DIY vocal pre-processor dissertation - advice needed

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rekkoned

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Jan 27, 2021
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Hi guys!
I'm a production student from the UK and I am plannig a DIY project for my dissertation for my final year. The project I had in mind is a combo of a preamp, eq and compressor, all built into one rack enclosure, not dissimilar to the UA 6176 and was hoping to get some advice/thoughts on the feasibility of this from all of you.

The plan is essentially to frakenstein together these two kits: http://www.audiomaintenance.com/acatalog/aml-17-020_extended_info.html
https://www.hairballaudio.com/catalog/fet-rack/fetrack-revision-acomplete-diy-kit

My plan to do is just to solder the output of the 1073 to the input of the 1176 and run them in series, however I do want to make a couple of mods and wanted to ask you guys whether this is possible and some pointers to parts that could make these mods easier.

The main mod I want to make is having only one power cable come from the unit, but I'm not too sure about the safety of joining two power supplies, so if anyone knows how I could do this safely, it would be greatly appreciated.

Another thing I'm worried about is grounding. Since both of these have to be ground to the chassis, would it be safe to ground both of these onto the same one? Also, I want to add switches so I could bypass the two units individually, but I'm not too sure about what the right switching mechanism/pcb would be for a rack compressor/eq, so any info on that would be greatly appreciated.

Initially I thought I'd be able to fit both of these into a 2U unit, but didn't realise how big some of the mains components are so its probably gonna be 3U, unless someone has some ideas how to make it fit into a 2U. The only way I could think of would be sodlering the pots to the board with wires instead of sodlering them directly into the pcb, but I'm not sure whether this would cause any problems with the range of the pots or anything like that.

I'll be designing a front pannel for it and will most likely end up buying a premade 2U/3U rack chassis which I will modify to build all of this stuff into.

I'd appreciate any type of feedback/criticism as I want to be sure that I can pull this off before buying most of the parts so that I can actually get it done. If anyone has any resources that could point me in the right direction I'd love that aswel. I have decent experience with soldering modular synths and pedals so at least I have that covered.

Thanks for any and all info! Much love <3



 

TwentyTrees

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Welcome to the board!

It's an ambitious project, but certainly a version of it is very achievable. You're right that two of the bigger issues you'd be facing with your proposed approach would be power, and mounting / metalwork. The 1176 and 1073 have quite different DC power needs, which as the two kits are designed would be two sets of AC > DC conversion. The Hairball FET/Rack is also designed with specific metalwork in mind, so you'd either need to reproduce that in your version or find some other ways to mount the various hardware. Doable, but a pain. It's a shame Hairball no longer sells the PCB sets for the 1176 clones.

One alternative approach occurs. Have you considered looking to the 500 series? Both the companies you've highlighted (and many others) offer DIY versions of those products in 500 series modules. That would simplify the power requirements drastically (everything set up to run from +/-16V), and it would be much simpler to rack three 500 series PCBs (preamp, EQ, compressor) in a 1U or or even 2U chassis with a single front panel, with sufficient room for power. It would also sort out your grounding and bypass questions, as they'd have been designed to work in a shared enclosure. The metalwork could be fiddly, as you'd need to figure out just how to mount the PCBs, but that would be how I'd approach it if I was looking to build something like this. 

Good luck! The first phase is always research, research, research, so you've started in the right place.
 

rekkoned

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Jan 27, 2021
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Firslty, thanks so much for the warm welcome and the advice! Just discovered this board recently and its been an aboslute goldmine of info!

I've looked at the lay out of the hairball and have defo considered the mounting issues, but they shoudln't be too difficult to accomodate for. I have indeed considered going 500 series, but since this is a dissertation, I'm trying to impress my teachers, and thought that bulding a rack from bare minimum would get me more brownie points with them than just building a couple of kits and throwing them into a premade rack. Then again I could make my own 500 series rack/power supply unit so that is definitely something I will consider, since I am pretty scared to toy with power supplies that run off of mains.

Thanks again!


 

abbey road d enfer

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rekkoned said:
I'm trying to impress my teachers, and thought that bulding a rack from bare minimum would get me more brownie points with them than just building a couple of kits and throwing them into a premade rack.
I don't know what kind of degree you want to obtain, but I believe your teachers would be more impressed with how you sorted out the powering issues than building a chassis (unless you're in a metalwork class).

Then again I could make my own 500 series rack/power supply unit so that is definitely something I will consider, since I am pretty scared to toy with power supplies that run off of mains.
You shouldn't be. The high-voltage part is no more complicated than wiring a plug for a bedside lamp.
 

dbelousov

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Jun 30, 2019
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Moscow, Russia
You can use 500 boards in your own chassis with your own PSU. It's what Millennia literally doing.

millennia_hvp_series_05b_HV_35P_inside-6rMejFnilB2nXXukGdhxItFzZDNrm.mX.jpg


+15/-15/+48 DIY PSU boards are not a problem to buy.
 

rekkoned

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Jan 27, 2021
Messages
3
dbelousov said:
You can use 500 boards in your own chassis with your own PSU. It's what Millennia literally doing.

millennia_hvp_series_05b_HV_35P_inside-6rMejFnilB2nXXukGdhxItFzZDNrm.mX.jpg


+15/-15/+48 DIY PSU boards are not a problem to buy.

This is actually really cool, thanks for the recommendation! Being new to diy rack gear though, I don't really know what psu pcb I'm looking for, would you be able to send me a link to something that would work for this use case?

I've had a quick look on mouser for PSUs and found this https://eu.mouser.com/ProductDetail/International-Power/IHAD15-04/?qs=sGAEpiMZZMs2%252BVrH5rwl1sQ7dUR7RAss7Hv4KOBtfj8%3D. Would something like this work or should I look for a pcb to build my own one?
 
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