Whistle Rock Audio ML12 preamp BUILD/HELP thread!

[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.

What is that power switch??

 

[sr1200]

What is that power switch??

Ulincos Latching Pushbutton... https://www.amazon.com/dp/B01N751TAW?ref=ppx_pop_mob_ap_share

It was all chrome when i bought it. Now looks like theyre making it out of plastic.

 

[Ricardus]

Ulincos Latching Pushbutton... https://www.amazon.com/dp/B01N751TAW?ref=ppx_pop_mob_ap_share

It was all chrome when i bought it. Now looks like theyre making it out of plastic.

So how do you have yours wired? The wiring description on the Amazon page assumes 12v power across the board. You you have on your mains, right?

-EDIT-
Never mind. I figured it out. I found an actual properly labeled pinout for the thing. I'll have to try one of these on a project,

 

[sr1200]

So how do you have yours wired? The wiring description on the Amazon page assumes 12v power across the board. You you have on your mains, right?

-EDIT-
Never mind. I figured it out. I found an actual properly labeled pinout for the thing. I'll have to try one of these on a project,

ive use similar ones on a few projects now, they have a nice feel and the illumination is pretty neat. (mine glows blue)

 

[oran.outan]

Hi all

@sr1200, I'll be interested in the Mod you made...
- for the DI Switch did you put the SPDT on pin 2 between the Main PCB and the DI PCB ?= open/close the Jack contact.

Also, on the DI PCB, there is that Jumper1, for choose between 1M/10M input impedance...
Did you put a Switch between there too ?!
Does change one of the resistor (R1 or R2) will make possible to work as a line input?
or using the 1M as a line in will be fine ?
Will be amazing to have that pre working in Mic/Hi-Z/line configuration...

thanks for you return !
Best
0-0

 

[Ricardus]

OK, my first 4 channels of ML12 are done and I am very happy.

 

[Ricardus]

Front panel glamour shot.

 

[TillM]

Really good work !
You will love that pre ! I used it since years and also rent it to recording engineers. Everyone loved it!
Instead of the DI I used the T-Pad.

 

[Ricardus]

Really good work !
You will love that pre ! I used it since years and also rent it to recording engineers. Everyone loved it!
Instead of the DI I used the T-Pad.

I am going to build some with the T-Pad as well, but first, I think I am going to build a 6-channel version with no DI's and no T-Pad, with en external PSU.

Can't wait to record some rock and roll!

 

[Bobby Baird]

My order of transformers arrived! Assembling one tonight for a test drive.

 

[oran.outan]

Hi

As I'm in EU, I was waiting for get Utm industry transformers but since he recently say that the 2622 type is wider and after measure will not fit i'm a bit in a dead end as it's almost impossible to put my hand on the EA 2622/2503 at the same time on the CAPI store...

On the manual the 2623 is mention.
Does anyone already used the 2623 ? as it's seems easier to get...

thanks
F

 

[Whoops]

On the manual the 2623 is mention.
Does anyone already used the 2623 ? as it's seems easier to get...

Yes, I used it, it works great as the output transformer in a 312 preamp.
You can use the 2623 or the 2503 as output transformers for the 312.

The 2623 was used extensively in API consoles, used for channels direct outs and in the summing amp.

It’s a good transformer

 

[oran.outan]

@Whoops, thanks for your reply...
another quick question and I will be done!

I'd like to add a Vu meter driver like that one (http://diy-tubes.com/image/data/manuals/vu-buffer-1.2-en.pdf), which is a line in...
Using the Aux out (which of course will need a 2503...) it be 75ohm... will that be a problem !?
Or just take the Main out and wire it to the vu driver input (and XLR out of course)?

thanks
F

 

[Whoops]

If you’re using a VU then it’s better to use the 2503 so you can use the isolated output from the third secondary to feed the VU

 

[Bobby Baird]

One external power supply built up using the ML12 Supply & the Triad VPT36-1390 in a Hammond 513-0900 enclosure.

​

 

[Ricardus]

One external power supply built up using the ML12 Supply & the Triad VPT36-1390 in a Hammond 513-0900 enclosure.

​

My next ML12 build will be 6 channels with no DI or attenuator with an external PSU. Hopefully done by new years. Then I'll have more than enough cool preamps.

I like that case. I'll probably end up using the same one.

What wire did you use for the multi conductor power cable to connect the PSU to the preamps?

 

[Bobby Baird]

16.4ft RVV Wire Cable Extension Cord Copper Wire Conductor 5 Core 18 AWG with an Aviation plug 5 pin. Case Handle 1427N2

 

[Bobby Baird]

Bench test sounds promising. Can't wait to get all 16 racked up.

 

[Ricardus]

16.4ft RVV Wire Cable Extension Cord Copper Wire Conductor 5 Core 18 AWG with an Aviation plug 5 pin. Case Handle 1427N2

Oh okay you need to power 16 units that's why you went with such heavy gauge wire. Cool.

I built a four-channel standalone unit and finally got to use it on a session last Saturday (the blue power LEDs aren't quite that blinding in real life). Sounds killer on the drums.

I'll use a 6 pin XLR for power on my next one kinda like Jeff from CAPI uses a 5 pin XLR for his 500 series racks. It can handle enough current.

 

[sr1200]

Hi all

@sr1200, I'll be interested in the Mod you made...
- for the DI Switch did you put the SPDT on pin 2 between the Main PCB and the DI PCB ?= open/close the Jack contact.

Also, on the DI PCB, there is that Jumper1, for choose between 1M/10M input impedance...
Did you put a Switch between there too ?!
Does change one of the resistor (R1 or R2) will make possible to work as a line input?
or using the 1M as a line in will be fine ?
Will be amazing to have that pre working in Mic/Hi-Z/line configuration...

thanks for you return !
Best
0-0

so the jumper for the 1m/10m is a switch on the back of the unit (too many up front). I also put a switch for the transformer winding (5:1/10:1) on the front. The mod is a simple perfboard thing where instead of the pin 2 connecting to ground via the sleeve of the instrument cable, the switch provides the ground which activates the relay on the main board to switch inputs from DI to MIC (vice versa). The DI input probably shouldnt be used as a line input as the gain here is probably going to be a bit much for a line level (its expecting instrument level signals) you'd probably be better padding down the mic input and using that for line if you're not adding anything else.