Whistle Rock Audio ML12 preamp BUILD/HELP thread!

[Whoops]

I have basically put the black to where it says AC on board, put the yellow to where it says AC on board, then i combined the red and orange and put them both to CT & CT.

Should be good, both CT points should connect to each other.
Check it out measure continuity between those 2 points.
Also reference with the schematic

 

[Whoops]

This will also work

 

[TillM]

Too much power?

It's 700mA per each primary. So it's good to power 4x 312 Mic preamps plus phantom power and still have some good safety margin.

No I mean I would take a transformer with 15vac at the secondaries.
But that’s just my choice.

 

[Whoops]

No I mean I would you a transformer with 15vac at the primaries.
But that’s just my choice.

Oh yeah, the 18VAC will rectify to 25,4VDC
A little more heat and wasted energy

 

[Whoops]

When you center tap them, you get 36vac.
So you have to put them in parallel.
So that you just connect the AC on your PCB.

Sorry TillM this is not correct, the CT is the 0V reference and connected to ground. So it's 18VAV on each side of the secondaries with opposite polarities

 

[TillM]

Sorry TillM this is not correct, the CT is the 0V reference and connected to ground. So it's 18VAV on each side of the secondaries with opposite polarities

Thank you for your explanation.

 

[Chris-audio.com]

Sorry TillM this is not correct, the CT is the 0V reference and connected to ground. So it's 18VAV on each side of the secondaries with opposite polarities

Thank you so much for your in-depth explanation and diagram, This has been so helpful and very much appreciated!! Both you and Tiim.

 

[JW]

Howdy folks,

I have a couple CAPI ACA boards that can fit 4 opamps each for a total of 8. I don't see why I couldn't put 8 in a single rack enclosure with the the ML12 power supply?

Couple questions though. Is there a stated maximum amperage for the ML12 supply? Or is it just up to the LM337/317 pair? I think a couple people have built 8 channel units, so that's why I'm here. On the 2520 data sheet I remember around 80mA current draw at absolute worst case scenario. If we over estimate for the possibility of (even more dramatic current drawing DOA's?) Let's say 120mA per channel X 8 = 960mA. A 1.2A PSU would cover just about any scenario I imagine.

Is there a torroidal power transformer one would recommend for this kind of power that could fit in a 1RU chassis? And should I be looking at changing the 337/317 transistors for something slightly higher?

 

[3nity]

Hello good people.
I'm helping a friend completing this project but no more schematics..
I'd like to find a pin out for the fet DI2. 5 pin connector..please let me know if you have it please e mail me at mayaaudio AT gmail.com please.

Thanks

 

[TillM]

I will take a look on my HDD when I’m back home.
I am sure I still have the manual.

 

[3nity]

Thanks

 

[Whoops]

Hello good people.
I'm helping a friend completing this project but no more schematics..
I'd like to find a pin out for the fet DI2. 5 pin connector..please let me know if you have it please e mail me at mayaaudio AT gmail.com please.

Thanks

Hi Jorge,
if you use wayback machine website and post the dead links there you can access the files

https://web.archive.org/web/20160322190325/http://www.whistlerockaudio.com/cart/documents/ML12/ML12%20v3.0%20-%20Schematic.pdf

https://web.archive.org/web/20160218185143/http://www.whistlerockaudio.com/cart/documents/ML12/ML12%20v3.0%20-%20PCB%20Manual.pdf

https://web.archive.org/web/20160322215846/http://www.whistlerockaudio.com/cart/documents/ML12/ML12%20v3.0%20-%20Mechanicals%20(PCB%203.1).pdf


Best regards

 

[3nity]

Thank you whoops!

 

[Ricardus]

TillM is using some sort of metal trim pieces with his LEDs. Does anyone have a part number for those?

 

[oran.outan]

Hi

I’d Like to used the ML12 as a Gain Make up after a passive summing mixer (DIYre SB2).
I will not need +48v/pad/pol/DI…

I understand the +12v is ‘mostly/only’ used to feed the Relays… will that be fine to not plug any 12v and not populate the board with the relays and use jumper instead (for signal link ) !?
And also, Not place the switch’s and let the holes empty !?
In that situation do I need to place :
- D1/R9/Led2 (Pad)
- R1/R2/R3/R4/R5/C5/Led1 (+48v)
- R10/R11/D2/Q1 (DI input)
- R14/D3/Led3 (Pol)

Thanks for you advise…
Florent

 

[Whoops]

Hi

I’d Like to used the ML12 as a Gain Make up after a passive summing mixer (DIYre SB2).
I will not need +48v/pad/pol/DI…

I understand the +12v is ‘mostly/only’ used to feed the Relays… will that be fine to not plug any 12v and not populate the board with the relays and use jumper instead (for signal link ) !?
And also, Not place the switch’s and let the holes empty !?

Yes.
And also remove all the components you posted.

 

[oran.outan]

Thanks for your reply***
best

 

[Ricardus]

I've begun my 4 channel ML12 project.

 

[Bobby Baird]

I've begun my 4 channel ML12 project.

Did you finish them. What iron? I just got parts for 2 supply's, and parts for 16 channels. Only things I don't have are iron and a couple face plates.

 

[Ricardus]

Did you finish them. What iron? I just got parts for 2 supply's, and parts for 16 channels. Only things I don't have are iron and a couple face plates.

About to finish soon. Money has been super tight for about 6 months. If all goes well I'll be ordering the metalwork from Frank this week. My modules have been built up for months. Just need the metalwork for final assembly.

I got all of the transformers from CAPI. All Ed Anderson.

I do want to build 4 more channels after this with UTC transformers.

What power supplies are you using?

Here is one of the finished modules, and all of the stuff laid out on top of a rack box of the same dimensions I'll be using.