John Curl's Blowtorch preamplifier part II

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@Scott: 815 power amp

Scott, as you can see, I completed that AD815 power amp.
Even changed the screws as per your instructions :)

Awaiting delivery of my dScope III for measurements.
But it sounds better than anything I have ever heard! :joker:

Jan
 

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Scott, as you can see, I completed that AD815 power amp.
Even changed the screws as per your instructions :)

Awaiting delivery of my dScope III for measurements.
But it sounds better than anything I have ever heard! :joker:

Jan

My goodness, I'll pass this around with the boys that remember that package! Going to be published? Possibly a good companion to Doug's mass of 5534's :D
 
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One can use multiple AD815s in parallel, as detailed in the datasheet.
On top of that, 6 of the leads are connected thermally to the die.
The do provide a path to get heat out from the die directly.

Maybe Scott can tell us whether the SOIC package has the same die size as the power package.
And what the Rthjc is from the die to the case, but also to the 8 thermal heat tabs.


Patrick
 
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To get the heat out from the thermal heat tabs, you just need to solder some copper litze (e.g. solder wick) onto each of those 8 SOIC legs closest to the case.
Then solder the other end of the litze (say 20mm long) to a cable lug.
Then screw the lugs (with as large a bolting surface as possible) directly onto a piece of copper.
The copper can be say 20x30x2mm.
This can then be bolted onto the heat sink through proper electrical insulation.
(I believe the thermal pads are connected to +Vs.)


Patrick
 
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Octo says 21k+ at Rochester.
$11 for 1-100, $9.50 for <1000, $8.30/pc for 1000 and up.

I probably still have a few tubes somewhere, and yes Rochester is our official discontinued part distributor so they are real.

I think it was Bonsai that found someone selling parts removed from service, which considering the package are very hard to fake.

There is only one die so the DIP is the same part with the heat spreading pads directly connected to the paddle. It is hard to get at the real thermal numbers because JEDEC standards don't allow you to add any cleverness when you characterize the thermal performance.
 
If you would tell me the die size in mm2, I can estimate the Rth to the legs.
Small legs though, since package is unfortunately SOIC and not DIP.
Rthjc can be rough guessed using numbers from other SOIC24 packages .....


Patrick

I'll have to get that from the databank at work. I think I mentioned this before our cost on the big package was $0.95 way out of line with current costs.

EDIT - This part is junction isolated, in this case the back of the die is/must be connected to Vcc.
 
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AX tech editor
Joined 2002
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If you would tell me the die size in mm2, I can estimate the Rth to the legs.
Small legs though, since package is unfortunately SOIC and not DIP.
Rthjc can be rough guessed using numbers from other SOIC24 packages .....


Patrick

You can probably find some ground cables with a lug and a flatcable the same width as the 4 pin spread.

Jan
 
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