Question for Stax SR-80

[Krasimir]

Hello, I fell pair of headphones Stax Sr-80 which are free of SRD-4 transformer box.I look for this transformer box to enjoy the sound of their?Thank you in advance to everyone who will answer me!

 

[JoeESP9]

In the past I owned a pair of those. They will not work without the SRD-4 interface. There are a couple available on that auction site.

 

[Raynald]

The SRD-4 is probably your best bet price wise, but if you run across a good deal on any other SRD box I believe they will work as well.

 

[wualta]

It's true, they will. The electret models are wired to ignore the DC bias voltage supplied by the SRD-5,6 and 7.

 

[clinic-audio]

Hello
As wualta said , they will ! electret drivers are charged when they are manufactured and don't need bias voltage , that's why there is one plug with "missing pin " in the middle !
they will also with all above models in S/B

 

[ericj]

What all those guys said.

Also, if you have some tube amp output transformers kicking around, you can just hook them up backwards. The low-impedance side hooked up to a speaker amp, possibly with some 4-ohm resistors protecting it. The high impedance side hooked up to the headphones. This is essentially what you get in the SRD-4, though the SRD-4 also has some protection devices on the low impedance side. I have part numbers for modern equivalents of the protection devices if you desire them - but the sr-80 has protection devices inside the cups as well.

 

[Krasimir]

I bought on Ebay SRD-7 transformer box, but sound in the headphones is very weak and large distortion! I do not know which of the two headphones or srd-7 transformer box does not work! Please help who had a similar problem? Thanks!

 

[JoeESP9]

IIRC the SRD-7 interface was for "standard" Stax phones that need a polarizing voltage. The SR-80's are electret devices and do not need the high voltage polarizing voltage. The SRD-34 interface (for SR-40's) does not have an AC power connection.

 

[Raynald]

The SRD-7 should work fine for the SR-30/40/80 electret models. Hard to know for sure with only one of each but it is more likely the SR-80 are the problem as there is more there to go wrong over time.

To be sure you will have to borrow at least one other piece to try. I can't think of any way to troubleshoot the set as is. Anyone else?

 

[JoeESP9]

I have heard that some electrets (diaphragm in SR-30/40/80) can lose their charge over time. That could explain the OP's problem. However, the SR-40's I gave to a buddy 10 years ago had been part of my gear since the early 80's. He reports enjoying them to this day.

 

[ericj]

I have heard that some electrets (diaphragm in SR-30/40/80) can lose their charge over time. That could explain the OP's problem. However, the SR-40's I gave to a buddy 10 years ago had been part of my gear since the early 80's. He reports enjoying them to this day.

The idea that electrets "lose their charge" is probably a myth. Electret materials are manufactured by physically orienting molecules of plastic so that like poles are all pointing the same way. This requires extreme energies, and it should require similar energies to reverse the process.

Sony decided in the 70's that it's more likely the opposite - that capacitive charge builds up between the film and stators that doesn't get drained off because there is no electrical connection to the diaphragm. They describe it in their uni-electret patent, which is a pretty interesting read.

https://www.google.com/patents/US3942029

Basically they use a semiconductor plastic to construct the housing of the transducer which allows the charge to drain off.

fwiw my sony uni-electrets work great. But so do my stax sr-30 and sr-80.

Actually, if I'm honest, i do have a dead sr-30 driver in the parts bin. And a spare good one.

I bought on Ebay SRD-7 transformer box, but sound in the headphones is very weak and large distortion! I do not know which of the two headphones or srd-7 transformer box does not work! Please help who had a similar problem? Thanks!

More likely that the headphones are damaged. If you're lucky it's only the protection devices inside the cups that are blown. But like any other transducer, if they are overdriven they can be damaged and fail.

If you're really lucky, you hooked up the SRD-7 wrong. Re-check the wiring vs. the hookup instructions printed on the back.

 

[JoeESP9]

As I said, my buddy uses them (early 80's SR-40) to this day.

 

[Raynald]

I have some SR-30 that are working fine. I agree, I am not so sure they necessarily wear down with time but they can be abused or have random breakdowns as with any component.

 

[wualta]

Agreed-- the headphones are most likely to be faulty. But, to my knowledge, the only way to be certain is to substitute another Stax headphone or another SRD-4/5/6/7, as Raynald said.