Dual Green pre done - Pics

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peterc

Well-known member
Joined
Jun 4, 2004
Messages
2,272
Location
Johannesburg, South Africa
Some pics of my latest incarnation of the good ol' Green....

Knobs from RS, front panel is Fotocal/Lasertran.

Dual-Green-1.jpg


Dual-Green-2.jpg


Dual-Green-3.jpg


Dual-Green-top.jpg
 
Hey Peter,

They look great, those knobs and pilot light look awesome! Where did you get the light?
Also I noticed you don't run a ground to the Pre's from the PSU, any reason?

Cheers

Matt
 
The pilot light is the Mains switch (RS 329-7128).

Also I noticed you don't run a ground to the Pre's from the PSU, any reason?


Well spotted! The pres are grounded via the screen on Chan 1 & 2's input cable, so as to avoid ground loops. Havent heard anything critical thro' it yet, I'll be using it in the studio tomorrow.

Peter
 
How many volts is that big blue 47uf?

And is it just me, or are your voltage regs on your psu aimed opposite the way they are shown on the parts layout?
 
Freekin' awesome Peter, looks great!

Got a question about the LED meter hookup. In the setup, in order to connect the meter before the trim, which I believe you are doing here, you run a link from the pad above and to the left of the 20K trimmer down to the silkscreened link below. That is the pale blue/green wire you've got in yours. My question is, do you ALSO put in the silkscreened link, or ignore it? (only use it for post-trim meter?)

thanks
andrew
 
Is there a reason for it being 100v? Mine is 63v

about the grounding...if you attach all the xlrs together and to the mains in ground, you don't have to use the preamps input ground wire, or shouldn't?

Oddharmonic, it looks like he skipped the silk-screeen link, I'm almost positive that it's one or the other.
 
Is there a reason for it being 100v? Mine is 63v

Because I had a few lying around. 110v will work as a 63v su. So will a 150v. So will a 250v. Get the idea :grin: .

The voltage is a "safety margin". You can use a higher voltage cap than that specified, but not a lower voltage.

about the grounding...if you attach all the xlrs together and to the mains in ground, you don't have to use the preamps input ground wire, or shouldn't?

Shouldnt. It will create a ground loop. Do a search for "star ground" here, & you will find out all you need to know about grounding issues.0

Andrew:
My question is, do you ALSO put in the silkscreened link, or ignore it? (only use it for post-trim meter?)

Ignore it.

Peter
 
I read that star ground article, and it makes sense, i just didn't consider for a second that it meant getting rid of the ground wire coming from the psu to the pre...
 
Peter,

Is this ground scheme you preference with the Greens? I was actually contemplating doing just that before I saw your pics, but I would not have known to remove the ground from the PSU to the boards, which is why I asked... is this a better way of doing things?

Cheers

Matt
 
If you are referring to those in the phantom section, I put them in before measuring the voltage as I didnt know what I would get as a final voltage. One is wired as an extra smoothing cap with a link underneath the PCb, the other is just....... there.

Peter
 
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