briangt PSU 1 transformer, 2 PSU, how to?

[sansbury]

So I have the BrianGT dual mono kit, most recent iteration. There are two PSU/rectifier boards. I am assembling one channel first to verify things.

One question that comes up is that the first PSU board I have has terminals to connect 4 wires to off the transformer. I have a Avel trafo from parts express and am following this wiring diagram from another thread:

http://www.diyaudio.com/forums/attachment.php?s=&postid=681376&stamp=1121283775

This shows all 4 secondary wires going into one PSU board. My question is, using one transformer, do I not use the second PSU board at all, or is there another way to wire this up?

 

[Mayday]

I split the secondarys like this:

An externally hosted image should be here but it was not working when we last tested it.

 

[sansbury]

Beautiful- Thanks!

 

[ianpengelly]

The only problem I have found is that you might experience hum due to the two channels interacting through the transformer with this set up. I think the Dual Mono Brian GT kits are designed to be used with either 1 power supply board or 2 transformers. I wrote a thread about it:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=95451

Fingers crossed you don't run into this problem, but I did and it bugged me for ages until I figured it out. Now I am waiting to fit the second transformer.

 

[Apex Jr]

I had my webguy put a picture of hookup of the
toroids I have in stock on the website

www.apexjr.com/miscellaneous.html

1/2 way down
Thanks to Troy St Germain

Steve @ Apex Jr.

 

[Mayday]

Looks like this now, and no more humming either...it's completely quiet.
Dual trafos is clearly the way to go with these dual-mono kits.
Noticed sound improvements aswell.

An externally hosted image should be here but it was not working when we last tested it.

Fan isn't hooked up, don't know that I need it yet.

 

[AndrewT]

Hi,
no hum.
How did you connect the two audio grounds to the safety earth?

 

[Mayday]

Used this as stargnd, and connected them to it and safety gnd to it aswell.

An externally hosted image should be here but it was not working when we last tested it.

 

[ianpengelly]

Mayday,

Glad you had good results from moving to two transformers... I'll be off to the garage today to try and get mine modified.

Andrew,

I am ashamed to say I still haven't got round to building a disconnecting network.

 

[AndrewT]

Used this as stargnd, and connected them to it and safety gnd to it aswell.

An externally hosted image should be here but it was not working when we last tested it.

Mayday,

Glad you had good results from moving to two transformers... I'll be off to the garage today to try and get mine modified.

Andrew,

I am ashamed to say I still haven't got round to building a disconnecting network.

Mayday has got it to work without a disconnecting network.
Look back to his amp photo and you can see his grounding wires going to the tag strip just above the CE label (right of centre).

 

[Mayday]

As you can see on the photo of my stargnd, all the solderpoints are connected to each other with a bit of copperwire(in this case silverplated) thats important.

 

[ianpengelly]

Andrew, that is how mine is effectively wired at the moment (from a grounding perspective), however, I am getting pops from my speakers when things like the fridge start. I am hoping that a disconnecting network will help to tame this, if not I'll be off out to get a filtered mains inlet.

 

[Mayday]

Sounds more like a wiring problem in your house. I'd get a filter with enough outlets for the entire stereo.

 

[ianpengelly]

I bought a russ andrews silencer plug in thinking that would help, but it hasn't. The stereo is plugged in directly adjacent to the fridge, when I move house in a couple of months I'll have to see if it is still as bad.

 

[ppcblaster]

What transformers did you select

and what is your rail voltages?

Thank you

 

[Mayday]

in my case it is -+35V

 

[ianpengelly]

2X22V for me.


I have just made the change over to two transformers and I am pleased to say no hum! And no pops and crackles last night despite not fitting my disconnecting network (ran out of time as Dr Who was on at 7:00, couldn't miss that!). So I am very pleased. I need to try it with music and see if there are any improvements made.

 

[ianpengelly]

Oops! sorry 2x22V transformers! So about 32V rails

 

[ppcblaster]

Two questions please

Mayday,

How did you silverplate the star ground,

and what type, size wire

is recommended for the internal wiring?

Thank you

 

[Mayday]

The stargnd is simply a solder support(don't know if that's even a correct name, just translated straight from swedish), I bought it silverplated, then i connected the solderpoints together using 0,8mm(diameter) silverplated copperwire.
Normally I'd use 0,6mm(diameter) solid silver with teflontubing as insulator as internal wiring, but this build was my first chipamp, I wasn't shure about soundquality so I didn't want to spend too much.

Wires from boards to stargnd are 1,5 square mm pure copper. Also from stargnd to safety earth.