Quote: Apart from the common balanced vs unbalanced discussion (better noise shielding, etc.):   If the source is a true balanced design, signal/sound quality could profit from it because 2 conversions are cut out (balanced to unbalanced and unbalanced to balanced) as all Stax amps...

Quote: SRM-T1 can also be converted to balanced inputs. The circuit board layout is prepared for it.

Quote: Consider a SRM-T1 as well. On normal bias lambda's it beats my SRM-1/Mk2 (p.p.) by a fair margin. Same comment as on the SRM-1/Mk2: replace old caps. Extra bonus: SRM-T1 can be converted to take ECC99 tubes (like SRM-600 Limited). Should be even more beatiful...  

Quote:   Congrats for achieving that! Still have to find the time to modify mine for balanced and upgrade some of the other parts. BTW: I fitted mine with one normal bias socket so I can use normal and pro bias phones...  

Quote: Then why not try a SRM-T1 and cut out the tube stage? In my experience, if the phone is not too hard to drive, like sigma pro or omega(2) etc., (and lambda's in general arent that hard to drive), the T1 beats the SRM-1/Mk2 by a fair margin. Unfortunately, I do not owm Lambda...

Have you tried to first get V_R+/G or V_R-/G to 0V DC and then adjust V_R+/R- for 0 DC? In other words: if there is no offset pot setting at which V_R+/G and V_R-/G is lower than 48V DC, then I assume that something is out of specs. BTW: did you close the volume pot to zero?

Quote: I remember I had the same experience when I adjusted mine. It seemed to me that balance and offset markings were switched on the PCB. If you adjust offset with the one pot and balance with the other and repeat measurements a few times (alternated), it should be possible to get...

Quote:   Balance + offset adjustment: With 1 tube per channel, adjustment of the balance between the tube sections is needed. The measurements can be made on the outside of the amp in the Stax socket between the + and - lead of the channel (L or R). Adjust for 0V DC. This can be hard...

This is all I got. It was once posted by Spritzer, so we would have to thank him.... If you save the jpeg and open it in a viewer it is a rather large file and easy to read.   The previous transformer wiring pic is from a valve amp (6.3V heater supply secundairy). Bottom line: primary...

Quote: In mine, which is wired for 240V, with AC mains of 230V, I measure 39V between the red secundairies and 480V between the yellow secundaries. So red would be step down and yellow would be step up.   Here is the schematic whee you can also see the details of the transformer...

Quote: Wiring is correct. The back panel was meant for the versions that were shipped with a plug to change the mains voltage in a more comfortable way... . If you don't use the plug, you don't need the back panel. But: be carefull and convince yourself that the connections you...

Mine is C4245 and has all the wires. Re-bias is always a good idea. Adjust balance and offset for 0V DC. Repeat measurements a few times. Remember that the power supply is not regulated, so your measurements will change as mains voltage changes. Also, the bias fluctuates heavy with the...

Quote: This is what I found on the net:   Here is the correct wiring: 100v: Gray+White White wire from the  ACplug+Brown+Green 117v: Gray+White White wire from the AC plug+Blue+Purple 240v: Blue+White wire from the AC plug Purple+Gray Should work for all Stax amps. ...

Quote: I consider mains supply as very important as it all starts with electrons coming "out of the wall" (unless battery powered...). For my main system: - Dedicated audio group with audio grade fuse - Shielded mains cable between the "fuse box" and the the wall outlet - Isolator...

Quote: Thanks. I will keep listening for noise.     Quote:   Although I don't have a KGSS to compare and I cannot switch back to the unmodded 727, I did experience quite an improvement in sound quality after the mod. Much more control. Especially in the bass/upper bass this...

  Quote: With 1 tube per channel, adjustment of the balance between the tube sections is needed. With 2 tubes per channel, adjustment of the balance between the tubes is needed (sections are paralleled). The measurements can be made on the outside of the amp in the Stax socket between...

I have no Lambda pro headphones, but with Sigma pro the amp sounds fine to me.   I would like to know about the gremlins of the gain mod as Spritzer mentioned.

I performed the "Spritzer mod", which consists of the re-location of 2 150K resistors in the feedback loops per channel, plus changing the values of 2 resistors per channel to fix the low gain issue. For the re-location of the 2 resistors in the feedback loops, the originals have to be...

I have performed the SRM-727 mod (4 resistors per channel) myself and I can really recommend it. I use it to drive the SR-007_MK2 and the SR-Sigma Pro (which also is difficult to drive) and I like the sound over an SRM-1 Mk2 and a SRM-t1. The latter I like with Sigma normal bias and Lambda...

Hello to all, I'm fairly new to this forum and untill now I have read a lot of posts to get a bit acquainted. For normal bias phones, I use a SRM-1/Mk2 which I would like to upgrade (actualy a P.P., but I fitted 1 normal bias socket). I have read about swapping out the power transistors...

Hello to all, I'm fairly new to this forum and untill now I have read a lot of posts to get a bit acquainted. For normal bias phones, I use a SRM-1/Mk2 which I would like to upgrade (actualy a P.P., but I fitted 1 normal bias socket). I have read about swapping out the power transistors...