The Headcase Stax thread

[Salt Peanuts]

In no particular order, Kuboten Audiocubes, and PriceJapan. I've used them all in the past and I've had no problems with any of them.

[bobkatz]

I just replaced the .0047 uF silver mica coupling caps in my SRA-12S with 2 uF Polys and also goosed the bias on the diaphragms to 300 volts. The bass response significantly improved so I highly recommend this mod for those using old Stax amplifiers. CAUTION: There is very little room inside the cabinet to fit these larger caps. I found it easier to put one cap on each daughter board and put the other caps underneath the chassis and add a 10 Meg bleeder resistor to the extra caps under the chassis.

The other thing I notice is that with the increased diaphragm bias (so I can gain some benefit from pro phones plugged into this amp) the high frequency response actually becomes smoother, perhaps too much rolloff now, darn. Perhaps it was not the bias, simply the psychological effect of the increased bass, but now the phones are bit too warm. I can live with it.... sounds fantastic, I wouldn't give up the increased bass.

With condensor microphones I am familiar with this effect, where the tension of the diaphragm is affected by the polarizing voltage on the diaphragm and affects the peak of the frequency response. I wonder if this has a similar effect on electrostatic headphones.

[spritzer]

Stax were always a bit stingy when it came to the size of coupling/output caps so I'm not surprised you like the effect of having much larger output caps.

You should be able to add a variable Pro bias supply pretty easily to your amp. Something like the KG Blue Hawaii supply (which is also used in your KGSS) is very simple to build.

The diaphragms in all of the Stax phones are as tight as drums so the bias won't alter their behaviour.

I have a Stax Monitor which has developed an intermittent fault in the left channel (of two separate phones). It sounds like a high pitched scratchy noise, and occasionally the image shifts to the right while this is happening. Any suggestions? The amp behaved perfectly at the techs recently - the curse of the intermittent fault.

Did it make any difference to turn the volume knob or engage/disengage the EQ?

[Asr]

Apparently the 507 list price will be $1099 in the USA, Elusive Disc now has them on their web site. Who is a dependable company to order from in Japan? Thanks.

Are you in Japan, or the USA? If the USA, wait for Elusive Disc's next 10% off discount, they seem to have one of those every time a holiday comes around (I predict the next one will come up around Labor Day, and then another for Halloween, then Thanksgiving/Black Friday, then Christmas).

And another site that exports Stax to the USA is Bluetin.com.

[John Buchanan]

Did it make any difference to turn the volume knob or engage/disengage the EQ?

No difference with engaging/disengaging the EQ.

It may be more frequent with turning the volume up also, but not 100% sure on that one, as it is intermittent. I don't think it's a scratchy volume pot, but may be happening more commonly the louder the phones is what I meant.

Thanks for your thoughts Birgir - trying to even find a tech over here is hard enough.

Edited August 27, 2010 by John Buchanan

[spritzer]

If it happens more often as you push the amp harder then it may be a thermal issue which would be a component somewhere on its last legs. I'd start off by replacing all electrolytic caps and if that doesn't cure it, it's time for more drastic measures.

[John Buchanan]

Thanks for the advice Birgir. A legend as always!

[postjack]

birthday present to myself: stax basic system II with 15ft extension cable (202 +212). $370 shipped from eBay, which I think is a good price. I've always wondered how this humblest of contemporary staxen sound. actually I haven't heard any of the pro-bias lambas.

[spritzer]

It's quite good actually. The SR-202 is far better over all than the 303/404 and the SRM-212 is a nice, low power version of the old SRM-1 Mk2.

[Dusty Chalk]

The SR-202 is far better over all than the 303/404 ...

Orly?

EDIT: Because they're black?

[spritzer]

Nope, they don't have the midrange shout of the other models which makes all the difference to me. The 303/404 have better bass and treble but that damn shout just kills it for me. I had a 404LE here at the same time with my last 202 and they were rather similar but the LE was more refined.

That said I do have a bong standard 404 here which doesn't have the midrange coloration. Now this could be a SR-SC1 which is simply missing the sticker on the plug but I doubt it. I don't want to mess with them either as they are my test/loaner phones.

[spritzer]

In other Stax news, KG has tracked down the reason why the 727 sucks so badly compared to the 717. This has already been posted elsewhere but I figured it should be here as well.

The 727 is in many regards a KGSSHV but with the output stage outside of the feedback loop. So while they added the CCS for the third stage they fucked up the output stage for no good reason. Help is at hand though as Stax were ever so kind to leave most of the feedback traces in place so there is no need to run wires from the plug in cards to the motherboard. Here is a picture of the mods (taken by Kevin so it is huge) needed to be done which I will do as soon as Kevin is done playing with the amp.

I also bought a SRM-300 for Kevin to take apart and here are some internal pics, front and back of the PCB. What we have here is an enlarged version of the SRM-001, capacitor coupled and running off a regulated PSU, complete with the rather nasty Alps RK097 volume pot. Due to that there is a rather unique balance function on the back panel, a fixed resistor for one channel and a cheap PCB mounted pot for the other...

[postjack]

It's quite good actually. The SR-202 is far better over all than the 303/404 and the SRM-212 is a nice, low power version of the old SRM-1 Mk2.

glad to hear it! I'll post my impressions here once they've shown up and I've spent some time with them.

[postjack]

It's quite good actually. The SR-202 is far better over all than the 303/404 and the SRM-212 is a nice, low power version of the old SRM-1 Mk2.

glad to hear it! I'll post my impressions here once they've shown up and I've spent some time with them.

[Currawong]

In other Stax news, KG has tracked down the reason why the 727 sucks so badly compared to the 717. This has already been posted elsewhere but I figured it should be here as well.

The 727 is in many regards a KGSSHV but with the output stage outside of the feedback loop. So while they added the CCS for the third stage they fucked up the output stage for no good reason. Help is at hand though as Stax were ever so kind to leave most of the feedback traces in place so there is no need to run wires from the plug in cards to the motherboard. Here is a picture of the mods (taken by Kevin so it is huge) needed to be done which I will do as soon as Kevin is done playing with the amp.

So 5 minutes of soldering results in an un-fucked 727? Why then was this amp such a load of fail? Don't they have anyone seriously capable of amp design in their employ? Or are their engineers just weird?

[The Monkey]

This is very interesting. So let's say one can "right" the 727. How do you guys think it would compare to a KGSS?

[spritzer]

So 5 minutes of soldering results in an un-fucked 727? Why then was this amp such a load of fail? Don't they have anyone seriously capable of amp design in their employ? Or are their engineers just weird?

Yup, should only take a few minutes thanks for the ever so helpful Stax engineers who left most of the feedback loop in place.

My take on this particular design is that they wanted to try something different and it simply failed. As KG said on HF, you need a lot more power going through this thing to behave without feedback and all the sims confirm it.

This is very interesting. So let's say one can "right" the 727. How do you guys think it would compare to a KGSS?

We'll see soon enough.

[spritzer]

Look what I just got, pulled SR-007 Mk1 drivers...

I haven't tested them yet but odds are that they are just fine. Also got an SRM-T1 which will be converted to accept ECC99's. The damn thing looks like new too boot...

[Les_Garten]

Very Kewl!

They look nice unencumbered.

[audiosceptic]

Although this isn't a Stax issue it does have to do with stats so I posted in this thread.

So I sold my HE60's through Audiogon to somebody who is also a member at HF. After receiving the headphones he reports that there is a problem where "the sound quailty was a bit distorted and the balance had pulled to the left". I offered suggestions and mentioned he could send them back to me for review. He immediately sent them back to me and wants a refund. They arrived in perfect shape and sound fine out of my BHSE. No distortion, no balance issues. The buyer is using a RSA A10 amp and now believes that perhaps the amp may not have provided enough output to drive the HE60's from the Stax jack or my HE60 to Stax adapter was faulty. First of all it's hard for me to believe that the A10 is so bad it can't drive the HE60 without distortion and balance issues from the Stax jack. I think I read Ray even demonstrates the A10 with the HE60 although I don't know how it is plugged in. And would the the Stax jack provide any different output than the HE90 jack on the A10? If the Stax adapter I am using with the HE60 is faulty, wouldn't I hear it on the BHSE?

I'm probably going to refund his money minus shipping because I like the headphones but really believe I wouldn't have to in this situation.

[Torpedo]

Were I in your situation, I'd return the funds and just try to sell the phones again to anyone else. Unless the guy goes to your place and listens by himself the BHSE does a much better job driving the HE60 than his A10, I don't think he'll be convinced his amp's is at fault.

[spritzer]

Any normal amp would run the outputs in series (as in the amp outputs are the same) and only the bias supplies are different. Now the A-10 is a steaming pile of fail and Ray is a half-wit so anything could happen. If the headphones work on the BHSE then the A-10 would be my first place to look for faults, same with any other amp/headphone fault situation.

[nikongod]

The buyer is using a RSA A10 amp and now believes that perhaps the amp may not have provided enough output to drive the HE60's from the Stax jack or my HE60 to Stax adapter was faulty.

People like to say low/lacks power when they really mean "generally fucked up"

Although its nice to have some extra power on tap, moar power != less fucked up.

Better design=less fucked up.

First of all it's hard for me to believe that the A10 is so bad it can't drive the HE60 without distortion and balance issues from the Stax jack. I think I read Ray even demonstrates the A10 with the HE60 although I don't know how it is plugged in. And would the the Stax jack provide any different output than the HE90 jack on the A10?

My bet is he is hunting for an excuse to return them for some unrelated cause (car needs work, lost job, sick wife, etc) and fishing for reasons.

If the Stax adapter I am using with the HE60 is faulty, wouldn't I hear it on the BHSE?

absolutely

I'm probably going to refund his money minus shipping because I like the headphones but really believe I wouldn't have to in this situation.

Aah, the ever present question of whether you will get into that....

Bear in mind that the seller ALWAYS looses if there is a disagreement through paypal if that applies, and you really cant make him take the headphones back now. See if you can get him to pay your audiogon listing fees, and shipping at least 1 way (preferably both), and refund the rest. Seems fair from my end. If you cant talk him into it, cut your losses and save your feedback rating.

Any normal amp would run the outputs in series (as in the amp outputs are the same)

The outputs are in parallel

Edited September 1, 2010 by nikongod

[mypasswordis]

Needs. Moar. POWAH!!! I wish moar powah would solve all my life problems like it can audio.

[spritzer]

The outputs are in parallel

Indeed good sir.