JoaMat
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Posts posted by JoaMat
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On 11/20/2022 at 11:40 PM, kevin gilmore said:
a pre turkey day new year teaser.
sanken output transistors, in parallel.
with appropriate switching power supplies, capable of about 25 amperes.
can be built with 30v, 35v, 40v power supplies
if you change out the pzta06/pzta56 with bf722/bf723 then you can go up to 60v supplies.
with 40v supplies and big enough heatsinks, 100 watts rms into 8 ohms.
lets see how much joamat can shrink this one.
balanced output impedance, .5 ohm
I give up, can’t find a way to significantly shrink it.
But this one has four pair output transistor each channel. BIAS servo controlled. Flat on Modushop 300mm x 80 mm heat sink. Project name is CFA3 smd something X4.
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Audiotailor “Jade” something. Current sources, surface mounted components and ordinary films and electrolytics in signal path.
Board size just within 100 mm X 100 mm. Then I get 10 boards for only 4.90 dollars. Shipping cost to Sweden is the “heavy” burden.
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2 hours ago, Satyrnine said:
The normally-closed cpc1117N relay is left unpowered, which should be "on" state... right?
With cpc117n unpowered D1/C4 are put offside and nothing out from Q3 is expected (I think). Power the relay or remove it and see what happens.
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mini T2 one channel lsk389 replacing 6DJ8/6922. Still on drawing table.
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Happy Birthday!
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7 hours ago, mrjayviper said:
can someone please share the link to the schematics/documents? I think it's a good drive link but I cannot find this link. Thank you.
look here
https://drive.google.com/drive/folders/1r3g2TAtBUaBdiMorTWX7yYgeJ7maQbYW?usp=sharing
https://drive.google.com/drive/folders/152thxfZafBmisG0CKCv6X82V-Ch9TjMH?usp=sharinglots of good stuff
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Run out of k216/j79? Go TTA004B and TTC004B. To my knowledge half a dozen T2 with “modern” components including TTx004B have been built in Sweden and owners/users seem to like them.
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Great! When the RIP MY T2 was announced, I said to myself - James will have a new T2 ready in 10 to 14 days…
Now only three days has elapsed. No rush, James.
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Happy Birthday!
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Happy Birthday, Antonio!
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On 4/15/2023 at 1:04 AM, JoaMat said:
DIY T2 amplifier with 300B tubes.
Amplifier is built on Kevin’s board. Only modification is decreased high voltages, +/-400V instead of +/-500V.
Homemade 300B to EL34 adapters connected to four Traco 5V switched PS for filament power.
I only replaced the EL34 with 300B along with the filament power supply. No other adjustments. It works – I’m in no harry to change back to EL34.
Have used the 300B tubes with DIY T2 for three months now. First two months with an amplifier with all original transistors and the last month with an all-modern transistors’ amplifier.
Only issue so far is a failed small solid-state relay in filament supply. Otherwise, I find the DIY T2/300B pleasant.
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A wise person once told me - the only sure thing is that it is uncertain (google translated from Swedish).
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On 5/23/2023 at 12:10 PM, audiostar said:
Exactly because of their physical properties and being so thin, I wouldn‘t even think in using them in HV environments with naked tabs and inox bolts. Heck, I am not using them at all, especially if space permits it.
Frst comments were already regarding those silicon insulators! Just no way one can tighten up the sands to specs at around 8-9 Nm with those without some damage .
21 hours ago, n_maher said:As far as I understand it the cm is just centimeters vs. meters so you metric folks should be well equipped to move decimal places accordingly. There should be 100 Ncms per Nm.
My torque setting of 82 Ncm equals to 0.82 Nm, or?
Upper post’s 8-9 Nm must equal to 800-900 Ncm
This link is very handy. https://www.convertunits.com/from/N-cm/to/N-m 😉
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On 3/11/2021 at 11:15 AM, JoaMat said:
Be aware. Recommended torque for 10PPSG is 0.565Nm to 0.678Nm. See attached Page from Aavid-Board-Level-Heatsinks-Catalog-2018-1507171.pdf for reference.
I use this setting
...and I don’t know how to convert Ncm from Nm 😢
Used above setting for a long time and haven't had any issues so far – knock on wood.
Also, in JoaMat kitchen we don’t use any kind of thermal compound...
, but we use 
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I believe the space around the rectifiers makes it risk free to use the uninsulated version on the original Kevin T2 PSU board.
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Maybe already posted… anyhow, it’s what I’m listening to right now.
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Happy Birthday, José!
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Happy Birthday, Birgir!
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Happy Birthday!
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Happy Birthday!
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Happy Birthday, Kerry!
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New T2 - great @s_r
Remote diagnosis is not easy… but the dark LED in red circle – is it dead or wrong orientation? Diode test might give some answer.
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They do sell as spare parts. You just have to dig deep enough. Click this link and scroll down till you find side panels 1/2/3/4 U and lengths of 170/230/280/350 mm.
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, but we use 
The ultimate DIY? A Stax SRM-T2!
in Do It Yourself
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Only positive voltage is expected to change.
Set voltage cross 22K resistor to 6.5V and don’t change that unless a good reason. Battery voltage of 740V is mostly a good value. But if 748V works be happy.