[kevin gilmore]

what are the part numbers on the output devices (those on the heatsinks) pretty sure they are pnp or p-channel
so this is an upside down version of the srm1/mk2
C101,C102 (still hard to read those numbers) are strictly in the balance circuit. No audio signal whatsoever.
You can replace with 110uf if that is what you want, or 220uf, will not matter in the slightest.
the neon lamp is strictly a safety circuit, and does not (and should not) be replaced.

as far as the cascode current sources, since they will be running at minus voltages, everything has
to turn upside down, so my board will not work. but the general idea works fine. contact jiml for more
information, or search srm-t1 modifications. each current source is a 2 wire device and replaces the pair of load resistors. you need 4 of them. dn2540+ixcp10m90s + 3 resistors each.

here is a more correct version of the circuit. lots of stuff including values and part# still hard to read.

 

[legopart]

thanks again!

I think that: B832 (Q110 Q111 Q210 Q211)

I will check and learn about this "cascode current source"
what the value of the 3 resistors, and the Watt power for them?
will this upgrade can improve the amp?

 

[kevin gilmore]

1/4 watt, and there are 2 resistors.
100 ohms
and the other one currently labeled as 93 ohms is trimmed for 6.5ma

 

[legopart]

I see only 2 resistors

ebay good enoth to buy this elements?
I can buy 100ohm resisters and 91ohm+2ohm (all of them 1/4w)
I cant find the 3rd resistor.
cant understand the 6.5ma explanation.

does it improve the acchivements from this amp?
does the main capacitors and this board supply can apply and hold this this additional board (replacement)?

 

[kevin gilmore]

do not buy these parts on ebay, you will be sorry.
everything is available at mouser.

google "modifying stax's srm-t1"

you will have to build something that fits your chassis.

The 93 ohm resistor needs to be adjusted to get the desired current. Or replace it with a 150 ohm pot.

 

[legopart]

Cant find the "ixcp10m90s" can you suggest another element to replace with?
I couldn't find any pictures for this mod
I would like to try it.

 

[kevin gilmore]

https://www.mouser.com/datasheet/2/240/DS98729A(IXCP-CY10M90S)-1547388.pdf

 

[legopart]

@kevin gilmore

Found this site and used google translate:
http://blog.prof-x.de/2019/01/26/stax-vacuum-tube-driver-teil-3-output-stage-mod/
his scheme little bit different

*where can I find this user here ?

@Firschi can you please help me with this mod, I want to improve my Srm-1, Thanks.


Can you recommend me which parts to buy from here?
https://www.mouser.co.il/

for transistors I decide to buy this
https://www.mouser.co.il/ProductDetail/747-IXCP10M90S
https://www.mouser.co.il/ProductDetail/689-DN2540N5-G

What resistors to buy ?

is this good for 100ohm one?
https://www.mouser.co.il/ProductDetail/660-MF1-2CCT52R1000F (1/2W 700v 1% 50PPM)

what additional elements do I need?

still need to buy some passive cooling.

thanks.



Still cant understand what this modding will improve ? (the amp sounds good as is)