Harrison 32/32 76' 2-channel box project

Hello all!

Let me start by already apologising for any dumb question I might bother you with in the very near future.
I have very limited knowledge about electronics but am very excited to start working on my 'winter project'. I'm mainly a musician/composer and I run a recording studio. At this time the studio is built around a Neotek Elan II desk, which I am very fond of. The previous desk we used was a Harrison built in '76 which turned out to be a prototype when we started recapping the desk back in 2007 (we were told so by a German technician who owned a 32 desk himself). Unfortunately the desk seemed to have had several issues in the past and it was quite difficult to get the master section working again. Eventually we got it to work but within a few years decided to switch to the Neotek console.

At that time I hard-wired 16 of the Harrison channel-strips, threw out the entire frame of the desk and was very happy to have 16 working pre's/EQ's & Filters and 16 spare channels. Recently I received several requests about wether I would be interested in selling some of my spare channels and if it would possible to build them into a two channel box with it's own power supply.  I have very limited knowledge of electronics, just enough to figure out how to hard wire the channels, but I figured it might be a nice challenge and I could learn a bit more about electronics along the way if I build the boxes myself.

At this point I'm figuring out where I can cut PCB's of the channelstrips in order to make the channels fit into a 19" housing and I've started to look into the power supply. The desk used a +24v / -24v and a +18v / - 18v circuit where it seemed the 18v circuit was for the LINE A return circuit and the rest of the desk operated on the 24v circuit.
Right now I am powering the channels in my 'lunchbox' with just the 24v circuit and the old (not original) power supply and that has been working very well. But, and here comes my question, I have no idea where to start in order to figure out what kind of power supply I should use if I want to power only 2 channels, how can I find out how many (m)A's I need?

I found some information about what I would need for the Phantom power circuit but in an ideal situation I would find a DIY build or working power supply for +24v/-24v *+  48v that I could build into the 19" chassis.

Any tips, help, Do's & Don'ts are extremely welcome.
I have all the blue prints and information on the desk, I've attached the blueprint for the Input/output module. Not all of the modifications I did are written here, I need to look up what I did exactly....
If anyone is looking for spare parts for a Harrison 3232, let me know I still have a lot of parts.

thanks!
Nitzan

You don't need logic circuitry anymore so you can use only +/-18V power supply and 48V for phantom. IIRC, 0,5A from each rail per channel is more than enough. Also you can use monitor pot as the master volume. You don't need all AUX , ECHO and Quad buffers so you can pull out those ICs.

thank you for the quick response! Cool! Yes I'm using the Monitor pot as the master volume in the 16 channel 'side-car'

I have 10 - Harrison PP1 modules with the full 32c E.Q.
Wondering if any of this info would apply to racking these modules?
I'll follow.

NitzanH said:

Hello all!

Let me start by already apologising for any dumb question I might bother you with in the very near future.
I have very limited knowledge about electronics but am very excited to start working on my 'winter project'. I'm mainly a musician/composer and I run a recording studio. At this time the studio is built around a Neotek Elan II desk, which I am very fond of. The previous desk we used was a Harrison built in '76 which turned out to be a prototype when we started recapping the desk back in 2007 (we were told so by a German technician who owned a 32 desk himself). Unfortunately the desk seemed to have had several issues in the past and it was quite difficult to get the master section working again. Eventually we got it to work but within a few years decided to switch to the Neotek console.

At that time I hard-wired 16 of the Harrison channel-strips, threw out the entire frame of the desk and was very happy to have 16 working pre's/EQ's & Filters and 16 spare channels. Recently I received several requests about wether I would be interested in selling some of my spare channels and if it would possible to build them into a two channel box with it's own power supply. I have very limited knowledge of electronics, just enough to figure out how to hard wire the channels, but I figured it might be a nice challenge and I could learn a bit more about electronics along the way if I build the boxes myself.

At this point I'm figuring out where I can cut PCB's of the channelstrips in order to make the channels fit into a 19" housing and I've started to look into the power supply. The desk used a +24v / -24v and a +18v / - 18v circuit where it seemed the 18v circuit was for the LINE A return circuit and the rest of the desk operated on the 24v circuit.
Right now I am powering the channels in my 'lunchbox' with just the 24v circuit and the old (not original) power supply and that has been working very well. But, and here comes my question, I have no idea where to start in order to figure out what kind of power supply I should use if I want to power only 2 channels, how can I find out how many (m)A's I need?

I found some information about what I would need for the Phantom power circuit but in an ideal situation I would find a DIY build or working power supply for +24v/-24v *+ 48v that I could build into the 19" chassis.

Any tips, help, Do's & Don'ts are extremely welcome.
I have all the blue prints and information on the desk, I've attached the blueprint for the Input/output module. Not all of the modifications I did are written here, I need to look up what I did exactly....
If anyone is looking for spare parts for a Harrison 3232, let me know I still have a lot of parts.

thanks!
Nitzan

Click to expand...

Hey there! I realize this is an incredibly old thread. I see you removed the switching FET from Line in A. Are you still using line in B to access the eq during mixing, or was that FET also removed? I have a pair of modules I want to rack up, and this section is one of my last questions. I'd like full channel functionality so I can use eq when tracking if desired, and have access to the eq from one of the line inputs during mixing. Seems like the ping switch (Harrison's "flip" switch?) will swap mic or line inputs as source. No idea. Never worked on this console before.