The Entry Level Stax Thread
Feb 9, 2019 at 2:11 AM Post #3,061 of 3,293

feilonghuynh

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Mar 2, 2019 at 10:38 PM Post #3,064 of 3,293

Ad720

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Does anyone know if an SRD-4 can power pro bias ear speakers?
 
Mar 2, 2019 at 10:48 PM Post #3,065 of 3,293

JimL11

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Does anyone know if an SRD-4 can power pro bias ear speakers?

In short, no. The SRD-4 is designed for Stax's obsolete electret headphones which use a membrane that is permanently polarized, i.e. the headphone is permanently self-biased. This means that the SRD-4 box does not have any biasing circuit of its own. In order to use it with a pro bias headphone you would have to install a bias circuit and connect it to an AC power line. The only stock Stax adapter that can be used with pro bias phones is the SRD-7 Pro, which is relatively uncommon.
 
Mar 3, 2019 at 8:03 AM Post #3,066 of 3,293

Ad720

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In short, no. The SRD-4 is designed for Stax's obsolete electret headphones which use a membrane that is permanently polarized, i.e. the headphone is permanently self-biased. This means that the SRD-4 box does not have any biasing circuit of its own. In order to use it with a pro bias headphone you would have to install a bias circuit and connect it to an AC power line. The only stock Stax adapter that can be used with pro bias phones is the SRD-7 Pro, which is relatively uncommon.

Thanks!
 
Mar 3, 2019 at 9:30 PM Post #3,067 of 3,293

ktm

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There is a headfi member that mods srd7 boxes to pro bias.
He has had a few for sale here and has one on the bay
Listed. You could also buy a standard bias unit and mod if yourself.
I paid about $55 for one last year. Parts aren't expensive but there
Is a challenge in whipping up a pro bias board and fitting it in
The box. Buying it already done is a lot less stressfull
 
Mar 4, 2019 at 9:48 AM Post #3,068 of 3,293

Ad720

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Thanks. I was just curious because I won an auction that is a set of pro biased ear speakers (5 pin) with a normal biased adapter (6 pin). I already own a pro biased Energizer that I plan to use with the ear speakers but I'm curious if the setup as it's sold would work and if it would be worth comparison.
 
Mar 4, 2019 at 2:02 PM Post #3,069 of 3,293

ktm

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Some of the combos on the bay are listed by crazy people. They often pair stuff wrong and ask
for $$$$. And they also like to state "not tested". Pro will work with standard bias stuff fine,
you just lose impact and volume. SRD4's just are for electrets. Be aware older stax extensions
will accept 5 and 6 pin. So watch that you don't plug in standard bias cans by accident to
pro bias. Electret's don't care, the bias pins aren't used.
 
Mar 4, 2019 at 5:33 PM Post #3,070 of 3,293

JimL11

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Some of the combos on the bay are listed by crazy people. They often pair stuff wrong and ask
for $$$$. And they also like to state "not tested". Pro will work with standard bias stuff fine,
you just lose impact and volume. SRD4's just are for electrets. Be aware older stax extensions
will accept 5 and 6 pin. So watch that you don't plug in standard bias cans by accident to
pro bias. Electret's don't care, the bias pins aren't used.

Yes and no. Standard bias stuff CAN'T be plugged into pro bias sockets - that's why Pro bias are 5 pin and standard are 6 pin - the center 6th pin blocks the plug from being plugged in. OTOH, Pro bias stuff can be plugged into standard bias - it just loses efficiency and impact. Electrets don't need bias but they are equivalent to standard bias or perhaps somewhat lower, so beware of over-driving them if you have a Pro series amp.
 
Mar 4, 2019 at 5:51 PM Post #3,071 of 3,293

Ad720

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The seller claims the setup works. Again, my plan is to use the energizer and sell the adapter to offset the cost since I got a pretty good deal and bought it only for the lambdas. But I want to make sure that I'm not going to fry anything if I test the adapter.
 
Mar 4, 2019 at 7:48 PM Post #3,072 of 3,293

ktm

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When using the classic round stax extension cable with headphones,
You CAN plug standard into pro bias. The plug is 5 pin, the socket
Is 6 pin. Other than that, you can"t. So it's a universal cable for
Pro and standard bias. I've seen someone make that mistake
swapping around gear late at night. Alcohol tends to cause a lot of
Whoops.

:beerchug:
 
Mar 5, 2019 at 4:45 AM Post #3,073 of 3,293

Pahani

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One of my Stax amps is an SRM-1/MK-2 Pro, with one EACH of Pro and "Normal" outputs. Problem solved!
 
Mar 5, 2019 at 1:28 PM Post #3,074 of 3,293

JimL11

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When using the classic round stax extension cable with headphones,
You CAN plug standard into pro bias. The plug is 5 pin, the socket
Is 6 pin. Other than that, you can"t. So it's a universal cable for
Pro and standard bias. I've seen someone make that mistake
swapping around gear late at night. Alcohol tends to cause a lot of
Whoops.

:beerchug:

Must be a newer cord. I have a really old Stax cord which is 6 pin to 6 socket, which I got for my ancient SR-5 headphone - but it dates back to before Stax introduced the Pro bias headphones, so presumably Stax made a change at some point. Not a good idea in my opinion because of the possibility of making a mistake, but what do I know.
 
Mar 5, 2019 at 3:40 PM Post #3,075 of 3,293

serman005

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Forgive me for asking something that I am quite sure has been covered already (there are 205 pages of posts!), but what is Stax support in the US like? Thanks in advance for taking the time to reply--I appreciate it..
 

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