Hibernate Audio
Member
A buddy of mine introduced me to these mixers a couple years ago, and I picked up the reverb unit just to see. I was expecting a gritty lo-fi box that I could hack into and play with occasionally - but this one sounded surprisingly hi-fi. I liked it enough to start down the rabbit hole of racking it up and building a whole preamp box around it...
Chassis and I/O
I kept the original chassis mostly intact, and mounted it in a 2U redco chassis. The faceplate is a Front Panel Express panel with UV printing and standoffs for the "input cards." The input cards let you select mic/line, phantom, instrument input, and pad settings. XLR and TRS inputs and TS unbalanced outputs on the back, TS instrument inputs on the front. Unbalanced TS input and output for the spring reverb channel.
Circuit Design
Circuit-wise, I clipped channels 1 through 3 out of the summing gain stage and wired them to each of their outputs. Channel 4 I left connected to the summing gain stage to keep one "high gain" channel.
I also clipped the reverb driver and post-amplifier out of the summing gain stage and wired them to their own I/O. I added a fuse to the auxiliary DC power output of the Shure power supply and wired it to each input card as 24V phantom power. Maybe someday I'll put a DCDC converter in there, but my more modern condensers are fine with the lower voltage standard. Lastly, I added an IEC connector and fuse and wired the Shure power supply into it.
End of Project Thoughts
Sound-wise, I'm pretty happy!
Pros:
- It was still cheaper than most four channel transformer-input mic pres.
- It sounds great, silky smooth with a really nice low end glue. It's amazing as a rhodes DI. I plan to normal my drum kit mics to it, we'll see how that goes.
- Whisper quiet, very little audible noise. Haven't done any measurements yet, but planning to take it into work soon.
- The reverb channel is super fun and sounds great
- Has my logo on it. Nothing beats that!
Cons:
- So much wiring.
- Channels 1 through 3 are pretty low gain, but it works really well as the first gain stage before going to an audio interface that has more gain on tap.
- It clips easy, and has no level indicators or gain control
Lessons learned:
- A 60s sheet metal chassis won't be square, CAD isn't real life. I think I would do the front panel cutout differently if I were to do it again.
- Next time I'm just going to build my own preamp instead of frankenstein-ing around a mixer...
- New rule for me: single channel only
Planning to get some audio samples later this week and start putting it through its paces.
Happy to share schematics, etc for this one if anyone would like. Took a lot of cues from ruffrecords, hairball, hamptone, etc for my input card design - thank you all.
Any comments/feedback/suggestions are welcome - it was a big project with a lot of compromises, so no ego here as far as things I could've done differently.
Chassis and I/O
I kept the original chassis mostly intact, and mounted it in a 2U redco chassis. The faceplate is a Front Panel Express panel with UV printing and standoffs for the "input cards." The input cards let you select mic/line, phantom, instrument input, and pad settings. XLR and TRS inputs and TS unbalanced outputs on the back, TS instrument inputs on the front. Unbalanced TS input and output for the spring reverb channel.
Circuit Design
Circuit-wise, I clipped channels 1 through 3 out of the summing gain stage and wired them to each of their outputs. Channel 4 I left connected to the summing gain stage to keep one "high gain" channel.
I also clipped the reverb driver and post-amplifier out of the summing gain stage and wired them to their own I/O. I added a fuse to the auxiliary DC power output of the Shure power supply and wired it to each input card as 24V phantom power. Maybe someday I'll put a DCDC converter in there, but my more modern condensers are fine with the lower voltage standard. Lastly, I added an IEC connector and fuse and wired the Shure power supply into it.
End of Project Thoughts
Sound-wise, I'm pretty happy!
Pros:
- It was still cheaper than most four channel transformer-input mic pres.
- It sounds great, silky smooth with a really nice low end glue. It's amazing as a rhodes DI. I plan to normal my drum kit mics to it, we'll see how that goes.
- Whisper quiet, very little audible noise. Haven't done any measurements yet, but planning to take it into work soon.
- The reverb channel is super fun and sounds great
- Has my logo on it. Nothing beats that!
Cons:
- So much wiring.
- Channels 1 through 3 are pretty low gain, but it works really well as the first gain stage before going to an audio interface that has more gain on tap.
- It clips easy, and has no level indicators or gain control
Lessons learned:
- A 60s sheet metal chassis won't be square, CAD isn't real life. I think I would do the front panel cutout differently if I were to do it again.
- Next time I'm just going to build my own preamp instead of frankenstein-ing around a mixer...
- New rule for me: single channel only
Planning to get some audio samples later this week and start putting it through its paces.
Happy to share schematics, etc for this one if anyone would like. Took a lot of cues from ruffrecords, hairball, hamptone, etc for my input card design - thank you all.
Any comments/feedback/suggestions are welcome - it was a big project with a lot of compromises, so no ego here as far as things I could've done differently.
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