Tom Visser Posted July 2, 2012 Report Share Posted July 2, 2012 Why? I have been kicking around the idea of a mixer with a crossfader for a long time now. Maybe it is from my days in NYC where I toyed around with DJ'ing (failing miserably) but I have always been enamored with the idea of using the DJ style crossfader. I searched long and hard, looking at almost every DJ mixer out there, to find something that I could adapt to my workflow. Nothing but the Allen & Heath XONE mixers came close, but not close enough, by a long shot. The XONE 464 is basically a WZ3 class mixer with some phono / stereo center section added, but was not adaptable to my needs. I found this baby randomly, absolutely no information on the web about it at all. JL Cooper does not list it in their archives. This was absolutely not DJ inspired. There are GPIO and RS422 inputs on the back that are likely designed to be slaved to a video wipe on a video mixer. And... it has a manual crossfader, perfect for my application. The push buttons select your audio matrix. A typical DJ mixer will have XY or LR buss assignment. This is basically the same, but substitute A for X and B for Y. 1st and 3rd rows are left and 2nd and 4th rows are right channels. You could for example, tell boom on channel 1 to be on left channel for both A and B routes. Radio mic on fader 2 could be assigned to A on right channel. Radio mic on fader 3 assigned to B on right channel. Then when you crossfade, you simply duck radio 2 and bring up radio 3 in a smooth movement with minimal sound power differences assuming gains and noise on each mic is similar. I tested it with a signal being routed to both A and B, when crossfading, I could not tell the signal was being affected at all, so it maintains absolute equal sound power throughout the fader throw. MISSION: I use a Nagra VI with Zaxcom QRX for talent receivers and Lectro D4 for hops. With the QRX, I don't need direct outputs, because the QRX has multiple outputs when using in mono mode. A mix would be broadcast to on the Lectro D4 1/2, IFB on 3, and boom PL on 4. Yep, buying some Lectro Quadra receivers shortly. With the routing features of the Nagra, I don't need aux sends or any specialized routing on my mixer and 3/4 would never need to be post-fade. Metering, PFL, headphone amps - absolutely everything I need is on board the Nagra, so just need to convert this little mixer to the best 6x2 line mixer it can be, in the spirit of the old Sela style "under Nagra" panels. If I ever sell the Nagra, this would likely be included in the sale, as it might be hard to adapt it to a new workflow - definitely the opposite of a flexible mixer, absolutely purpose designed for a single setup and accessories. SPECS: ? nothing available from JL Cooper. 6 balanced line inputs, 2 balanced external inputs, 2 balanced program outputs, 2 balanced monitor outputs, tone OSC and meter trims, GPI inputs, power, and RS-422. To do list: 1) POWER - operates off of a 9VAC wall wart power supply. I will hack this apart, removing most of the power section, and putting in a 12VDC system. The internals run off of +/-15VDC bipolar rails and a +5VDC for logic functions. This is a moderately digitally controlled mixer, so a lot of IC switches and control computers on board. BONUS - add a LiFePO4 battery system so can run off of internal batteries or cart power with full charge management system. 2) FADERS - channel faders are short throw 60mm and crossfader is 100mm. This is the exact opposite of what you want. Will use 104mm P&G log channel faders and a short throw 45mm P&G linear crossfader (VCA). 3) LAYOUT - the channel matrix arrangement seems odd. The button / LED combo seems cheap. I like my crossfaders horizontal. I'll change the matrix to match a horizontal approach so everything is logical. 4) METERING - indecisive here. It would never really be used as a standalone mixer, and the metering on my Nagra VI is perfect. I'll either delete the LED meters or replace them with something really nice. 5) AUDIO OUTPUTS - both sets of stereo outputs are the same source. I'm make the fixed gain program outputs feed an A/D converter which will send AES input to my Nagra VI's AES B input for channels 7/8. The variable monitor outputs will be wired up to a headphone amp, for the times when I'm hard lined and want to listen for a confidence monitor, maybe a good reason to keep the meters on board, so I can still listen to PFL but see meters jumping from the camera return. BONUS add recorder so it would double as my backup recorder. 6) FIDELITY - at cranked levels, there was some background noise. It could have been power supply induced. I did notice that the bipolar supply rails were not matched or possibly due to bad caps, although this design is not "that old." The noise was not egregious and given that the faders have +10dB of gain in hand, I don't think it is out of the ordinary. Regardless, the TL072 dual opamps are socketed, bless JL Copper's heart, and will be swapped out for something more modern. The overall PCB design is rather minimalist and where bypassing caps could have been used, they were not. This will never be a Cooper of Sonosax level product, but I think I can get it to sound good and keep the noise floor down to an insignificant level, certainly better than a Sela! 7) delete all other unnecessary features, such as GPIO, tone (comes from QRX for calibration and Nagra VI for production) All in all, this will obviously require a completely new case and will likely be the single most expensive part of the project. I'm humping a bag for a show the rest of the summer. My goal is to have this complete by September or so, where hopefully I can get onto a cart and do some films! Quote Link to comment Share on other sites More sharing options...
Tom Visser Posted July 2, 2012 Author Report Share Posted July 2, 2012 By the way, if anyone has 10K audio log 104mm P&G faders for sale, let me know please... could be single or dual channel Quote Link to comment Share on other sites More sharing options...
Jeff Wexler Posted July 3, 2012 Report Share Posted July 3, 2012 See, this is what I was talking about when I suggested that Tom Visser was the most qualified to comment on the other thread (open source, build your own, etc.). I continue to be impressed. Thank you. Quote Link to comment Share on other sites More sharing options...
Richard Newton Posted July 11, 2012 Report Share Posted July 11, 2012 Tom, Just spied this on eBay, and thought you might want it for your project. http://www.ebay.com/itm/400294900689?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 Rich Quote Link to comment Share on other sites More sharing options...
Tom Visser Posted July 11, 2012 Author Report Share Posted July 11, 2012 Tom, Just spied this on eBay, and thought you might want it for your project. http://www.ebay.com/...984.m1423.l2649 Rich Thanks for the heads up Rich, but the unit pictured above is actually mine, I had already purchased (for a much cheaper price than that eBay auction too). A little progress report. I ordered the 45mm cross fader today, a bunch of board/cable Hirose/Molex style connectors to facilitate the switch / connector replacement. I've done a layout for the metalwork and think I'm actually going to order the top panel and the front / back extrusions... will hold off on the side cheeks, which will have all the connections, and the bottom plate, until I'm sure I got all the sub-boards laid out properly. It is a little scary ordering metal since it is relatively expensive and you never really feel that your done futzing around with the design. I'm wasn't able to find any 104mm faders for a decent price, so think I'm going to drop it down to 83mm, which I already have several of, and the board is a bit on the big side as it is. Quote Link to comment Share on other sites More sharing options...
Philip Perkins Posted July 15, 2012 Report Share Posted July 15, 2012 All very impressive, but I'm really not clear on what you are trying to accomplish with this mixer--you want to smoothly crossfade from mix A to mix B? I guess with some channels common to both? Couldn't you do that with two aux sends on an MI market mixer, cheaper, smaller (Mackie 1202 etc)? I ask because you are embarking on a big project converting this mixer for field "combat" usability, and you didn't seem all that thrilled with the basic specs/sound of the mixer. I think you're right about its lineage--probably a short lived attempt at an online video suite mixer, from the 1990s? PS--I recall you were converting another inexpensive mixer for cart use (Behringer?) and got pretty far with it, did that one work out well? phil p Quote Link to comment Share on other sites More sharing options...
Tom Visser Posted July 15, 2012 Author Report Share Posted July 15, 2012 The Behringer was a great little mixer but ultimately, I didn't like the short fader throw and to build it out the way that I wanted, would have cost quite a bit of money. There was also the issue of serviceability. Everything on the Behringer is surface mount and pretty much a single PCB. I could have frankensteined the heck out of the signal routing and made things work, but down the road serviceability was going to be an issue. With the JL Cooper, everything is through hole design and I've order the adapters required to fit some high fidelity modern op amps in there, and am doing it right this time by putting Hirose and Molex quick release cable connectors on everything so that replacing individual components and general serviceability will much improved. Some of the metalwork should arrive in about 2 weeks, although I'm scheduled to go off island for work at about that time, so hope to show some real tangible progress in a relatively short time afterwards, after I return home and can put some attention to this. If my Mouser order gets here early next week, I may even be able to start digging into the PCB modifications in full. Quote Link to comment Share on other sites More sharing options...
Philip Perkins Posted July 15, 2012 Report Share Posted July 15, 2012 So what opamps will you go for? Are you figuring they will drop in w/o mods to the rest of the circuit? Is the Cooper PCB two sided and or multilayer? That's what I see as the issue w/ boxes like that Behringer--they really are made to be tossed if they have any problem, something you wouldn't want to do if you'd done a lot of mods to it, I agree. But to my other question--this is really goimg ot be a monitor mixer, right? IE not something you are recording the output of? phil p Quote Link to comment Share on other sites More sharing options...
Tom Visser Posted July 16, 2012 Author Report Share Posted July 16, 2012 So what opamps will you go for? Are you figuring they will drop in w/o mods to the rest of the circuit? Is the Cooper PCB two sided and or multilayer? That's what I see as the issue w/ boxes like that Behringer--they really are made to be tossed if they have any problem, something you wouldn't want to do if you'd done a lot of mods to it, I agree. But to my other question--this is really goimg ot be a monitor mixer, right? IE not something you are recording the output of? phil p The original opamps are TL072. I don't really see any reason to try anything other than their modern replacements, the TL2072. TLE2072ACP from Mouser are $2.16 a piece and the beautiful thing is that JL originally used sockets for their opamps, so you can literally pull them out and put in a replacement in a few seconds. Using something high performance like an OPA2604 probably would require additional work to make them stable and not oscillate, but the 2072 is a pretty safe upgrade path for the 072. The PCBs are double sided, but use 100% through hole components, mostly populate with DIP and SIP devices. In fact, every single IC in the design is socketed, not just the opamps, almost seems like a prototype stage of design, as most manufacturers would have skipped the cost of the sockets and go directly with soldered on components. This is one nice thing about using older designs as more attention was paid towards serviceability. In this case, I will in fact record the mix, so production sound will in fact pass through it. It should be on par with the best of the best mixers from a pure fidelity standpoint, as the circuit is pretty simple, no EQ, no routing, aux sends, etc... in fact, probably has the advantage in some respects due to the fact that it is more or less a naked 6x4x2 summing matrix and nothing else. Quote Link to comment Share on other sites More sharing options...
Philip Perkins Posted July 16, 2012 Report Share Posted July 16, 2012 Well, another big prop to Andy C for putting in sockets--is that ever a thing of the past these days. I'm looking forward to seeing pix over your reborn Cooper. phil p Quote Link to comment Share on other sites More sharing options...
al mcguire Posted July 16, 2012 Report Share Posted July 16, 2012 are andy cooper and jl cooper related ? Quote Link to comment Share on other sites More sharing options...
Tom Visser Posted July 16, 2012 Author Report Share Posted July 16, 2012 Cooper Sound was based near San Luis Obisbo, a fine retired maker of analog mixers for film production. JL Cooper is out of El Segundo, and mostly make controllers for video trucks, studios, and other automation / control industries. I didn't think that there was a relation. Quote Link to comment Share on other sites More sharing options...
Philip Perkins Posted July 16, 2012 Report Share Posted July 16, 2012 are andy cooper and jl cooper related ? Good catch--Cooper to me means Andy, I haven't ever used an audio device made by JL, although I've had their controllers in the studio for years. Goofy me--I kept wondering why Andy Cooper would have wanted to make an online suite mixer. YES! The Fabulous Cooper Brothers: ANDY, JL and MINI ! phil p Quote Link to comment Share on other sites More sharing options...
studiomprd Posted July 16, 2012 Report Share Posted July 16, 2012 " . I didn't think that there was a relation. " both have a lot more history, but you are correct, no kinship involved. Quote Link to comment Share on other sites More sharing options...
André Boisvert Posted July 16, 2012 Report Share Posted July 16, 2012 YES! The Fabulous Cooper Brothers: ANDY, JL and MINI ! Let's not forget the very appropriate D.B! Quote Link to comment Share on other sites More sharing options...
Tom Visser Posted July 24, 2012 Author Report Share Posted July 24, 2012 I flew home yesterday and had a metal panel waiting for me. I just couldn't resist and dummy loaded a few components onto it. I have to fly out again tomorrow and can't wait to get some down time to start doing the real work. Quote Link to comment Share on other sites More sharing options...
Vincent R. Posted July 24, 2012 Report Share Posted July 24, 2012 Visser industries looking good! Quote Link to comment Share on other sites More sharing options...
studiomprd Posted July 24, 2012 Report Share Posted July 24, 2012 Familiar meter.... Quote Link to comment Share on other sites More sharing options...
Jeff Wexler Posted July 24, 2012 Report Share Posted July 24, 2012 Familiar level of craftsmanship, aesthetic and design (conspicuously absent from most "modern" gear). Looking good! Quote Link to comment Share on other sites More sharing options...
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