spritzer

It doesn't make any sense to use a PSU that is not better than the KGSSHV unit as you'd just degrade the performance. Dropping the voltage with a resistor for the front end doesn't have that big of an impact though. For a transformer you might get away with an oversized 230VAC unit. The margins are very small and I'd use a 250V unit instead but it could work without dropping out of regulation. The SRD's use an input limited voltage multiplier. It can't take any load though which means they are all but impossible to measure.

Happy Birthday Justin!! I hope you got something nice like an Audio Precision workstation...

Yeah, it's just those two boxes glued together as they don't even share a power transformer. Also the XLR inputs on the back aren't balanced at all so bone stock ED-1 and SRM-1 Mk2.

That's how we roll...

Yes but it's not something I'd ever eat. It's a hodge podge of soy, wheat fiber and starch.

Yup if we go that high in current. No way we will go higher than say +/-450V on it.

I'd stick with the stock CCS but it can be modernized with new sand. The TOGTE uses stacked devices and both NPN and PNP. Speaking of sand, this is a pretty sight: That's enough for a few HV's...

Going by the sugar content, that is more into cake territory...

That was too funny, 5% distortion is good enough...

The output voltage is a problem but it's just goes hand in hand with the bad engineering. This amp has a total of 6 triodes to generate a four phase output at a gain of at least 500. This really isn't enough and you would need a bunch of transformers to help out. That brings its own problems and adds to cost which could be avoided with good engineering. Not enough voltage swing, clearly very high distortion so hardly fitting for a transducer that runs at about 0.1%THD. About the simplest tube amp there is would need 8 triodes even if it was single ended only. Now the output tubes are max 300V units hence the low output voltage swing but why not use 6SN7GTB's which can take 450V and run off +600VDC? Much more voltage swing which is actually usable. As for amps for the 407, they are not the nicest sounding set Stax have ever made so even something like the 006t would work. Should help with that glaring top end.

I just bought a bunch of tubes off ebay and it was... interesting. I bought close to 100 units and many are great but some are just crap. Some are even original factory rejects...

I had 20 minutes to kill... Haven't tested it yet so hopefully soon.

This was posted on the other side, HAD AudioLab Maestral 4STAX... http://www.had-audiolab.com/products/power/maestral-4stax Has to be the crappiest name ever and that amp design also has to be the worst anybody has ever thought of. Why do all the Euro amps have to be shit?

Yup, black plate is RCA and gray is GE. I have some RCA here that are gray plate though and then we have the Japanese versions.

No subs for the 6S4A's but the amp can be redesigned to fit some other tubes if supplies run out. They are even more oddball and nobody has any use for them... Tubes have to be matched pairs but ideally matched quads of the same identical construction. The biggest difference is GE or RCA manufacture but there are a few sub groups of the different tubes. While on the subject, the KGST power supply PCB's just arrived so I'll see when I'll have the time to stuff one and test it.

Doesn't even air this year...

There are some slightly different versions of Teflon so some might work better than others. Delrin would also work well... I honestly can't remember, it's been a while since I had a 4070 here. The walls are very thin and that shape is hard to make from wood. Could be some resin filled wood though. That shape is just so awesome though, somebody really knew their electrostatic dispersion theory.

Definitely switch to stock speed and see what happens. This is normally done in bios but some motherboards (all? I stopped doing this in 2002...) can do it in Windows. Could also be a failing capacitors somewhere. Most motherboards have stopped relying so heavily on electrolytics but the PSU still has them.

Hmmm my HE90 needs a new plug... No opening and the damping is a thicker type of wool than the one found in the Sigma. The real start here though is the housing, it took real skill to design something like that.

I had a pic of it somewhere but I can't find it. Basically it's a slot cut into the edge of the baffle on both sides that tapers off a few mm from the end. The pads then partially close it.

The main reason to swap to 10M90's is that they are cheap, easy to get (well if you are in the US) and can handle far more voltage. 2SA1156 won't work here due to voltage constraints so we'd need 2SA1968. Not everybody is sitting on a few hundred of those...

Indeed though the LL is based on the older SRM-1 Mk2. As for explaining that circuit, it's about as simple as it gets.

That's excellent, well done Tyll!!

We will probably start off at 20mA but it's also a simplified KGSSHV with the last stage removed. Pretty much a solid state KGST then.

The output capacitance is still a bit too high for most of these. This one makes me a bit happier... www.cree.com/~/media/Files/Cree/Power/Data%20Sheets/C2M1000170D.PDF Special SR-009 amp using these in the works. Price didn't pan out and I didn't want to drop 7k$ on transistors in one go. I haven't stopped looking though... I did manage to score a few thousand 2SC4686A's but they are all earmarked for KGSSHV production as I was running out of parts.