Dima202
New Head-Fier
This is from #Zeos on freenode IRC today.
Dukem
Hello all, I got the Zeos virus and started shopping for audio equipment. Got my hands on SRD-7 and Stax Lambda Pro. Hooked it up to an amp and put the amp up too high... Now almost no sound is coming out of the Lambda not sure if it's the SRD-7 that blew out or the Lambda.....
The reason I put amp up too high is because i had regular headphones in "REC" mode and forgot so I put the volume up all the way in like What is the volume not changing.
Dukem
I hope it's the SRD-7 because SR Lambda pro is a rare headphone
zzz_
yeah, I don't think that would mess up the amp
with sound off, measure L+ to bias. should be 200v
(DC)
(not AC)
then put a steady tone through the amp (low volume) and measure AC voltage L+ to L- and R+ to R-
then vary the volume a little
both channels should show same value and the value should scale with volume
that'd be how I'd test the transformers
if either channel is at 0 or jumps around even when fed a steady tone, that channel's broken
if bias is not what you expect it to be, the bias is broken
if the amp measures fine, the phones are broken
zzz_
hmmm, and I guess make sure your voltmeter can handle the voltage
sorry, should have mentioned that earlier
like, if it only goes to 100V, don't test the bias. can still measure channels at low volume
most of the time, electrostats stay in an okay range voltage-wise
Dukem
Mine goes up to 10k v
zzz_
the +/- 500V is for peaks
Dukem
i am reading -109v
zzz_
perfect, no worries then
sign doesn't matter
Dukem
it peaks up to 121v when i raise the volume
zzz_
the bias?
or channels?
Dukem
L+ to Bias
R+ to Bias also
zzz_
that's probably okay. the bias is a really low-current supply, so the voltmeter is likely drawing the voltage
so the bias seems fine to me
(when I was building stax amps, I think the bias was fed through a 100kohm resistor, so a voltmeter would easily affect the measurements)
now, AC on channels should be <10V at low volume and get to, I don't know, 50V when you start cranking it
the important thing is numbers should be steady and match L vs. R
at same volume
Dukem
L- to L+ is 0.02 to 0.3V DC
zzz_
don't measure DC
AC
Dukem
i think it auto senses
zzz_
L- ideally is an inverse of L+, so DC between them is expected to be 0
okay
play a steady tone and increase volume. if you're doing that and it's still showing ~0V DC, then yeah, that channel look dead
so my initial guess was off
well, at least the phones are okay if that's the case!
though I admit that I could never get over how creaky the lambdas were
Dukem
no you were right i was measuing ac
i got a different meter and it blew the fuse
nvm'
Dukem
L- to L+ 0 to 140v+
zzz_
that's a healthy range
Dukem
140v is mid range on my volume
after 140v this tester dies
zzz_
okay, so the amp looks healthy after all
(or at least the left channel)
alright, I gotta try to get 4 hours of sleep
good luck
---------------------------------------------------------------
Will keep this thread updated
Observation 07/13/2017 3:58AM
Playing a constant tone while measuring L+ L-
Voltage appears to be jumping all over the place from 150V to 10V AC
-This could be a bad reading of the cheap multimeter. I need to re-test tomorrow with Fluke 87.
-Although zzz_ also said, "if either channel is at 0 or jumps around even when fed a steady tone, that channel's broken"
Kenwood KC-209 & Kenwood KM-209 is set to Volume 15 or 12 o'clock
Dukem
Hello all, I got the Zeos virus and started shopping for audio equipment. Got my hands on SRD-7 and Stax Lambda Pro. Hooked it up to an amp and put the amp up too high... Now almost no sound is coming out of the Lambda not sure if it's the SRD-7 that blew out or the Lambda.....
The reason I put amp up too high is because i had regular headphones in "REC" mode and forgot so I put the volume up all the way in like What is the volume not changing.
Dukem
I hope it's the SRD-7 because SR Lambda pro is a rare headphone
zzz_
yeah, I don't think that would mess up the amp
with sound off, measure L+ to bias. should be 200v
(DC)
(not AC)
then put a steady tone through the amp (low volume) and measure AC voltage L+ to L- and R+ to R-
then vary the volume a little
both channels should show same value and the value should scale with volume
that'd be how I'd test the transformers
if either channel is at 0 or jumps around even when fed a steady tone, that channel's broken
if bias is not what you expect it to be, the bias is broken
if the amp measures fine, the phones are broken
zzz_
hmmm, and I guess make sure your voltmeter can handle the voltage
sorry, should have mentioned that earlier
like, if it only goes to 100V, don't test the bias. can still measure channels at low volume
most of the time, electrostats stay in an okay range voltage-wise
Dukem
Mine goes up to 10k v
zzz_
the +/- 500V is for peaks
Dukem
i am reading -109v
zzz_
perfect, no worries then
sign doesn't matter
Dukem
it peaks up to 121v when i raise the volume
zzz_
the bias?
or channels?
Dukem
L+ to Bias
R+ to Bias also
zzz_
that's probably okay. the bias is a really low-current supply, so the voltmeter is likely drawing the voltage
so the bias seems fine to me
(when I was building stax amps, I think the bias was fed through a 100kohm resistor, so a voltmeter would easily affect the measurements)
now, AC on channels should be <10V at low volume and get to, I don't know, 50V when you start cranking it
the important thing is numbers should be steady and match L vs. R
at same volume
Dukem
L- to L+ is 0.02 to 0.3V DC
zzz_
don't measure DC
AC
Dukem
i think it auto senses
zzz_
L- ideally is an inverse of L+, so DC between them is expected to be 0
okay
play a steady tone and increase volume. if you're doing that and it's still showing ~0V DC, then yeah, that channel look dead
so my initial guess was off
well, at least the phones are okay if that's the case!
though I admit that I could never get over how creaky the lambdas were
Dukem
no you were right i was measuing ac
i got a different meter and it blew the fuse
nvm'
Dukem
L- to L+ 0 to 140v+
zzz_
that's a healthy range
Dukem
140v is mid range on my volume
after 140v this tester dies
zzz_
okay, so the amp looks healthy after all
(or at least the left channel)
alright, I gotta try to get 4 hours of sleep
good luck
---------------------------------------------------------------
Will keep this thread updated
Observation 07/13/2017 3:58AM
Playing a constant tone while measuring L+ L-
Voltage appears to be jumping all over the place from 150V to 10V AC
-This could be a bad reading of the cheap multimeter. I need to re-test tomorrow with Fluke 87.
-Although zzz_ also said, "if either channel is at 0 or jumps around even when fed a steady tone, that channel's broken"
Kenwood KC-209 & Kenwood KM-209 is set to Volume 15 or 12 o'clock
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