David Kronemyer

Rane – TubeTech 576 Channel Mixing System

February 16th, 2009 by David Kronemyer · 3 Comments

DAVID KRONEMYER: The studio where I do a lot of work has a variety of synths and synth modules. As a matter of performance ethic we decided we wanted to keep all of them on, all of the time, and accessible via a master stereo buss. Over a period of time we attempted to devise a variety of ways to accomplish this result. For different reasons the solutions we implemented were unsatisfactory. Our Solid State Logic console lacked sufficient inputs. The new SSL XLogic SuperAnalogue X-Rack has an XR624 eight channel input module going to a summing mixer, which allows for 28 stereo inputs in four rack spaces (60 stereo inputs with two racks). To be sure this is a high density count however all of the inputs come up at unity gain (none of them have variable gain controls). Furthermore the on-board computer (which adds considerably to the cost) doesn’t do anything for this module configuration. The Speck Ultramix is an elegant solution however even with its high input count it taps out and was unable to put enough inputs on a single buss.

We therefore determined to use the Rane SM26 for the mono synths and the SM82 for the stereo synths and modules. We acquired 24 of the SM26 and 24 of the SM82. We rechipped several of the older units. A few of them did not function properly and in lieu of trying to fix them ourselves we sent them off to Rane for repair. We would like to complement Rane’s product support department, which restored them to pristine working condition quickly and inexpensively.

The SM26 has six input channels and the SM82 has eight stereo channels (actually nine if you use the stereo return as an input channel, which we did). Both have a feature where you can chain several modules together on a single buss, which we did in combinations of two or three. We evaluated several master buss modules, including the attractive and desirable Neve 8816 summing mixer. We ended up selecting the TubeTech SSA 2A, which has eight stereo pairs and four mono channels. I have the feeling these master buss summing mixers are marketed as a tool for digital audio workstations such as Logic and ProTools, so one can take separate stems from the DAW and mix them down “outside of the box.” Although our purpose might not be the one initially intended, it works great.

All of the modules terminate at the back of the racks on EDAC/ELCO 90-pin connectors. The snakes then lead to (a) stage boxes throughout the studio for the keyboard synths, or (b) EDAC/ELCO 90-pin connectors on the back of the racks for the samplers ROMpler modules. This was a considerable wiring project, as one might imagine. Here’s a photo of the front of the racks:


This supplied us with a total of 576 channels. The stereo buss is whisper-quiet, even when pushed to higher gains. We attribute this primarily to (a) plenty of AC headroom (900 amps coming into the studio); (b) use of Equi=Tech balancing transformers, reducing the noise floor by about 10db; (c) we tied all of the power supplies together to a single transformer; (d) careful wiring practices such as separating all power from all audio; (e) progressive optimization of the chips inside of the mixers; and (f) over-all component excellence.  We sincerely appreciate the great modules from Rane and Tube-Tech which made this project possible.

BTW we still need some more channels.