SSL (Or Similar) Console Saturator/Distortion

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living sounds

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It's funny to build this with a THAT20180. I replaced the old DBX2150's in all my console channels with 2181A to actually have less degradtion (or coloration). :)
 

Michael Tibes

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the SSL driven sound I suspect is a result as mentioned above, many Op amp stanges and a couple of transformers...

If I'm not totally confused there was only 1 transformer in the 1st micpre (not in the later version), the rest of the signal path is transformerless.
 

iampoor1

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If I'm not totally confused there was only 1 transformer in the 1st micpre (not in the later version), the rest of the signal path is transformerless.
Correct. I have worked on a few very early 4k's and the only transformer is in the mic pre....and even then its still a jensen!
 

TheJames

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So the "sound" of the SSL is really just a ton of 553x opamps and not-so-great VCAs, all fed from a massive linear PSU. :)

While I know it's not particularly cool to suggest software for such stuff here, I have to think that this is exactly the right domain for software to experiment and figure out if this is something you really want to pursue and exactly how much of this do you actually need? If you haven't, I would suggest you try that first. I don't know about this plug specifically, but Voxengo plugs are pretty nice.



This might do what you want without any fuss.

I sometimes use a parallel path with a high-pass filter into a distortion for some "HF Excitement" that I blend in to taste.
 

Michael Tibes

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So what's the 4k sound? Maybe between 10 to 15 NE5534 / 5532 with some level up and down, coupled mostly with polarized electrolytic caps (back to back), some fet switches in between, some DBX VCAs (the old discrete ones, not the chip versions), a summing amp with a LM394 / NE5534 circuit? That's the basic signal path without EQ and channel dynamics, relatively clean. The eqs and channel dynamics have a very typical sound, together with the bus compressor in action, not unused. In my opinion the eqs and compressors contribute the biggest part of the characteristic sound. So I'd go for the bus compressor first, it is an easy, affordable and well documented project. Actually I did go for the bus compressor, it's always on my mix bus ;-)
 

TheJames

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So what's the 4k sound? Maybe between 10 to 15 NE5534 / 5532 with some level up and down, coupled mostly with polarized electrolytic caps (back to back), some fet switches in between, some DBX VCAs (the old discrete ones, not the chip versions), a summing amp with a LM394 / NE5534 circuit? That's the basic signal path without EQ and channel dynamics, relatively clean. The eqs and channel dynamics have a very typical sound, together with the bus compressor in action, not unused. In my opinion the eqs and compressors contribute the biggest part of the characteristic sound. So I'd go for the bus compressor first, it is an easy, affordable and well documented project. Actually I did go for the bus compressor, it's always on my mix bus ;-)
Yeah man. The first time I heard playback hitting the bus comp there was THAT sound (ha ha!! Literally THAT!). I pretty much immediately started digging in to the bus comp and decided on building the SB4000. I absolutely love that thing. Hands down one of the best additions to my setup.

I could be wrong, but I thought those old DBX 202 VCA's on the 4K's were only on the main faders? Maybe the bus comp? The basic single VCA was used everywhere else (channel dynamics). Somebody correct me if I'm wrong on that. I haven't looked into the 4K much.
 

cpsmusic

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I've been digging into this a bit more and remembered that the 500-Series VHD+ SSL Mic Preamps have the harmonic generator feature - this makes me think that it can't be anything too complicated?

So to recap, so far there are the following:

1. Louder Than Liftoff Hitmaker 4000
2. SSL 2/2+ USB Interface "4K" button
3. SSL VHD+ 500 Series Variable Harmonic Drive

I'm actually tempted to get a second-hand version of (2) or (3) to try to figure out what's going on.

Cheers!
 

cpsmusic

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So the "sound" of the SSL is really just a ton of 553x opamps and not-so-great VCAs, all fed from a massive linear PSU. :)

While I know it's not particularly cool to suggest software for such stuff here, I have to think that this is exactly the right domain for software to experiment and figure out if this is something you really want to pursue and exactly how much of this do you actually need? If you haven't, I would suggest you try that first. I don't know about this plug specifically, but Voxengo plugs are pretty nice.



This might do what you want without any fuss.

I sometimes use a parallel path with a high-pass filter into a distortion for some "HF Excitement" that I blend in to taste.

Funny that you mention software. I work mostly in audio post (editing) so most of my time is spent in the world of software. The reason I'm interested in making a hardware saturation device of some sort is because I want to see if it sounds different to software saturators. I've been looking at these (and other non-linear software processors) and I have a feeling that a lot of them don't handle aliasing very well (or at all). So I plan to put together an analog pre-mix hardware chain and test out my "theory".
 

Script

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Looking into the THAT2181 datasheet, there are two paragraphs addressing distortion that might be interesting to you to play around with.

(p.7) High-frequency distortion
It says input resistor should be kept to 10k or above as asking for too much gain will lead to high-frequency distortion.

(p.10) Stray signal pickup
The VCA produces second harmonic distortion if the audio signal is present at the control port.

Now could go and do bad design intentionally.

//
Also, for THAT215x, I think, some designs have a 22M or so in parallel from VCA in to VCA out for small-signal integrity. Opposite of bad design (possibly) for older THAT VCAs.
 

TheJames

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Funny that you mention software. I work mostly in audio post (editing) so most of my time is spent in the world of software. The reason I'm interested in making a hardware saturation device of some sort is because I want to see if it sounds different to software saturators. I've been looking at these (and other non-linear software processors) and I have a feeling that a lot of them don't handle aliasing very well (or at all). So I plan to put together an analog pre-mix hardware chain and test out my "theory".

Correct me if I'm wrong, but I believe pretty much all of these sat/dist software processors are performing a 2-8x oversample, executing the process, then down-sampling to get the output. As such, they should be free of any aliasing artifacts.

As for hardware, the Colour module is $100. Pick one up. While you're at it..Get the TM79 too.
 

cpsmusic

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Correct me if I'm wrong, but I believe pretty much all of these sat/dist software processors are performing a 2-8x oversample, executing the process, then down-sampling to get the output. As such, they should be free of any aliasing artifacts.

As for hardware, the Colour module is $100. Pick one up. While you're at it..Get the TM79 too.

Actually the opposite appears to be the case! There some very long and detailed threads over at GearSpace which examine various plug-ins in terms of their aliasing.

Testing Aliasing of Plugins (measurements) - Gearspace.com

Lets do it: The Ultimate Plugin Analysis Thread - Gearspace.com

The thing with the Color Modules is that they need a host of some sort which makes the whole exercise a bit too expensive!

And BTW, I'd probably go for the Royal Blue module if I was getting another one.

Cheers!
 

abbey road d enfer

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Correct me if I'm wrong, but I believe pretty much all of these sat/dist software processors are performing a 2-8x oversample, executing the process, then down-sampling to get the output.
That is true, and necessary. Contrary to analogue, where the intrinsic speed limitations take care of the issue, distortion in the digital domain extends the harmonic spectrum way beyond 20 kHz, which always challenges the anti-alias filters. Distortion algorithms often imply discontinuities, which are known to generate harmonic components up to digital infinity (Nyquist frequency).
As such, they should be free of any aliasing artifacts.
They are not "free" of them, they handle them more or less well.
 

living sounds

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So what's the 4k sound? Maybe between 10 to 15 NE5534 / 5532 with some level up and down, coupled mostly with polarized electrolytic caps (back to back), some fet switches in between, some DBX VCAs (the old discrete ones, not the chip versions), a summing amp with a LM394 / NE5534 circuit? That's the basic signal path without EQ and channel dynamics, relatively clean. The eqs and channel dynamics have a very typical sound, together with the bus compressor in action, not unused. In my opinion the eqs and compressors contribute the biggest part of the characteristic sound. So I'd go for the bus compressor first, it is an easy, affordable and well documented project. Actually I did go for the bus compressor, it's always on my mix bus ;-)
I agree that the EQs and dynamics (including channel gates) are the biggest part of the sound. However, lot's of mixers relied on driving the 4000 console mixbus a little into the red to get the characteristic "rock crunch". The 4000 starts to distort gradually wheras the 9000 series has more overall headroom, but once you reach the clipping amplitude, distortion sets in hard and sounds nasty.
 

TheJames

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Actually the opposite appears to be the case! There some very long and detailed threads over at GearSpace which examine various plug-ins in terms of their aliasing.

Testing Aliasing of Plugins (measurements) - Gearspace.com

Lets do it: The Ultimate Plugin Analysis Thread - Gearspace.com

The thing with the Color Modules is that they need a host of some sort which makes the whole exercise a bit too expensive!

And BTW, I'd probably go for the Royal Blue module if I was getting another one.

Cheers!

Ooof....I looked at that first thread. I do appreciate the premise of the topic, and any study that advances sound quality is a worthwhile one.

The aliasing issue is a (presumably) well known one that has been recognized and (again, presumably) mitigated with oversampling for years. I guess I'm just a little surprised to see the topic show up again, and more surprised that developers are failing at implementing schemes for managing it.

While maybe not as popular, running higher sample rates and properly gain staging your signal path will go a long way towards minimizing these issues. Then it's up to actually measuring and analyzing software that performs non-linear processing to make sure it doesn't introduce nasties. One would think that the developers would do this themselves, but apparently not.

As for SRC itself, in even multiples (x2, x4), I've found the impact to be negligible. Every mathematical function will impact and "degrade" the sound. Period. The goal of software developers should be to make that degradation minimal and in the event of artifacts, they should be the least objectionable at worst and even pleasant at best.

For what it's worth, I run everything at 96k. It's been the best balance for me from a sonic/performance perspective.
 

living sounds

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As for SRC itself, in even multiples (x2, x4), I've found the impact to be negligible. Every mathematical function will impact and "degrade" the sound. Period. The goal of software developers should be to make that degradation minimal and in the event of artifacts, they should be the least objectionable at worst and even pleasant at best.
Depends on the source and the listening environment. To my ears converters these days pre-degrade the signal by using digital HP and LP filters that may measure well in many respects but mush up the presentation. And they are all Delta Sigma design, which never sounds as clear and punchy as multibit to my and many other people's ears (at least with real world clock implimentations)...

I've got (discrete R2R resistor) DACs where you can insert your own filters, and the differences by changing seemingly irrelevant details that should be out of most of the audio band are stunningly obvious. The best sounding filters at lower sample rates sacrifice high end bandwidth for a much more natural sound, something converter and plugin manufacturers are unwilling to do, probably because their customers would demand performance on paper rather than sound quality where it matters to the human ear.
 

abbey road d enfer

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The aliasing issue is a (presumably) well known one that has been recognized and (again, presumably) mitigated with oversampling for years. I guess I'm just a little surprised to see the topic show up again, and more surprised that developers are failing at implementing schemes for managing it.
Actually many DSP engineers have little concern for things such as distortion and artefacts. They develop algorithms based on academic formulae, and very often they don't know how to measure teh results in a meaningful way. Asserting quality of a digital algorithm with another digital algorithm is often bound to let problems unearthed.
A long time ago, when Steinberg started VST, their EQ's were doing strange things; I measured them with an AP and the problem was obvious. As much as the expected boost or cut was correctly located in frequency and amplitude, as much the skirts were just plainly wrong, with a deep notch attached to the boost or vice-versa. No one at Steinberg had thought one moment of measuring the response with conventional analogue gear.
As for SRC itself, in even multiples (x2, x4), I've found the impact to be negligible. Every mathematical function will impact and "degrade" the sound. Period.
Current DAW'suse polyphase filters for SRC. SRC is treated in the same way whatever the ratio.
The goal of software developers should be to make that degradation minimal and in the event of artifacts, they should be the least objectionable at worst and even pleasant at best.
Often, their design brief is to provide as many functions as possible in the least possible dev time, sound quality being of s condary importance.
For what it's worth, I run everything at 96k. It's been the best balance for me from a sonic/performance perspective.
I do too. The most revered digital audio specialists seem to agree that more than 64kHz SR is not necessary.
Now I wished I could find a not too expensive soundcard that does about 200kHz flat...
 

Newmarket

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I've seen people discuss the channel VCA's (for automation) on the 4K's as having some sonic imprint, but that was greatly reduced by the time the 9K's rolled around. I seem to recall accounts of engineers avoiding these VCA's because of the detrimental impact they had on the sound.

That's pretty much what I recall people saying about early SSL when I was more professionally involved with pro-audio design and studio visits about 20+ years ago.
Compressors yes but never heard anyone deliberately chasing the 'VCA' sound. Moving Faders preferred.
 

Matt Syson

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Well in a 'real' 4/6K desk you not only have a a few bucketfuls of 5534, quite a few FETs and the VCA of course but also varying degrees of crosstalk from within the signal path you are 'currently' using to itself which depending on the exact route the signal is taking EQ in/out or insert in/out and so on will also impact the individual signal whether the crosstalk is in phase, or out of phase at various points along the path so rather more complicated than in a 'stereo' unit where the main crosstalk 'point' might be around a pot or switch due to close circuit traces which tends to give a relatively simple 20dB/oct 'monoing' effect, presumably appeciated as 'lack of channel separation'.
Matt s
 
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