The Headcase Stax thread

[judo]

Not so absurd. I have two old sr-003s and nowadays I am using them for movies with a carbon. They are not perfect I am thinking about refurbish them. Cleaning, rebias, repair the contacts etc. Any experience ?

[spritzer]

8 hours ago, Scgorg said:

Getting parts from Stax turned out to not be a pain! I had to go through my country's Stax importer but it was a pretty painless process so now new wool and 234BL earpads are on the way! I was wondering about the resistors/thermistors/whatever in the earcups though. What is their function? Current limiting the stators? Could they become an issue with time? I'm refurbing this pair of lambdas to be as nice as possible, so I'd like to remove/replace them if that is necessary when I open the headphones.

They are silistors actually and yeah, overload protection, and I remove them as they serve little to no purpose these days. 

[Mach3]

On 8/16/2019 at 5:16 AM, kevin gilmore said:

just because its a great amplifier does not mean that it likes to drive pure transformers.

decca ribbon tweeters, quad esl56 and 63, klh 9 etc are all considered very hard to drive loads.

transformers for electrostatics are much harder to wind than you might think, not a standard thing

On the topic of hard to drive. I recently acquired a Stax ELS-F81, oh man this thing is damn hard to drive.

73db/1W, only thing that drives it half decent is my 100 watt tube amp powered by 8x KT-150 power tubes.

the impedance curve of these speakers sucks the life out of any SS amp I've tried so far.

[soundwave]

Hi all, a new user here. I got my first Stax set about a month ago and I have been really enjoying my L300 Limited + 252S combo. After getting these, all other headphones just don't sound right anymore. I guess this is the downsize of owning Stax? ? If I may, a couple of questions:

- I haven't seen any amp measurements yet - are there any? It seems it's much trickier to measure Stax amps compared to normal headphone amps, but one would think it's still doable?

- When reading for example this thread, there is suprisingly little discussion about applying EQ to Stax headphones. I applied EQ to my L300 Limited based on oratory1990 measurements and the result is phenomenal compared to no EQ. Is this the case or are you all using EQ with your Stax?

- I audiotioned both the 252S and 353XBK amps and decided to buy the 252S since I heard no difference between them. Now after owning it for a while, I might have second thoughts... it looks and feels a bit whimsy. I would like to have a neutral sounding + measuring solid state amp, which would have to be smallish, since I use it on a desktop setup. Ideally it would be 21cm (or more) wide and not very deep like all the Stax amps, so that it would stack nicely with my RME ADI-2 DAC. And it should be black. ? Are there any other choices than the KGSS Klassik? (thanks spritzer for asnwering my email questions!)

Thanks for all the help in advance!

 

[jamesmking]

 

The blue hawaii is going to be too large for you, I managed to get it into a single case but that case is 400mm deep, 85mm tall and 19" rack mount wide. It needs a lot of heatsinks and the power supply is large.... and the wiring needs to be carefully routed to avoid hum from the rather large mains transformer (120mm diameter, 65mm height) in my case...

The alpha centauri is not much smaller - same case but 300mm deep

Are you buying pre built or DIYing your amp? It looks like you dont have enough space for valve... the tiny 6cg7 in the stax amps have very little drive, all the better valve amps use more poweful and therefore larger and more power demanding valves like 6sn7 (alpha) or el34s (hawaii).... But that means a bigger psu, bigger transformer and more heatsinks....

Personally I think the stax'es own modern energizers sound absolutely terrible in every respect. They don’t have enough drive to drive the headphones properly and as a result the bass is just muddy and flat and gets worse as you increase the volume. I had a stax srm006t and 404 signature combo and found them to be bright, fatiguing, not very musical and poor bass. I simply did not enjoy most music with them.  I felt that my brain was on over drive and I could not relax into the music the way I could with my electrostatic main speakers. I spent a lot of money (for me) upgrading to a set of sr-007a and ran them on a stock stax energizer and the sound was better but I was still never happy with the sound. It was still a bit flabby, lacking in warmth in the bass and got worse as the volume increased. I felt the upgrade from 404 sig to sr-007a was bearly worth it. I felt my Quad 2905 speakers and Lemma Hydra amp sounded way better, more relaxing, better bass and far more musical.

I tried parametric eq to try to make the stock stax amp sound more musical and failed, if I increased the bass all I got was more mud and the mud got thicker sooner, it sounded different but not ultimately better. The issue was the amp design.

I built a alpha centauri stax amp http://www.high-amp.de/html/hybrid-amp_eng.html and found it to be a *massive* improvement on any current production stax energizer from stax. Beter and deeper bass, more control, less flabby and muddy, far far better dynamics and stereo imaging, nicer trebble - it was an improvement in every respect except size and power consumption - neither of which I cared about. My only criticisms of the alpha was that I still could not relax into the music and the bass was not rounded or warm enough - it went deep but the mid and upper bass was lacking. I also found that there was very little depth to the stereo imaging. It was far better but still I could not fully relax and just let the music wash over me... still my brain was analysing the sound.

I just finished the electricals on a blue hawaii build... case is still to be machined and milled but I have had two days to listen to it. My word its good! without any audiophile components except for cardas chasis wire and ptfe tube sockets it sounds amazing. Its as much of a improvement over the alpha as the alpha was over the stock stax. The blue hawaii is fantastic - I can just listen without strain, without my brain trying, the detail is amazing but its integrated and does not just throw detail at you. The treble is sweet and the bass is rounded, warm and full. It sounds so much like my quad 2905/leema hydra combination that I seriously wonder if its worth running a conventional amp and speakers anymore. I tried my sr-404 signatures on the hawaii and it made the signatures sound very good too - better than the sr--07 on the stax OR alpha! I am convinced that most of the stax headphones are not bad but the stax stock energizers are just complete junk.  Anyway, sorry for the rambling. But I think what I am trying to say is that to get descent sound from the stax headphones get a realty good energizer, then later you can think about upgrading the headphones. Upgrading the headphones on a stock stax energizer gets you better sound BUT all the weaknesses of the stock energizers - the lack of drive remain. I have not built or listened to an KGSS but my thoughts are that if its close to the blue hawaii in sound then go for it - and there is not much reason to think it will not be given the simularities in the circuit, power supply and the designers ear. The blue hawaii murders, stomps, crushes, destroys and dismembers the stock stax amps. In my opinion electrostatics are not easy to drive and they demand a top flight amp to have good bass and musicality.  

regards

James

 

 

 

 

 

[soundwave]

Alas, I don't have the DIY skills to build any amps. I wish I did! ? The bass was also a bit weak in the L300 Limited, but EQ fixed that pretty nicely. Here's a good ASR thread about L300 Limited measurements and EQ'ing them.

I am under the impression that the 007 and 009 require more power, but these lambdas are much much easier to drive. I just wish there were proper Stax amp measurements like there are with normal headphones. Maybe somebody here has the knowledge to explain why Stax/electrostat amps are harder to measure?

 

[mwl168]

50 minutes ago, soundwave said:

Alas, I don't have the DIY skills to build any amps. I wish I did! ? 

It's never too late to pick up the soldering iron. If you invest the effort to learn, with diligence and good common sense those DIY amps you mentioned in your posts are really not that difficult to build. 

[soundwave]

Aah... I am tempted! I love DIY and I have even forged a couple of knives. I have a master of science degree in computer science and I hate to confess that electricity was the area in physics I always hated the most. Now I would have motivation though... I am tempted!! ?

[jamesmking]

I also have a BSc and MSc in computer science, but for the last few years I have been lecturing Cisco networking and computer network security rather than programming.

If you have the time and the space, DIY is a lot cheaper than buying... My total cost for the blue hawaii build as less than 1/4 of the price I could buy one for new. Even second hand I probably could not afford to buy one. (OK the case will not look as nice and I did not go for a crazily expensive volume pot, but I could add one later). Apart from the satisfaction when its built and working, I know that in the future I can upgrade/modify/repair/service the amp.

The blue hawaii is only my second high voltage DIY hifi build. (before this I built the hi-amp alpha centauri and have built a DC electronic load and a few other low voltage DIY projects). I didn’t hate electronics but I don’t "get it" the same way I "get" programming.: I can write programs from scratch in my head... I can't design more than a simple circuit full stop... although I am getting better at understanding and reverse engineering other people’s circuits and modifying them a little bit...

The alpha build was tough, there where errors in the pcb, silk screen, component list, I killed a transistor adjusting the psu, the psu specs were  marginal, as was the temperatures on the DC valve heater transistors. I think so few people built it that the information did not get debugged. It took some problem solving to get it working but it was a learning experience. In contrast the blue hawaii has been almost plain sailing. Enough people have built them that any errors seem to have been ironed out. The psu worked first time as did the right channel. The left channel hand one issue which I spotted with my magnified visor: a almost solder bridge which would arc at about 65V. Trivial to fix and the amp now works fine. My biggest issue with the Kevin Gilmore designs was getting my head around all the terminology used in the filename of the gerber files used for the PCB creation. I sent a few private messages to Kevin Gilmore and he was very helpful and responsive.

To sum up I’m so glad I decided to go DIY, I have learnt a lot and the satisfaction outweighs the frustration when things go wrong.... (just dont ask me to confirm this when im in the middle of something being wrong  )
regards and sorry for my rambling

James

[jamesmking]

1 hour ago, soundwave said:

I have even forged a couple of knives.

you should not have any trouble with the amp then.... (the SS in KGSS stands for sharp silcer depending upon how sharp the heatsinks are...? )

 

[mwl168]

The good news here is that for the KG electrostatic amps that are often mentioned here (such as Blue Hawaii, KGSSHV, Carbon, Grounded Grid, etc.), there are proven PCB's for both the amps and the PSU's that many have built working and reliable amps with, myself included and I do not have a science degree and never forged a knife in my life!  

Extra safety precaution does need to be followed strictly given the high voltage involved! With that said, if you source correct parts from reliable vendors (Mouser, Digikey, etc., not eBay, not Taobao...), stuff the right parts in the right spots on the PCBs, exercise good soldering practice (many good tutorials on Youtube) and pay attention to layout of components (circuit boards, transformers, connectors, etc.) and wiring, your success rate is very high.  

On top of that, many knowledgeable people here will come to rescue should some things do go wrong provided that you have done your homework!

It's lots of fun and a very rewarding experience!

    

[gepardcv]

To address the point about using EQ with Stax: I did a little adjustment for the 007A using the RME ADI-2 built-in PEQ, and would not go back to stock. (Also will not use a DAC without DSP in the future.)

[soundwave]

9 hours ago, gepardcv said:

To address the point about using EQ with Stax: I did a little adjustment for the 007A using the RME ADI-2 built-in PEQ, and would not go back to stock. (Also will not use a DAC without DSP in the future.)

Yes, same here. I love the ADI-2 DAC at home and in the office I now have to play with software equalisers, which do work, but I just prefer the DSP option in the DAC. Has the Stax 007A been measured and did you apply the EQ based on those measurements, or did you apply the EQ just be ear?

Thanks for the encouraging words about building an amp myself! If I were to proceed with this, is there a separate post/thread which has all the necessary information I would need? The starting point for me would probably be a small enough circuit board - what models are the smallest? 

[jose]

Do you use the equalization to fix recording problems or to modify the response of the headset?

Personally I think that modifying the response of the headset makes no sense. With speakers, equalization can be a useful tool (room problems, resonances, etc.), but with a headset you don't have most of those problems. Headphones are "cheaper" than speakers and there are thousands of different profiles, you just have to try them.

As for DIY, I agree with Mwl168. I can only give you two tips:

Start with something simple (a C-Moy for example) to learn how to soldering and then continue with something more complicated.

It was one of the first things I did, buy a good soldering iron and a good multimeter. In the future you will appreciate it.

 

[jamesmking]

23 minutes ago, jose said:

It was one of the first things I did, buy a good soldering iron and a good multimeter. In the future you will appreciate it.

 

I second the good iron.... I bought a cheap iron with crap thermal regulation and little thermal mass... so as soon as it touched a joint it would cool down. So I increased the amount of time the iron was in contact with the joint.... this increases the time the joint has to oxidize, the flux in the solder would all burn off and the joints were horrible. The solder would not stick to the oxidized joints and it was frustrating. Some years ago, I purchased a hakko fx888d and instantly my joints improved thanks to the good thermal regulation and thermal mass I only needed apply the heat for a short time. So, the flux built into the solder not run out before the was made and cooled. (There is a wealth of good information on you tube) I high recommend the eevblog

I would also say a good desoldering station like a duratool d00627 makes like much easier. It has a built-in heater and vacuum pump. You place the tip over the joint, wait for the joint to melt, hit the trigger and the solder is gone.  Its far easier and more reliable than trying to hear the tip with a soldering iron and use a spring loaded pump in your other hand, or using solder braid. It gives you the confidence that if you screw up (and I have multiple times) you can fix the mess easily and without lifting tracks off the pcb. Its so useful. I had a problem with the 400V- on my alpha centauri power supply. I figured it had to be one of the transistors, so I desoldered all of them on the -400V side tested each one found a transistor that had decided it was two back to back diodes, put all the other transistors back, replaced the bad transistor and had the psu up and running in half an hour.)

I also second the good multimeter with input protection in all modes is also a must. I have this bad habbit of working on amps after work when im tired so I make mestakes... I managed to have my multimeter in ohms mode and tried to measure +400V.... I got a spark just before the probes touched the screw terminal. The psu went into current limit mode and the multimeter survived... a bit of a drama but no harm done. A cheap multimeter without input protection would probably have died. I have a brymen bm869s, its overkill for features and accuracy but its very robust . The brymen being abiused 

Regards and please consider DIY...  

James

 

 

[soundwave]

^^ To modify the response of the headset. In my opinion most of the headphones benefit hugely from EQ. For example the L300 Limited has a nasty +7dB bump at 1300Hz which needs to be corrected. Now when I toggle EQ on/off the sound difference is like night and day in benefit of the EQ.

https://www.dropbox.com/s/sknm9lejxobvo17/Stax SR-L300 LTD.pdf?dl=0

[jose]

If the headset has that horrible peak, why did you buy it? Maybe that horrible peak is nice for another... EMO with the EQ we tend to make everything sound the same.

Do not misunderstand. I have no doubt that you can take advantage of the equalization. I only think that each headset has some features, such as a good wine...

I guess I'm getting older.

[soundwave]

^ I didn't know about these measurements when I bought the L300 Limited. In fact, I thought they sounded fantastic without any EQ. ? Once I saw that ASR thread and applied the EQ corrections, I was more or less blown away, that how could I have liked the sound so much. The EQ reveals a 'hollowness' in the stock L300 Limited sound which is quite apparent in some songs, but not in all. 

Btw, I have mild tinnitus in one ear and some drops in hearing around 6KHz. Hearing problems is another great reason to apply EQ, but I haven't ventured in to that area yet myself. 

Regarding building the amp myself, Audiophonics seems to sell also DIY components. Any experiences with them around DIY projects? I have bought some devices from them without any problems.

[jose]

OK, a physical problem is something different. Sorry.

For components, distributors such as Mouser, etc. are a guarantee. If you are going to do is an amplifier designed by Dr. Gilmore, maybe some member of this forum can sell you pcb´s.

 

[Scgorg]

I agree with what has been said here, never too late to learn to use a soldering iron! That is really the hardest part since people who are way smarter than me have created great circuits that are free to use, you simply need to assemble it all. I technically did know how to use a soldering iron when I decided to start DIYing stuff about a year ago but my knowledge of everything about analog electronics were quite rudimentary, and I'm still in the same boat as jamesmking that I can't really make any circuits myself barring really simple stuff. After about 5 months of DIY I started the KGSSHV which was my first HV build and it went surprisingly smooth even with a so-so soldering iron and my general clumsiness. You really can save a lot of money and it is EXTREMELY rewarding to finish something you made yourself. Just be careful about high voltages like the others have said

While I have no experience with audiophonics myself I know a few people who have liked what they bought from there (mostly chassis though).

 

[Pars]

The hardest part for me in DIY is the casework. With your experience making knives, you will probably have a leg up on many of us for that.


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[catscratch]

I always use EQ. With a well implemented EQ there's very little reason not to. The degradation in sound quality is minimal, and the improvement from having a more linear FR is very noticeable. For instance, I always hear a resonance around 7.5khz in full-size over-ear headphones (probably some outer ear resonance, it isn't there in measurements) and EQ lets me minimize it, making things much smoother. There are obviously limits to what EQ can correct, and it's not going to turn a turd into something listenable, but it can definitely take an already good headphone to the next level for very little cost. I'm still learning how to use it properly, but using a sine sweep or a test tone generator with a frequency slider to hear where the peaks and dips are, and then correcting based off of that has worked pretty well so far.

[soundwave]

Thanks again for these comments. Pursuing the DIY path would allow me to build the amp into a case of my liking, if there are small enough circuit boards available?? 

[MLA]

Very small does not mix too well with high voltage + significant wattage. See Spritzer’s page for a good overview of what the amp size limitations are: https://mjolnir-audio.com/

[spritzer]

Yeah, small size does add a lot of issues if you scale up power just a little bit.