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Compression, is it still relevant?

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Re: Compression, is it still relevant?

Postby CS70 » Mon Mar 16, 2020 12:18 pm

The Elf wrote:The thing is, most people bandy around the term 'compressed' as if it is one specific effect. It very much isn't! Compression can reduce dynamic range, but it can also *increase* it

The gospel is above.

As an addition, it may be worth commenting that what has become (largely) irrelevant - or, better, a "matter of personal preference" as opposite to "need" - is applying compression when recording.

You once needed to compress in input it because the recording medium had limited dynamic range, and considering that you wanted a good amount of headroom, compressing was often a necessity. Now the recording medium (24-bit PCM data streams) has much more range than needed to record any sensible audio, so you can just skip compression when recording and applying afterwards if you so like.

That said, if you get a good sound and trust your monitoring, you can still compress in input just fine - all of my vocal recordings tend to have a LA2A somewhere in the chain, and recently the Pultec clone in bypass mode as well, because I would just do the same first thing anyways.
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Re: Compression, is it still relevant?

Postby Hugh Robjohns » Mon Mar 16, 2020 12:41 pm

Arpangel wrote:I still don’t get it, compressed bass always seems to have well, less bass.
Drums sound lifeless compared to uncompressed, in fact, most things sound better without it.

If that's the case, you're doing it wrong! it is very easy to flatten the life out of almost anything with the excessive and inappropriate use of compressors/limiters. The skill and art is in choosing the right settings that control the dynamic range in an appropriate way without killing it.

And as the Elf says, it's perfectly possible to also increase dynamic range, either in real physical terms (although that's less frquenctly required) or in a pyschoacoustic way. The ear -- like most body senses, responds strongly to changes rather than absolutes.

Here's a handy teaching experiment: find a good source of spoken voice -- Radio 4 for example -- and pass it through a compressorset with a 2 or 3:1 ratio, and set it up for 6dB of gain reduction. The attack time won't matter too much for this, you're just going to play with the release time.

Start with the release time at 2 or 3 seconds... notice how smooth and flat the voice sounds. Lifeless... Now reduce the release time to about 100ms (the actual value is not critical). What happens?

The voice sounds louder, more interesting, even more exciting... And it's not because it is louder and the speaker hasn't suddenly become more excited about what they're reading. It's purely because the rate of change of volume between and across words has increased... and our ears/brains get more interested in that.

So get the settings wrong with a bass guitar and you can certainly strip all the life out of it. Get them right and you can enhance the impact while still retaining control. Same with drums and anything else.

H
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Re: Compression, is it still relevant?

Postby Tim Gillett » Mon Mar 16, 2020 1:10 pm

Ever since moving to digital I've almost never compressed when recording, especially on one off live recordings where the exact compression needed in the context of the complete sound cant be known until it's mixed. Usually compression cant be undone.

I'd much prefer the luxury of applying compression at leisure after the performance was captured where I can listen to everything with single minded focus, giving it my full attention.
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Re: Compression, is it still relevant?

Postby Arpangel » Mon Mar 16, 2020 7:06 pm

Seeing as I’m recording mostly to cassette these days, I guess I don’t need compression, it’s already there!

:D
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Re: Compression, is it still relevant?

Postby Tim Gillett » Mon Mar 16, 2020 10:41 pm

Yep the gear does it all for us, automatically. The box is ticked...
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Re: Compression, is it still relevant?

Postby Arpangel » Tue Mar 17, 2020 8:03 am

Hugh Robjohns wrote:
Arpangel wrote:I still don’t get it, compressed bass always seems to have well, less bass.
Drums sound lifeless compared to uncompressed, in fact, most things sound better without it.

If that's the case, you're doing it wrong! it is very easy to flatten the life out of almost anything with the excessive and inappropriate use of compressors/limiters. The skill and art is in choosing the right settings that control the dynamic range in an appropriate way without killing it.

And as the Elf says, it's perfectly possible to also increase dynamic range, either in real physical terms (although that's less frquenctly required) or in a pyschoacoustic way. The ear -- like most body senses, responds strongly to changes rather than absolutes.

Here's a handy teaching experiment: find a good source of spoken voice -- Radio 4 for example -- and pass it through a compressorset with a 2 or 3:1 ratio, and set it up for 6dB of gain reduction. The attack time won't matter too much for this, you're just going to play with the release time.

Start with the release time at 2 or 3 seconds... notice how smooth and flat the voice sounds. Lifeless... Now reduce the release time to about 100ms (the actual value is not critical). What happens?

The voice sounds louder, more interesting, even more exciting... And it's not because it is louder and the speaker hasn't suddenly become more excited about what they're reading. It's purely because the rate of change of volume between and across words has increased... and our ears/brains get more interested in that.

So get the settings wrong with a bass guitar and you can certainly strip all the life out of it. Get them right and you can enhance the impact while still retaining control. Same with drums and anything else.

H

I normally use very little compression, 2.5/3 ratio, medium/high threshold, fairly fast attack and a medium release, plus a bit of limiting on my BSS DPR402, just to catch peaks.
On my electric piano I use more extreme settings, to emphasise the attack, and bring up the tail of the notes, it’s very extreme, like the type of compression you hear on old films.
In fact, the worse the design, the "better" it sounds!
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Re: Compression, is it still relevant?

Postby CS70 » Tue Mar 17, 2020 11:39 am

Arpangel wrote:Seeing as I’m recording mostly to cassette these days, I guess I don’t need compression, it’s already there!

:D

Well a cassette has 60 to 70dB of dynamic range, so you may need some - depending on what you record and which kind of fidelity you want (which I reckon isn't much as otherwise you wouldn't use them :)).

On the other side cassettes have also a quite limited bandwitdh, rolling off bass and highs (not to mention what happens when you bounce) so compression can well be the last of your problems :D
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Re: Compression, is it still relevant?

Postby Tim Gillett » Tue Mar 17, 2020 2:04 pm

70 db S/N is very optimistic for a cassette unless Dolby C or DBX NR was used.

It's no surprise better equipped portable cassette field recorders from Sony, JVC and others usually carried, in addition to Dolby or DBX NR, a switchable limiter to handle "overs". Unfortunately the meters didn't always tell you how hard the limiters were working which could lead to wildly overcompressed field recordings unless you also monitored the recording with headphones.

Many analog tape recordings were prone to print-through echoes, and it got worse the longer the recordings were stored, but cassettes because of their very thin tape stock were even worse. I have some cassette recordings of broadcast radio programmes recorded direct within the radio station but upstream of the broadcast compressors, and the print through now is often horrendous. Particularly bad on solo speech or interviews. You hear every pre and post echo. Compression/limiting could be very effective in masking print-through echoes though.
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Re: Compression, is it still relevant?

Postby Hugh Robjohns » Tue Mar 17, 2020 2:10 pm

Tim Gillett wrote:70 db S/N is very optimistic for a cassette unless Dolby C or DBX NR was used.

It would still be optimistic even then!

I suspect the figure CS70 quoted has come from the highly dubious wikipedia page comparing analogue and digital audio formats:

https://en.wikipedia.org/wiki/Comparison_of_analog_and_digital_recording

... which seems to think the compact cassette format has exactly the same dynamic range as a 1/4-inch open reel machine. :roll:
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Re: Compression, is it still relevant?

Postby Tim Gillett » Tue Mar 17, 2020 2:34 pm

True, a Tascam 122 MkIII using Dolby C with a Metal cassette could manage 78db S/N but only above 1kHz . Dolby C petered out at about 200 Hz so in the noise floor the lows predominated, and mains induced hum into the repro head could be an extra problem.

And yes the claim that NR allowed cassettes to now match open reel was very misleading. The cassette figures were with NR engaged while the open reel figures were without NR. With the same assistance of NR, open reel stayed well ahead, as we would expect.
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Re: Compression, is it still relevant?

Postby Arpangel » Thu Mar 19, 2020 9:56 am

I sometimes use noise reduction on my Tascam 414, depends what I’m doing.
I love all the hiss and noise though, it’s like a giant noise generator, if you treat it like that you’re OK.
I recorded an electric piano track yesterday, I’ve got the line output of the 414 connected to an old Yamaha GC2020 compressor, and it’s amazing, it makes the 414 sound like an old 40's film soundtrack, the 2020 only really has two settings, off, or pumping!
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Re: Compression, is it still relevant?

Postby Tim Gillett » Thu Mar 19, 2020 8:35 pm

I have a GC 2020 in my TV audio system. It seems like a standard comp limiter to me. In 40s optical film sound tracks the background noise doesn't pump although ham fisted modern attempts at denoising can give them a shocking gated sound. Sometimes I use the compressor to try and undo that horrible effect to help restore clarity to a now unintelligible dialogue track.
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Re: Compression, is it still relevant?

Postby Hugh Robjohns » Thu Mar 19, 2020 9:17 pm

Arpangel wrote:... the 2020 only really has two settings, off, or pumping!

The more you say about compressors, the stronger my conviction that you don't fully appreciate the functions of their generic controls.
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Re: Compression, is it still relevant?

Postby Arpangel » Fri Mar 20, 2020 9:39 am

Hugh Robjohns wrote:
Arpangel wrote:... the 2020 only really has two settings, off, or pumping!

The more you say about compressors, the stronger my conviction that you don't fully appreciate the functions of their generic controls.

The GC2020 is bad Hugh, it’s OK for light compression, or as an effect.
I have a BSS DPR402 and have mo trouble with that at all, it’s my best compressor, and we use it in the piano room where we want something half decent.
I also have a Behringer Composer, that’s fine too, great at transparent compression, and easy to set-up.
I think I understand how to use them, and don’t have any issues normally, I’m using the GC2020 purely as an effect, on the output of my Portastudio, to emphasis the noise and grunge. I like that gated noise effect, and it’s good at that.
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Re: Compression, is it still relevant?

Postby Tim Gillett » Fri Mar 20, 2020 10:35 am

Arpangel wrote:

...The GC2020 is bad Hugh, it’s OK for light compression, or as an effect.
... I’m using the GC2020 purely as an effect, on the output of my Portastudio, to emphasis the noise and grunge. I like that gated noise effect, and it’s good at that.

I checked my old Yamaha 2020II compressor today. All functions work, at least they did after I put it on the bench some years ago and cleaned the dirty switches and pots.

It's not highly sophisticated but it does what it's supposed to. Variable ratio, attack, release, threshold, input and output gains. Ganged or separate, and has a separate gate/expander on each channel. I'm not surprised it was popular and Yamaha kept it in production for some years.

I wonder if you are not understanding that compression and expansion are opposite functions. The gate is a downwards expander. To bypass the gate, the knob needs to be turned fully counter clockwise until it clicks. In my TV listening application I never use the gate.

Also with the two separate channels it's easy to mismatch the settings and for the stereo image to jump left and right. Sometimes to make it simpler on a mono source such as an older movie I only use one channel. No need to match two sets of settings.

Hope this helps.
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