Diy Stax-Srd7 for about....hmmm...$20

[hyperma]

Hello everyone, hope everything doing very well today.

Few days ago I found two transformers in my dungeon, which named by my wife. I mentioned it has 16V out and double 110V in, so I guess perhaps could make something like stax srd-7.

Then I made a pcb and give most places to voltage doubling rectifier, as same as srd-7, and... it works.

Well somehow the bias unable to reach 580V, only around 490V, the sound quality, of course, bass section bit weak, so I have to turn the EQ on, then everything fantastic.

 

BOM:

 2 30W transformers 110-0-110 in 16V out, 1 50W transformer 220V in 110V out.

1 fuse @200ma

6 0.1uf 630V caps

1 0.01uf 630v cap

6 1n4007 diodes

4 speaker connectors

2 2M2 resistors @ 2W (for safety consideration no less than 1/2W)

1 15k resistors ( to light up led)

2 5R resistors @5W for dummy load

1 1M resistor

1 stax standard electrostatic can connector

Infact if I could spend enough time on it, hand wired construction must be better and cheaper.

So I call this project "Ghetto SRD-7".

 

 

 

 

[Blueman2]

Neat!  When you say your bias is only able to reach 490, how are you measuring that?  You cannot just measure with a normal DMM as it's own impedance will give a false low reading.  

And where did you get the board made?  Looks quite nice.  

Edited September 30, 2020 by Blueman2

[hyperma]

measured by a high voltage probe of oscillator, yes ,you right, the bias has fallen down when the probe touch the bias connector.

I drawn this pcb by AD11 and made in JiaLiChuang, which has two factories in south of China, cheap and quick.