Ask Ralph : # 4 - What Is 'Compression' - ?

[westgrandboulevard]

'Ask Ralph' thread series :

# 1 - How A Track Was Mixed
# 2 - How A Tape Was Edited
# 3 - What Is 'EQ'- ?

- and -

# 4 - What Is 'Compression - ?

...and why is it necessary?

[ralpht]

Good question, West. I'm out for a day or so. I'll get back to this. Unless someone wants to jump in.

[thomas96]

I'll chip in on this in a little while when I have some more time to think and type. Good thread. As said before, we NEED MORE threads like this. Thanks, West.

[soulster]

Compression. Hmmm...there are several types of compression, and they each have different uses. I'll just give the very basics.

Compression makes louder sounds softer, and softer sounds louder, thereby reducing dynamic range.

Compression is an essential part of the pop recording process. Compression allows instruments and vocals to sit together in a mix. If one did not use compression, one would have a somewhat disjointed recording, and the recording could not be reproduced adequately on vinyl or on most stereos and radio. Just about every pop/rock.R&B recording has had compression used during the process or recording and sometimes mixing.

However, one does not need compression in the mastering process, although it is commonly used today in order to make the music louder on your CD. This has a detrimental effect on the music and results in a sound that does not sound like the master. The problem today is that the end-listener is so used to that compressed sound that they expect it, and think it sounds better.

Compression makes louder sounds softer and softer sounds louder, but the result is that transients are softened or blurred, and the sound is more "in-your-face".

Band compression: compressing one frequency range or octave.

Broadband compression: applying compression to the entire sound.

Limiter: limits the peaks of the musical signal or file, while maintaining the RMS [[Root Mean Square). This can be used independently, or in unison with a broadband or band compressor. The combination os often used in mastering to raise the overall gain to make the music louder. Unfortunately, this has a detrimental effect on the sound of the music.

It must be made clear that data compression, as with mp3, is something totally different than the compression we are discussing here, except, both types of compression still have similar sonic effects.

[thomas96]

Compression makes louder sounds softer, and softer sounds louder, thereby reducing dynamic range.

Not entirely true. I don't believe it can make softer sounds louder.

[westgrandboulevard]

Thank you Ralph, Thomas96 & Soulster.

One thing I've noticed over the years is sometimes the tonal quality of the instruments on the finished recordings seems reduced. I guess then that must be the compression used, to squeeze bass, drums, piano/organ, brass section, strings, vocals ,and the kitchen sink, into the finished recording.

To my ears, there's a much better quality of sound to the brass and drums on, say, Stevie's 'Music Talk', or the trombone/brass sound on Shorty Long's 'Baby Come Home To Me' than on many other tracks from Hitsville Snakepit. I've often wondered why that is so. Maybe it was just the way those tracks were recorded, or maybe less compression was used on those two particular tracks?

Is compression always present on a master disc? If so, presumably the degree of it can be varied on any subsequent remasters and/or remixes?

I understand Soulster's point about newer mastering wanting to maximise the volume, to the detriment of the sound quality. I guess the 'boom' factor is considered as very desirable.

I often wondered if a standard sound level was a requirement on the Motown albums, both on the tracks featured on each album, and also between each album. I remember noticing that 'Standing Ovation' by Gladys Knight & The Pips seemed much louder [[more compression?) and also the Jackson 5 albums.

As for the singles, 'Does Your Mama Know About Me' by Bobby Taylor & The Vancouvers always sounds under-recorded to my ears, no matter where it features...but I'm unsure if that is just in the production, or if it has anything at all to do with compression.

[soulster]

Not entirely true. I don't believe it can make softer sounds louder.

But, it does. It has that effect. If you have some audio software with a compressor, try it yourself.

Compression is exactly the thing that is too commonly used on the CDs we buy today, and why so many of them sound bad.

Once the effects of compression are pointed out to you, you always hear them. Thing is, most people do not know what to listen for or what they are supposed to hear. That is probably why you don't believe compression has the effect of making low-level sounds louder. In fact, that's precisely why it's used. It helps people hear the softer sounds in a recording on, say, your smartphone or in your car, or when playing music at very low levels. It makes the music sound more one-dimensional, in-your-face, with little or no front-to-back depth to the sound that lends to the illusion of realism.

Stick with me. I'll turn you into an audiophile yet! LOL!

[soulster]

Thank you Ralph, Thomas96 & Soulster.

One thing I've noticed over the years is sometimes the tonal quality of the instruments on the finished recordings seems reduced. I guess then that must be the compression used, to squeeze bass, drums, piano/organ, brass section, strings, vocals ,and the kitchen sink, into the finished recording.

To my ears, there's a much better quality of sound to the brass and drums on, say, Stevie's 'Music Talk', or the trombone/brass sound on Shorty Long's 'Baby Come Home To Me' than on many other tracks from Hitsville Snakepit. I've often wondered why that is so. Maybe it was just the way those tracks were recorded, or maybe less compression was used on those two particular tracks?

Rape, when saturated, presents its own kind of compression by the dynamic range being reduced. Bouncing, if done enough times, can also have a similar effect.

Is compression always present on a master disc? If so, presumably the degree of it can be varied on any subsequent remasters and/or remixes?

Just about every pop/rock/R&B recording made in the last 55-60 years has some type of compression used on it. Again, compression is what makes the instruments and vocals sit well together. A limiter, which Motown used, is also a compressor.

I understand Soulster's point about newer mastering wanting to maximise the volume, to the detriment of the sound quality. I guess the 'boom' factor is considered as very desirable.

Well, compression reduces bass, not in volume, but in intensity or strength. many times, when mastering compression is used, the sound is also EQ'ed to help make up for what is lost with compression. So, many of the CDs we get today, and for the last couple of decades, are really jacked up.

I often wondered if a standard sound level was a requirement on the Motown albums, both on the tracks featured on each album, and also between each album. I remember noticing that 'Standing Ovation' by Gladys Knight & The Pips seemed much louder [[more compression?) and also the Jackson 5 albums.

There are no standards in the audio recording industry, although Bob Katz has introduced the K-2 system, which mimics the standard used for the motion picture industry. Apparently, not too many engineers are using it.

Now, there are ways of making your sound louder without using compression, and, one of them involves deliberately clipping the digital signal [[putting the meters into the red).

As for the singles, 'Does Your Mama Know About Me' by Bobby Taylor & The Vancouvers always sounds under-recorded to my ears, no matter where it features...but I'm unsure if that is just in the production, or if it has anything at all to do with compression.

You are probably used to compressed CDs. What you're hearing on that song is dynamics. Dynamics provide peaks and valleys in the recording that make it exciting. You don't say whether you are referring to the stereo or the mono mix. As we all know, many times the stereo mixes, usually done after the mono mix, sounded weak. Some engineers in the 60s also added a bit of reverb to the stereo mixes for no other reason than to make them sound different from the mono mixes.
Note that a lot of those new stereo mixes that were done by Harry Weinger a decade ago, or the original stereo mixes that were reissued on CD, do not have extra reverb added. They sound drier as a result.

This is generally how compressors are used in mastering these days: You compress the music. That has the effect of increasing the RMS and reducing the peaks, thereby reducing the dynamic range. This can be done carefully as to not draw too much attention to itself. Next, you raise the overall volume of the music. This can now be done because the compressor has already reduced the peaks. In digital, you can't have overs, so you would also employ another compressor: a limiter, to ensure those peaks don't exceed full-scale digital. That limiter, like the other compressor[[s) has settings for attack and release so one can tailor the settings to the music to minimize the effect of compression. Ever rip a CD and look at the wave in an audio editor? Does it have long jagged edges? Short ones? Does it look like a "brickwall" with no peaks and valleys? That last one is not natural, and you can be assured that it is not the way that master tape or hard drive sounds. And, today, unfortunately, it is because the recording and mixing engineer built in the compression. Not good. You can't even get rid of it by doing a remix! One example I can think of is Paul McCartney's "Memory Almost Full" album. The compression is baked in the multitrack. There's no remixing it. Ruined for all time. On the other hand, remember Daft Punk's "Get Lucky" from last year? Sounds better, doesn't it? The vinyl version wasn't compressed during mastering. But, again, compression is used on all pop recordings, but this one wasn't over-cooked. Compression was used on the drums and the vocals, for sure.

I'm rambling now. I've been up all night and have to go to work later.

[soulster]

OK guys, I found an excellent tutorial of what compression is, and it is consistent with a lot of what I wrote above, including why it makes softer sounds louder and louder sounds softer. This tutorial uses Stevie Wonder's "Superstition" as an example.

[soulster]

Here's one about compression ratios. And, BTW, the topic of compression is so large and diverse that one could write an entire book on it.

[westgrandboulevard]

Soulster,I really enjoy these 'show and tell' tutorials.

If one could indeed write a book on the topic of compression, why should it not be you - ?

[ralpht]

Sorry I've been away for a bit and just catching up on this interesting discussion. Not much more I can add, other than, don't over complicate compression. Used sparingly it will do wonders for a recording. Over use it and you will ruin a song. Most of what comes out in today's "music" is way over-compressed and any dynamic range the mix might have had is shot.

Personally I most always put a little compression an the snare drum. I never liked the sound of a slightly ringing and sloppy sounding snare. A little compression always tightened up the sound, bringing it solid into the mix.

Good job guys.

[westgrandboulevard]

Just reading through Soulster's post # 8.....

What is meant by 'Rape' and' Bouncing' - ?

How is/was reverb[[eration) achieved - ?

To demonstrate the effect of reverb, are there any examples which can be offered demonstrating the presence of reverb - and then, in contrast, another example of the same track, but where reverb is not present?

[soulster]

Just reading through Soulster's post # 8.....

What is meant by 'Rape'

Oops! Typo! I meant "Tape".

How is/was reverb[[eration) achieved - ?

To demonstrate the effect of reverb, are there any examples which can be offered demonstrating the presence of reverb - and then, in contrast, another example of the same track, but where reverb is not present?

You can actually learn a lot of this stuff online. http://en.wikipedia.org/wiki/Reverberation

Are you familiar with the version of "Do You Love Me" by The Contours on "The Complete Motown Singles Collection"? Well, that would be the "dry" version' The actual single version on the first Hitsville U.S.A. boxed set would be the one with the reverb added to it.

[Doug-Morgan]

Were devices like an Echoplex or Fisher Spacexpander used in the studio? At a radio station I was at we used an Echoplex on the mike, and if you listen to some very old WKNR aircheck, I swear you can hear the spring reverb of a Spacexpander.....

[ralpht]

Doug,

When I first got involved in what would evolve into Tera Shirma, I had, in the studio, some sort of spring driven echo device. I can't remember the make though. It worked.

[soulster]

Here ya go! http://www.soundonsound.com/sos/mar0...singreverb.htm

[westgrandboulevard]

Soulster....

Yes, I can indeed hear a difference between "Do You Love Me" on the CMSC Vol 2 set, and on the Hitsville USA collection.

The first one [[the 'dry' version, as you say) to me lacks some of the sound qualities which epitomise the 'Motown Sound'...[[but which probably only says something about how I personally perceive The Motown Sound!)

I have some topics noted for further 'Ask Ralph' threads. One of them is how that 'Hitsville Echo' was created....but now I'm wondering....was what I have always felt to be 'echo' really not that at all...but actually reverberation - ?

If it was, that proves we learn something new every day.

If it was not, I'll start another thread....

[drlorne]

Thanks for sharing your knowledge Soulster and Ralph....learning new sftuff and finding answers to things I wondered about.

[soulster]

I have some topics noted for further 'Ask Ralph' threads. One of them is how that 'Hitsville Echo' was created....but now I'm wondering....was what I have always felt to be 'echo' really not that at all...but actually reverberation - ?

This is very likely the exact one Motown used:
http://mixonline.com/TECnology-Hall-...reverb-090106/


It was literally a large unit that was placed in an isolated room.

[westgrandboulevard]

That's very interesting. It sounds much more primitive than modern technology, but it served its purpose well.

Was it a true story that a hole was knocked on the ceiling of the Snakepit, to give a bigger sound?

[ralpht]

Soulster,
What you're showing in the picture is an EMT. It utilized a large metal plate to create reverb. In the early days, Motown didn't have one. In fact I don't remember Studio A ever having one. They were pricey. I had one in TS Studio B. Until digital reverb became more sophisticated, this was the best there was.

[westgrandboulevard]

If an EMT was not used, how was the reverb [[had the same effect as 'echo'??) tackled in Studio A, Ralph?

[soulster]

Soulster,
What you're showing in the picture is an EMT. It utilized a large metal plate to create reverb. In the early days, Motown didn't have one. In fact I don't remember Studio A ever having one. They were pricey. I had one in TS Studio B. Until digital reverb became more sophisticated, this was the best there was.

OK. I believe you. I was going off what I once read. A "name" engineer who worked on Motown tapes once stated that Motown most likely had an EMT plate. What I am wondering about is where would they have put it?

[soulster]

If an EMT was not used, how was the reverb [[had the same effect as 'echo'??) tackled in Studio A, Ralph?

The stairwell or the bathroom were popular places for studios because you typically had natural reverberation in those places.

[ralpht]

Motown L.A. did have a couple of EMTs but the best reverb at Studio A Detroit was a live chamber that utilized attic space, thanks to Mike McLean.

[westgrandboulevard]

Ah yes, that's it. I've never been to Hitsville, but felt sure I had heard that something had been done with the space above the studio.

People who have visited that, I believe, relatively small recording studio often seem to say they can't understand how such a big sound came from within.

On one of the radio programmes here in the UK many years ago, someone connected with Motown commented that they approached Hitsville one day, when a Martha & The Vandellas track was being recorded - and they could feel the ground shaking...

Has Mike McLean set out anywhere his recollections of those days, for the rest of us to read - ? I seem to remember reading that he said there were three echo chambers on WGB. the one at 2648 was the original, and there were two others..and one burned down - ?

[soulster]

Motown L.A. did have a couple of EMTs but the best reverb at Studio A Detroit was a live chamber that utilized attic space, thanks to Mike McLean.

Cool! I didn't think an attic would have reverberation. Well, we don't have attics or basements out here, so, how would I know?