Seperate EI Trafos or Multiwinding Toroid? (G9 Related)

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Philip_BlueFX

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Feb 27, 2020
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Studying the G9 schematic and jumping around in the threads, a question sprouted inside my helpless mind.

Our power needs are 12V...Heaters, 245V...HT, 48V...phantom.
What's there to stop me from getting a custom toroid transformer and regulating-filtering each step for my power needs?
Instead of getting a 220:15+15 and 15+15:220, voltage trippler for phantom etc.?
My understanding is that the PSU was originally designed for the 220:15+15 that, I suppose, where heavily available at the Gyraf factory.

So, what's the underside of getting a multiwinding toroid in a case like this?
 
Philip_BlueFX said:
...What's there to stop me from getting a custom toroid transformer and regulating-filtering each step for my power needs?
Nothing.  Gyraf's  solution is DIY solution (cheaper transformers and easier to find and realize worldwide). 
 
Check out Don Audio and you will find they do several multi-secondary toroids with the three voltages you require for tube pre work.

However, some of us are moving over to small SMPS for phantom and heater supplies (if you can arrange your heater chain  to work on 12V). The you just need a single 230V secondary transformer for the HT - something like the TRIAD VPT230-110.

There is an argument against using a single multi-secondary transformer especially where one secondary is used for a linear heater supply. The argument  goes that the very high peak diode currents the heater dc supply creates can find their way to the other secondaries and appear in the HT or phantom supplies. However, I have never observed this.

Cheers

Ian
 
Philip_BlueFX said:
Studying the G9 schematic and jumping around in the threads, a question sprouted inside my helpless mind.

Our power needs are 12V...Heaters, 245V...HT, 48V...phantom.
What's there to stop me from getting a custom toroid transformer and regulating-filtering each step for my power needs?

Nothing, that's what I would use.

Philip_BlueFX said:
So, what's the underside of getting a multiwinding toroid in a case like this?

No underside. Go for it
 
I was actually planning on building one channel G9 and one 1176N in series in a single unit.
So I am designing my new kind of PSU for that. I actually don't know yet if I am going for the single multi-toroid or seperate ones.
It mostly depends on the cost and availability. Will do my research locally on that.

I am wondering. If I connect together the negative output sides of the 220:15+15 trafo of the G9 (the first psu trafo), can I get the ground for the 1176N ?
Schematic provided because I am having trouble describing accurately :)
Thank you all.
 

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Philip_BlueFX said:
I was actually planning on building one channel G9 and one 1176N in series in a single unit...

It is quite a demanding project, and as far as I can see, you are still inexperienced. So I would suggest you building a microphone preamp and compressor in separate boxes with separate power supplies. Your power supply scheme doesn't work.
 
Philip_BlueFX said:
Schematic provided because I am having trouble describing accurately :)
As moapms wrote, it won't work, because you are taking grounds from three different nodes. You can't connect them. Even if you powered separate units, they could not be connected.
Since you have a center-tapped secondary, you don't need a bridge rectifier.
There are many examples available on the net.
With these two xfmrs, you can make 12V for heaters, 48V for phantom and HT, but forget about +30V. Make a separate PSU.
 
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