[NoPants]

 
I don't think there's a huge difference in performance between the left and right ends of that chart, and I own both the GP and 007mk1. The Sigmas are truly polarising, however.

 
It seems it's not half as polarizing as the 007/009. Those mids are no joke though

 

[Keithpgdrb]

Seems that I will not have the time right now to start my recap on the srm1mk2.  I would however like to test the amp to see if its working.  the dc offset and balance dial in without a problem.  Can I assume then that it is safe to plug in my NB lambdas?

 

[NoPants]

if dc offset, balance, bias all check out then that's the the dc conditions are- you can't damage the headphones

 

[Keithpgdrb]

balance and offset are fine on the pro socket. I forgot I need to check the normal socket still.  the bias is a separate check?  how is this done?

 

[NoPants]

Measure the voltage between bias and ground, before whatever output resistor there is.
 
At the jack it should be less than 230V if it also comes out of a 4.7M resistor.

 

[Keithpgdrb]

  Measure the voltage between bias and ground, before whatever output resistor there is.
 
At the jack it should be less than 230V if it also comes out of a 4.7M resistor.

hmm.  looks like I need to do the restore.  Normal bias pin reads 148V, pro bias pin reads about 332V.  those should be about 230V/580V yes?

 

[arnaud]

I don't think you'll get the full bias voltage reading at the phone jack because of the voltmeter used. Someone technically capable should explain but, in practice, it's more like 360V read at the pro bias socket.

 

[NoPants]

I said before the jack/ before the resistor- the voltage at the jack is lower because the multimeter's probe resistance is dragging it down. The reading becomes load dependent. Someone else might have a more accurate way to measure but I don't know how Stax implements their bias. Everything I have on hand is the spritzer/gilmore/headamp implementation, which might be different. At the very least you can't damage your headphones by running them at too low a bias. 
 
long story short you might be and probably are fine, but someone who has more experience with actual stax equipment should chime in. I can't measure anything atm
 
google-
 
http://www.head-fi.org/t/447304/stax-srm-1-mk-2-pro-bias-voltages-only-measuring-350v

 

[cucera]

hmm.  looks like I need to do the restore.  Normal bias pin reads 148V, pro bias pin reads about 332V.  those should be about 230V/580V yes?

Quite normal outcome as the standard meter has an impedance (~6MOhm in this case) that is too low compared to the Output resistor. You build a voltage divider with the meter and the protection resistor. To be sure measure with an Voltmeter with >100MOhm or simply before the 4.7M resistor.

 

[wink]

 hmm.  looks like I need to do the restore.  Normal bias pin reads 148V, pro bias pin reads about 332V.

That looks good.  Plug in the phones and ENJOY.....     

 

[crazychile]

I currently have a pair of Koss ESP-950 that I use with the stock energizer. My plan has been to move up to a Stax or other electrostatic amplifier, like the latest Srm-727, and then potentially upgrade the Koss' to SR-007s when budget allows. But the more I read these threads the more I get confused. The SRM-727 seems to be good but best with mods, and Ive read that the recent production '007s aren't as good as the originals.

I want to buy new, don't have the time or desire for a DIY project, and the KGST availability is dependent on someone to build one, has options that need to be decided...etc. I also don't want to spend more than 2.5-3k For both when I finally get done. What should I be looking at for my next 'stat upgrade path?

thanks in advance...

 

[Keithpgdrb]

I currently have a pair of Koss ESP-950 that I use with the stock energizer. My plan has been to move up to a Stax or other electrostatic amplifier, like the latest Srm-727, and then potentially upgrade the Koss' to SR-007s when budget allows. But the more I read these threads the more I get confused. The SRM-727 seems to be good but best with mods, and Ive read that the recent production '007s aren't as good as the originals.

I want to buy new, don't have the time or desire for a DIY project, and the KGST availability is dependent on someone to build one, has options that need to be decided...etc. I also don't want to spend more than 2.5-3k For both when I finally get done. What should I be looking at for my next 'stat upgrade path?

thanks in advance...

buy one of these amps.
 
http://mjolnir-audio.com
 
You won't find a better deal for the quality.  hold on to the koss.

 

[edstrelow]

The older Stax 717 is very good and doesn't need modding. They are a bit hard to find but seem to sell for about $1K. As regards the 007 , check out my thread on the use of sorbothane. My modded 007 beats the 009.

 

[Scottsmrnyc]

Well, I only heard them on one occassion; that being the Munich High End Audio Show that just pasted. But I was impressed with the SR- 507s. They are very reasonably priced. I did an informal AB test between the SR 007s, SR009s and the SR507s and I actually prefered the 507s. I am now awaiting the delivery of the 507s and will keep you posted on any additional incites. All the best.

 

[crazychile]

 
buy one of these amps.
 
http://mjolnir-audio.com
 
You won't find a better deal for the quality.  hold on to the koss.

Thanks, I need to bookmark that site as I can never find it using a Google search.
Looks like Spritzer has one amp on his site right now that fits my price range. And I do like tubes....