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I am starting this thread for all that are or will be building JoaMat's mini T2 to share information, ideas, thoughts and experiences. The attached schematic is an updated one .The resistors in the BOM are thick film ones and can be replaced with thin film ones for likely better outcome. The power supply requirements for this amp are +400VDC, -460VDC (EL34 output stage), +220VDC (6922/6DJ8 front end), +15VDC, -15VDC (servo, cathode current source) and 6.3V filament supplies for the 6922/6DJ8 and EL34 tubes that can either be AC or DC. I also plan to use the +15VDC for the CPC1117N high tension delay. EDIT (Feb. 2020): updated schematic and BOM (Thanks JoaMat!) Note: PCBs pictured below are of older version. miniT2 v22 schematic.PDF miniT2 v22 BOM -Date_2020-02-16.xlsx

Sri Lankan Curry. Prep. Results

An imposing site that is...

Board size 160mm x 100mm. Sure it's possible to shrink it, but that will be the micro T2, then we have nano, pico ….. Thinking about the possibility to use an unmodified T2 PSU. If applying +250V instead of +220V you get +79V at upper 6922’s grid and +230V at anode (with no changes on the board). T2 has +69V resp. +200V. Power at HN4A51J goes up from 2 x 76mW to 2 x 87mW, so still OK I think. Question is if the higher tube voltages make any difference. But I don’t think it’s wise to put 48V cross HN4A51J when bringing down anode voltage to +200V (with +250V supply). As for +/-500V; no problem with 01N100D it’s a 1000V device. I do think it might be possible to use original DIY T2 PSU. Has to be proven.

OK – Connected an unmodified T2 PSU. Raised voltages to +250 and +/-500V. Top 6922 anode voltage sits at 227V and grid at 78V. So far it works. Will run this for a while and check for darkening spots on the boards.

Here's a pic of the 35mm multioutput boards I had run. DImensions are 116 x 107mm, with the mounting holes on 106 x 97mm centers. On Semi schottky rectifiers, 30mm caps installed. I'm working on shrinking this down to match the size and mounting pattern of Kevin's boards (110 x 93 with mtg. holes 100 x 83), and so far it looks good, though I'll probably have to lose the following: power LED and resistors the current board allows 220uf caps that are 18mm diam. with 7.5mm lead spacing in the upper corners. Not sure what cap was the target here, as a Silmic is 12.5mm d x 5mm ls (for 35V). This will shrink to Silmic size (though I don't use them). This doesn't have the rail balance pot and stuff on it (to equalize the +/- rails). I'll take a look at that and see if it would fit. I'll probably ditch the 1uf film caps following the main filter caps. Not sure they are really of any benefit. These boards do support R-C snubbers. You could also do Mark Johnson's (diyaudio-Quasimodo thread) favored R-C-R snubber by soldering the 0.01uf film caps across the 2 AC inputs on the bottom. I may try to accommodate these on the board itself.

Phew. I need to maintain a solid role model/mentor for my retirement goals.

TIL: Hard Rock Cafes are still a thing. At a Nirvana Tribute Band double feature to celebrate Kur(d)t Cobain's birthday. It's what you do when you're in Seattle and not from Seattle, right?

Test Tone @ Home live right now: http://mixlr.com/illuminator/chat

Ooh that's big news! I liked being co-gentlemen of leisure though. Might pout.

They don't need to know that, do they? You are still of counsel in certain matters one assumes?

I had the same thought Kerry! ?

I have to appear in two weeks. As a litigator, I never get selected but we shall see how it goes when I am not gainfully employed...

Bought a 2465A... hopefully its a good one. https://www.ebay.com/itm/183692541596 This was the one I was originally going to buy https://www.ebay.com/itm/TEKTRONIX-2465A-350MHz-OSCILLOSCOPE-TUBE-AUDIO/283374991066?epid=96991967&hash=item41fa7736da:g:jGYAAOSw~TNcP5sP

just arrived! going to be comparing the S3000 Pro and Airpulse A100 against my current S2000 Pro for the computer system

I'm thinking that the Brooklyn Bridge, a hard drive and my ATC speakers would make a hell of a system. I also think it is kind of amazing that they include a phono stage if you want to mix in some old school.

Received my mini T2 and CFA PCBs from mwl168 this morning. These are excellent quality! Many thanks to Michael and Joachim!

Happy Birthday, Dan!

Happy Belated birthday Dan! Got you on time on Facebook though

I don’t really want to make any comments on how things sound and compare them. Mainly because it makes me feel uncomfortable and I also lack the ability to analyze the sound. Anyhow I’m very happy with “mini T2” and I want to think that it is quite similar to THE DIY T2. Now I have put the original DIY T2 in the closet and I don’t miss it. I still have my modified T2 in our summer cottage and I like that one as much as the “mini T2”. But I have three more original T2 boards and all sands for them – no duck feeding the next couple of years.

Happy Birthday Dan!

Happy Birthday, Dan!

After two days of voir dire they seated a jury and I am not on it! Yaaaaaas! Jury duty... really interesting and fun to do once, after that, pass!

Happy Birthday Dan! Best wishes roast master!

Thanks for this thread. I have been working on my ES1 for a while now -- learning a lot. I have been using this old HP at work (HP spun off -> Agilent spun off -> Keysight) (I now work for Keysight). It seem like a solid scope (more than I need for sure). I maybe doing scope shopping in the future. I am trying to talk them into letting me take this home...

Breakfast. Egg Hopper https://www.atlasobscura.com/foods/egg-hoppers-appam Bacon, Baked Beans It's like The Empire never left!

a new favorite emerges...DACs are just better when they're wireless

Family trip to Hamilton. Better late than never!

ok that took me a minute i send my shipments of parts to the anodizer one color at a time as that's the only way it doesn't get messed up