8 channel 312/M1 type build!

It's finally done! (I started this design almost a year ago!) 8 channels of 990 based preamps on my newly designed hybrid 312 PCBs. 4 channels straight up 312 style and 4 M1 style (2 with JE JT16A and two with Lundahl LL1538) with DC input bias and output DC servo.

I'm excited to do some tracking with them!

More info on the PCBs or for anyone interested in buying any: http://www.bicyclerecordings.com/312

So that's why digikey are out of stock on the GrayHills !! :grin:

Looking forward to getting my boards

Nice work Bob

GREAT WORK !
I love that perfect front to back fit too

MM.

:shock:
Now that is one beautiful build!
Nicely done!

Yeaaaaaaaaaaaaaaaaaaaa :thumb:

That's nice man. :guinness: :sam: :guinness:

[quote author="MartyMart"]GREAT WORK !
I love that perfect front to back fit too

MM.[/quote]

It was fun designing it. And I was totally nervous before I sent out for the board order and the chassis engraving in case I messed up and it didn't fit. Would have been an expensive mistake. But they fit in there perfectly!

[quote author="nickt"]So that's why digikey are out of stock on the GrayHills !! :grin:

Looking forward to getting my boards

Nice work Bob[/quote]

The three times I've ordered Greyhills they've had a lead time of a month or a month and a half... (I actually ordered these last ones back in June)

Very cool, Bob. I'm definitely interested in some of your boards.

They look very nice!
Remind me of your Fabio 8 channels box.

Looks great! How does the power work for these and is that power daisy chain included in the bom?

Is there anyway to get carnhills on these somehow to create a neveish sound?

Do these have line input to use for mixing and if not is that easily added?

I have an external power supply connected with 7 pin XLR jacks. The hookup wire for the supply rails is not on the BOMs but everything else is.

As far as I've seen the Carnhill outputs are much bigger than the API outputs. You could chassis mount the Carnhill though.

There is no specific line input functionality on this PCB. What do you mean by
"use them for mixing"? As a summing amp? The way I have the BOM built, the minimum gain with pad enabled is +6dB. You could in many cases probably run a line input at this gain and be fine. You could also easily build an inline pad that had more suitable input and output impedances for this purpose (I have one built that I use for testing).

Got it, cool, well maybe I'll order one up and give it and try and see if the line works at that level. Yea basically send tracks out of PT and into it then back in.

What options are there for the psu, do you have any specifics you recommend buying/building for the newb. Can you also give me the part # or anything on the power rail cable. Thanks!

I've used the JLM PSUs for some of the stuff I've built. You'll want to get the 5 rail model.

The wire is just standard hookup wire. I have a roll of 22 gauge Alpha which I've been using for a lot of different projects. Do a search on the forum for hookup wire.

I'm just getting into possibly using a 312 as a line amp as well. Is it not just a matter of dropping out the input tranny out of the 312 and cross-referencing the 312 schematic with a 325 schematic?

I don't know experientially, but from what I've read that is, for the most part true.

Looking at these schematics, there are some different values for common components and there are parts of the circuit that aren't on listed here but I believe the changes are minor.

I'm thinking of picking up maybe 4 channels. I PMed you about the switches. Is there a way to add a trim pot to these as well?

Hi, you should have a response waiting from your PM.

I included solder pads in the design to accommodate an off-board switch or variable resistor of whatever sort.

Is that in addition to the Grayhill or an alternative? Thinking 4x of these will be my next project after my 4x 1290s and Drip 72.

As an alternative. You'll only need one variable resistor (whether it's switched or continuously variable).