CRL SEP400A In Action

[@judsonsnell]

I'm thinking of saying "what the hell" and grabbing a pair of these for studio use. Just to have a different shade of compression/eq to try out on subgroups or 'something different'. Old broadcast gear really does something different and wild. Any thoughts on that? Should I put my wallet away?

[@SweetbeatsTechStop]

Super good question. Due to multiple life circumstances I’ve not had the chance to really use these, OR the SEC-800/SGC-800 combo I bought earlier this year (the SEC-800/SGC-800 units comprise a later generation stereo iteration of the SEP400 series), or spend any real time doing critical listening or A/B comparison using these devices. What I can tell you is they are unique, and well-built, and use proprietary VCA modules for gain control. What’s important to understand though is these are really designed as sort of “one-knob” set and forget dynamics processors okay? These are NOT your compressor with adjustable attack, release, threshold, ratio, makeup gain…all of the attack and release parameters as well as gain reduction and peak-sensing is all automatically handled by the proprietary “analog computer” VCAs…the “EQ” bands have nothing to do with driving gain reduction…they are gentle peaking filters that FOLLOW the gain reduction processing stages so you can conservatively shape the post-gain processed program content. But it’s not like a traditional multiband compressor where, for instance, turning up the low band drives gain reduction processing and overall increase in perceived loudness after makeup gain. In the case of the CRL broadcast dynamics processors, there’s an initial gain preparation stage to control gain, the aggressiveness of which is set by a stepped control, then the signal is split into 4 bands, and each band has discrete proprietary circuitry to analyze the program content within its band, and adjust attack and release parameters depending on program content, and reduce gain peaks according to a stepped user control that is ganged across all 4 bands. Then comes the EQ control section allowing the operator to adjust the 4 band spectral balance. Then the bands are summed and in the case of the SEP400 series there is then a limiter stage applied to the sum, which is also auto-processed for attack and release depending on the program content, and how aggressive the limiter acts is controlled by a stepped control. Unique, right? At least as far as us multitrack audio production folks know. In the broadcast world this is all more conventional. The goal of the design is transparent gain reduction. Having automatic real time analog analysis of the program divided into 4 bands allows for dynamic changes to attack and release performance, as opposed to fixed as it would normally be with user controls for these parameters on the device…like I would typically set attack and release depending on the source or program and then leave it alone for the take or mixdown or whatever, because I’m not that good to know what to do with these controls throughout the performance. But the CRL boxes do it automatically. And of course applying gain reduction independently to 4 spectral bands helps with transparency. SO…you see…for the operator who wants control, these units are limited. But for the operator who wants a device to figure it out for them, while still allowing some global control over how much things are smashed, and control over spectral shaping, this is a relatively unique device and opportunity. Note the SEP400 series are mono devices. If you want to try these out on a stereo buss you need two, and then to keep them somewhat in sync you need a scope and I have some instructions from a tech at Orban for how to do it. In fact at one point Bob Orban stepped into the conversation himself and provided some technical assist. All super nice people and really responsive…extremely uncommon support for a truly legacy device. But anyway using the two mono devices on a stereo buss, it’s not ideal, because the inputs are not linked. But it could work. To really do it you want one of the stereo units, the SEP800, or like I have the SEC-800 with it’s partnering gain preparation unit the SGC-800. These are the devices that made music loud on the radio. That’s what they do. And to do it as transparently as possible. But I’ll tell you you can still make them behave so you can hear them working. I really want to try a mono unit on bass guitar…and I’m curious to try my stereo set on a master buss in parallel, but I still have a couple repairs and upgrades to finish before I can do that. My console has two identical discrete master busses so I could do parallel compression on the master buss using the SEC-800/SGC-800 set on one buss insert and really smash it, and leave the other buss uncompressed. These are on my to do list. Also note the first version of the SEP400 and the early versions of the SEP400A use 4558 opamps throughout. You can upgrade the input and output opamp stages with anything you like, but you have to leave all the interstage alone. So you’re stuck with the 4558s on those. Which may be good or bad depending on your perspective. I suspect the 4558 equipped mono units could be neat for special effect dynamic processing on a single source. The typical SEP400A and the SEP400B use the TL072 which is fine. The SEP800 uses the TL072. Also note the power supplies in all these units need larger primary filter caps. Easy to do, but the original value is too close to lower thresholds and as they drift with age cause oscillation in the regulation circuit. Let me know if you have any more questions. Definitely a niche device, but high quality components, pedigree pre Orban design, proprietary VCAs, etc. And let’s be honest…they look cool. Lol. The prices have come up on these, so it’s a more expensive gamble. I have an SEP400, two early SEP400As, two typical SEP400As, and the SEC-800/SGC-800 combo.

[@judsonsnell]

@@SweetbeatsTechStop Hey, thanks for the detailed response. And yeah, I have all the 'controlled' compression I need both in DSP and racked up. Looking more for those 'wild card' sorts of deals like, 'hey, let's try throwing a parallel drum submix through this and see what happens when we rub the lamp'. There are some absolute treasures from radio's golden decades that have found favor - the Gates Sta-Level and CBS Audimax would be great examples. Now I'm really interested to know what this proprietary VCA element is since almost every VCA comp in studios now is based on a THAT 218x IC. I've built up some SSL-style compressors using the original David Blackmer black and gold cans that give you a much more rock and roll response. Since FM radio was the original 'volume war', the weapons they fought them with lets you color with some different shades. I really don't use much outboard to 'gently smooth 3db on peaks' so much as try to make otherwise boring recordings grow some bull balls. Alison Research and Aphex created some of my favorite compression circuits (the GainBrain and CX-1). So yeah, you're right, this would be something of a wild card purchase - I found a decent working pair for $400. A little banged up but they're 100% working. A good recap later, who knows? Might just have found something. A few years ago I picked up a Harris / Gates 994 (AM) that, after a little elbow grease, became one of my favorite things to record guitar through on the way in. Anyways! Thank you for the detailed response - I'm even more unsure than before but I appreciate you giving me the 'hey, hold up there, studio guy' warning.

[@SweetbeatsTechStop]

Hey totally didn’t mean to come across like “hey hold up studio guy”, I’m a studio guy myself…it just took me awhile to understand how these devices work and what they do…to learn the broadcast-ese around them. And I guess that’s what I was trying to share. Anymore it seems like $400 for a pair is going rate. Are they the “A” or “B” version? If the “A” version is the chassis natural aluminum or black? You’ll want to ask for pics of the interior and there should be 5 larger black boxes each. Those are the proprietary processing modules. You want to make sure they are all there. I totally relate to the “rub the bottle” convention. I do that too. Sounds like you have some diverse experience and have some idea what you might be getting into and why and that sounds pretty spot on. I wish I could report more real-world experience with them. My SEC-800 for sure makes things louder, and at the lower gain reduction settings it’s hard to hear it working. But it is. At the higher settings you can hear the smashing, so I think there’s good potential for working it into the signal path in unique ways.