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A DIY electrostatic amp for intermediate DIYers?

Jan 31, 2009 at 3:25 AM Post #16 of 593
Quote:

Originally Posted by DKJones96 /img/forum/go_quote.gif
I've always wondered about using microwave transformers for the ESL amp, they have the turn ratio required just not sure if they meet any of the other specs, plus, they'd be cheap(or even free).


Microwave transformers are horrible horrible iron, bad core, and definitely not built for 100% duty cycle.
 
Jan 31, 2009 at 3:47 AM Post #17 of 593
Yes, but Pabbi, you arnt looking at an arrangement that could be considered normal or intermediate level.
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Would probably be best for any group buy to have at least PCBs and LSK389, everything else is pretty straightforward. Maybe a custom transformer too. KGSS could be done with two off the shelf, but I will probably be getting a custom for mine, just so I dont have to use two separates. Allocating $100 for the transformer and $20 for the PCB, I think I figured about $50 for the parts needed to stuff the PCBs once, so all transistors, resistors, and capacitors. Should come in around $300 or so for a normal build done with a group buy, including a decent, but not excessive, case. More if people want fancy things like stepped attenuators.
 
Jan 31, 2009 at 5:41 AM Post #18 of 593
Well, looking at the KGSS parts, the 2SC380 is nominally available, but newark (really MCM) only has 53 of them. I don't immediately see another reputable dealer. bdent doesn't have any.

bdent has the 2SA1156 "in stock" and nobody else does.

2SC3675 is in short supply at newark (60ish). bdent seems to have a good supply at $1.66 each.

So if we go with the KGSS as it existed in 2000, I think that bundling a full complement of transistors along with the board is a very good idea. I'm certainly not opposed to it, but it means that we would need buy-in from someone like glass jar audio to really pull it off.

Don't get me wrong, I'd love to build a KGSS. But if we're talking about a hundred people building a KGSS at the same time, some parts are going to be in short supply
 
Jan 31, 2009 at 6:01 AM Post #19 of 593
2sc380 isnt on the KGSS schematic anywhere; I have no idea why KG even mentioned it in the writeup. Seems BDent only has 197 of the 2SA1156, though this part should be fairly easy to sub. The 2SC3675 is the only part that gets kind of tricky. BDent only shows having 226 of them.
 
Jan 31, 2009 at 9:58 AM Post #20 of 593
woa, that can be some nice project. I've been looking into DIY for an amp for my HE60's (which will arrive in a month or two for sennheiser).

the only question now is are there any people here who have the skills, time, and will to put this thing together
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Jan 31, 2009 at 12:31 PM Post #21 of 593
A KGSS would be nice to build but parts are a problem so an all tube amp would probably be better all round. Then there wouldn't be a problem with heatsinks and we could use some very cheap tubes which are in ample supply.

As for transformers there are those R-cores on ebay and many other places. I got some recently and they are very nice quality and some even have two 0-xxxv windings which would suit us. Most have filament windings but for a two stage amp we would need two separate windings which could be a problem.

The PSU could be something simple (R-C network) or something along the lines of the Gilmore designs. I'm going to be testing a cheaper sub to the 2SA1968 soon so that made the PSU a whole lot cheaper to build. That said, the 450v capacitors aren't cheap but what can you do...

We could also always just wire it P-P like this:
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It would have been much neater if I had been able to buy all the parts I wanted to use but I promised my self to use the cheapest stuff I could find locally.
 
Jan 31, 2009 at 2:09 PM Post #22 of 593
Interesting Idea. My final goal is to build my own bh or kgss so if this is ends up as a group buy i'm in. Strangely enough i was talking recently about parts on the Stax thread and the idea of a full tube design would be interesting. I'm a long way from an expert but i would help in any way i able to.
 
Jan 31, 2009 at 4:08 PM Post #23 of 593
I really like the idea!
My DIY skills are quite limited though. But may be willing to give it a go...
 
Jan 31, 2009 at 9:10 PM Post #27 of 593
I am in full support of this idea. I really like the idea of being multiple bias. I love my sr-lambdas, but finding the good amps is a pain. and I would love to be able to have some pro cans as well as maybe some koss? my diy skills are non existent, but I'll get practicing so I can be ready.
 
Jan 31, 2009 at 9:26 PM Post #29 of 593
Quote:

Originally Posted by TimmyMac /img/forum/go_quote.gif
Does anyone have approx build costs for the KGSS and KGBH?


There is no way to put a figure on that as no two amps are alike. The BH I'm working on will probably be less then 1.2k$ all in all and then there is the cheaper version I'm also trying.
 
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