Stax SRD-4 into SRD-6 - how?
Feb 10, 2008 at 3:56 PM Thread Starter Post #1 of 13
d.phens

d.phens

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I have no clue but somebody on the Stax thread posted about that as if it were not only possible but even quite easy...
 
Feb 10, 2008 at 4:22 PM Post #2 of 13
follow the srd-7 schematic and add a bias circuit. It's an srd-6 at best because the 7 has better iron in it.
 
Feb 10, 2008 at 5:13 PM Post #3 of 13
The normal bias supply is a simple voltage double from 117v in some versions (it was 200v up to 1977) but others use zeners back to back and then multiply that voltage 80v times 3 for normal bias and times 7 for Pro bias. Just add a 5meg ohm resistor on the bias line to control the charge. I have the SRD-7 Mk2 schematic somewhere if you want it.
 
Mar 4, 2008 at 2:30 AM Post #4 of 13
Important notice: I need it for 230/220V
I'd love the SRD7 schematic but I still don't know the difference between SRD6 and SRD7.
Judging by looks SRD4 is really like SRD6 but with no bias.
 
Mar 4, 2008 at 7:09 AM Post #5 of 13
I think the 7 has two output jack while the 6 has only one. Correct me if I am wrong.....

now, to convert the 4 into a 6, you will need a bias generating circuit, one end of the bias goes to the bias pin in the jack, the other one..... in a 7 it goes to the center tap of the transformers, but do the trans in a SRD-4 has center tap also? If not, you will need two 10M resistors arcross the transformer output and connect the "other" bias wire to where the resistors meet.....

That said, I was under the impression that the 4 has smaller trans than the 6 (I think I got the info from Birgir), so the 4 probably won't sound as good anyway, might not worth the trouble to convert it.....
 
Mar 4, 2008 at 8:11 AM Post #6 of 13
main.php

This the the schematic from the SRD-7 MkII instructions manual. Since there is a pair of zeners on the input it is compatible for all input voltages. The SB version is the same with a third transformer lifting the signal voltage off the secondary of one of the transformers and feeding it to the bias supply.

The SRD-6 has the same transformers as the 7 but only one output socket. The SRD-4 uses the smaller transformers that were used in the SRD-5.
 
Mar 5, 2008 at 12:34 PM Post #9 of 13
It seems to make more sense converting 110V SRD6 (US version) into 230/220V. Any conception?
 
Mar 5, 2008 at 1:29 PM Post #10 of 13
Quote:

Originally Posted by d.phens /img/forum/go_quote.gif
It seems to make more sense converting 110V SRD6 (US version) into 230/220V. Any conception?


You would need either a normal step down transformer or two 110v zeners back to back at the input.
 
Mar 5, 2008 at 3:31 PM Post #11 of 13
Mar 6, 2008 at 5:28 AM Post #12 of 13
What's better for sound and money?
I don't know where the zeners should go BTW. Can you pinpoint it on the schematic? I'm an unskilled amateur. -thanks

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif
You would need either a normal step down transformer or two 110v zeners back to back at the input.


 
Mar 6, 2008 at 8:04 AM Post #13 of 13
Quote:

Originally Posted by d.phens /img/forum/go_quote.gif
What's better for sound and money?
I don't know where the zeners should go BTW. Can you pinpoint it on the schematic? I'm an unskilled amateur. -thanks


The Z101 on the above schematic is a dual zener and lowers the input voltage of the circuit so it can be used world wide. You also need the resistor to limit current.
 
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