stax srm-1 mk-2/lambda pro channel imbalance!

[d-cee]

hi all,

i left my lambda pros plugged into the srm-1/mk-2 and switched on while i was at work today so that they could "charge" so that when i got home they would be ready to sing.

however when i got home i got the biggest shock of my life to find that the right channel is substantially lower in volume than the left channel

i first checked my source, then my cables and then used them all in my dynamic rig(s) and they sound normal

the amp has independant volume controls for left and right and i can compensate, but if i turn the volume up or down i have to re-adjust the right channel because it gets too loud or too soft

i have no other electrostatic gear so can't narrow it down between the amp/earspeakers

experienced electrostatic users could you please chip in and let me know if earspeakers or amps are more prone to slowly dying out? (i am assuming this is what's happening) or do they just fail completely, my other suspicion is that it could be the pot.

anyway, is there any measurements that i can do with a multimetre to determine whether it's the amp or earspeakers that is failing and then take action from there...

thanks in advance!

 

[spritzer]

It's always the headphones that develop this issue. There might be a bad contact in the driver or at the terminals. Unplug the headphones and short the plug with your fingers to discharge them. Check and see if they are still unbalanced.

If that doesn't fix them you'll have to open them up and pray for a bad connection. The drivers are impossible to fix and have to be replaced with new units from the current lineup. They are better then the ones you are using now but it won't be cheap.

 

[d-cee]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif It's always the headphones that develop this issue. There might be a bad contact in the driver or at the terminals. Unplug the headphones and short the plug with your fingers to discharge them. Check and see if they are still unbalanced. If that doesn't fix them you'll have to open them up and pray for a bad connection. The drivers are impossible to fix and have to be replaced with new units from the current lineup. They are better then the ones you are using now but it won't be cheap.

damn it! so not what i wanted to hear!

well i've ruled out the pot as the culprit

I've reversed the inputs, then reversed both input and output and it's still the right channel that is quieter, to totally eliminate the amp though

i need to reverse the left and right channels any idea which pin(s) are for left and which are for right and how i would go about reversing them?

i'll open up my earspeakers now and look for bad joints :'(

 

[Carl]

Quote:

Originally Posted by d-cee /img/forum/go_quote.gif damn it! so not what i wanted to hear! well i've ruled out the pot as the culprit I've reversed the inputs, then reversed both input and output and it's still the right channel that is quieter, to totally eliminate the amp though i need to reverse the left and right channels any idea which pin(s) are for left and which are for right and how i would go about reversing them? i'll open up my earspeakers now and look for bad joints :'(

Discharge the stators (touch the pins for a few seconds) and then recharge them overnight before you reach for the nuclear option. Sometimes they just right themselves (of course, sometimes they don't...)

 

[d-cee]

yeah i did the discharge thing thanks for that spritzer, Carl

only heard the pop in the left ear :'(

unfortunately it didn't resolve the issue

it's oK Carl i'm one step ahead of you, starting to look for best prices on SR-404 and maybe an HE60...

 

[spritzer]

They can just be alright tomorrow but lets plan for the worst case scenario. If you want to open them up, lift the four corners of the earpads and under there are the screws. Now the plate with the drivers attached is loose. There 3 terminals on the bottom of the driver and the bias is connected to the middle one. Pull it gently and see if the wire is loose. You might try to resolder it but then you have to cover the driver because excess flux can burn through it.

This is the Stax socket so the plug is a mirror image.

 

[d-cee]

thanks guys

well i have well and truly removed the last shadow of doubt that it is the stator

i opened up both earspeakers and re-flowed the solder, same result

so i carefully de-soldered the connection terminals and swapped the left and right incoming cables

hooked her all up again and yeah, still the right side is playing up

for the time being i guess i will just have to re-adjust the right channel on the pot until it dies completely... (will it gradually get worse and worse or just konk out one day?)

here's to hoping it fixes itself tomorrow...

 

[d-cee]

false alarm

still unbalanced

 

[spritzer]

Did you swap the cables between earpieces or just the wires in each cup? You should try to connect the bias in both cups together with a piece of wire. If there is an intermittent connection in the cable this will be a sure way to test for it.

It's normally not a gradual death. They develop this channel imbalance and stay that way even for a long time. I they are in a very humid environment some contacts can continue to tarnish and the signal will be weaker.

 

[d-cee]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif Did you swap the cables between earpieces or just the wires in each cup? You should try to connect the bias in both cups together with a piece of wire. If there is an intermittent connection in the cable this will be a sure way to test for it. It's normally not a gradual death. They develop this channel imbalance and stay that way even for a long time. I they are in a very humid environment some contacts can continue to tarnish and the signal will be weaker.

i swapped cables between earpieces

i may try shorting the bias wire tomorrow

australia is very humid :$

all other tips appreciated!

 

[d-cee]

damn, hasn't fixed itself. if anything, i think it's even lower in volume today and also it distorts on bassy sections =(

should i take these off my head before i get zapped in the ear with 580v or should i switch it off completely before it kills my driver unit?

I'm scared... and also in the market for a new electrostat headphone

 

[spritzer]

Quote:

Originally Posted by d-cee /img/forum/go_quote.gif damn, hasn't fixed itself. if anything, i think it's even lower in volume today and also it distorts on bassy sections =( should i take these off my head before i get zapped in the ear with 580v or should i switch it off completely before it kills my driver unit? I'm scared... and also in the market for a new electrostat headphone

If the bias line comes into contact with your head, the bleeder resistor will self destruct so you're in no danger and it will cost a few cents to fix.

This sounds like a broken bias line or a bias connection problem. Try to swap the bias wires or connect between them an see if that corrects the problem.

 

[d-cee]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif This sounds like a broken bias line or a bias connection problem. Try to swap the bias wires or connect between them an see if that corrects the problem.

if it's the bias wire, last night when i switched the cables for left and right around wouldn't that have caused the other earspeaker to play up?

i will try later tonight when i get back

 

[spritzer]

Quote:

Originally Posted by d-cee /img/forum/go_quote.gif if it's the bias wire, last night when i switched the cables for left and right around wouldn't that have caused the other earspeaker to play up? i will try later tonight when i get back

If you switched all three then yes. Now there are only bad options left.

 

[d-cee]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif If you switched all three then yes. Now there are only bad options left.

yes I did

What options are left, is there anywhere to buy just the drivers? I imagine it'd be cheaper than buying a whole new phone

If I go down that path I'd also like to keep the black casing, looks better than the brown of the SR-404 of which I am strongly considering and putting money aside for