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Could you post the picture of the ok ones? I am recently interested and thinking to try one. Thanks!

I am more interested in the R-core transformer. Where did you get that? Is that good?

http://20cheaddatebase.web.fc2.com/STAX/STAXindex.html I accidentally found a website about the history of Stax, which is very interesting.........in Japanese. I really don't know Stax had produced so many kinds of headspeakers. Google translator is your good friend.

Ahh, also EI? toroid? R-core? For a 300VA transformer, toroid ones can be easily mount in a case while EIs don't. But someone told me EIs are better for high voltage usage.

Talking about transformer..... Some will prefer a much over killed ones like 500VA, while others will just meet the spec. How do you guys think?

There are LSK389A, B, C. Which one is suitable in stax mafia's design? The GB here is LSK389B and I am using LSK389A in KGST, which seems no problem at all. Does it matter?

So @spritzer what do you mean new ones 007 are ok? Do you mean sz-3xxx or even later? It's harder to find a mk1 in good condition now, so if mk2.5 are near equally good and I will have them.

I had built a KGST already. It cost me only about $1.2K. Really really good for the price. I also appreciate people on HC a lot for their help. What I want to say is 1. Not every stax owner outside of English speaking world knows stax mafia and what they are doing. 2. Some of my friends want it easy. Pay-and-get. No collecting parts. No debugging. We all know Birgir's doing quiet good. Mjonir audio still needs time to be come famous enough worldwide.(not sure if Birgir wanted to)

Oh I actually means in my country, few people know who's Birgir and what's Mjonir audio. Mjonir audio still need time to become famous. Not everyone here knows English. Many audiophiles still rely on local distributors.

For DIY, you pay your time. Not everyone can solder and take the risk of high voltage. For 3-party, what comes into your mind? Let's not talk about sth like WES and A10. How about BHSE? Indeed a nice amp. Sounds great and decent case work. But you have to wait a loooong time, and pay much more than a 727. Mjonir Audio is doing good. But it still needs time to become a "brand".(no offense) For $2K, there's only 007, 727 and GES.

Does latest 007 means mk2.5 (sz-3xxx)? or even later? BTW, I think the design of 009 included compensation for the 007/727 since they can't output so much power. You can choose either warmer 007 or a leaner 727. Perfect? absolutely not. Good? of course yes. Buyers can adjust front end or wires to adjust the sound. Stax really can't count on everyone buying 3-party amps to make their phone sounds better.

How about 007 mk2 or mk2.5 without mod? I am thinking to borrow a pair of 007 to test on my KGST. Likely to be mk2 or 2.5. Since I can't mod them, are they simply different phone or same phone from different batches? I mean are the difference very significant? I like 009 quiet much and never heard a 007 been well driven. 007 on 727 is..... far from acceptable. veiled and foggy.

T2 naked will even be better in that case. OMG.

Edifier says the new Stax flagship amp is on final stage. Going to release this year. Wait and see........ And new 002 and a new basic amp with DAC intergrated coming soon.

Nice anodize!

And why high voltage supply? Why won't something like 300V rail work? Sth like 300+-250V things. Or you mean 400+- 300v is more better?Is this to avoid the non-linear area of tubes working under low voltage? Oh and I thought 1Khz and 20Khz are more like issue with current, not voltage? Thanks for replying!

Yesterday, my friend was debating with me why does we need high voltage supply. As the Stax spec says 101dB / 100V r.m.s. 1 kHz. Then Vpp will be about 281V to be very loud. Voltage swing will be 400V+-281/2=260-540. In his opinion, 300B and lots of other tubes were able to do this too. I think this sounds wired but I can't point out. So could anyone explain why we need output stage to reach 1000+volts?

My 6S4s are from a local dealer outside of US and not selling worldwide. Sorry for that. He claimed all tubes are matched on TV7 for free. However, I rarely believed in those commercially matching services. Tubes need about 50 hours or even more to become really stable as I know. If the QC processes are total 10 hours in the factory. Then we'll still need many hours to lit them up and wait. Most of those tube shops only put tubes on a tester for 1 hour or so. Not even mention those tubes are not matched on your amp's working point. So I've already gave up getting real matched tubes. For new-production EL34s, I recently found a dealer on Taobao claiming they age the tubes for hours until they stabilize and traces the curves individually. Then matching is based on those curves. If they really did those processes, and this will be the best matching service I've ever know. If someone is interested too, then I'll post the link. Any opinion on matching tubes? After searching, I think EL34s are more fun to play with. Much more choices and yes, better. So I think I'll go for EL34. Feel sorry for my wallet. Really interested in Gold Lion KT77s too. What's sonic difference between el34, 6ca7, kt77?

Actually, I could get 6S4 NOS for about $10 each.(out of production so of course NOS) Dirt cheap for getting octets. Winged Cs or sth like re-issue Mullards are really not bank breaking. But for NOS vintages like Mullards or RFTs......... Of course EL34s looked much better when lit up.

One more question. How about paralleling 6S4 to get 20ma@400V ? Comparing to EL34s, those are real triodes and have a much more reasonable price for NOS. Any pros and cons?

Is DC supply here be a better choice to reduce humming issue? (compromise though) This make it easier for tube rolling.

How about those VR for balance and offset? I think mounting on the same side of tube will make it easier to adjust when operating. edit: and LEDs?

for AC coupling caps, any suggestions?

one stupid question: Is this fixed bias or self biased?

How about PSU? Same as carbon? or the KGSShv PS?