Whistle Rock Audio ML12 preamp BUILD/HELP thread!

[Bobby Baird]

Nice! I have the original ML12 PSU boards from when DIYRE had them for sale. Wish they would have released the gerbers for that as well. Its a nice board. Going to have psu in separate chassis. Circuit Specialist has a cheap case compared to hammond. They want way to much.

 

[Bobby Baird]

I see you have the JLM supply. I built there VUPPM 500 love it. I use it for my Radial workhorse mixer meter bridge.

 

[Bobby Baird]

My case has room for another db-25 connector for the Aux out. It's gonna be tight for me to get all of the di phone connectors fit on the back panel as well.

 

[Ricardus]

Nice! I have the original ML12 PSU boards from when DIYRE had them for sale. Wish they would have released the gerbers for that as well. Its a nice board. Going to have psu in separate chassis. Circuit Specialist has a cheap case compared to hammond. They want way to much.

Yeah, they couldn't find the Gerbers for the original ML12 PSU so I ended up finding a guy in Russia who had a board. It might be a copy of the JLM because I posted a pic of it somewhere and I think it was the JLM guy, he responded to me asking me where I got the board. He was not happy they cloned his board. I actually like this PSU more than the ML12 to be honest. It's smaller, and has an extra rail.

I think the place I got the board was called DIY Tubes or something like that.

Like I say, if all goes well I should be able to order my panels and case tomorrow.

 

[oran.outan]

@Bobby Baird, I suppose the 'level' on the front panel is a level output attenuator ?
did you make it by adding a 10k dual lin pot between pcb lineout and XLR connector !? I like having level output...

About 4 rail PSU, I recently discover this one, in France : Alimentation PSU4 – PCB | Studio Delta Sigma
I order one and give a try in the next month certainly...

++
0-0

 

[Ricardus]

@Bobby Baird, I suppose the 'level' on the front panel is a level output attenuator ?
did you make it by adding a 10k dual lin pot between pcb lineout and XLR connector !? I like having level output...

About 4 rail PSU, I recently discover this one, in France : Alimentation PSU4 – PCB | Studio Delta Sigma
I order one and give a try in the next month certainly...

++
0-0

Oooh. Another PSU option is always appreciated. I ordered 3 or 4 from the DIY Tubes before I realized he was cloning someone else's work. So I'm good for now. But in the future it's always nice to have an option. Let us know what you think when you get it.

I opted not to to use the panel designs that are built around the pushbutton toggle switches. I decided to run wires from the PCBs to some high quality toggles I'll be using on the front panel. I also chose not to do the output attenuator like many people added because I didn't want any more complications in my first build of these. I also didn't like that they put the DI input to the left of the gain pot. I like the symmetry of having it on the right.

 

[Bobby Baird]

@Bobby Baird, I suppose the 'level' on the front panel is a level output attenuator ?
did you make it by adding a 10k dual lin pot between pcb lineout and XLR connector !? I like having level output...

About 4 rail PSU, I recently discover this one, in France : Alimentation PSU4 – PCB | Studio Delta Sigma
I order one and give a try in the next month certainly...

++
0-0

Yes output attenuator goes between J5 Line Out & XLR. I use these 600 ohm t-pad attenuators. Classic Audio Products, Inc.

 

[Bobby Baird]

Really good deal here on relays. Hope there legit I ordered 48. Panasonic Electric Works TQ2-12V
Capi has better deal on op-amp pins than mouser or digi-key as well.

 

[Ricardus]

Yes output attenuator goes between J5 Line Out & XLR. I use these 600 ohm t-pad attenuators. Classic Audio Products, Inc.

I would be curious to see a more detailed breakdown of how you did this so I might attempt it in the future.

I also didn't add output attenuators because my goal was mid '70's 312's with this build. The transformers Jeff sells are Ed Anderson clones of mid 70s API, and I will be running Huntington era DOAs in these. So hopefully it will be pure '70s API goodness.

I actually have 4 Neumann DOA's built up for my next set of 4. Using those UTC transfomers with those DOAs should give me a little different flavor.

 

[Ricardus]

I ordered the metalwork from Frank yesterday, so in 3 weeks or so I should be able to start final assembly.

 

[Bobby Baird]

I ordered the metalwork from Frank yesterday, so in 3 weeks or so I should be able to start final assembly.

I just ordered 16 - RE-0887PC & 16 - CM-3301 from cinemag. These are the Wally Heider modeled input transformer with the custom quad-filler output transformer designed for CAPI's Platinum series pre's. Oh I also have 16 CA-0252 op-amp kits. Should be good!

 

[Ricardus]

I just ordered 16 - RE-0887PC & 16 - CM-3301 from cinemag. These are the Wally Heider modeled input transformer with the custom quad-filler output transformer designed for CAPI's Platinum series pre's. Oh I also have 16 CA-0252 op-amp kits. Should be good!

Man, that wasn't cheap! Yer killin me!

Now that I have my own boards for the Huntington era DOAs, I don't think I'll buy DOAs from anyone else for anything. Very happy with these and can roll my own from scratch. I filled my Studer EQs with them. I also have boards friends did for Neumann and Jensen 2520 style opamps.

I'll probably stop with 8 of these, because I will have 8 of the Sound Skulptor 573s done soon, and I already have two CAPI VP25s. So 10 channels of API style will be enough for me. I also have a ton of SSL9000 pres, with a smattering of others here and there. And I have to get 2 of Volker's Neumann preamp clones also.

 

[oran.outan]

Hi All

try to move forward on my build...
Panasonic TQ2-12v are out of stock basically everywhere, with a long delay...
and don't want to make a special order as it will cost me more on shipping than the product, I only need 2...
Do you know any replacement one's !?
maybe someone have 2 in spare that they can ship into EU !?

//
@Edit : I find that one which should work ! it appear to be the same, with 'Self-clinching terminal' who look like a little bump on the terminals pin that clamp on the PCB...

https://www.mouser.fr/ProductDetail...-Devices/TQ2H-12V?qs=YINDDaGsG3GG6wT1xiNklA==
and that one seems to be equivalent too : https://www.mouser.fr/ProductDetail/KEMET/EA2-12NJ?qs=rjnFDYRVT0qLfSdrx1tU9Q==
//


thanks
F

 

[Bobby Baird]

Hi All

try to move forward on my build...
Panasonic TQ2-12v are out of stock basically everywhere, with a long delay...
and don't want to make a special order as it will cost me more on shipping than the product, I only need 2...
Do you know any replacement one's !?
maybe someone have 2 in spare that they can ship into EU !?

//
@Edit : I find that one which should work ! it appear to be the same, with 'Self-clinching terminal' who look like a little bump on the terminals pin that clamp on the PCB...

https://www.mouser.fr/ProductDetail...-Devices/TQ2H-12V?qs=YINDDaGsG3GG6wT1xiNklA==
and that one seems to be equivalent too : https://www.mouser.fr/ProductDetail/KEMET/EA2-12NJ?qs=rjnFDYRVT0qLfSdrx1tU9Q==
//


thanks
F

Either one will work I'd get the kemet it's a euro cheaper.

 

[Ricardus]

Progress.

I chose not to go with the pushbutton PCB mounted switches and used some nice C&K toggles.

 

[Bobby Baird]

I'm curious does any one know if the di input can be made to accept line level effectivly bypassing input transformer similar to a 325 Line amp? From the schematic it seems possible.

 

[sr1200]

You can but you need some iron on the input side ideally as youre going to need to drop that signal quite a bit coming in.

I considered doing that on my 8ch build but since i didnt put output attenuators i didnt see the need to add more weight/cost to the build. I have run line thru it via reverse DI boxes for some reason I cant recall which, if youre not planning to run line through it all that often might be a better option.

 

[Ricardus]

You can but you need some iron on the input side ideally as youre going to need to drop that signal quite a bit coming in.

I considered doing that on my 8ch build but since i didnt put output attenuators i didnt see the need to add more weight/cost to the build. I have run line thru it via reverse DI boxes for some reason I cant recall which, if youre not planning to run line through it all that often might be a better option.

Holy cow, nice build. I wouldn't even have considered that possible, let alone tried it.

And here I thought my 4 channel was cramped!

What PSU is that?

 

[sr1200]

@Ricardus its the whistle rock power supply. And yeah, its tight. I added meters, and extra relay boards so i could leave the DI's plugged in and switch them on and off with a button on the front. Also added transformer ratio switch.

Using one of CAPI gears relay boards you could route the input to the mic/line transformers. (mounting a line in trafo and connecting the output to the DI in.

 

[Bobby Baird]

To make line level you could swap out or switch out R7 & R8 681r pad resistors with some .1% 4.22k resistors. This would give you 35dB of attenuation. IMHO the cheapest solution. I think I'll add DPDT switch on the back panel and do this.