Zen V-4

[microwalsh8504]

After reading the pdf file on the Zen varation part 4 I saw it was possible to get 100watts a channel. Is the possible? Has anyone done it? What changes would you need to make to achieve this rating?

thanks,
Mitchell

[breguetphile]

You'll need some even beefier heatsinks than are already required. Its only a 2.2dB difference so I would make sure its worth the extra $$ invested in power supply and thermal dissipation.

[microwalsh8504]

I have been looking into different varities of heatsinks and I came apon a company called Conrad Heatsinks. Has anyone gotten heatsinks from them. Have they perfromed well?
I found one i may be interesetd in. Would one of these heatsinks be able to dissipate the power of one channel? Do you need a heat sink for the transformer?

here is some info on the heat sink.

http://www.conradheatsinks.com/products/single_f.html



Thanks!

[crown300]

Zen V4, page 4, bottom right;

"about .3 deg C./watt".

Those heat sinks you show above are .78 deg C./watt. This means they are to small to get rid of the heat a normal Zen4 would produce.

I would prefer (for a stock Z4) the MF-35-100 with its .28, however please note that it will still get 80 degrees C above room temp - that means you could fry eggs on it.
(to get a sample of the heat problem, find a 100 Watt light bulb in your house).
My Z4 is awaiting the solution to its heat sink problem. Currently I run two small sinks with a fan on them, but this will overheat after a while.
Don't give up, you are on a steep learning curve!

[crown300]

microwalsh8504, I just noticed this, click over to www.passdiy.com and look at the "Gallery" of units others have built for an idea of the heat sink sizing.

I noticed this from one Z4 builder:

"heatsinks measures 400*180*40mm 40 fins, and dissipate 150W each with the temperature that doesn't rise over 55°C."

My caculator says that is 15"x7" in size.

[Nelson Pass]

Originally posted by microwalsh8504
After reading the pdf file on the Zen varation part 4 I saw it was possible to get 100watts a channel. Is the possible? Has anyone done it? What changes would you need to make to achieve this rating?

It's possible, but not for the faint-of-heart. I recommend not
only tons of heat sinking, but that you think of beefier transistors
such as the IRFP250, which has lots more die area and a higher
wattage rating.

While there is no theoretical limit to the power you could get,
it will be easier (and better performing) if you think also in terms
of bridging (or balancing, if you will) two such circuits.

[ThomasLMcLean]

The link to Conrad heat sinks is interesting. They list a model MF30-151.5 with a thermal rating of 0.25 C/W @ 80 deg. C. In their technical data they provide a correction curve that allows the 80 deg. C rating to be corrected to the more commonly used 50 deg C rating. This comes out to be 0.30, the rating recommended in the original article for the Zen V4.

Using the math and examples from the 1999 ARRL Handbook, the voltage and current values from Passes article, and thermal resistance ratings from the IRFP044N data sheet; the junction to case temperature for the hottest transistor (Q1) should be below 125 deg C. This is an acceptable continuous duty value.

The Conrad MF30-151.5 heat sink is about 6 in by 12 inches. Using a pair of them it should be possible to build a 50 watt balanced mono amp in a 12 by 12 by 8 inch box.

50 watts,
Low distortion – less then 1 %
Balanced input
Small ~ ½ cubic foot
Tube like sound from solid state hardware

SWEET!

Build four and bi-amp. for 100 watts a channel. Add a BOSOZ and a hi – low pass and you will have a system that can not be beaten.

[relder]

Can't remember the exact model I have, but here's some Conrad's on my Aleph 30:

YAA! (Yet Another Aleph) Complete

Nicely made and look good, if you can deal with the shipping charges from down under. I got mine in a group buy a year and a half ago.

[ThomasLMcLean]

Relder:

A very nice looking amphlier. The heat sinks look like Conrads model MF30-2F-151.5, also rated at 0.25 C/W (80 deg. C). You could have moved one of the transistors to the lower rail for a little better heat distrabution.

How hot does your amp run?