The Headcase Stax thread

[KrypticMind]

I never bothered to figure out what was wrong with the one I bought from you, but I think whatever the issue is will be fixable when I get around to it. It may involve complete disassembly of the drivers... but it is fixable. Maybe I'll redo the mylar diaphragms and make a little project out of it.

With pics? Everyone loves some softcore Stax.

[mypasswordis]

I'm not going to get around to it for a loooooooooong time, but when I do, sure I'll take some pics.

[spritzer]

Also, Stax, bitches.

Amen brother...

Soldered to the tabs, which are directly connected to the stators (no big deal) and diaphragm (big deal). Too much heat, especially on the bias line, and you will have problems. And I don't trust that he did a good, quick, clean job of it, plus all of the other issues.

The stators are pretty fragile too as they are fixed to the molded plastic frame via tiny plastic pieces which could melt pretty easily. Shouldn't happen but then again nobody should be able to melt an XLR plug while trying to solder to it but it happens all the time...

[mrarroyo]

I got a Lambda Pro from Birgir, although I had listened to Stax ear-speakers before at meets I had never owned one. It is being driven by an SRD7/Pro modded by Birgir and IMO this combo sound fantastic! Not quite as good as the K1000 but very satisfying and enjoyable. BTW I am using either a vintage Marantz 2238B or a RWA Signature 30.2 to provide the "juice" to the SRD7/Pro.

[deepak]

I got a Lambda Pro from Birgir, although I had listened to Stax ear-speakers before at meets I had never owned one. It is being driven by an SRD7/Pro modded by Birgir and IMO this combo sound fantastic! Not quite as good as the K1000 but very satisfying and enjoyable. BTW I am using either a vintage Marantz 2238B or a RWA Signature 30.2 to provide the "juice" to the SRD7/Pro.

Miguel get an Omega 2, it will leave that K1000 crying for attention

[faust3d]

I sold my Normal Bias Lambda, since I much preferred LNS to it. I would never buy that poor butchered Lambda

[Cynric]

The Lambda NB isn't a bad phone, but to me it seriously lacks bass extension (and a little quantity, but that is subjective anyway and can be modded in later on).. The Pro just goes quite a lot deeper..

[mrarroyo]

Miguel get an Omega 2, it will leave that K1000 crying for attention

Can't afford it since I would then need a whole new amp, besides I have listened to the O2 at CanJam 08 in TTVJ's room and although very nice I am not sure it will better the K1000.

[condor]

and although very nice I am not sure it will better the K1000.

[Sherwood]

I sold my Normal Bias Lambda, since I much preferred LNS to it.

I bought it, and might well prefer the LNS as well. Nonetheless, I dearly love your old NB. And deepak, if you see good normal bias sets come up for around $200, let us all know.

[manaox2]

I would take a good condition LNS over my NB possibly. I liked them for the short time I had them, pretty sure I would take those over the 404LE too.

[deepak]

I bought it, and might well prefer the LNS as well. Nonetheless, I dearly love your old NB. And deepak, if you see good normal bias sets come up for around $200, let us all know.

Will do. I haven't followed vintage Stax recently, but that was a pretty common selling price. I always thought the most expensive Lambdas were the 580v bias models minus Lambda Pro.

[manaox2]

Will do. I haven't followed vintage Stax recently, but that was a pretty common selling price. I always thought the most expensive Lambdas were the 580v bias models minus Lambda Pro.

They were, though Id be tempted to buy a second pair at that price. Think many of us would, its just too tempting.

[KrypticMind]

They're still around $200-300 these days, and once every blue moon, there's one in decent condition that's under $200. Gotta check pretty often though. They only come up like once a month, but they seem to be getting rarer.

On a side note, I'm tempted to sell my 5NBs that I bought from mypasswordis as they've been getting zero action ever since the O2 came in. They really helped when I was going through my "imbalanced sigs" phase where every sig I was hearing/buying was imbalanced. Kept me sane, to say the least.

[Currawong]

I'm listening with the 404LE more than the LNS these days. Maybe I'm just getting used to the more forward mids. It helps that if you lose seal with the 404LE, the bass doesn't explode like it does with the LNS.

Moving this other discussion to a more appropriate thread...

I sent an email yesterday to the guy running the Unofficial Stax site to see if he has high-res pics of the SRM-600 which should be all I need to know what has to be changed. I just put in a bid on a T1 but it wouldn't hurt to ask Craig about that T1S... As it stands now, lift pin 9 on the tubes and replace the plate resistors with 30K/2W units and the amp should work.

Most of the transistors for the exstata can be substituted with far superior Japanese parts and I'm sure you can find the same resistor values in the Xicon lineup at a lower price. The rest is easy...

Mouser, which kindly redirected me to their Japanese site, lists so many of the PS parts out of stock, some of it until December, that I'm going to have to ask for help just finding some of the parts (I know enough to put the right things in the right places and the right way around, just not enough about types of parts or about transistors). I don't like asking people for help, but I'm thinking I might just have to swallow my pride and start a thread here for myself. The resistors, caps and diodes should be ok, but FETs and MOSFETs are going to be an issue.

[spritzer]

Your best bet really would be to sell the boards and wait for the next release as it will be far, far better. The short story is that KG and I both built our P-P versions of the amp (not using the stock PSU which is IMO rather terrible but rather a known benchmark which is the BH supply) and we were not happy with the results. Now KG measured the build and it wasn't pretty, distortion many orders of magnitude higher then the KGSS (1%!!!!!) but until an amp had been built using the stock boards we couldn't be sure what was going on.

Now fast forward to this weekend and Kevin finishes a bone stock amp exactly like the BOM on the stock boards and exactly the same results. Throw the circuit in a sym and the SRM-212 circuit absolutely thrashes the Exstata let alone the more advanced versions of the same circuit. Now KG gets tinkering and modifies the Exstata circuit so it is far, far better. Alex will then supposedly make those changes to the next board run.

In other news, we are also working on quite a few things right now, including a +/-500V capable SS amp which isn't quite as insane as the KGSSHV. Cheap to build too...

[Tachikoma]

*Edit* nevermind. I suppose its a good thing for me if its easy enough for KG to build two versions in 4 days (going by the date of his reply on the head-fi thread).

[kevin gilmore]

OK, lets see if i got this right, since my dsl is down, i think i brought all the right stuff to work.

So as spritzer says, before CJ, i built by hand an exstata solid state version. Perfboard version.

And it sounded lousy, and it tested lousy. ONE PERCENT thd at reasonable signal levels.

Fast forward a bit, i got alex's boards, built them with exactly the same parts as the BOM

and guess what, exactly the same performance. synthesized here.

http://gilmore.chem.northwestern.edu/exstatas.pdf

sure enough slightly more than ONE PERCENT THD (second harmonic, top trace in distortion graph)

and third harmonic pretty miserable too.

so i started investigating and came up with this.

http://gilmore.chem.northwestern.edu/exstatas1.pdf

way better, .01% THD. and the sound is night and day better too.

but when you clip the thing, it got nasty. SO...

http://gilmore.chem.northwestern.edu/exstatas2.pdf

but really, the more i play with it, the more it looks like what

it actually came from, which still performs almost 5db better.

http://gilmore.chem.northwestern.edu/srm313orig.pdf

of course with modern day parts you can bump up the srm313

to higher voltage...

http://gilmore.chem.northwestern.edu/srm313.pdf

and of course you could do the same with the exstata's, but why bother.

fact is that the 2sj74 is a lot less trouble than the j271 and you don't have

to buy 50 parts to get 4 that work.

and guess what the same thing for the exstata tube version.

http://gilmore.chem.northwestern.edu/exstatat.pdf

and with fixes...

http://gilmore.chem.northwestern.edu/exstatat1.pdf

fact is that the kgsshv still performs better than all the above

and at higher voltages. i'm working on it to make it even better

now.

[kevin gilmore]

I should also mention that this is a relative thing.

many people would be happy with an exstata in stock form.

spritzer and i are not in that group of people. Not after listening to the T2, BHSE, BH...

whether it is fair to compare an amp that is $500 in parts to an amp that is $4000 in

parts is not my problem

[faust3d]

How does something like SRM-1Pro or SRM-T1s mesure compared to Exstata?

[kevin gilmore]

How does something like SRM-1Pro or SRM-T1s mesure compared to Exstata?

Before or after spritzer modifies the hell out of it??

A 6s4a is a WAY better tube than any 6fq7/6cg7!

not sure about the ecc99

[Beefy]

I should also mention that this is a relative thing.

many people would be happy with an exstata in stock form.

Indeed! I was going to ask what you meant by "ONE PERCENT thd at reasonable signal levels."

FWIW, mine sounds a lot better than the SRD7-SB with a normal bias Lambda, and for now that is good enough. I'll build a KG** one day......

[kevin gilmore]

reasonable signal levels. 100 volts peak to peak. amp capable of about 600 volts peak to peak. (stator to ground)

anything sounds better than a transformer box. unless you like that kind of sound.

[spritzer]

As Kevin has pointed out, we aren't normal but I for one don't get the point of 3rd party amps if aren't getting any real improvements for your money. My SRM-Xh has the same voltage swing and a lot less distortion in a tiny box.

How does something like SRM-1Pro or SRM-T1s mesure compared to Exstata?

The SRM-1 Mk2 (not the Mk1, very different design) is mostly identical to the SRM-313 except different parts used. This isn't a bad amp but comparing a stock unit to anything modern is madness since the PSU caps will be way past their sell by date.

As for the SRM-T1, it's a good circuit built on the cheap and with the wrong tubes. The ECC99's should solve some of the compression issues but the real "fix" is the KGST. 6S4A tubes with a 10M90 CCS which I should have up and running as soon as I place a new order with Mouser. I'm as you all know certifiable so I'm running it at +/-400V for added effect...

[kevin gilmore]

here is another one pointed to me by minivan

before at TEN percent distortion. (yep completely open loop, no feedback)

http://gilmore.chem.northwestern.edu/vhvtest1.pdf

(well some local feedback around the output stage)

and after at .01% THD.

http://gilmore.chem.northwestern.edu/vhvtest2.pdf

with added low impedance input and nelson pass super symmetry

who is going to be the first to build it.

6 power supplies. Think T2 power supply only bigger... !!!

+/-660 (650)

+/-240 (250)

+/-87 (90)