The Headcase Stax thread

[Arthrimus]

5 hours ago, alcofribas said:

Thanks a lot Arthrimus.  Now's my chance to figure out how a voltage doubler works.  Unless I'm completely out of it, your circuit is meant for 117V, right?

Pondering over this circuit reminded me that the WEE has a voltage conversion switch... and something clicked in my head.   What, do they have a transformer to handle AC in there?

And it looks like it...  talk about overdesign.   At least this gives some kind of protection, same kind as razors in bathrooms.

This circuit is universal it has a bidirectional 100v Zener Diode on the input that limits the voltage to 100v for the multiplier so it can work worldwide. It's basically Stax's SRD-7 Pro circuit, with a couple of components reorganized to fix their mistake of putting R103 and R104 before C107 and C108 instead of after.

Z101 can be substituted with 2 back to back unidirectional 100v zener diodes if a bidirectional one can't be found. I've used a pair of 1N527 for this. Also you can sub 1N4007 diodes for D101-D106.

Edited April 11, 2017 by Arthrimus

[Torpedo]

Did Stax ever release a SRD-6 with a TRS plug to be used from a headphones output, or is this just a "custom operation" by some ignorant moron?

[alcofribas]

10 hours ago, Arthrimus said:

circuit is universal it has a bidirectional 100v Zener Diode on the input that limits the voltage to 100v for the multiplier so it can work worldwide.

OK, so Z101 is not just a surge protector and we Europeans get slightly higher quality bias.

I suspected that the 1N400X would be just fine, thanks for pre-empting my question.

And a voltage doubler/tripler etc. is not rocket science at all.  It's particle physics!  You can look up https://en.wikipedia.org/wiki/Cockcroft–Walton_generator for nice pics and suggestions for high-end energizer designers.

[JimL]

1 hour ago, alcofribas said:

And a voltage doubler/tripler etc. is not rocket science at all.  It's particle physics!  You can look up https://en.wikipedia.org/wiki/Cockcroft–Walton_generator for nice pics and suggestions for high-end energizer designers.

I remember seeing/using one of those as a physics grad student using an accelerator for alpha particles (He nuclei) looking for a low energy resonance in C12 to O16.

[spritzer]

15 hours ago, Torpedo said:

Did Stax ever release a SRD-6 with a TRS plug to be used from a headphones output, or is this just a "custom operation" by some ignorant moron?

I don't think there ever was one like that (the SRD-X did use a 1/4" plug though) and you can see the label for the input wiring on the back so this is a mod. 

[wink]

14 hours ago, JimL said:

I remember seeing/using one of those as a physics grad student using an accelerator for alpha particles (He nuclei) looking for a low energy resonance in C12 to O16.

.... and you ended up with CO2   right.......?

I used one to make a negative ion generator.

There were about 5 of us working in a closed room with only 2 doors, no windows with a bunch of printers being repaired and tested.

By mid afternoon most of us were getting very drowsy.

I built a negative ion generator and installed in a cardboard box  and placed it on a cupboard, and it really did wonders.

One day an engineer came in and asked what was in the box with the 5 needles sticking out.

The boys told him what it was and dobbed me in as the builder.

I was then called up to explain the deal.

When I finished, the engineer told me it was all a lot of rubbish.

After everyone assured him it wasn't, he asked how I knew it was pumping out negative ions, and not positive ones.

I explained that it was dependent upon the direction of the diodes.

He demanded to know how much voltage it was pumping out and how we could test it.

I produced an Anderson static tester and gave it to him.

He pointed it at the generator and it read 4KV positive and gave me a very surly look.

I pointed out to him that you need to calibrate the tester first and then take a reading.

When I showed him how it was done, he took another reading, which read just over 6KV.negative as specified.

He then got all huffy and told us to go out and get a commercial one.

We all ignored the demand and went back to work.

 

As a back note to his, A few years later I had reason to go to a Sagem factory (French exocet missile producer) to look at their premises where they were assembling and testing telex machines.

They had this long bench about 50 metres long with finished machines running under test.

I noticed that they had 3 negative ion generators fixed to the ceiling.

I asked the manager what he thought of them, and he said that it was the best things they did to the place.

[JimL]

Actually, should have gotten to oxygen.  What we were investigating was the assembly of elements within stars, which was an active area of investigation back then at Caltech, which had a very strong astrophysics section - Willy Fowler was there and he won a Nobel prize in physics some years after I left.  Helium is two protons and two neutrons.  In theory the next step would be to fuse two He nuclei together to make beryllium, but Be8 is unstable (the stable atom is Be9 - 4 protons and 5 neutrons).  So Fred Hoyle proposed that 3 He atoms would make C12, but in order for that to happen, there had to be a resonance in the cross-section just above the ground state that would allow that to happen with sufficient frequency to form C12 to any extent, and in fact, that was found.  My experiment was designed to look at the next step, which is C12 + He going to O16, so I had a very pure C12 target and relatively low energy alpha particles bombarding it, and measuring the cross-section to see if there was a low energy nuclear resonance that would allow that next step to occur.  The resonance itself was too low in energy to measure directly but the idea was to measure the tail of the resonance which should have resulted in a higher cross-section than expected without it.  Actually I am surprised that I remember much about it considering how long ago that was.  Also, somewhat off topic.

Edited April 12, 2017 by JimL

[Torpedo]

7 hours ago, spritzer said:

I don't think there ever was one like that (the SRD-X did use a 1/4" plug though) and you can see the label for the input wiring on the back so this is a mod. 

Thanks Birgir, that's what I thought. The user of that energizer is experiencing distortion at mid to high listening levels that I don't think is normal. He's most likely experiencing the distortion from the headphones output of his amplifiers.

[spritzer]

As if we needed a reason not to buy a new Stax amp...I was just sent this pic:

So they are down to a single 100V primary on the new amps.  This is from a 007tA but it uses the same transformer as the 727 so it will be identical. 

[mwl168]

WTF???

[spritzer]

No cheap amps from Japan for anybody.  I just don't get this shit in this day and age... 

[luvdunhill]

Same as new Esoteric stuff

[Tinkerer]

So, I was just fooling with an SRM-Xh I got in. Everything turns on fine, all LED's on the boards light up etc. The balance on the right channel is within a couple volts. Offset is fine on both channels. But the left channel balance is almost -20VDC. There's no pots or anything on the inside to adjust.

 

What's the likely deal? Carbon film resistors aging or did these things ship this way?

[spritzer]

Might have shipped like that.  20V balance is nothing to loose sleep over. 

[Arthrimus]

My 727 has that same transformer. It's a pity, I have to use a step down transformer.

[Ali-Pacha]

Simple question about cable capacitance : as 60% of the headphones capacitance are within the cable, is it really interesting to shorten the cable and/or to change it with the most recent stax cable ? I'm thinking cloth cables, of course, but also first ribbon cables like those on Lambda Pro, Lambda Signature...looks like large ribbon cables have 10 pf less than narrow ones (see SR-307 vs SR-407 specs), which are a small 10%.

Thanks.

Ali

Edited April 15, 2017 by Ali-Pacha

[spritzer]

Lower capacitance will always help, making the whole system easier to drive.  That said, the older cloth cables were mated to drivers with far lower capacitance so they would be about par with the modern stuff.  Still it wouldn't hurt to use a lower capacitance cable. 

Going the whole HE-1 route though is just idiotic.  Cramming class A/B drivers (at best) into the capsules and instead carry a pile of signal into the phones is a pretty crappy compromise.  Reeks of the usual Sennheiser "we did something cool but utterly stupid (HE90 glass stators)" which they are kinda known for... 

[catscratch]

The Stax amp thing really pisses me off. This is the sort of shit that can kill a business. You have an anti-consumer practice (their pricing structure in this case), and when customers find ways to get around it, you restrict them more with another, even more anti-consumer practice. What's the end result of this going to be if not less sales? I'm more hesitant now to buy Stax amps. Remind me why this is a good thing for your business again?

How do we get it through to them that they need to 1) knock it off and 2) equalize pricing all around?

Edited April 15, 2017 by catscratch

[kevin gilmore]

stax is certainly not the only company doing this.

krell in a whole bunch of its products puts in a custom microprocessor chip that looks at line frequency, so if you have a usa unit at 60hz it won't even turn on at 50hz. and of course a few have developed plug and play circuits to fake the 60hz.

 

[mwl168]

2 hours ago, kevin gilmore said:

stax is certainly not the only company doing this.

krell in a whole bunch of its products puts in a custom microprocessor chip that looks at line frequency, so if you have a usa unit at 60hz it won't even turn on at 50hz. and of course a few have developed plug and play circuits to fake the 60hz.

 

Reminded me of my experience long time ago trying to buy a Kawai piano. They have a "territorial" system in US that does not allow one region to sell brand new piano to customers from another region which enables my local dealer to charge outrageous price which is more than 20% higher than what I could buy the same piano for from another dealer.

I called the Kawai headquarter in US and asked them how this policy benefits their customers. After putting me on hold for about 10 minutes, the rep came back and told me they have no good explanation.

I went and bought a different brand piano.  

[mypasswordis]

15 hours ago, Ali-Pacha said:

Simple question about cable capacitance : as 60% of the headphones capacitance are within the cable, is it really interesting to shorten the cable and/or to change it with the most recent stax cable ? I'm thinking cloth cables, of course, but also first ribbon cables like those on Lambda Pro, Lambda Signature...looks like large ribbon cables have 10 pf less than narrow ones (see SR-307 vs SR-407 specs), which are a small 10%.

Thanks.

Ali

What Birgir said. I really wouldn't worry about it too much, as the new ribbon cables are all 5 pin so if you use them to recable old normal bias headphones with cloth cables you have to take extreme caution and remember not to plug them in pro bias sockets. Risk of damaging drivers outweigh a minimal potential increase in SQ IMO. Using extension cables is another story as I did find the old ones to alter the sound. 

Were you and Sorrodje planning on redoing your vintage Stax measurements? I see Tyll has posted some new measurements on Innerfidelity but most of them are measured with poor seal and he clearly changed something in the coupling/measuring setup compared to before because the measurements are vastly different from his previous Stax measurements. 

10 minutes ago, mwl168 said:

Reminded me of my experience long time ago trying to buy a Kawai piano. They have a "territorial" system in US that does not allow one region to sell brand new piano to customers from another region which enables my local dealer to charge outrageous price which is more than 20% higher than what I could buy the same piano for from another dealer.

I called the Kawai headquarter in US and asked them how this policy benefits their customers. After putting me on hold for about 10 minutes, the rep came back and told me they have no good explanation.

I went and bought a different brand piano.  

Sort of similar but not a 1:1 analogy IMO. Pianos are kind of like cars, in that they depreciate. They are different from cars in that every piano, even of the same model, is different. A lot of the times it makes more sense to buy used, if you find the "right" one. If you buy an amp with only 100V transformer windings, whether it's new or used doesn't really matter, and each amp presumably sounds the same.

[alcofribas]

Is it really Stax that should be the focus of all that wrath?

-- Switching from a multi-tap transformer to a simple one decreases production costs while Krell's microcontroller hack almost certainly increases them.

-- If Stax didn't want to bow down to the importer mafia, what could they do?  Some boutique constructors like Origin Live can be successful by mostly selling from their website.  Stax may be small but they're not boutique, they're part of a conglomerate, and they already have commitments all over the world.  Is there another possibility for them?

Please enlighten me, those of you who know more about the business.

In France importers of HiFi are greedy pigs, as they are for so many other countries.  In the particular case of Stax, the German importer seems to be even greedier, if you can believe.  If you happen to be in France but live near Belgium or Luxembourg or Germany, buy your foreign gear there.

[Ali-Pacha]

9 hours ago, mypasswordis said:

Were you and Sorrodje planning on redoing your vintage Stax measurements? I see Tyll has posted some new measurements on Innerfidelity but most of them are measured with poor seal and he clearly changed something in the coupling/measuring setup compared to before because the measurements are vastly different from his previous Stax measurements. 

Why redoing it ? We did it once, with all the warnings included (system, procedures, etc...), one should take it as it is and go on with the hobby  And btw I sold my 007mk1 some weeks ago...

Ali

[spritzer]

14 hours ago, kevin gilmore said:

stax is certainly not the only company doing this.

krell in a whole bunch of its products puts in a custom microprocessor chip that looks at line frequency, so if you have a usa unit at 60hz it won't even turn on at 50hz. and of course a few have developed plug and play circuits to fake the 60hz.

 

Madrigal did this back in the day and charges some obscene amount to alter the older products for use in other areas. 

2 hours ago, alcofribas said:

Is it really Stax that should be the focus of all that wrath?

-- Switching from a multi-tap transformer to a simple one decreases production costs while Krell's microcontroller hack almost certainly increases them.

-- If Stax didn't want to bow down to the importer mafia, what could they do?  Some boutique constructors like Origin Live can be successful by mostly selling from their website.  Stax may be small but they're not boutique, they're part of a conglomerate, and they already have commitments all over the world.  Is there another possibility for them?

Please enlighten me, those of you who know more about the business.

In France importers of HiFi are greedy pigs, as they are for so many other countries.  In the particular case of Stax, the German importer seems to be even greedier, if you can believe.  If you happen to be in France but live near Belgium or Luxembourg or Germany, buy your foreign gear there.

Well they didn't do this for decades so as soon as ordering from Japan has become easy as pie...they do this.  Of course we should be pissed off as it means cheaper amps are now much harder to source.  A modded 727 was always a good starter amp so now the used ones with a proper transformer will be come scarce. 

1 hour ago, Ali-Pacha said:

Why redoing it ? We did it once, with all the warnings included (system, procedures, etc...), one should take it as it is and go on with the hobby  And btw I sold my 007mk1 some weeks ago...

Ali

I did think that the Innerfidelity measurements were off.  The SR-1 almost certainly and the 4070 sounds a lot like the one fitted with 507 drivers I had which sounded terrible...

[Ali-Pacha]

Correct seal has always been something tricky with lots of Stax phones. No problem with Omega nor with latest Lambdas (real improvement IMO), but from Lambda NB to SR-507, one has to be very careful. My bald head has some advantage in that, perfect seal everywhere, from SR-5 to SR-009 through SR-X (yes ! Stax-proof earlobes inside) and any Lambda / Sigma 

Apart from drivers swapping, Innerfidelity measurements may be a bit strange indeed, but they reflect this seal issue somehow and would be "true" on their own with some disclaimer. I remember our measurements session with Sorrodje as he struggled one or two times with Lambdas to get a proper seal (Lambda Signature especially...no idea why).

Looks like Stax did learn from that, SR L-x00 look like they have a perfect pad seal no matter which head, but could be leaky by design for tuning reasons (more low-mids / oomph but less quality bass). Not sure about that, as some did measure a flat bass response and some others are like me on a leaky sound signature (as well as measurements).

Ali

Edited April 16, 2017 by Ali-Pacha