[HeadphoneNewbiee]

Good weekend everyone. I am possibly going to buy a pair of stax lambda pro (1982 version). I am going to see and hear them in person but Im not sure how to know if they are in good condition so what should I be looking for?

 

[Vanheim]

So I have the stax srm-727a driving my 009S for now. I use the topping a90 as a preamp and bypass the volume pot on the stax amp completely, sounds much better to me that way. My question is, would upgrading from this to a srd-7 or woo wee with a good speaker amp like the Hegel-h95 be a good idea instead of going down the path of electrostatic speaker amps which often seems to get crazy expensive?

 

[tjlindle]

I've been doing a bit of research and I still can't figure out what in the world the center pin does on the NB 6-pin layout. Bias is on the same pin as the 5-pin (which makes sense otherwise 5-pins wouldn't work in a NB socket) so...??? Does that mean if I had a 6-pin extension cable, I could just remove the center pin on the amp side and essentially turn it into a 5-pin Pro Bias extension cable?

Good weekend everyone. I am possibly going to buy a pair of stax lambda pro (1982 version). I am going to see and hear them in person but Im not sure how to know if they are in good condition so what should I be looking for?

Definitely listen to them closely for either a channel imbalance between the two drivers, or any faint squealing noises.

The pads themselves you'll want to check too, make sure they're in good condition because that will also directly affect the sound.

Everything else is mostly just cosmetic and doesn't really matter unless they're having major problems, like the headband being ripped up or loose.

For something this old, if it sits properly on your head and sounds good, it is in good condition lol.

 

[pspentax]

I've been doing a bit of research and I still can't figure out what in the world the center pin does on the NB 6-pin layout. Bias is on the same pin as the 5-pin (which makes sense otherwise 5-pins wouldn't work in a NB socket) so...??? Does that mean if I had a 6-pin extension cable, I could just remove the center pin on the amp side and essentially turn it into a 5-pin Pro Bias extension cable?

Just for protection of the headphone.
You can connect a Pro bias headphone in a normal bias output ... but you can’t connect a normal bias headphone to the Pro bias output.

 

[bearFNF]

Just for protection of the headphone.
You can connect a Pro bias headphone in a normal bias output ... but you can’t connect a normal bias headphone to the Pro bias output.

This is true for just the headphone cables, but if you use an extension cable, then all bets are off.
I have (theoretically) OE Stax extension cables from the 80s that have six pin female connectors on the earspeaker end and five pin male connectors on the amp end.
So be cautious and ALWAYS check to make sure you are plugging into the correct socket.

 

[poemadevil]

I bought a MC34-B pushpull tube amp some time ago and had it connected with the speaker terminals to a step up transformer. This morning I decided to connect the headphone directly to the power tubes (6L6GC, made in china) and use an Aliexpress step up booster for the bias. And...it just works. I have no real experience in electronics or so. Neither did I drill holes in the tube amp, just soldered 4 wires to go out of the amp into an enclosure with the dc booster and the headphone connector. Using a 207 headphone. I find the sound the best I've heard so far. I'am I just lucky or is it really just so simple ?

 

[HeadphoneNewbiee]

The pads themselves you'll want to check too, make sure they're in good condition because that will also directly affect the sound.

Thanks I will definetely lookout for the pads as they do look a little thin on the photos I have been given compared to other lambda pros.

 

[Vanheim]

I wanted to sell these and get the Susvara, but as spectacular as they are themselves, I think I’m a stax mafiaso at heart. Happy listening folks!

 

[KDS315]

I bought a MC34-B pushpull tube amp some time ago and had it connected with the speaker terminals to a step up transformer. This morning I decided to connect the headphone directly to the power tubes (6L6GC, made in china) and use an Aliexpress step up booster for the bias. And...it just works. I have no real experience in electronics or so. Neither did I drill holes in the tube amp, just soldered 4 wires to go out of the amp into an enclosure with the dc booster and the headphone connector. Using a 207 headphone. I find the sound the best I've heard so far. I'am I just lucky or is it really just so simple ?

Of course that'll work if the anode voltage is high enough. You'd better add some safety resistors between the anode connection and the outputs. What's that "Alienexpress step up booster"? You need to provide a 580Volts DC voltage for the bias for STAX PRO headphones.

Most tube / hybrid STAX amps use that...this should be the schematics of yours...

and this of a known Amp for Stax:

 

[kevin gilmore]

hooking directly to the plates without safety resistors (5.1k or so) and 1uf series caps is a very unsafe idea.
also messes with the bias voltage.

 

[poemadevil]

Sorry regarding the dc booster, it wasn't AliExpress but Ebay: this one.

Schematic of my amp:

And it looks like this:

External case is just an (now) empty Micro Seiki with the dc booster placed, connected to a 5v power adapter and the original headphone plug replaced with a 5 pin Stax. I admit, not the best looking setup but as I said: it works. I don't have the knowledge to get the 580V diaphragm bias from the internals of the amp. I wish I had. Furthermore I agree that this is not a very safe way to go and would not recommend doing this. Just illustrating that a "cheap" Stax tube amplifier sound is possible. Would be a nice service if one could send in his own tube amp to have it rebuild adding a Stax output. I don't think such a service exists, not in The Netherlands anyway.

 

[pspentax]

Let’s go... one more try...

 

[ufospls2]

Oh well, I figured if I'm going to do the electrostatic thing for a while I may as well go full potato.

Kerry DIY T2 on order. And thus, the wait begins : )

 

[buzzlulu]

Oh well, I figured if I'm going to do the electrostatic thing for a while I may as well go full potato.

Kerry DIY T2 on order. And thus, the wait begins : )

Come on in the water is fine.
Hey @Kerry - hurry up with mine

Best
Gregg

 

[Chefguru]

Does anyone have any tricks on storing their 009/srx9k/omega to avoid stretching the headband?
The 009 fits best on the smallest setting - but now, after owning them for a year - I've found the headband has lost some of its tightness due to the Stax headstand putting pressure on the leather. I'm hesitant about using the plastic piece of the headband since the wiring into the cup then has to bend to avoid pressure from the table