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12AU7 Starving student - Finally finished !!!

post #1 of 34
Thread Starter 

I thought I'd have a go at one of these

 

many thanks to Dsavitsk for the modified circuit

 

 

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The case is the next problem, but it sounds great so I'll worry about it later :-)

 

its nice and stable just sitting on the caps

 

anyhow

just sharing

 

cheers

FRED

post #2 of 34

heh that was quick "fred", didn't realise you were going to do it immediately when you only mentioned it yesterday!

post #3 of 34

Nice! Are the heatsinks sufficient for the amp?

 

I had gathered the parts for a point to point build for the 12AU7 version. Only thing stopping me is working out a case design to fit it in.

post #4 of 34
Thread Starter 

I had the layout pretty much sorted in my head so just a matter of laying it out so I could etch the boards this morning, I was going to make 2 at the same time but I ran out of 63v caps, I like to make all new things 2 at a time its easier to trouble shoot when things go wrong.

 

anyway this just worked no hassles

 

yes the heat sinks seem to be running about the same temp as my other SS so all good I don't think I'd like to enclose them :-)

 

cheers

FRED

post #5 of 34

What! No tube LEDs? 

Just kidding, looks good Fred. How did you attach the heatsinks? It looks like they are held in place by the mosfets. Correct?

 

I'm curious how hot the metal tabs of your mosfets get. Did you apply some thermal grease to them? When I inserted a heat transfer pad between mosfet and heatsink the heatsink temperature rose, indicating a better transfer of heat away from the mosfet.

 

For my next build I'm gonna use 2.5" tall heatsinks as the 2" tall ones in my current build get quite hot. I wouldn't even dare to use those smallish heatsinks you used.

post #6 of 34
Thread Starter 

Yes you're spot on, the heatsinks are held by the mosfets, thats why you can see fibre washers under them to insulate from the tracks.

 

My thinking was that I will have to air wire them to the outside of a case, rather than board mounted

 

I'm using IRF610's and they are good from -55 to 175 degrees C according to my home made temp probe the heatsinks are sitting on 71 degrees so certainly hot but well within specs, I'm not using any paste just a good tight fit. If I use a Hammond case I may just bolt them to the metal sides that'll keep them happy

 

cheers

FRED

post #7 of 34

Quote:

Originally Posted by Fred_fred2004 View Post

Yes you're spot on, the heatsinks are held by the mosfets, thats why you can see fibre washers under them to insulate from the tracks.

 

My thinking was that I will have to air wire them to the outside of a case, rather than board mounted

 

I'm using IRF610's and they are good from -55 to 175 degrees C according to my home made temp probe the heatsinks are sitting on 71 degrees so certainly hot but well within specs, I'm not using any paste just a good tight fit. If I use a Hammond case I may just bolt them to the metal sides that'll keep them happy

 

cheers

FRED

 

 

 

Clever thinking using fiber washers to insulate the heatsinks.

 

If you wire the heatsinks outside of the case don't forget to move the gate stopper resistors (R3 & R9) too. 

 

I'm sure the 610's can stand the heat but wow, 71°C! That's HOT!

caution_hot_surface_warning_sticker.jpg

post #8 of 34
Thread Starter 

Finally got time to case it up

 

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I tried different coloured leds, the blue gave the warmest mids so I stuck with them

 

anyhow

thanks for looking

 

cheers

FRED

post #9 of 34

lookin' good mate

post #10 of 34

thats a beautiful custom amp i'm sure it sounds as good or better than it looks

post #11 of 34

You etched the board yourself? Where did you get the lithography machine?

post #12 of 34

Hi Fred,

Would you sell 1 or 2pcs the pcb for this 12AU7 Starving student?

Anyway,your amp looks great

tommy

post #13 of 34
Thread Starter 

Hi sorry I made the boards as a one off using toner transfer, if you want to make your own I'm happy to supply the layouts

 

cheers

FRED

post #14 of 34
Quote:
Originally Posted by Fred_fred2004 View Post

Hi sorry I made the boards as a one off using toner transfer, if you want to make your own I'm happy to supply the layouts

 

cheers

FRED



Sir, this is awesome...

 

post #15 of 34

Fred, if would like to share the layout it would be superb!

 

beyersmile.png forever

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