[mikefatom]

Hello all,

This shall be the BUILD/HELP thread for the Whistle Rock Audio ML12 preamp project.
Please don't hesitate to post any questions here and share your build photos/tips for everyone's benefit.

Cheers,

Mike

PROJECT DOCUMENTATION

ML12 Microphone Preamp
- Webstore Product Page
- ML12 - PCB Manual
- ML12 - Schematic
- ML12 - Bill Of Materials on Google Drive
- ML12 - Mechanicals
- ML12 - Front Panel Designer File  (Right-click and Save As)


ML12.DI1 passive DI add-on module
- Webstore Product Page
- ML12.DI1 - Bill Of Materials on Google Drive
- ML12.DI1 - Schematic

ML12.DI2 active JFET DI add-on module
- Webstore Product Page
- ML12.DI2 - Bill Of Materials on Google Drive
- ML12.DI2 - Schematic

ML12 PSU designed for the ML12 preamp and more
- Webstore Product Page
- ML12 PSU Manual

[mikefatom]

Reserved!

[mikefatom]

Reserved!

[okgb]

Your Opamps are great , thanks !
you should consider a full[er ] kit minus the xfmrs for your 500 pre
[ don't underestimate the one stop shop! ]

[mikefatom]

Thanks Greg!

I did consider a partial kit for the ML12 but it always comes down to time and capital.
There is now the option of ordering a partial kit for the HZ-51X though.  I have about 6 parts kit ready to go for those interested.

Anyway, back to the ML12!

Cheers,

Mike

[buildafriend]

Hey guys,

I was wondering if you think that this toroid will work for the Whistle Rock PSU
https://system.netsuite.com/core/media/media.nl?id=12598&c=ACCT126831&h=f45394ec671010085fcd&_xt=.pdf

I have one on hand so I'm hoping I can use it..

Here is the PSU board info
http://www.whistlerockaudio.com/cart/documents/ML12%20PSU/ML12%20PSU%20Manual.pdf

[mikefatom]

Hey buildafriend,

This TX will work great.
How many ML12 preamps are you planning on running with this? At 25VA, I wouldn't run more than 2 pres off of it.

Cheers,

Mike

[mikefatom]

First post updated with a bunch of documentation links.

The BOM contains Mouser/Digikey part numbers for easy sourcing.  I will update the Google Drive BOMs whenever required to make sure all the parts for the project are always available from one source or another.

Thanks!

Mike

[buildafriend]

Hey buildafriend,

This TX will work great.


How many ML12 preamps are you planning on running with this? At 25VA, I wouldn't run more than 2 pres off of it.

Cheers,

Mike

I need to power 6 ML12s. So do I need 75VA?

[Rocinante]

Hey Mike,
The boards just came in and look great. I have some leftover components from other builds I'm gonna consolidate and then see what is needed. The bom (esp the Google doc) is impeccable. Excellent job and makes sourcing a ton easier. Thanks.

[mikefatom]

Hey buildafriend,

This TX will work great.


How many ML12 preamps are you planning on running with this? At 25VA, I wouldn't run more than 2 pres off of it.

Cheers,

Mike

I need to power 6 ML12s. So do I need 75VA?

2x18VAC @ 60VA would do fine for 6 ML12 preamps. Although, it seems easier to find 2x18VAC @ 80VA transformers.

[mikefatom]

Hey Mike,
The boards just came in and look great. I have some leftover components from other builds I'm gonna consolidate and then see what is needed. The bom (esp the Google doc) is impeccable. Excellent job and makes sourcing a ton easier. Thanks.

Thanks and enjoy!

Mike

[buildafriend]

I decided to go with this power transformer.
http://www.mouser.com/ProductDetail/Triad-Magnetics/VPT36-2780/?qs=%2fha2pyFadujUGzmE%2fHhVxqSf61PtIPcEf4xQgizhBOilWpPdDd8xbQ%3d%3d

Might I consider upping the power rating on any R's in my PSU board? I'm not sure if 100VA is a lot for the board to handle because I don't recall ever using one this big on anything solid state. I'm assuming the regulators will be okay with getting his with this. I'll up the size of my heat sinks.

moving along here.. thanks guys 

[mikefatom]

buildafriend:  A 2x18VAC @ 100VA transformer is way more than needed for 6 ML12 preamps but you can still use it with the PSU just fine.  The heatsinks don't need to be any bigger than if you had used a 2x18VAC @ 60VA transformer (the preamps draw the same amount of current).

Cheers,

Mike

[buildafriend]

buildafriend:  A 2x18VAC @ 100VA transformer is way more than needed for 6 ML12 preamps but you can still use it with the PSU just fine.  The heatsinks don't need to be any bigger than if you had used a 2x18VAC @ 60VA transformer (the preamps draw the same amount of current).

Cheers,

Mike

Okay, Thank you.

The power supply is up and running like a champ!

I'm curious if the power out ground and chassis ground should show continuity.

[mikefatom]

Nice build buildafriend!

The PSU has a chassis grounding point marked as 'star ground'.  This is shorted to the power output ground as well.  So yes, there should be continuity.

Cheers,

Mike

[MountCyanide]

Sweet build!
Ahh good to know about that star ground. Sharp, Mike.
I decided to daisy chain a couple more pres off of my psu.
What kind of 5 pin cable are you guys using?
I've got a DMX cable. Is it cool to run the ground through the (unshielded) shield strand?

[Rocinante]

Hey
So I've just finished collecting components and am stuffing the PSU now. On the PSU PCB at c11 there are three points; the two usual points for the 1000uf cap and a third that leads to the output section. Is this third point significant?  Also I have 8 1000uf 50v caps left over from another build as well as two 1000uf 63v caps that will make up the ten needed for this PSU. It's safe to assume I can mix these up without any concerns correct? I know its a noobie question but I don't feel like it hurts to ask and I've been wondering about mixing caps with different voltages for awhile.
Thanks

[mikefatom]

The third point is a PCB via.  Don't use it.
You can mix cap voltages as long as the voltage rating of each cap is higher than what is called for in the BOM/Manual. That is the safest approach for any build.

Mike

[Rocinante]

The third point is a PCB via.  Don't use it.
You can mix cap voltages as long as the voltage rating of each cap is higher than what is called for in the BOM/Manual. That is the safest approach for any build.

Mike

Thanks Mike. That's what I figured but doubt myself.
Cheers