[sachu]

LIstening to an SR-404 on an eXStata..Running balanced out from a presonus central station.This is quite good.
 
i just wish the arc assembly wasn't so creaaky..annoying as hell if you move your head even the tiniest bit.
 

 

[sachu]

A few quick impressions. The detail level is real nice and all but its the standard electrostat sound regardless of what amp or stat i have heard. Great imaging and soundstaging, and you definitely get that light feel to the music, but that's what is exactly wrong for me. Compared to the LCD-2 and the EHHA I have here or even the thunderpants, i'd pick the latter every single time for that weight they bring to the music and be willing to sacrifice a little detail. That weight in the music is severely lacking for nearly all stats I have heard, but the O2 and even the O2 doesn't quite match up to the orthos here. This seems to be the only reason stopping me from going all out on a stat system. I truly do appreciate what the better stats can do. Goes to show no one headphone will fit all. That said, I am definitely going to pick up a used O2Mk1 in the next couple of months.

 

[MuppetFace]

Finally got my SR-507 in.
 
http://www.head-fi.org/forum/thread/506765/stax-sr-507-sept-1-2010-stax-sr-207-oct-1-2010-what/375#post_7039871
 
Some quick initial impressions posted in the 507 thread.

 

[n3rdling]

Thanks for the impressions Romy

 

[svyr]

mhmhmhmmh. While fiddling with the DACs I found a 2 pin power cable (came with SRM-300...or MD11, I can't remember now), (JP), connecting it to the SRM-1, instead of the standard Australian 3 pin one, via a jp->aus plug adapter made the ground loop noise go away. Yay no more running the laptop on battery for playback/finally everything seems to work without any issues. 
 
2 prong plug <3

 

[spritzer]

Just finished this, SRM-T1 to SRM-600 conversion:
 

 


This only requires new anode resistors for the tubes (30K instead of 33K), rewiring of the tube sockets to get the correct filament voltage for the ECC99's and to rebias the amp.  I also swapped out all of the electrolytic caps as the stock units were close to 20 years old. 

 

[MuppetFace]

Quote:

Just finished this, SRM-T1 to SRM-600 conversion:
 

 


This only requires new anode resistors for the tubes (30K instead of 33K), rewiring of the tube sockets to get the correct filament voltage for the ECC99's and to rebias the amp.  I also swapped out all of the electrolytic caps as the stock units were close to 20 years old. 

Beautiful work!

 

[Michgelsen]

Looks neat. Does the hood of the amp still fit, or is it the photo that makes the ECC99 look that tall? And, of course, does it sound better or is the amp limited by other factors than the tubes?

 

[spritzer]

The ECC99 is just a little bit taller so the lid fits just fine.  The sound is a lot cleaner now but whether it is up to the new tubes or the new caps is hard to know...

 

[svyr]

>Just finished this, SRM-T1 to SRM-600 conversion:
 
o.O sooo SRM-600 is better or because you could?

those resistors are huge, spritzer 

 
Quote:

Just finished this, SRM-T1 to SRM-600 conversion:
 

 


This only requires new anode resistors for the tubes (30K instead of 33K), rewiring of the tube sockets to get the correct filament voltage for the ECC99's and to rebias the amp.  I also swapped out all of the electrolytic caps as the stock units were close to 20 years old. 

 

[spritzer]

The ECC99 is a better tube on paper, it can handle more voltage and it has nice a feature which I value highly.  There is only one manufacturer who has ever made it so there is no way to roll it.  There is a gold version but it is just the same with gold printing on it.  Well then there is just wanting to try it for the heck of it too...
 
The really big resistors were stock, I only added the green Kiwame resistors which are at least three times smaller than the units which Stax used, though also 2W. 

 

[svyr]

 
but won't tell us about 

 
btw, what's the transparent box thingy with 'OMRON' on it.
Quote:

The ECC99 is a better tube on paper, it can handle more voltage and it has nice a feature which I value highly.  There is only one manufacturer who has ever made it so there is no way to roll it.  There is a gold version but it is just the same with gold printing on it.  Well then there is just wanting to try it for the heck of it too...
 
The really big resistors were stock, I only added the green Kiwame resistors which are at least three times smaller than the units which Stax used, though also 2W. 

 

[jgazal]

General Purpose / Industrial Relays DPST-NO 3A 12VDC 400Ohm Through Hole (G2R-2A-H-DC12)
 
Guess this amplifier has also one for a similar purpose: 
 
Quote:

Tube Headphone Amplifier/Preamp with Relay-Based Input and Power Switching by Helmut Ahammer
(...)
This amplifier features relay-based input and power switching. The stepped and slow turn-on for the power supplies result in less stress for the tubes and other components and reduces turn-on thumps that could damage headphones. Most tubes fail at turn-on. Without the slow turn-on, if the tube heater filament is cold, the resistance is lower and the in-rush current of a cold filament could be very high and cause the filament to break. And if the filament is not hot, it is better that the plate voltage is not applied. Applying the plate voltage with cold filaments can reduce the lifetime of the tubes.
(...)
 

 
Is that right, spritzer?
 

 

[spritzer]

The special feature is that you can't roll the tubes. 

  I like that since the horrors of tube rolling and how clueless people are about the roles tubes play in the amps frightens me.  Some actually think it is ok to remove the tubes while in use...
 
All the Stax amps have a delay which warms up the tubes before applying the HV.  Not really needed but it can't hurt.

 

[jaycalgary]

Do you use just off the shelf parts for upgrading capacitors and new ones a lot smaller? I have an SRM/1 MRK/2 that I am thinking it may help to change the electrolytic capacitors. There is a electronic parts store here in town but the parts would be average new replacements.
Would there be anything else in this amp besides the electrolytics that would be a good idea to change? Thanks for any advice.