Peter's TO220/47 Insulator Question

[roddyama]

Hi Peter,

Now that you've had a chance to live with the TO220/47 insulators for a while, I'm wondering what your thought are on them. Do they transfer heat as well as you expected?

 

[Peter Daniel]

Is that regarding berylium/aluminum oxide type?

 

[roddyama]

I believe those are the ones. I thinking of the ones you (and I, and others) waited so long for. They were the individual thick white little stiff rectangles.

 

[Peter Daniel]

Well, I didn't use them much in class A amps (or maybe the other way). But they work very well in GC. I think those pads are very good and I will use them again if building another "big" amp.

I can only confirm that silicone impregnated pads (Silpads?) work very well, as I had them in my amps for at least 10 years without any problem. Those thick aluminum washers didn't see much of the heavy use, but I believe they will be fine.

They are nice to work with, the chances of short circuit are practically none, they reduce capacitance between device and heatsink and their thermal resistance is very low.

I also have some small stock of berylium washers for personal use and I think those are even better

 

[roddyama]

I plan on using them for my bridge rectifiers. I'll have to mount 16 of the MUR1560's for two Aleph5 (or mid-powered AlephX) monoblocks. I haven't decided which way to go yet. I have the parts for either.

Thanks,

 

[Peter Daniel]

For bridge rectifiers those are perfect. As to which Aleph to built, it's a tough call. What makes me wonder is why Pass Labs used Alephs in Rushmore and X only in subwoofer. It couldn't be only because of the PS rails matching

It is also probably dependant on power rating. If you want to built big amp, maybe Aleph X is a ticket, but for smaller amp, regular Aleph might be a more appropriate choice?

 

[BrianGT]

I am using them for my version of the Mini-A that I started working on this evening. The interesting fact is that 4 of these pcbs would fit in the size of one of my original Aleph pcbs. (2"x3" size)

--
Brian

 

[roddyama]

The interesting fact is that 4 of these pcbs would fit in the size of one of my original Aleph pcbs. (2"x3" size)

--
Brian

Brian,

Have you been holding out on us? Where did that board come from?

 

[BrianGT]

Brian,

Have you been holding out on us? Where did that board come from?

I made the layout one night a while back, after seeing another one on the forum. I wanted to try an SMD diy project, and it was fun so far. I managed to fit the pcb for it on the cdpro2 pcb:
http://brian.darg.net/cdpro2-pcb2

Look at the middle, and you can see the little board.

I doubt that many are interested in a SMD board, since it takes more patience to stuff. I also haven't matched the devices for the input stage (see above the board and you will see my matching board, with the plan to clamp the SMD IRF9610S devices to it for testing), so I am getting more DC offset than expected.

--
Brian

 

[roddyama]

What makes me wonder is why Pass Labs used Alephs in Rushmore and X only in subwoofer. It couldn't be only because of the PS rails matching

I kind of thought it was that the small Alephs were getting less then top reviews in the bass region.

I made the layout one night a while back, after seeing another one on the forum. I wanted to try an SMD diy project, and it was fun so far.

Now that you mention it, I do seem to remember you posting that thought.

I doubt that many are interested in a SMD board, since it takes more patience to stuff.

You're probably right in general, and I sure you're right WRT me. I just wanted to give you a hard time about it.

 

[BrianGT]

Rodd (and others),

I posted more pictures to the original thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=20912

This is actually the first Aleph amplifier that I actually finished to the point of working. I have a couple of pairs of stuffed board that I made a long time ago, but I never got around to hooking up the output devices.

It sure is easier to test the amplfifier when it draws little enough current to run on a bench supply, and this is probably the only Aleph that can run on the bench supplies that I have access to. It is nice to be able to limit the current to 1A... (in case of a failed smoke test)

--
Brian