The rise in noise in compressors usually comes from the make-up gain amplification. This means that the more you compress, the more make-up gain is needed, and more amplification noise is introduced to the signal (and that may be avoidable when using compression in a smart way). That noise propagates further in your setup and could be amplified by the following pedals which add their amplification noise as well, including the amp used at the end of the chain. Similarly, any amplification device placed in front of the compressor may add amplification noise and that is picked up and amplified by any make-up gain circuit further down the line.
It is important to note that if your compression setting needs a lot of make-up gain then the amplification noise will be way higher and audible during the absence of the working signal (music pause). This is because the signal to noise ratio is very low during such pauses (actually, the noise is higher than zero signal, which means you are in negative SNR) when compared with the signal to noise ratio during compression. You should not expect to dial in +20dB of gain and hear no noise. However, if you compress the signal -20dB then recover it with +20dB of gain then the amplification noise is only hardly audible, yet obviously there. You cannot avoid this. And, if you want to understand how hugely loud 20dB of gain gets, set the compression to 1:1, dial in the make-up gain to the maximum and play. In fact, if you need the entire available make-up gain you are in hard-limiting territory and no longer compressing.
To correctly compare compressors noise, they must be set for the same exact amount of threshold, ratio, and make-up gain, and be fed the same reference signal. Some manufacturers limit the Ratio of their compressors to 7:1 or as low as 3:1 and those indeed make for “very silent compressors” because they don’t need as much re-amplification. Of course in this regard, the “silence” characteristic has a subjective meaning if it’s not a misleading statement.
Particularly with the CompIQ Twain, it is easy to add more noise than necessary in the Stacked Mode, which puts the compression engines in series, like you would stack two pedals. We do explain more about this in the Twain Settings Examples, and the trick to controlling amplification noise in this mode is to use the last (highs) engine compression and make-up gain more than what you use in the first (lows) engine. You would try not to compress too much in the first engine and keep the make-up gain low, then go furthermore in the second engine and use its make-up gain as a master gain. Another trick is to pass some of the frequencies to compress to the second engine by means of, raising the lows threshold, using the Low or Deep side-chain filter, and using the soft knee to mitigate either noise or compression feel. You may combine these controls in both engines to find the sweet spot for your application.
The dual-band processing is usually more tricky and is more of a specialty type of compression, where it is easier to set it “wrong”, although there is no wrong in setting it in any way. It is just that what works for full-band compression cannot be applied one-to-one to dual-band compression.
Besides that, the crossover used in dual-band compression is an “always-on” circuit that has many passive components which are needed in the filters section, and all the resistors that compose these circuits inherently add what is called “thermal noise”. And that, of course, is also getting amplified with the make-up gain. This is valid for any dual-band compressor.
Here is a working strategy. Try to understand how the compression controls (threshold, ratio, knee, timing, blend, side chain filter, gain) affect compression in general and ask yourself what you are trying to achieve. Combine these parameters to set up compression in such a way that the make-up gain can be set lower.
Worth knowing:
- at higher input signal levels, the makeup gain-related noise will be lower, because you deal with a bigger signal in the first place;
- if you set a higher threshold, hard knee, and inf:1 ratio and you affect only the peak of the signals – as this limiting setup makes sense to be used – the noise will be inaudible.
- for weak magnetic pickup signals, at the lowest set threshold and with ratios around 4:1 (which is a fair amount of compression), the CompIQ make-up gain will introduce noise similarly to studio-grade equipment.
- on top of Threshold, you have the MIX control which helps reduce noise by blending in the dry signal;
- using a soft knee also contributes to reducing the need for make-up gain, so implicitly it reduces potential noise.
Power sources are also a proven source of adding noise to electronics. Switching power supplies will almost always add hiss. We recommend using only good quality, well filtered, and regulated power sources. The pedals in general do not have enough space to fit large capacitors and additional necessary electronics for good power conditioning. And, pedals are not supposed to filter power sources anyway.
CompIQ ONE
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CompIQ TWAIN
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Overdrive / Switcher
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