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stax t8000 clone (well sorta)

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If dual tube input. One tube as upper device and the other as lower like T2 or one tube each side?

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  • Now with top plate.     Aerial view, the two holes in front of outer small tubes are for balance trimmers. Adjust balance after some time of warm up and then insert jumpers for the ser

  • kevin gilmore
    kevin gilmore

    Well its not like the stax mafia aren't busy and we certainly are not going to do an output stage with 8ma of current, and therefore no reason for a 4 stage amp, and since tube inputs seem to be

  • kevin gilmore
    kevin gilmore

    using Kerry's servo, but a resistor to make +200 by the way the alternate name of this board will be t8000DR   (DR as in done right) edit: fixed font sizes      

Posted Images

I wanted to compare the dual input tubes (like in the T2) against the single. I'd build the dual first first though.

  • Author

one comment about the tubes, have tried many tubes on testbench, 12au7,12ax7,12at7,7308 etc

you need a mu of at least 33 and a transconductance of at least 12500

 

  • 1 month later...

Anyone about to build this, Megatron, etc and don't want to use a dropping resistor, I might have some spare power supply boards for tube front ends soon. O0 Works up to 250V no problem, 300V is possible if you find caps that fit and heatsink appropriate parts properly.

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  • 1 month later...

How come T8000 fires is slowly fading away ? We need more fuels ?

29 minutes ago, mwl168 said:

Where  was the fire?

+1

Sounds like the consensus was t-POS...


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56 minutes ago, Pars said:

Sounds like the consensus was t-POS...


Sent from my iPhone using Tapatalk

What ? T-Perfected-Over-Standard ? JK, but that is sad....we need Stax to be serious again

Edited by Whitigir

i'm mostly just waiting for the version with ss output and tube ccs

  • 1 month later...
On ‎2017‎-‎07‎-‎06 at 7:26 PM, kevin gilmore said:

power jumper block cleaned of all the epoxy

j1,j3,j4 for 100v remove all others

j2 j3 j5 for 120v remove all others

j5,j6 for 240v remove all others

and servo board pictures, unnecessarily complex

tube rollers are going to have a lot of trouble with this, the servo has a pretty limited range, and the Russian similar's definitely will not work

 

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How to make the servo less complex?

  • Author

servo attaches directly to the plate of the tube. similar to T2. no way to make less complex.

Moving the servo to the cathode would that be a good idea?

 

  • Author

better idea would be to use the servo from the kgsshv-carbon

but does not compensate for the tube drifting section to section

 

  • 4 months later...

Draft of dual 6922 input (similar to T2 input), with current tunnel (as Carbon etc.)

5ae8d5fd7f151_T2-Input-15Vcurrenttunnel.thumb.jpg.2cc8c10b940b89de836b64474994a1ce.jpg

Voltage cross 2sa1486 580V and 700mW of heat.

  • 3 months later...

Trying to use the above draft in a board layout. The print out is roughly a quarter of the original DIY T2 board in size. Output section reminds of T2 less unnecessary parts.:peter:   This is progressing very slowly and I’m thinking it might go into trash can before it gets to the CNC router. Hmm..  probably trash can.

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More paper work. Width incl. heat sinks 9.5in and length 7.9in. No angel brackets sands mounted direct on heat sinks, saves 1.6in.

  IMG_0187.thumb.JPG.6f653df93c7583ab3b58ba123c877c0b.JPG   IMG_0189.thumb.JPG.18d12330c24f8002fa71e1cfcae7b72b.JPG

 

I like it, you are going in the other direction from the original T2, small amp chassis and a huge PSU. 

Very nice Joachim!

With the micro golden reference HV power supplies (which do work very nicely) and lower voltage (less caps) you could get the power supply size down a bit as well :) 

Thanks.

Yep, your micro power supplies are very interesting. My idea is to make a PSU with +/-15V, +220V, +400V and -460V.

Shooting from the hip - how about producing 580V (BIAS) by GRHV? 

All components are now on the right channel board. More work is to be done but so far it has gone quite nice.

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bottom.thumb.JPG.bb233ec0f6454fd842b9950f14b36806.JPG

By the way, I think I've learned netlisting and I love it - tells me when I'm out of track.

Netlisting is even better if we were ever to bother with schematics...which we never do.  ;D

 

29 minutes ago, spritzer said:

Netlisting is even better if we were ever to bother with schematics...which we never do.  ;D

You guys have it in you - the schematic in your heads. I’ve no head and therefor I use schematic which I derive from your layouts    hihihihi

Edited by JoaMat

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