Problem with Stax Sigma Pros and or Stax SRM 007ta?? Help and or Advice.

[Scottsmrnyc]

 I have a relatively new Stax SRM007ta which I have been using with a pair of Stax Sigma Pros.  I have now gone through two pair of Sigma Pros with the right earspeaker dying out with now sound.  Originally, both Sigmas worked fine; but after approximately a year of use with each one the right earspeaker died.  There is not sound coming from the right earspeakers' of both units. 
 
Do you think this problems is caused by the fact that the Sigma Pros are roughly thirty years old and just died out?  Or is it a SRM00ta problem.  I am hesitant to plug any of my other Stax Pro speakers into the SRM007ta at this time. 
 
Any advice is welcome. 

 

[spritzer]

Even with excessive offset or bad tubes then the amp shouldn't be able to hurt the transducers.  The bias is shared so that's not a factor either.  Still I would measure the offset just to make sure it isn't a problem.  Just measure all of the pins on the Stax socket WRT ground and see if anything super high pops up.  One will be 300V+ but that's the bias. 

 

[Scottsmrnyc]

Thanks Spritzer- but what do I measure them with and where do I get such a measuring tool?  I am a layman about this kind of stuff.  So I get the measuring tool, insert it into each recepticle opening and see what it reads?  Thanks for you advice. 

 

[spritzer]

You need a multimeter, preferably an auto ranging one.  You just insert the red probe into each post on the Stax socket in turn with the black probe connected to the ground post on the back of the amp. 

 

[Scottsmrnyc]

This may sound crazy but should the SRM007ta be on or off.  Going to look on EBay for a Multimeter.  Thanks Scottsmrnyc

 

[Scottsmrnyc]

Okay, I just bought a Multimeter on Ebay.  It may take a while for delivery.  We continue when I take possession of it.  Thanks  Scottsmrnyc

 

[spritzer]

The amp has to stay on for this. 

 

[Scottsmrnyc]

I just wanted to let you know that my meter is on it's way from China.  I just checked it's location on Ebay via China Post and it is now at a USPS office in NYC.  I should get it today or soon after.  Then I can move forward in checking the five pin recepticle. Thanks for waiting.

 

[Scottsmrnyc]

My multi meter has arrived.  It's a YH 102.  I am studying it's manual as we speak.  I will get back to all of you in a day or two. Thanks for your help.

 

[spritzer]

Nothing to study really, plug the black probe into the com jack and the red one into ohm/V/mA etc. socket, switch it to V---- (there is a line above the dashes) and 600 on that range (just below the off setting) and you are done., 

 

[Scottsmrnyc]

Okay I have used the Multi meter.  In the manual I tried the AC VOLTAGE MEASUREMENT TEST.  The dial of the meter has all kinds of numbers and symbols that I am not that familiar with.  I had the dial turned to the 200K mark.  I then put the black leed to the ground post on the back of the amp and the red leed to each recepticle.  I should point out that my Stax SRM 007ta is the Japanese model; therefore it has some sort of box connected to the power cord that came with it.  The multi meter did read a multitude of numbers as I poked the red leed into the various sockets of the two headphone sockets.  Just to make sure, I am going to retry the process a couple of times.  When in the process, the meter of the MM continues to move up and down.  I guess that is because the power coming from the wall outlet is constantly changing it's voltage.  In general most of the holes of each socket read roughly 3.2 to 10.0....  Three of the sockets also had a higher reading of 90.0, 58.1 and 160.0.   One of the holes had no reading at all. 
 
I am going to retry the whole process a couple of more times to see what happens and to get more consistency in the readings.
 
I sure hope I am doing this correctly.  Any help would be greatly appreciated.  I will check back in a couple of hours or late tonight. 

 

[spritzer]

200K is the resistive reading and we do not want that and the readings are meaningless.  On the left side of the dial there are two 600 settings, above and below the OFF position, set it to the lower one which is 600VDC range.  Unscrew the ground plug on the back of the amp and plug the black probe through the hole.  Now use the red probe in the 5 different spots on the Stax sockets and report back. 

 

[Scottsmrnyc]

Thanks Spritzer.  I see it and have made the adjustment to 600.  I will certainly report back either later on today or tomorrow.  I think I have it now.  Thanks  Scottsmrnyc

 

[Scottsmrnyc]

Okay- here is what I did.  I place the dial on the lower 600 and had the red cable plugged into the COM. The black cable plugged into theVQmA etc.  I then plugged the Black to the back ground and then proceeded to place the red poiint into each of the socket holes.
 
Starting at the 1 oclock position and moving clockwise so that it goes 1, 2, 3, 4, 5 clockwise- with 5 being the top hole; here are my readings.  I did this three time to insure I was accurate.
 
Socket A-  1-000,        2-000       3-054     4-000    5-000 or 001
 
Socket B-  1-000        2-000       3-054      4-002    5-000
 
I  don't know what this all means but I think it isn't to good.
 
Thanks Spritzer and others. 

 

[spritzer]

The black is the common hence it goes into the ground on the back but it doesn't really matter as the polarity is just swapped. 
 
The numbers look fine for such a cheap meter.  The input impedance is probably very low hence the bias supply being so low.  The rest looks good and the amp is working just fine.