HELP with Stax SR-5 electrostatic headphones

joshua lutz

New Member
Been trying to find someone who can fix these sr-5's to no avail. Yama said they can't help me with the headphones, only the Stax box (sdr-6) if it has indeed failed. Any techs you can recommend I might ship this amazing set of speakers out to? Any advice would be super helpful. I know so little about electrostatic but I really want to get these old dogs up and running and hear what the big fuss is about! I'm on AKG K701's now but can't wait to hear the difference. Thanks in advance - Joshua L. in nyc
 
Hello Joshua

What is your trouble with these headphone ? You don't explain what the problem is . Do you know how to connect it and how to use it ? IF yes , do you have sound ? On one channel ? Both ? Distorded sound ? on one or two channel ? waiting knowing more
 
IIRC I seem to remember that these needed to be powered up for awhile before they made sound. Like the had to "charge up" the elements.
 
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Hello Joshua

What is your trouble with these headphone ? You don't explain what the problem is . Do you know how to connect it and how to use it ? IF yes , do you have sound ? On one channel ? Both ? Distorded sound ? on one or two channel ? waiting knowing more

Very kind of you to offer help, I see you have experience with these so thanks in advance. I was just initially just looking for a tech to send them out to though but I'm down to try to problem solve first if you've got the patience.
So The issue is that I'm getting little to almost no gain from these and what little whisper of db coming through them is only high end (no distortion, just shrill bright high end only at a whispers volume). The Stax box is a sdr-6 which I believe is not the original model the sr-5's came with but I was assured it worked at one time and then stopped. I've inspected the diaphrams and removed them they look to be in fantastic condition although I wouldn't know what to look for other than loose solder or frayed wire. Both sides are outputting the tiny signal. I have it connected properly to a nice Yamaha receiver. I've tried these on a few amps and the guys at Accutech (Yama's Service Dept) say any decent amp should work. I believe it to be the "stax Box." From what I've read, it is a myth that they need to "warm Up" and that they should fire right up but I may be mistaken. Thanks again - Joshua
 
Hello Joshua


To solve the trouble by yourself is not a problem in itself but as you don't know this technology it would be complicate for you to understand .

Understand what you are doing is the key .

You can send them to me for repair or try to do it by yourself as I said . The difference is I will be faster than you, and shipping cost go and back will not be cheap .

Now, go to the STAX :

the fact that you are using an SRD6 or any other electrostatic STAX power supply is not important .

Do you have any measurement tools ?


Are you sure that there is no damaged connection between the power supply and the SR5 ? Easy to check with you meter in continuity test .


Can you take a look on the bias voltage : you schould have around 90 V / 100 V DC in parallel of zener bias diode Z1082 . This voltage can be measured with ordinary DC Voltmeter .


If bias voltage is not there you can’t get any sound at all in the headphone .


Once you did that , take an audio generator and connect it to your YAMAHA amplifier at AUX input .

Connect your headphone to SRD6 and your SRD6 to the speaker A output left and right .


If you don’t have audio generator , you can use a TEST CD with 1khz recorded on it .


Come back to us with requested answers !
 
Joshua

I did this file for you . With that, you can double check if all cables are well connected and at the right place in each acoustic chamber !
 

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I awoke to my son watching Spongebob on our projector screen wearing the Stax I had plugged into the receiver the night before!! Turns out these DO IN FACT need to be charged up over night even though the audiophile I got them from said they no longer worked and was throwing them out! I had tried everything and given up until I read a thread where some claim they need 24 hours of charge before they hit full volume. This turned out to be true because low and behold, for the first time, they finally work and sound amazing after leaving the SRD-6 Adapter plugged in all night. Amazing.

I hope this helps someone else down the road and a huge thanks to clinic-audio for your help. It's so great to have these resources on the net, even if sometimes the answer is easier than expected :)
 
IIRC I seem to remember that these needed to be powered up for awhile before the made sound. Like the had to "charge up" the elements.

boyah baby - I confirmed this to be true today. Takes about 24 hours to fully charge the electrostatic diaphragms apparently. I feel like Indiana Jones triumphantly emerging from the temple of doom... with a pair of early 70's Stax!
 
Joshua

Normally, your SR5 should work immediately after that you switch the power supply "on" (power on pisition is "headphone" position ) . If your headphone need to be "charged" is not normal at all , except maybe with very very old drivers because they are bad .
 
ahhh very interesting. So ast night they put out the tiiiniest signal. I had to crank the amp almost all the way up to get any signal at all and it was shrill. This morning however, they worked fine and I did nothing at all. So something is wrong with them? I've read many others say they need an overnight charge but you don't think so? These are definitely old, these are all original from early 1970's so...
 
STAX drivers for SR3 / SR5 / SRX / SRX MK3 / SRLAMBDA / SR SIGMA , in fact ALL electrostatic don't need to be charged
 
Glad they are working! They are very cool.

I know they do not "need" to be "charged up", but I've read many times that some do need to, for some reason I forget now. Anyhow, moot point.
 
but I've read many times that some do need to , forget these comment coming from bad informed people repeating from one to each other ....Sound will come immediately if right bias voltage is there . If somebody still say that they need to be charged , it is because they don't know what they are talking about !
 
but I've read many times that some do need to , forget these comment coming from bad informed people repeating from one to each other ....Sound will come immediately if right bias voltage is there . If somebody still say that they need to be charged , it is because they don't know what they are talking about !

I am sure you're right since you have experience with these old Stax. The result then was that they didn't work yesterday but after leaving them on overnight they just started to work. For whatever reason that may actually be, I'm just happy to have a great pair of Stax now that sound great :) and I thank you for your insight on these! I will certainly bookmark this thread if I come across another paid that may need fixing.

My take away from these electrostatic "ear-speakers" are two very interesting observations. Firstly, the frequency response they produce (...and don't). To me, these represent a time capsule into what humans used to desire in their listening experience and how drastically our collective ears have changed over the last 40+ years. I believe what was popular in music at that time directly correlates with the coloring of the tone these produce. I've noticed the same frequency responses in old Alnico speakers and similar cabinets from yesteryear too. These Stax have so very little low end but the presence of the midrange and definition of the high end is jaw dropping. If you look at what society was listening to when these were manufactured (and leading up to), and you look at the analog outboard gear and linear 2" reel, 1" reel, 1/2" and 1/4" tape media in the studios at that time, these headphones make all of that music just shine. From classical to jazz, rock, r&b, to even, I would imagine, disco of that era. But if you look at what teens, 20's and 30 somethings are listening to now: hip hop, pop, folk pop, dubstep, dance, trance EDM, polished funk and hard rock, it's all so digital and shiny. All of this new stuff sounds just awful on these Stax but boy oh boy does old music sound deep and rich and airy on them! Yes modern mixes are much more compressed with absolutely no headroom but also very bass heavy and punchy which definitely has it's place too in this new digital era. The second half to all of this is -> look at what 90% of these kids and young adults are listening to their music on here in 2016! Beats by Dr. Dre. It's like 9 out of 10 humans under 50 own a pair, it's just crazy (I do not care for them at all). I see budding teenage audiophiles listening to techno in $1500 neon red "beats" cans. Then I turn and picture the man I bought these Stax from in his 20's at home with his direct drive Technics with Stanton needles listening to the Association or Stavinsky in a beanbag chair and it's so very interesting to have been exposed to these observations through this single pair of headphones I've acquired. I never would have even seen all of this if not to stumble on these unique headphones and the subculture that exists so thanks guys! Sorry for rambling on about it but these headphones have given me quite an adventure and I thought I'd share. Thanks again for your wisdom with this brand, your knowledge is a great resource to others so thanks for being so active on this blog, it's great to see they still manufacture new stuff too! If I were stupid rich, I would certainly pick up a pair of Stax sr-009's immediately.
Thanks again - Joshua
 
hello there
very simply, when a stax driver doesn't work normally, meaning you have to wait for it to sound right, it just means that the myla inside has to be recoated. originally, it is coated with a chemical product that makes it electrically chargeable and able to be moved and make sound. with time, the properties of theis product which is spread on the mylar change, and mylar by itself cannot make sound, because it cannot be moved by the copper parts that induce the signal. it is very possible to recoat these with the right product, but it is not very easy. Some say it is not possible and it will destroy the drivers, this is not true at all.
I mend stax srx and also turn them to pro bias models, for info.
 
Keep in mind that the SQ of these 'phones is very dependent on the quality of the amp you run them off. I listened to SR-5 for a long time, and eventually replaced the adapter with a STAX tube amp, running off the preamp. It was icing on the cake.
 
Stax has had powered energizers, and self powered energizers that require an amp
connection on one end, and the stax headphone on the other. in addition, there have
been two energizing voltages.

providing you have it all together, it should work immediately.

The Stax electrostatics are the very best. has the treble clarity of expensive speakers.

enjoy.
 
Two types of energizers exist.

Speaker Powered. The first is ones which derive the bias voltage from the speakers, instead of being mains powered. They may need to briefly charge prior to use.

Mains Powered. These use a mains transformer to produce the bias voltage and are thus instant-on. The big issue with mains-powered energizers is dissipating parasitic charge building up which must be neutralized by the energizer. That takes time.

The energizer bias circuit is high impedance as does the membrane in the element. So very little current changes hands and it slowly does so. As a result, when charge builds up on the membrane surface it is not easily or readily dissipated. Worse yet, the membrane is non-linear and its impedance characteristics (it is coated during manufacture to even them out) deteriorate with age and become non-linear. Localized hot spots of charge can more easily arise and these do not readily redistribute, no matter what the remainder of the membrane is doing. This is a problem in electrostatic speakers, and some spray their speaker or headphone membranes with an ESD spray like Licron to recreate the even impedance. (I'm not advocating spraying electrostatics, btw. This is an academic discussion of the issue. I don't know how well it works, only have read about it.)

This is why a charging period is necessary. It isn't strictly a charging issue in a powered energizer, it is more discharging what is there.

I have entirely too many electrostatic headphones. The ones using a Stax SR-3 OEM element benefit from charging, but they are quite old and the membrane coatings are likely degraded. The KOSS ESP-9 also benefits, and it is more recent, but not that recent.
 
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