spritzer

Nothing wrong with AC coupling....

Yeah, pretty much any bipolar PSU will do.

Yup I have some prototype boards for sale.

They were anodized.

While the tubes will get hot it's above the caps so they won't see too much heat. Electrolytic caps are rated to 85-105°C but film caps can take way more than that.

Here is what I've been doing for the last day or so when time allowed... This one has the tubes mounted on top of the board to make building and testing far easier. This version uses the old KGSSHV transistors and works with both the fancy teflon tube sockets and the standard ceramic/plastic stuff. This gives the added benefit of extra holes to cool the tubes. Boards are 4.7" x 4.7" and as soon as we are happy I'll order some prototypes.

Sadly it's all the electrostatic amps eating up my time. This will be finished at some point though...

It does drive them quite well.

They are nice for the price but nowhere near the US/Euro milspec stuff.

They dry out simply sitting there. ...and on that note I'm so going to put my Black Gate stash on ebay soon.

Marc drew it up (or had it drawn up, can't remember) back in the day and it's basically the front end off the SRM-007t coupled to a CCS loaded quad of 6S4A's. I modified the boards to turn them into a KGST so just one tube per phase and a simple 10M90 ccs. Works well enough but I'll probably put the boards back on a shelf in favor of the ones I'm designing now. This is a part of larger move to possibly make a limited run of KGST amps. A couple of friends have been asking for a mini Blue Hawaii that would be as slim as is possible for desktop use. The KGST is the most logical circuit for that and it would be fun to do a custom chassis with some over the top PSU design in a separate box. The design is pretty much ready in my head but I simply need to find some time to invest in it and see if any of this can be done locally for me. None of this would be cheap though but that's hardly the point when making something cool...

Happy Birthday Nate!!

That's odd behavior but don't mess with the dust covers. Damage them and the drivers are totaled... The most plausible explanation would be the charge leaking to the stators which stops when you force the parts. Could also be a cable issue or the contacts inside the earcups.

Yup, normal drift and warm up found in all circuits.

Can you get those amps to make some sound? Sure but it will sound like shit for obvious reasons. A further point that eric is not well in the head, he's running the 009 single ended... Even if the - stator is grounded then the THD is still orders of magnitude higher than when driven push-pull.

That's quite sad. Some crazy ideas from him which I do like.

You can just order some for yourself. I have plenty of the older style PSU boards for sale though.

I just like it that somebody uses a Lambda at the lowest setting. For me they are snug at max...

The -430V is generated on the psu board by stacking a TL783 supply "underneath" the -400V supply. No need to cascode the 10M90's, single units per tube are just fine. Heaters can just be left floating or take a voltage divider from the B- line. Stax tied the heater directly to the B- line in the T2 so that would work here too. That chassis is similar to what I'm using for the small KGSSHV and they are nice to work with. The umbilical connector can be something like this: http://www.ebay.com/itm/1-Military-Gold-10-Pin-Twist-Male-Female-Connector-M10P-/300562711241?pt=LH_DefaultDomain_0&hash=item45faef02c9 Been using them for years and there is also a female version. You can also just generate the normal bias from the B+ inside the amp chassis via a voltage divider.

That's what I'm doing and why I might thin the Mk1 heard a bit.

My only problem is the cost...

Any Lambda would be a small incremental upgrade or a simple change of flavor but I'd hold out for a 007. Something I just found in storage, my modified KingSound M-10: Whole bass boost BS removed, RK27 installed instead, crap sand cast "plate" resistors replaced with Kiwame Carbon units, output caps upgraded and installed some heatsinks with some thermally conductive epoxy. Far better now but still not a good amplifier...

No need for that, just measure before the ballast resistor i.e. the resistor next to the bias output.

Happy Birthday!!!

Ditto what Kevin said and it is perfectly fine to have the amp "playing" when testing it.