The Stax thread (New)

[livewire]

Hey guys,
 
I just received a pair of SR-202's.  Currently though all my adapters are normal bias.  I've heard about people modding the SRD-7 to Pro bias levels.  Does anyone have directions on how to do this?  Thanks.
 
EDIT:
 
Seems I just have to convert it to a voltage quadrupler.  Is there a specific diode and voltage/capacitance caps I should use?
 
PS:
 
It says in the manual that using the SR-202 with normal bias rather than pro may damage them if used at a higher volume?  Does anyone have any info on why this is and whether I should be concerned or whether it's alright for the time being in your experience?

 
Spritzer has mucho experience with this topic.
I believe that he was selling some bias adapter boards a while back.
 
As far as driving the 202's with the lower bias voltage, dont do it.
The current level is probably too high, especially at "higher volumes", whatever that might be.
It would be a pity if you damaged them.
 
Look for a used SRM-212 or SRM-252 energizer amp.
Shouldnt cost more than $200 tops.
Not too powerful, but sounds pristine, they will drive the 202's to ~90dB.

 

[Region2]

Quote:

Hey guys,
 
I just received a pair of SR-202's.  Currently though all my adapters are normal bias.  I've heard about people modding the SRD-7 to Pro bias levels.  Does anyone have directions on how to do this?  Thanks.
 
EDIT:
 
Seems I just have to convert it to a voltage quadrupler.  Is there a specific diode and voltage/capacitance caps I should use?
 
PS:
 
It says in the manual that using the SR-202 with normal bias rather than pro may damage them if used at a higher volume?  Does anyone have any info on why this is and whether I should be concerned or whether it's alright for the time being in your experience?

 
Spritzer has mucho experience with this topic.
I believe that he was selling some bias adapter boards a while back.
 
As far as driving the 202's with the lower bias voltage, dont do it.
The current level is probably too high, especially at "higher volumes", whatever that might be.
It would be a pity if you damaged them.
 

 
Is this true?  I did not know you can damage pro headphones by putting them in normal biased amps/energizers.  I know that plugging in a normal biased headphone into a pro bias will destroy the diaphragm, but how does the current level ruin them when plugging in a pro biased headphone into a normal biased jack?  Is this conjecture or is this based upon something?
 
Sorry, if you think I'm attacking you, this is not my intent.  I am curious about this statement since this runs counter to what I thought I knew about stators.

 

[Shike]

 
Quote:

Quote:

Hey guys,
 
I just received a pair of SR-202's.  Currently though all my adapters are normal bias.  I've heard about people modding the SRD-7 to Pro bias levels.  Does anyone have directions on how to do this?  Thanks.
 
EDIT:
 
Seems I just have to convert it to a voltage quadrupler.  Is there a specific diode and voltage/capacitance caps I should use?
 
PS:
 
It says in the manual that using the SR-202 with normal bias rather than pro may damage them if used at a higher volume?  Does anyone have any info on why this is and whether I should be concerned or whether it's alright for the time being in your experience?

 
Spritzer has mucho experience with this topic.
I believe that he was selling some bias adapter boards a while back.
 
As far as driving the 202's with the lower bias voltage, dont do it.
The current level is probably too high, especially at "higher volumes", whatever that might be.
It would be a pity if you damaged them.
 

 
Is this true?  I did not know you can damage pro headphones by putting them in normal biased amps/energizers.  I know that plugging in a normal biased headphone into a pro bias will destroy the diaphragm, but how does the current level ruin them when plugging in a pro biased headphone into a normal biased jack?  Is this conjecture or is this based upon something?
 
Sorry, if you think I'm attacking you, this is not my intent.  I am curious about this statement since this runs counter to what I thought I knew about stators.

That's what I was wondering.  I always thought voltage controlled amount of force (amplitude) so it struck me as odd that a lower voltage would somehow damage them :|

 

[Region2]

Quote:

 
Quote:

Quote:

Hey guys,
 
I just received a pair of SR-202's.  Currently though all my adapters are normal bias.  I've heard about people modding the SRD-7 to Pro bias levels.  Does anyone have directions on how to do this?  Thanks.
 
EDIT:
 
Seems I just have to convert it to a voltage quadrupler.  Is there a specific diode and voltage/capacitance caps I should use?
 
PS:
 
It says in the manual that using the SR-202 with normal bias rather than pro may damage them if used at a higher volume?  Does anyone have any info on why this is and whether I should be concerned or whether it's alright for the time being in your experience?

 
Spritzer has mucho experience with this topic.
I believe that he was selling some bias adapter boards a while back.
 
As far as driving the 202's with the lower bias voltage, dont do it.
The current level is probably too high, especially at "higher volumes", whatever that might be.
It would be a pity if you damaged them.
 

 
Is this true?  I did not know you can damage pro headphones by putting them in normal biased amps/energizers.  I know that plugging in a normal biased headphone into a pro bias will destroy the diaphragm, but how does the current level ruin them when plugging in a pro biased headphone into a normal biased jack?  Is this conjecture or is this based upon something?
 
Sorry, if you think I'm attacking you, this is not my intent.  I am curious about this statement since this runs counter to what I thought I knew about stators.

That's what I was wondering.  I always thought voltage controlled amount of force (amplitude) so it struck me as odd that a lower voltage would somehow damage them :|

If I recall correctly, there's not actually a lot of current and the headphones only take what's needed.  So I don't think it has to do with current.  There could be damage if you do so but this is beyond what I know atm.  And considering it's a Japanese manual, they're careful about writing warnings for everything.  I have plenty of Japanese appliances the missus buys and though the power brick is clearly marked 100-240v but the manual states that you should always use a step down transformer.  So it could just be classic Japanese (over) cautiousness.
 
Though, I hope someone more knowledgeable on the subject can chime in.

 

[deadlylover]

It probably has something to do with the stators swinging to a higher voltage than the diaphragm when it is only charged at normal bias levels.
This is why they warned against turning them up too loudly in the manual.
The diaphragm will become negative in relation to the stators and some funky stuff may start happening.

I could be completely wrong of course, as the normal bias stuff shouldn't be swinging that much voltage anyway, making pro drivers immune to arcing/whatever

 

[livewire]

Quote:

Quote:

Hey guys,
 
I just received a pair of SR-202's.  Currently though all my adapters are normal bias.  I've heard about people modding the SRD-7 to Pro bias levels.  Does anyone have directions on how to do this?  Thanks.
 
EDIT:
 
Seems I just have to convert it to a voltage quadrupler.  Is there a specific diode and voltage/capacitance caps I should use?
 
PS:
 
It says in the manual that using the SR-202 with normal bias rather than pro may damage them if used at a higher volume?  Does anyone have any info on why this is and whether I should be concerned or whether it's alright for the time being in your experience?

 
Spritzer has mucho experience with this topic.
I believe that he was selling some bias adapter boards a while back.
 
As far as driving the 202's with the lower bias voltage, dont do it.
The current level is probably too high, especially at "higher volumes", whatever that might be.
It would be a pity if you damaged them.
 

 
Is this true?  I did not know you can damage pro headphones by putting them in normal biased amps/energizers.  I know that plugging in a normal biased headphone into a pro bias will destroy the diaphragm, but how does the current level ruin them when plugging in a pro biased headphone into a normal biased jack?  Is this conjecture or is this based upon something?
 
Sorry, if you think I'm attacking you, this is not my intent.  I am curious about this statement since this runs counter to what I thought I knew about stators.

Yes, what I said about the current was conjecture.
(I did say "probably" and was wrong)
I just looked at a few amp schematics that have dual biasing
with fixed current limiting output resistors in each bias leg.
Doing the math, the current is indeed about half for the normal bias side.
 
I would not dismiss what is written in the manual. Stay on the safe side.
 
So I guess that it does have something to do with what deadlylover posted?

 

 

[jjinh]

Quote:

Originally Posted by Region2 /img/forum/go_quote.gif
 
Is this true?  I did not know you can damage pro headphones by putting them in normal biased amps/energizers.  I know that plugging in a normal biased headphone into a pro bias will destroy the diaphragm, but how does the current level ruin them when plugging in a pro biased headphone into a normal biased jack?  Is this conjecture or is this based upon something?
 
Sorry, if you think I'm attacking you, this is not my intent.  I am curious about this statement since this runs counter to what I thought I knew about stators.

I've tried some of my pro bias headphones from normal bias plugs in the past but only for very brief periods of time (...out of curiosity. IMO it sounds crap). No (apparent) damage but I know close to zilch about the current level and other technical aspects so I could be wrong.

 

[Region2]

Quote:

Yes, what I said about the current was conjecture.
(I did say "probably" and was wrong)
I just looked at a few amp schematics that have dual biasing
with fixed current limiting output resistors in each bias leg.
Doing the math, the current is indeed about half for the normal bias side.
 
I would not dismiss what is written in the manual. Stay on the safe side.
 
So I guess that it does have something to do with what deadlylover posted?

 

Thanks for the answer.  I was just curious why you picked current and was wondering if there was something written about
 
As for deadlylover's post, the reason for arching is the other way around if you plugged a normal into a pro (a bit difficult with trying to squeeze a 6 pin to a 5 pin jack though).  And speaking of pins, I thought they made it so you could plug a pro into a pro, a pro into a normal, a normal into a normal, but not a normal into a pro due to this reason.
 
Edit: found a post from Spritzer on it.
 
http://www.head-fi.org/forum/thread/249297/normal-bias-stax-plugged-into-pro-energizer-after-plug-modding#post_3121935

 

[Region2]

Quote:

I've tried some of my pro bias headphones from normal bias plugs in the past but only for very brief periods of time (...out of curiosity. IMO it sounds crap). No (apparent) damage but I know close to zilch about the current level and other technical aspects so I could be wrong.

Braver man than me.  If I even think I a little bit of sweat, I spend quite a bit of time with the hair dryer before I even put on my Stax.

 

[jjinh]

Quote:

Braver man than me.  If I even think I a little bit of sweat, I spend quite a bit of time with the hair dryer before I even put on my Stax.

It's more like stupid

 

[Michgelsen]

You can all relax now. There is no harm in using pro bias 'phones with normal bias. Stop spreading false information and 'theories'.
 
If it were a problem, Stax wouldn't have made the plugs of pro bias earspeakers compatible with the normal bias outputs.
On amps with both types of outputs, the outputs are the identical except for bias voltage. Pro bias 'phones will therefore receive the same audio signal as normal bias headphones, even when you use pro bias out of the normal bias outputs. Pro bias make the 'phones slighty more efficient, but not much.
The SRM-T1 (both pro and normal outputs) can deliver more voltage (max 300V) to the stators than the normal bias voltage (230V). If this would be so dangerous, Stax would not have made the amp this way. Whether it would be a problem when the stator voltage becomes higher than the bias voltage, I don't know. Remember that the max output of 300V is RMS voltage, so you get to a real 230V even faster.

 

[Shike]

Quote:

You can all relax now. There is no harm in using pro bias 'phones with normal bias. Stop spreading false information and 'theories'.
 
If it were a problem, Stax wouldn't have made the plugs of pro bias earspeakers compatible with the normal bias outputs.
On amps with both types of outputs, the outputs are the identical except for bias voltage. Pro bias 'phones will therefore receive the same audio signal as normal bias headphones, even when you use pro bias out of the normal bias outputs. Pro bias make the 'phones slighty more efficient, but not much.
The SRM-T1 (both pro and normal outputs) can deliver more voltage (max 300V) to the stators than the normal bias voltage (230V). If this would be so dangerous, Stax would not have made the amp this way. Whether it would be a problem when the stator voltage becomes higher than the bias voltage, I don't know. Remember that the max output of 300V is RMS voltage, so you get to a real 230V even faster.

That's what I thought myself, I thought the bias voltage would determine amplitude (efficiency).  I've tried them at fair listening levels (85dB maybe?).  If the only benefit from going to a pro bias is amplitude then I'm not sure I'll bother keeping them.  They're really missing a chunk of the low and mid bass I'm used to and really don't seem to fit the music I'm listening to either (techno, rock, metal, etc).

 

[svyr]

You can all relax now. There is no harm in using pro bias 'phones with normal bias. Stop spreading false information and 'theories'.
 
If it were a problem, Stax wouldn't have made the plugs of pro bias earspeakers compatible with the normal bias outputs.
On amps with both types of outputs, the outputs are the identical except for bias voltage. Pro bias 'phones will therefore receive the same audio signal as normal bias headphones, even when you use pro bias out of the normal bias outputs. Pro bias make the 'phones slighty more efficient, but not much.
The SRM-T1 (both pro and normal outputs) can deliver more voltage (max 300V) to the stators than the normal bias voltage (230V). If this would be so dangerous, Stax would not have made the amp this way. Whether it would be a problem when the stator voltage becomes higher than the bias voltage, I don't know. Remember that the max output of 300V is RMS voltage, so you get to a real 230V even faster.

your mixing up bias and output voltage.

Output voltage is your AC L or R +- voltage (signal). It's not the bias voltage (separate pin, different function http://books.google.com.au/books?id=jCUDAAAAMBAJ&pg=RA1-PA167&lpg=RA1-PA167&dq=electrostatic+speaker+bias+voltage+role&source=bl&ots=1XEhbTSSO3&sig=AlSC2SXSSAAbCF86mEGfMhNS2Fk&hl=en&ei=Z1tSTcODEJC8vQPh0oWKCQ&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEoQ6AEwCA#v=onepage&q&f=false ).

 

[Shike]

 
Quote:

Quote:

You can all relax now. There is no harm in using pro bias 'phones with normal bias. Stop spreading false information and 'theories'.
 
If it were a problem, Stax wouldn't have made the plugs of pro bias earspeakers compatible with the normal bias outputs.
On amps with both types of outputs, the outputs are the identical except for bias voltage. Pro bias 'phones will therefore receive the same audio signal as normal bias headphones, even when you use pro bias out of the normal bias outputs. Pro bias make the 'phones slighty more efficient, but not much.
The SRM-T1 (both pro and normal outputs) can deliver more voltage (max 300V) to the stators than the normal bias voltage (230V). If this would be so dangerous, Stax would not have made the amp this way. Whether it would be a problem when the stator voltage becomes higher than the bias voltage, I don't know. Remember that the max output of 300V is RMS voltage, so you get to a real 230V even faster.

your mixing up bias and output voltage.

Output voltage is your AC L or R +- voltage (signal). It's not the bias voltage (separate pin, different function http://books.google.com.au/books?id=jCUDAAAAMBAJ&pg=RA1-PA167&lpg=RA1-PA167&dq=electrostatic+speaker+bias+voltage+role&source=bl&ots=1XEhbTSSO3&sig=AlSC2SXSSAAbCF86mEGfMhNS2Fk&hl=en&ei=Z1tSTcODEJC8vQPh0oWKCQ&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEoQ6AEwCA#v=onepage&q&f=false ).

So how would that impact the headphones then running from normal compared to pro bias?

 

[svyr]

 
Quote:

Quote:

You can all relax now. There is no harm in using pro bias 'phones with normal bias. Stop spreading false information and 'theories'.
 
If it were a problem, Stax wouldn't have made the plugs of pro bias earspeakers compatible with the normal bias outputs.
On amps with both types of outputs, the outputs are the identical except for bias voltage. Pro bias 'phones will therefore receive the same audio signal as normal bias headphones, even when you use pro bias out of the normal bias outputs. Pro bias make the 'phones slighty more efficient, but not much.
The SRM-T1 (both pro and normal outputs) can deliver more voltage (max 300V) to the stators than the normal bias voltage (230V). If this would be so dangerous, Stax would not have made the amp this way. Whether it would be a problem when the stator voltage becomes higher than the bias voltage, I don't know. Remember that the max output of 300V is RMS voltage, so you get to a real 230V even faster.

your mixing up bias and output voltage.

Output voltage is your AC L or R +- voltage (signal). It's not the bias voltage (separate pin, different function http://books.google.com.au/books?id=jCUDAAAAMBAJ&pg=RA1-PA167&lpg=RA1-PA167&dq=electrostatic+speaker+bias+voltage+role&source=bl&ots=1XEhbTSSO3&sig=AlSC2SXSSAAbCF86mEGfMhNS2Fk&hl=en&ei=Z1tSTcODEJC8vQPh0oWKCQ&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEoQ6AEwCA#v=onepage&q&f=false ).

So how would that impact the headphones then running from normal compared to pro bias?

beats me.
When I plugged in my sr404 pro bias to test the normal socket when fixing my srm1 (needed to know if L-L+ and R-R+ were still ok) they sounded like horse crap and they were a lot quieter. I suppose I would first and foremost turn them up a lot louder when using them this way, so maybe that would be the danger.

If anyone knows whether running at lower bias voltage makes the diaphragm more likely to crash into the stator or something (e.g. as per the alleged role of the bias from the book above),do let us know