My Poweramp-thougts. Need input

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Hello all DIY folks, ladies and gentlemen :)

This is my first post here, at last. I have been lurkin here for ages. Thats not normal for me. :cheeky:
I am often a contributor and have no problem with the verbal or writing in several different forums around the world. I am a big hobby enthusiast in electronics, but also genealogy and old American musclecars, among some other things. :cool:

My desire for a power amplifier which I have built myself have come up to my mind lately. I have gathered components through the years but after some extensive reading at this forum, old and new threads, several hours a day the last week :blush: , I understand that my old 4 pairs of TO3 Toshiba's, 2SB557 and 2SB427 is more or less obsolete and weak when it comes to the specs.

What I have in parts, whiches and knowledge
I have two EI transformers which I don't have data on but have measured to be something a bit over 200 VA or 58VCT@3.6A.
Four fresh electrolythics 10mF 63V. I have then about +/- 45 volt at idle and ~ +/- 40 after rectifyer and elyts.
The hardware including the cooling is no problem. I have plenty of surplus. I also want to etch my PCB for myself. I have equipment and experience but only for singlesided boards.

I have come over some ThermalTrak devises I would like to use in two pairs per cannel for this PSU's. So about 80W@8 ohm, 150W@4 ohm and maybe some current limit at 200w/channel.

What have I seen in this community?
I have read a lot of good reading and have get stucked on two designs that I want to do.
No.1 is Marshall Leach low TIM amplifier, version 4.5. When I first read about it here I faintly remembered an old article I have in a binder i our cellar. Could it be the same Mr. Leach ? Yes, I realised I had a copy of the first article from a Magazine called Audio, from 1977. I was in highscool then.I have memorys from a teacher who was sold on that amp.
Another fine "cute" project is MikeB and his Symasym 5.3 and particulary the one that evolved from the really capable authority roener at this forum. He also did a very fine singlesided Eagle layout but then... What happened? Is there anyone out there that has got one to share. I would very much like to continue with that one. Maybe MikeB knows of any further development and variants of the Symasym5.3 with the option to have two pair of ON Semiconductors ThermalTrak devises?

I would be glad for any project suggestion using two pairs of output transistors, ThermalTrak devices which will fit the PSU's I have at hand, Thank you.
Ha ha
I'm sorry
I see why I don't got any answers on this one :D

So, if I triggered some more people that doesn't bother to read it all. Your not alone. Let this thread be a learning lesson.

I'm sorry, I allways speak and think to much ... :p


Should admit that the lengthy question did surely also
beg some lengthy time....

Here we are !
In the waiting, did you find a design that fits your expectations.?....
After many turns I bought 6 PCB cards from another DIY member
It uses the nice National Instruments LME49810/11 as driver for thermalTrak devices. Why bother do do my own PCB when it's allready done as I want it? :cool: I gained some time there.:)
Those 6 amps will be the ground for my active speaker projekt.
First I thought of building my own filter but instead i bought the really good Behringer Super-X Pro CX3400 for 171$. I couldn't even buy the contacts and knobs for that price if I would build my own. :p

That project is on rest for a phono amp at the moment. I'm fiddling with the really simple but good sounding and measuring FET RIAA stage.
American muscle car

Hi jacco

I reckoned your alias as well. Didn't you fart in the 10w class A from the aussie man ... what was his alias... ? The Kleinschmidt 10A
Hmm. I just now discovered that he had disengaged his user id. That was not so funny. He was a descent good thinking idé maker of a man. ... Not good at all.:(

Anyway jacco ... are you doing any Nobel prize projects ftm. ?
Sot Fart multi-room media/music server, Knobby prize maybe.
No room for Thermaltraks though.

(modular thing, Dominican rep. made split bobby PS, balanced discrete stuff, integrated Phily cd-pro2. Something like an olive/kaleidescape/crestron mix, but much biggy. Steal much, invent little)

Ditto, still sorry he Skippy'd out.
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(it'll probably take 10 years for thermaltrak devices to become established, 10 more to see designs, which is around the time the parts turn obsolete)

You might want to have a look at the August issue of Everyday Practical Electronics, where a 200 watt amp. using Thermaltrak items is put forward as a construction project.

4Hz to 50kHz
135W into 8R
200W into 4R
Noise -122dB at 135W output
Distortion 0.001% typical.

I think you'll find many amp designs using these devices coming out much quicker than you might think.:p

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