Krell KSA 100mkII Clone

[Mark A. Gulbrandsen]

How about this heatsink for the driver stage?

Mark

[jacco vermeulen]

Stuart,

A typo i think, you probably mean the NAD 3020.
Which was a NAD highlight, the 4020 was a tuner model afaik.
(3020-3020A-3020B-3020i)

I recall reading in those days about a NAD Integrated being hooked to Apogees, that must have been you.

Nice heatsink profile, volume were it is supposed to be.
(btw, i've just ordered a pair of aluminium fluid coolers for a Scuba Krell)

[grimberg]

Originally posted by Mark A. Gulbrandsen
How about this heatsink for the driver stage?

Mark

Looks good! I just bought one like this from Steve and am about to slice it and dice it to make four heatsinks out of it; 2 for the KSA-50 and 2 for the KSA-100.
Do you need help with the group purchase for the ThermaFlo? Or are you still researching the best option? I could save this one for some other project.

[Stuart Easson]

The heatsink looks ideal...

Jacco, you're probably right about the model number being wrong, though I still have the NAD piece, and it's definitely not the 3020, which, IIRC was an integrated amp, this is a reciever...4030 perhaps...

Oh well not important really...just don't trust those companies that use labels instead of transistors...but I'm obviously preaching to the choir here...as if any of you guys would consider skimping on transistors...

Intel makes very limited edition extreme edition processors for nut case game players, can we get on-semi to make their to3 parts in oxygen free copper cases? Silver/gold plated perhaps? is there a special grade of epoxy we ought to be asking for when we order to247 parts?

On a different note: How come the legs on a to3 stick out of the heat dissipating side of the case, if the idiots put them on the other side the heat transfer capabilities of the case would be enhanced, and it would be a million (approx.) times easier to mount as well...or is it just me?

Stuart

[acenovelty]

Hi Stuart,
How about making them out of this stuff?

500ºF Thermally Conductive Epoxies from:

http://cotronics.com/vo/cotr/ea_thermallyconductive.htm

"a million (approx.) times easier to mount as well...or is it just me?",
Nope, a few of us wonder the same thing.

[AndrewT]

Originally posted by Stuart Easson
The heatsink looks ideal...


On a different note: How come the legs on a to3 stick out of the heat dissipating side of the case, if the idiots put them on the other side the heat transfer capabilities of the case would be enhanced, and it would be a million (approx.) times easier to mount as well...

If the PCB is placed "side up" rather than "end up" the sink would be even better.

Stuart,
try cutting the silly legs off, then you can bolt them down onto a flat sufaced heatsink.

I bet they will run cooler that way!

[Stuart Easson]

...literally and figuratively...

I'm done bolting transistors, I'm going to stick them on the heatsinks with solidifying heat conductive goop, just clamp them until the stuff sets and voila...I've always hated drilling and tapping aluminum, has anyone actually used this stuff, does it work as implied/advertised?

If they used this to encapsulate the transistors we could use heatsinks on both sides of the plastic packages, I'd guess it would help the overall thermal capacity of the package.

Stuart

[acenovelty]

Yup, works as advertised. Requires only 3- 5 mil to bond. Slight pressure with about 250 degrees in your oven improves the bond on some versions of the epoxy. Doesn't come off easily, so placement is critical, and when the transistor lets out the magic smoke..........

HTH

[Mark A. Gulbrandsen]

Zobel Network??? Went back through and could not find the values... The older 1983 schematic calls for 5.6 ohms and 1uf in series... does anyone know if this is correct for the MK-2 version of the amp. 1 uf seems a bit high to me..... What ever it is I will post it in the WIKI.

Thanks!
Mark

[PWatts]

I've posted the zobel values twice on this thread so far: 100nF and 5R6.

Those wanting to imitate the original closely (for whatever reason), the resistor is a Dale 5W and the capacitor a Philips MKT (those orange ones) in the Mk1 and some green-looking thing (perhaps Mylar, it's enshrouded in heatshrink) in the Mk2.