Hi David,
There is no reason to guess at how to use a compressor/limiter. And certainly no reason to settle for a “preset”... a compressor/limiter much like an Equalizer is a device that truly depends on the incoming signal. While someone could very generally tell you how to EQ a vocal, it really *depends* on actually hearing the voice being recorded.

The thing about setting a Compressor/Limiter is you have to be there to know how to set the critical parameters that allow the device to do what it is designed to do. Fortunately, when you know what to look for, you can know exactly what to do, and you can know you are getting the results you require.

It is totally serendipity (luck) when a preset happens to be the right setting. Presets are provided to help people get in the general ballpark.

A Compressor/Limiter is an amplifier that the more signal you put in, the less you get out. The “threshold” is the setting at which instead of allowing the Amplitude to proceed to increase, the device ‘kicks in’ to reduce the amount allowed out.

Example, say you have signal that un-effected wanted to exceed the point of clipping... you would set the “Threshold” so that once the Amplitude reached a certain point, the compressor would automatically begin to turn the signal down. A RATIO of 2:1 (two-to-one) would prevent a signal that wanted to go 2dB above the threshold point to only exceed that point by 1dB. If that signal wanted to go 4dB above the threshold the compressor would only allow it to go to 2dB above that point. Two-to-one.

2:1, 4:1, and 8:1 are considered a Compression. The result overall is reduced in output because you are starting to control (restrict) how loud the signal gets, you are literally “compressing” the dynamic range. The result is the soft sounds (which are unaffected) are now closer to the loudest sound... the overall distance between softest and loudest has been reduced, compressed.

Ratios of 10:1 and 20:1 are considered Limiting. The fact that you would need energy enough to exceed the threshold point by 10 or 20dB just to get 1dB louder is, in effect (pun intended) Getting no louder. A “drop dead” Limiter is used in most situations when singers on stage are fond of “dropping the mic” at the end of the show. Without a LIMITER on that microphone, dropping a mic on stage could do thousands of dollars in damage and cause scores of law suits, as you might windup deafening hundreds of people. A Limiter will prevent major spikes in volume from damaging delicate components (not only in the gear, but in the listener’s ears)!

What happens if set improperly is a Compressor/Limiter can remove all dynamics... a situation where the soft and loud sounds are so close together the sound is literally “squashed”. And because we have a brain attached to our ears, we can interpret the nature of sounds... here’s what that means. If you whisper, other humans know that this is meant to be ‘for your ears only’ - we have an expectation that this is soft. When over compression is severe... a whisper is still excepted as soft (even at 120dB) if you shout into that over compressed situation, the shout will be so reduced, that you may start to perceive it as actually being softer than the whisper... because a shout, we anticipate to be loud... so reducing it (or better put) over reducing the loudest sounds makes us think it is actually softer.

Either way, overcompression kills the joy of dynamics. Avoid over compression. You do so by setting the Threshold point wisely. Experience is the best teacher... that and knowing what to listen for.

You want to set that Threshold point (not from a preset, not from a piece of paper) but based on the person attacking the instrument you are compressing. You want to preserve as much of the normal/natural soft-to-loud dynamics as possible. Knowing now a Limiter virtually prevents the signal from exceeding the Threshold, you want to set that point so that at your very strongest playing the Limiter is just starting to reduce the signal. Why -0.5dB is a typical setting should now be obvious... if 0dB and above is clipping, then this is ver close to edge and will likely stop clipping. But that is assuming something the person creating the preset CANNOT POSSIBLY KNOW! and that is — the current specific input.

That is your job. What if your signal never reaches -0.5dB? You’ll get no reduction in signal at all. Expect to SET the Threshold. It varies on different inputs, it can vary on different types of songs... it’s the wildcard. Expect to lower it. And to keep lowering it until you start to clearly hear it messing with the normal dynamic of your soft-to-loud... and *know* that it now sounds weirdly squashed — avoid the weirdly squashed by backing off in the other direction. Like setting all utility processors... experiment with knowledge... the Threshold is the key in this device. It’s setting is critical above all others. As compression or limiting occurs your perception of sound changes as well. The sound will be fatter, thicker, seems to have more ‘presence’, more weight... these are terms we tend to use when listening to compressed signal.

Attack and Release. If set improperly you will never hear what you want... the more percussive the sound the lower the Attack time. Drums and mallets sounds should be set for a reasonable fast attack. If set to high, your mallet strike and entire sound will have come and gone before this has a chance to kick in. The Release should also be fairly short because you want the compressor to reset for the next Note.

The Output Gain, or ‘Make up’ Gain is there so that you can get soft-to-loud dynamics you need, which if you are getting this... is handled by leaving the softer sounds alone and manipulating the ceiling. If you lower ceiling, so the louder sounds are now closer to the softer, you have done so by “turning” the overall signal down (an amplifier the more put in the less you get out) the Output (make up) allows you to now boost the entire dynamic range, offsetting it louder so that “unity gain” can be achieved... you can be as Loud as you were but now you *know* you will not clip the system.

A controllable ceiling. I would recommend using the “Classic Compressor” for your purpose. It has just what you need (the Uni Down has items you are not using and are not at all necessary for your stated use). This can be applied as an Insertion Effect on a per Part basis.

The “VCM COMPRESSOR 376” is based on the very widely used Urei1176... back in the day, it was everywhere. This one can be used on the Part or as a Master Effect.

Hope that helps.

@David

BM alluded to this - but, in Yamaha terms, the "Master Effect" is applied at the end of the effects chain and automatically will cover all PARTs including anything such as A/D inputs that are output to the Main L&R output. You can edit the master effects by pressing [PERFORMANCE] so you are at the "HOME" screen. Then press the Performance name at the top. A side menu will pop up, choose "Edit". Then go to the menu "Effects" -> "Master FX".

A lot of info there, BadOne...I'm not trying to do anything here except be sure that peaks don't cause clipping / distortion in the signal chain downstream; in fact I don't want any typical compressor effects like reduced dynamic range, increased apparent loudness, more presence / weight, etc....so it seems like with threshold to slightly below 0.0db and ratio set high, then the compression effect would never kick in unless there was a peak that was going to cause a problem, and below that the signal level, dynamics, and tonal quality would be essentially unchanged, which is what I want...

Make Up Gain is probably a non-issue here, since the compression would typically never kick in...as you say, Attack and Decay should be fast for mallet sounds, but again it's probably a non-issue in this application...the MODX doesn't have a "Classic Compressor" effect; the Multi-band Comp may be closest to that, although with separate low, mid, and high frequency compressors, it's more than is necessary, too, for this use...and VCM Compressor 376 doesn't have a Threshold setting, it's probably optimized for that "classic Urei 1176 sound"...

df

Not sure if reference to "Classic Compressor" is literal or not (in terms of Yamaha's "Classic Compressor" ), but the "Classic Compressor" effect is available on MODX as a System effect - although, true, not as a master effect. You can therefore apply "Classic Compressor" to all PARTs' system effects.

I think that I'd want limiting as the master effect, to apply to everything just before the output (and I'm pretty much using up the other effect slots, anyway)...I notice that a lot of the preset performances have the Multi-Band Comp compressor as the master effect, although it's not turned on...I'll experiment with that a bit, since it's probably the most flexible of all the compression effects...

df