i'm on a roll... the kgsshv

[El_Doug]

huzzah!

Thanks guys for the good words.

Thank you Doctor G for bestowing your latest SS design on me.

FINALLY! IT LIVES! OMFG I CANNOT BELIEVE IT!

After three months of blood, sweat and tears I can hear music through my Stax on my KGSSHV.

The 2SK170 sand did the trick. The +/- bias sits right on zero volts now.

I still need to do a little tweaking on the +out to ground zero bias.

Pics to follow in a few days...

[ujamerstand]

excellent!

[Spychedelic Whale]

congratz

[deepak]

Thanks guys for the good words.

Thank you Doctor G for bestowing your latest SS design on me.

FINALLY! IT LIVES! OMFG I CANNOT BELIEVE IT!

After three months of blood, sweat and tears I can hear music through my Stax on my KGSSHV.

The 2SK170 sand did the trick. The +/- bias sits right on zero volts now.

I still need to do a little tweaking on the +out to ground zero bias.

Pics to follow in a few days...

Nice, congrats!

Did you have to make any additions to this BOM:

[livewire]

Good to hear the PSU is working fine. Did you get the 2SK389s from the the guy 'tubeseller' from ebay? I got some caps from him, all are fine, not sure about other stuffs though.

I already finished populating all the boards and also done with the chassis so hopefully I could catch up with you soon.

Got a stunning looking attenuator today too

Good to hear of your progress!

I really dont remember who I bought the fake 2SK389's from.

I do remember they took six weeks to get here.

What kind off attenuator did you get?

Mine is a POS ALPS job. I intend to upgrade it in the near future.

I went the "econo route" on my build.

Plain Jane stamped chassis, I'm gonna dress it up with some bumper stickers.

The theme is "Back To The Future" as in paying homage to the orignal KGSS.

[livewire]

Nice, congrats!

Did you have to make any additions to this BOM:

That BOM is for the 500 volt version with the T2 / BHSE style external heatsinks.

I built the 450 volt version with internal heatsinks.

The BOM for it is much different and has fewer parts, but count em -> 27 heatsinks!

And yes, there are a few revisions to be made.

KG is aware of them, I dont think anything new has been posted recently.

I would be glad to proofread it when posted.

[Lil Knight]

Wow, I missed your post! Congrats! So jealous. Tomorrow is April Fool's so I hope you aren't kidding too soon

Heck, I even went with a cheaper way than yours. I'm thinking of using the Alpha pot that I got from Birgir for the build. Gonna switch to something else later but priority is to finish the amp first.

The pot I just got is Khozmo, SMD version. Got both of their versions and all I can say is perfect. The SMD one, I could say, is the baby RK50. Much, much cheaper but build quality is out of this world. This one will be in the T2 later.

They had some stupid issues back then, but now I think it's safe to buy stuffs from them. Seriously they did a great job to pull back the reputation. So far I already bought 5 attenuators from them, all arrived safe and sound.

[ujamerstand]

Woah. Looks hefty. Do you mean both series and shunt versions when you said both versions?

[livewire]

Wow, I missed your post! Congrats! So jealous. Tomorrow is April Fool's so I hope you aren't kidding too soon

Heck, I even went with a cheaper way than yours. I'm thinking of using the Alpha pot that I got from Birgir for the build. Gonna switch to something else later but priority is to finish the amp first.

The pot I just got is Khozmo, SMD version. Got both of their versions and all I can say is perfect. The SMD one, I could say, is the baby RK50. Much, much cheaper but build quality is out of this world. This one will be in the T2 later.

They had some stupid issues back then, but now I think it's safe to buy stuffs from them. Seriously they did a great job to pull back the reputation. So far I already bought 5 attenuators from them, all arrived safe and sound.

Thanks! I may be a fool for attempting KG's high voltage madness, but no April's Fools.

It's the real deal, finally.

WOW! That Khozmo looks like it could withstand a nuclear blast.

That is what I call "over-engineered". Tis a thing of beauty indeed!

[Lil Knight]

Woah. Looks hefty. Do you mean both series and shunt versions when you said both versions?

They only have the shunt now. The other one is built by Dale resistors (also has the all PRP version). Hard to say which I prefer, both are beautiful.

[kevin gilmore]

Yeah team...

I'm getting REALLY TIRED of the fake parts...

There has to be something we can do about this.

Maybe massive group buys directly from the manufacturer.

The fake 2sk389's are not a surprise.

Hey linear systems, get off your fucking ass and finally

release the lsj109's please (after 3+ years)

I'll have to clean up the bom one of these days.

Edited April 1, 2011 by kevin gilmore

[kevin gilmore]

I'm cleaning up the BOM now...

I only found one error (C9---C10)

If others know of any errors, post/PM/email please.

http://gilmore.chem.northwestern.edu/kgsshv.xlsx

Edited April 2, 2011 by kevin gilmore

[justin]

i'm interested in the Khozmo attenuators, but the unknown is how those switches are going to hold up after years of use

[morphsci]

How well has Eastern European technology held up in the past?

[Lil Knight]

i'm interested in the Khozmo attenuators, but the unknown is how those switches are going to hold up after years of use

One thing worth paying attention is that, while their pots are great, they don't have a stable design. AFAIK, they've changed the designs on both types at least 3 times.

The very first ones have PCB pins which would fit for your need but later, they no longer did that way. No idea why.

The SMD one even has more stupid design. The wires are pre-soldered to the pot and you have to make sure about the correct length before ordering. Of course you can change the length but that'd require opening the pot.

The Dale one has very stiff feeling and requires a shitload of force to turn the shaft, I couldn't make any step without using a heavy knob. The SMD, however, feels just like the DACT.

Both are huge, maybe about twice the DACT.

Oh, I forgot about the price but it'd be better to leave it to private.

[kevin gilmore]

Just noticed that if you are using the lsk389, you have to solder it in

to the bottom of the board...

The 2sK170's are fine.

I'll fix the board layout quick.

Edited April 2, 2011 by kevin gilmore

[livewire]

@KG - ygpm

[kevin gilmore]

bom errors fixed except for the transformer description

which i will have to dig up.

[livewire]

Here is a pic of the kgsshv on the bench while doing final testing.

Please note that I was doing a lot of unhooking and reconnecting of the wiring during board removal.

I do intend to clean up the wiring before casing it up.

Still need to paint the cover, then will post more pics.

[rille]

I finished the PCBs today and will start to test the amp tomorrow.

The pots at the power supply board have to be set fully counter clockwise for initial setup?

[Lil Knight]

I asked Dr Gilmore about that before. Setting the trimpot in the middle would be fine.

[livewire]

rille, looking good!

I hope all tests ok, looks like it will.

Somebody wanted to be able to read the Stax tribute on one of the amp boards?

[rille]

The boards will be mounted with a little overlap to fit in the case. So this capacitor had to be mounted at the back side.

[spritzer]

Looking at the pics I really should do the Exstata V2 treatment to the HV boards as well. So much unused space but no free time...

[rille]

No good news. The power supply makes problems. The positive rail is not working proberly. First it had a very low output voltage, ~80V. After some testing the output voltage was the same as the input voltage and two parts are defective:

D1 (zener diode 24V)

Q8 (IXYS 10M90S)

Both have a short. The other parts seem to be ok. I made a diode test at the bipolar transistors. The FQPF8N80 are not shorted. I hope there's noting else damaged.