I just read the article on the VCM 376 compressor, and saw the masterclass dvd. I think this is amazing and it’s going to boom the face to another space. But to understand it thoroughly I would thank Mr.Phil to remove the mist from these last questions I have on it:

1- I understand that a ratio of 20:1 is very severe, and it is considered a limiter, but how come I get more level when it is on 20:1 and less level when it’s 2:1 ?

2- in the article it says “The more you compress and the longer the release the longer the perceived sustain.” I understand that the sustain is percieved longer because the initial peak is compressed, and the same level is percieved for a little longer, but why would it be percieved longer because the time for the indicator to go back to 0 VU is longer?  (I made up a semi convincing answer to myself after reading it several times, but am not sure if it’s right, so.. I had to ask)

3- quote: “if the signal was strong enough to reach the threshold point and want to go 10dB above that point then the compressor only allows it actually increase 1dB above that point”

in the Masterclass, it is said that the ratio 2:1 allows you get half the dbs of the signal. but on the above quote it seems that it can go above the threshold?  ... I think there is something I’m not seeing, please help.

4 - quote from the power user, again, about the “pumping” : “..as if somebody was pumping in and withdrawing air from the environment. The silence will feel like fresh air and when the voice comes in the air is removed.”
shouldn’t the air feel removed when attack is too quick? instead of release being “improper”?

thanks in advance!

Yamaha made a power user called VCM compressor 376..Check the support section…

I know, my quotes are from that text… thanks anyway!

1- I understand that a ratio of 20:1 is very severe, and it is considered a limiter, but how come I get more level when it is on 20:1 and less level when it’s 2:1 ?

To understand a compressor it is all about perception of sound as you change the energy.

To keep the math simple: Lets say you set the THRESHOLD (the most important parameter in a compressor) to 0 on the meter. WHat this means is the compressor/limiter will activate anytime the signal reaches 0 on the meter.

All signals under 0 are not affected by the compressor/limiter AT ALL. All signals under the THRESHOLD are unchanged.

It would take a signal of +20VU to make the meter go to +1 if you set the Ratio to 20:1
The same signal would go to +10VU if you set the Ratio to 2:1

Now how a compressor/limiter is actually used - you set the THRESHOLD at a point that deflects the volume and keep it from clipping. So your THRESHOLD is always some negative number (before the signal reaches 0) After all the objective is to prevent the signal from exceeding 0.

So as a signal rises in Volume a compressor is a leveling amplifier that once you pass the threshold - the more you put in the less you get out. While a limiter is an amplifier where the more you put in (past that threshold) the output remains (virutally the same).

How this plays on the human perception is this. When you have a large (uncompressed) dynamic range, the soft sounds are far away from the loud sounds.

As you squeeze or compress the dynamic range the soft sounds are now closer to the loud sounds. Things that were soft (like breathing in, and lip smacks) are now right up front - yet the Loud sounds are not allowed to get much louder (they will be reduced by the math of the RATIO). As you change the RATIO you may notice an overall change in the OUTPUT level - but remember it is the distance between SOFT and LOUD that we are listening for. As you compress or as you limit the sound output is reduced but…

The OUTPUT parameter’s specific role is allow you to restore overall OUTPUT. You have reduced the SOFT/LOUD distance - to return the overall OUTPUT level to unity - so that the strength of the signal going into the COMPRESSOR/LIMITER is the same coming out. Thats what OUTPUT is about in the compressor/limiter.

When you A/B before and after - although the meters may not change much, your perception of what is more “in-your-face” definitely changes. Energy cannot be lost - it is converted - our perception is the sound is more “present” - phatter, thicker, more weighty, etc., etc. - a thousand other subjective descriptions for the science we have just described. The meter will tell you that it is not necessarily more energy, but your perception is that because the dynamic range has been reduced and the OUTPUT LEVEL restored, you can hear it better. Which as a human you swear that it is LOUDER. So even though the signal does not exceed 0, with the degree of compression or limiting will alter your perception of what you think is LOUD.

LOUD is a perception (subjective).  The fact that the soft sounds are no longer as soft (means you are less likely to ignore them) yes the brain tends to pay more attention to loud than soft.

2- Correct. By squashing the time of the peak and initial drop off - the signal remains consistent at a single volume for a time. The loudness envelope of a guitar compressed wave starts to resemble an organ envelope: rise to full volume and remain there (of course it is not indefinite) the string vibrates for the same length of time it always does. It simply stays at a consistent volume for a longer time. Remember the OUTPUT LEVEL can be used to boost the compressed signal to its full original volume

3- is a ratio (don’t mix these up with the Sound Pressure Level use of dB - like a jet taking off is 130dB (that is some kind of science made easy scale of the ratio of what will make your ears bleed versus the threshold of hearing… still a ratio, just not the one found on studio meters. Your job in the studio is to never let a signal go over 0 on the meter, ever.

If a singer whispers the first words of a song barely -20 on the meter, and then later shouts out the chorus and reaches +4 on the meter. This is a case where you need to make that whisper closer to the the shout, and you need to adjust the signal so that at no time it goes over 0. That is what a compressor is for. It will allow you to bring the whisper up and the shout down (narrowing the dynamic range)

4- Get a mic - you do it and you will hear what I’m describing. Like describing ice cream - words don’t do it justice.

You are not aware of any anomaly (at the attack) you become more aware when silence returns. Its like you don’t miss the air until its gone - and the big impact is when it returns!  As strange as this sounds - it is the return of silence that defines that silence.

Now that’s an explanation!

Ok, hope you can forgive me if I ask the why of the why, and maybe the why of that why. I think that it is critical to understand the mechanics of this. The *same* day that I was going to enroll on a sound engineering school, a friend’s friend came and told me the first classic music university of Peru was open, so I went for that, now I finished that school, and basically have learned about audio engineering concepts from Yamaha, maximum respect. And now I’m getting closer to understand the power of the Motif (I suspect/hope this understanding will get better), it’s architecture is genious and maybe not many, including me some time ago, have an idea of the energetic control it can offer.

There are a couple of things on the physics of the VCM compressor that I can’t picture yet. 

[quote ]Lets say you set the THRESHOLD (the most important parameter in a compressor)

My understanding is that the INPUT parameter is how much signal is being allowed to come in from another OUTPUT (or somewhere else), and at the same time, in some sort of “proportonal mechanic”, the THRESHOLD is set. what is this “proportional mechanic”? I can’t see the THRESHOLD, right? if it’s the most important parameter, why?

I understand the concept of compressing, and about the OUTPUT parameter-- compressing the peaks so that they are closer to the bottoms and then rising this compact dynamic range so that it has more “face-punch”.

the more you put in the less you get out. While a limiter is an amplifier where the more you put in (past that threshold) the output remains (virutally the same)

So here is one of my main blurs:

If more energy is put in, then less comes out. Does this mean that if I hit a key and give it more level, it will come out less?

20:1 = +1 2:1 = +10

Is the ratio something that affects the signal coming in or the signal coming out?

If a ratio of 20:1 lets me get (out?) +1, and a ratio of 2:1 let’s me get +10 (out?) of the compressor ... why does the 20:1 ratio sound with more “level”?

isn’t the 20:1 “squashing” more? 

why does the output remain the same when the ratio is higher (now deserving the name of limiter)?

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2- Correct. By squashing the time of the peak and initial drop off - the signal remains consistent at a single volume for a time… the string vibrates for the same length of time it always does

The length of the vibration time is the same, just that the peak is “pleateaued” and you can raise the output, but/so, how could long release then make the sustain longer? (I quoted a piece of text from the power user saying this on my initial post)

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4- Get a mic - you do it and you will hear what I’m describing. Like describing ice cream - words don’t do it justice.

You are not aware of any anomaly (at the attack) you become more aware when silence returns. Its like you don’t miss the air until its gone - and the big impact is when it returns!  As strange as this sounds - it is the return of silence that defines that silence.

Ok, I will try with a mike when I go home after work (haha). I basically get the point. But again, my question is/was, what is the relation with this and an impropper release setting? what is “impropper release setting”?  too quick? or too slow?

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Maybe I would/should make this last question in another time/space, but I wont, due to the interest of leveling up in a holistic way.

At the end of the power user of the VCM compressor, Toshi is quoted and he says that it’s not difficult for the VCM technology to reproduce expensive analog consoles and stomp boxes, or tube amps. I understand that the XS has a 24 bit resolution, how is this possible? I don’t really understand the relation between analog and digital, I only have a rough idea, is there any sound from the XS that comes out of the XS actually analog? or is it that just the VCM devices can mimic analog to a very close degree?

please enlighten me on sound.

The VCM COMPRESSOR 376 is a physical model based on classic 1970 Compressors - where the INPUT parameter represented a combination of INPUT and THRESHOLD. These are not science projects they were recording tools. basically you know what level you are sending into the device the threshold ‘ganged’
with the threshold parameter determines when the compression begins. The GR setting for the meter sets the meter at 0 and deflects downward showing how much peak reduction you are doing. That is what will help you visually.

The clasic compressors of the era (at least several of them) used this INPUT/THRESHOLD combined function and became the way many learned to use it. I’m sure I mention this in the article.

You don’t need to see the threshold - it is all about the results you are getting - GR - Gain Reduction. While some old school compressors had a separate THRESHOLD parameter, even then manufacturers where attempting to make this (often) misunderstood device easier to operate. The old dBx one-knob compressor gangs input/threshold and output to one knob.

All sound is analog. You cannot hear digital. To get audio into your Motif XF it has to go through an A/D converter (Analog-to-Digital) in order for the signal to get out of your Motif XF it has to go trhough a D/A converter (Digital-to-Analog).

The number of bits carrying the signal varies throughout the product. Most musician do not understand (nor do they really need to understand) how the bits do what they do. It is much like a saxophone player does not have to understand Bernulli’s Principle - the sax doesn’t work without it, but you’d interview a hundred sax players before you find one that knows what it has to do with playing a sax.

The effect processors process at 32-bit, the D/A and A/D are 24-bit, the sampler is 16-bit - don’t worry about it. Sound is always analog. It is always air molecules in motion.

got it… I also understood the pumping, it’s due to too much release.  but could you please check these other questions ?

So here is one of my main blurs:

If more energy is put in, then less comes out. Does this mean that if I hit a key and give it more level, it will come out less?

20:1 = +1 2:1 = +10

Is the ratio something that affects the signal coming in or the signal coming out?

If a ratio of 20:1 lets me get (out?) +1, and a ratio of 2:1 let’s me get +10 (out?) of the compressor ... why does the 20:1 ratio sound with more “level”?

isn’t the 20:1 “squashing” more?

why does the output remain the same when the ratio is higher (now deserving the name of limiter)?

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2- Correct. By squashing the time of the peak and initial drop off - the signal remains consistent at a single volume for a time… the string vibrates for the same length of time it always does

The length of the vibration time is the same, just that the peak is “pleateaued” and you can raise the output, but/so, how could long release then make the sustain longer? (I quoted a piece of text from the power user saying this on my initial post)

Don’t overthink things, that’s my advice. Turn the knobs, change the settings, see what happens. That’s how you learn what the compressor does.

Take your question about the 20:1 setting. The point is not why, but rather that “when I set it to 20:1, this is what happens”. It’s not just
setting the compression ratio, by the way - it’s the combination of ALL the settings that affect the sound, PLUS the kind of sound you are feeding into the compressor - a pad, a drumkit, a guitar, brass, each of
those instruments are going to sound different and changing the compressor;s settings will affect each of them in a different way.

Bad Misters’ explanations are detailed and exactly right. I’ll just add to that - when I was a young punk starting out in recording studios, I
didn’t have any manuals for the compressors in the studios - nor did I
really even know what compression was. I learned by turning the knobs this way and that until I eventually got the hang of what would usually
happen if I set things a certain way, on certain instruments.

ok, thanks, I let go of the others, but I would really like to understand this ratio parameter, I think I understand the rest now.

please :

If a ratio of 20:1 lets me get +1, and a ratio of 2:1 let’s me get +10 of the compressor ... why does the 20:1 ratio sound with more “level”?

isn’t the 20:1 “squashing” more?

Yes the 20:1 is limiting the signal and that means it is squashing it more. WOULD HAVE gone to +20, WOULD HAVE gone to a certain amount - but is prevented from going there - More squashed will sound louder at unity gain (equal output levels)… more energy is being squeezed.

In the LIMITED signal the soft sounds are now very very close and that plays with your brain’s expectation. I mentioned it several times but you have not picked up on it yet. You can no longer ignore breaths, lip smacks - they are now up front too. In the COMPRESSED signal soft sounds can still be ignored, because they are not as close.

When you begin to turn down the signal with the leveling amp you are changing the overall output of the signal.... and again this is the purpose of the OUTPUT parameter to return the processed signal to unity gain (means that if you had a certain amount of signal coming in, you want the same or approximately the same level going out).

That is when you need to make your comparison about which one is perceived as LOUDER - only after you have restored UNITY gain. Until you have restored Unitly you cannot appropriately compare the signals because each is a separate set.

When you set a threshold and the signal crosses it, that is when the compressor/limiter does something. Signal below the threshold is not affected at all. The signal must pass the threshold and then it is squashed.

Your “perception” is that the compressed/limited signal is louder once you have restored UNITY GAIN.
You are asking why the LIMITED signal is perceived as louder than the compressed signal. But have you accounted for restoring both to the same OUTPUT level? And that anything in the background is likely now up front and present.

That said, if you think LOUD tells you how much work a sound is doing - you will be surprised that your ears can lie to you (versus what the meter shows). In the equivalent to an optical illusion - where your eyes tell you that one this is true when it is not.

The only difference between LIMITING and COMPRESSION is a matter of degree. You may still experience silence in a compressed signal, in a limited signal you get no such sense of the soft dynamic.

A severly compressed (Limited) signal will seem louder and in your face. A whisper is so close an intimate your brain prepares for LOUD signal- a whisper still sounds like a whisper but the volume of the whisper causes your brain to anticipate what the normal singing or speaking voice would sound like.

A shout still sounds like a shout but with a 20:1 situation your whisper and your shout will be approximately the same on the meter. but your brain and ear will begin to question which one is actually louder.

You expect the whisper to be soft and the shout to be loud, but your ears say the whisper seems loud and the shout is soft - thus the illusion. I guess it has to do with expectations. Warm water seems cold if you moved from a hot tub, and seems hot if you were in ice water.

Trying to describe an aural illusion is as difficult as decribing an optical illusion. But if you ever begin to think you ears cannot be fooled - STOP. They certainly can.

A great book on aural perception: “This is Your Brain on Music”
- a must read for all musicians.

Would someone mind posting the link to the original article. I can’t seem to locate it and I ‘think’ this discussion has filled in some blanks I have had about the subject.
Thanks in advance
TBxR!!!! You ARE....The Bad 1!!!!

HEY DAVE P!!!!

TheDukester - 02 February 2012 02:08 PM

Would someone mind posting the link to the original article. I can’t seem to locate it and I ‘think’ this discussion has filled in some blanks I have had about the subject.
Thanks in advance
TBxR!!!! You ARE....The Bad 1!!!!

HEY DAVE P!!!!

You DK, send me an email or a pm, haven’t heard from you since I sent you
a Christmas email.

http://www.motifator.com/storage/support/Compressor1.pdf

It is a part of the Motif XS article on “Introducting the Motif XS Effects”

DaveP....will do.

Thanks, Bad 1!!!
Now as you know I am using an S90 XS. I have been fairly successful coming ‘here’ to the Motif XS on Motifator to get information on the axe.

Devoid of the big screen access, does this document serve as a guide in the S90 XS? Will I be able to use this document and find the accesses and make adjustments in the S90 in the way of Effects?

I know the task it must be to write these Power User Guides and it if you were to write them for both the Motif and the ‘S’ Series, you would probably get no chance to get out of the house.

Just ‘how close’ and ‘how much’ of the Motif XS articles and guides will I find useful for the S90 XS. I know the difference with Patterns, Songs and access and control to Arp editing and User Arps (and I’m exploring the possibility of getting a Motif XS) but I do run into some difficulties ‘translating’ some of the info.

Thanks in advance.......
TBxR!!!!

The S90 XS is the same synth engine as the Motif XS with a few exceptions everything that is about the XS will apply to the S-series XS’s.

The main differences are the ISS (Integrated Sampling Sequencer) - the Motif-series has it, the S-series does not. The Motif-series has the large screen because you can edit at the ELEMENT Level. The S-series does not need the large screen because you cannot edit at the ELEMENT level (without the EDITOR). They both feature the same 8 ELEMENT VOICE architecture

The S-series has more access to the architecture via its lighted front panel, while the Motif-series allows the person interested in sampling and building sounds from scratch to do so right on board the keyboard (or with the Editor).

So the articles on the Motif XS will apply to the S-series XS unless it deals with SAMPLING or the SEQUENCER. ANy article that deals with editing at the ELEMENT level - just know that you need to find that parameter in the EDITOR.

Also the Motif XS and XF are 8 ZONE master MIDI controllers, the S90 XS/S70 XS are 4 ZONE