All about compressors (links broken: sorry!)

[bmanic]

and just a thought, although it's not strictly compression, a real crunched reel to reel sound would do just fine in this thread. Don't suppose you've got an example handy with that drum loop of yours?

Not with the drumloop but you did abuse one of your tracks a lot. Wanna post a before and after snippet here? I could put it up on my server.

Next time I'm in the studio I'll run that drumloop and the vocals trough the tape.

Cheers!
bManic

[jess123]

This is slightly off topic but related to compressors.

When somebody says, use a threshold of -X db, what does it mean for a compressor such as this SSL http://www.waves.com/content.asp?id=2061
or even this
http://www.solid-state-logic.com/music/duende_sbc.html

1. If somebody says, compress it with a threshold of -21db, then wouldn't those bus compressors (link example above ) be not applicable as their max is only like -15db or -20db respectively?

2. Is there a diff between bus compressor and the 'normal' compressor like from Kjaerhus GUP/GCO or WAVES C1? I usually find bus compressor has positive db whereas the 'normal' compressor has only negative dbs.

Just wanna understand bus and normal comp a bit better(if there's a diff).

Thank you.

[bmanic]

First of all, if somebody talks about "set the threshold to this or that" then they do not know at all anything about compressors. The threshold is a setting that can not be used as a basis for a preset or suggestion as it is completely dependant on the incoming audio signals amplitude.

Second, a buss compressor is just a normal compressor that people like having over the final mix buss. The SSL buss compressor is famous because the big SSL desks came with a quad (4 input channe;s and 4 out) compressor that could be routed to any of the main output busses. So, any compressor can be a buss compressor, though one usually wants a stereo compressor for the task to keep a stable image (two independent mono units do work as well but are tricky to set up, especially if they are old and have worn out pots).

Most analogue compressors have a threshold from negative values to positive as the signal can be extremely hot in the analogue domain and the compressors might have a very soft knee settings. In fact, some compressors like the classic fairchild, are compressing all the time a little as they have a "continuous knee" or something like that (it just means the knee is extremely soft and starts compressing at even very low levels).
Remeber, the maximum, the "roof" of digital is always at 0dBFS (full scale) so it would make no sense to have positive values for threshold. In the analogue domain there really is no such roof at all which is why there are both negative and positive values. I think the modern unit in the analogue domain today is the dBU unit (somebody please correct me if I'm wrong).

Hope this answers a few questions. Cheers!
bManic

[jess123]

Thanks bmanic. I understand about threshold alone being lame in audio engineering etc.

I'm in the digital world, but when I turn the knob of say, an SSL compressor (that has +ve db threshold), to say positive 13db, I still get db reduction as indicated by the db comrpession meter. Normal?

The SSL compressor website says their meters are calibrated to 18 dBu = 0 dBFS.(not sure whether this make sense, but I don't). Does that explain anything why a +ve threshold still get reduction?

[jess123]

A silly question here: -

Why do most compressors have a make up gain knob? I always thought after the compression, I can always push my channel volume up. But,....I'm now not really sure is this the same functionality....after all why would developers spend time on making a make-up-gain knob.

Would it makes sense to push, say 1 db up, in the make up gain be equivalent to me pushing 1 db up in volume on the channel?

Pls help.

[BertKoor]

So threshold is set at +13dB while they labelled 0dB as being -18dB in reality. That sets the real threshold value at -18 + 13 = -5dB relative to the full scale.
You MAY feed your compressor with a signal that's hotter than average (in VST floating point processing you can go far over the full scale without clipping) so ofcourse there's still compression happening.

You do understand how compressors work? Whenever a signal gets above the threshold, a gremlin in the box turns down a fader for you. So a signal processed by a compressor is probably softer than what you put in.

People don't like it when their signal gets softer. Actually they prefer loud whenever they can. That's why there is another gain stage after the compression. Both in real hardware compressors and in software. Without that, they wouldn't be complete since you need it!

Would it makes sense to push, say 1 db up, in the make up gain be equivalent to me pushing 1 db up in volume on the channel?

If that channel fader is after the compressor, then it does not matter. But if it is before, then your carefully chosen threshold settings need to be readjusted.

[hifiboom]

So as this one is still missing in the comparison,
ladies and gentlemen ...
Creamware Vinco :

Dry
http://home.arcor.de/soundspace2/Plugin ... op_dry.wma


InputGain 6 Attack 0,5ms Release 30ms Compress 4:1
http://home.arcor.de/soundspace2/Plugin ... 0_4to1.wma

InputGain 8 Attack 0,5ms Release 30ms Compress 4:1
http://home.arcor.de/soundspace2/Plugin ... 0_4to1.wma

InputGain 8 Attack 0,5ms Release 100ms Compress 4:1
http://home.arcor.de/soundspace2/Plugin ... 0_4to1.wma

InputGain 10 Attack 0,5ms Release 30ms Compress 4:1
http://home.arcor.de/soundspace2/Plugin ... 0_4to1.wma

InputGain 10 Attack 0,5ms Release 100ms Compress 4:1
http://home.arcor.de/soundspace2/Plugin ... 0_4to1.wma

seems to come close to this original one UREI 1176 - just raised the volume slightly for comparision:
http://home.arcor.de/soundspace2/Plugin ... p_4to1.wma

UAD is known for good compressor emulations, but I think the CW one is even closer to the original one...

[akisd28]

I haven't tried Vinco, but other people I know that have tried both Vinco and UAD1176LN, say the UAD-1 is closer to the original. A classmate of mine at the Uni just made a shootout between a couple of UREI's, UAD, BF76, Liquid Mix etc. for his Master's (he didn't have access to Vinco) and the UAD1176LN nailed even the all-button mode. See and listen here:

http://www.chrismilne.com/uadforums/vie ... php?t=5329

[akisd28]

BTW, hifiboom, your last Vinco example nails the UREI sound - good job!

[hifiboom]

thanks for the link, will give it a try ...
at least I can't compare, I don't have the UAD-1.


I could not distinguih between Vinco sample and the original one, because it sounds like an 1:1-copy...
At least the UAD demos on this thread cannot compete with the Vinco samples.

I would like to do further testing...

I think the worst on Scope and Creamware is their bad way of marketing...
UAD and Powercore are quite good at that point...

[Artgiver]

i've been manually editing all my tracks by hand since i can't find a compressor that raises valley's and trims peaks evenly (one whereby you can't tell a comp is being used)? Does anyone here know of such a thing (under $300.00). Sorry for deviating a bit from the thread topic, but you guys in this thread know more about comps than me. I've an ear like a dog but a brain like an ant. I've done as much 'homework' as i can, but all that i've demo'ed to date either pumps or are uneven. Manual comping is SO time consuming! I need one that's transparent (no color). A track plug, not a mastering plug; for Windows. Thanx for any comments guys!

Tim

[bmanic]

You should try Voxengo Polysquasher. I find it extremely transparent. Another option is to check out the Sonalksis Compressor (the SV-whatevernumberthing series) and use it's Mode II, dial in a maximum soft knee, lowest ratio and fast attack. There you go, super smooth compression.

Oh, and I forgot to mention the free MjCompressor. Don't be fooled by it's freeware status, it's one of the best compressors around in any format. It can be extremely smooth if you tweak it properly (low ratio, Hilbert thingy on, tweak the sidechain filters to get the signal you want and use the dry/wet parallel compression option).

Cheers!
bManic

[Artgiver]

thanx bManic!
i'm off to try them out. i tried out Polysquasher awhile back and it was indeed transparent but you could tell a comp was being used (you know, the uneven volume rise & fall thing).

[Rune L-H]

thanx bManic!
i'm off to try them out. i tried out Polysquasher awhile back and it was indeed transparent but you could tell a comp was being used (you know, the uneven volume rise & fall thing).

The "volume rise & fall thing" is an inherent part of the concept of all compressors. Paying attention to how you tweak the attack and release time is key to getting transparent compression. Perhaps try to increase the release time.

Another idea is to put two compressors in serial and don't drive any of them too hard. Experiment with different settings on the two compressors, for example one to do slow gentle leveling and another to shave off peaks.

Rune

[bmanic]

Good idea. Several compressors in series mixed with parallell compression (basically allowing the dry signal trough in the background) could create for some extremely subtle, transparent compression.

Artgiver: Do you happen to have any audio examples in .wav format that you would like to have very transparently compressed? I could try out all my compressors and see what I come up with. It would be an interesting challenge as I'm usually after pumping and breathing (in a musical way) as I mix a lot of pop/electro/dance things (or "punch" when doing rock/heavy/metal).

Cheers!
bManic