

Generally no, at least not in a compressor with an analog signal path. A DSP-based compressor which converts the signal to digital then back to analog would add a small amount of delay (latency).

Dynamic range compression - Wikipedia, the free encyclopedia
 
#6
Kinda what I thought.

I want to ask another question then: a compressor or limiter - can it be used on both or just one side of the output signal?

I mean - since there is push-pull signal to the speakers, can just one side of that be limited or compressed and that would affect both sides of the signal?

It seems to me that one could both limit the output or limit the return and that would be like the same thing.

Wouldn't that simplify the compression/limiting process and make the device that much less expensive and even more adjustable?

I had a thought when I was running my sideband radio today and switching from Upper to Lower got me thinking.
 
#7
I think it's possible to just compress one portipn of the waveform. My knowledge of their function isn't complete so I'm not entirely sure. I don't think it'd be the same as compressing the full thing though; compare symetric and asymetric clipping. It would be less intense of course, since there isn't clipping, but it would be a similar sound difference I assume.
 
#8
SurferJoe46 said:
a compressor or limiter - can it be used on both or just one side of the output signal?
I mean - since there is push-pull signal to the speakers, can just one side of that be limited or compressed and that would affect both sides of the signal?
It seems to me that one could both limit the output or limit the return and that would be like the same thing.
Wouldn't that simplify the compression/limiting process and make the device that much less expensive and even more adjustable?
Click to expand...
No. There is nothing about the idea of compressing just the part above "zero" or just the part below "zero" that would even remotely suggest using fewer parts, a simpler circuit, lower cost, or anything like that. It's not like half the components in the circuit are for the + half of the wave and the remainder for the - half. Think about a passive volume pot: it acts on the whole wave at once. A compressor is just an elaborate type of volume pot.
 
#9
bongomania said:
No. There is nothing about the idea of compressing just the part above "zero" or just the part below "zero" that would even remotely suggest using fewer parts, a simpler circuit, lower cost, or anything like that. It's not like half the components in the circuit are for the + half of the wave and the remainder for the - half. Think about a passive volume pot: it acts on the whole wave at once. A compressor is just an elaborate type of volume pot.
Click to expand...

+1. Asymmetric compression would probably also introduce higher harmonics of your regular signal, AKA distortion.
 
#11
Regarding delay, there can be a delay in the reaction of the volume-control device, but the audio signal itself is not delayed by this--it continues on at approximately the speed of light, near-zero measurable delay even through the gain stages.
 
#13
I guess if you think about it, your 20' bass cable is introducing about 15 picosecinds of delay. (ballpark math so don't correct or quote me - I could be way off.). Yes, it creates some delay but nowhere close to enough that you will perceive it.
 
#14
Any signal traveling at close to the speed of light over very short distances will not introduce any perceptible delay, certainly not in comparison with the speed of sound in air. Send it to the Moon and back.... and that's another matter....
 
#16
SurferJoe46 said:
^ then anything less that tape delay is nonexistent?
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No. Anything that involves data processing can introduce measurable delay. And it is possible to create analog systems that create delay by capacitance, electrostatic charging, and other means--but you really have to intentionally TRY to make that happen.
 
#17
bongomania said:
No. Anything that involves data processing can introduce measurable delay. And it is possible to create analog systems that create delay by capacitance, electrostatic charging, and other means--but you really have to intentionally TRY to make that happen.
Click to expand...

Yep... BBDs or Bucket Brigade Devices are a good example:

An analog signal is briefly stored in a capacitor and then sent off to the next capacitor according to the tick/tock of a digital clock. Do this hundreds or thousands of times and you've got analog delay. What's neat about it is that the signal itself remains analog throughout... even though the process involves sampling. Bit off topic though....

Back to an earlier point... if an analog compressor takes too much off of the beginning of the note, it might sound somewhat delayed because the immediacy of the initial attack has been lost or moved back a little. Also, if the compression ratio is high, it may make the notes appear to sustain longer because the compressor is bringing up their relative level as they taper off. But these effects are not representative of any significant delay in the actual signal... just representative of how the compressor has altered the signal's dynamic envelope.
 

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