SOZ amp general questions

[MEGA-amp]

I am in the (very slow) process of finding parts for
the SOZ amp. The recommended transistor, the IRFP244
is rated at 250V, .28 Ohm, 15 Amps, 150 W Pd.

I'd like to build this amp like a mack truck. (50
W/channel of course) I found Mosfets at
http://www.advancedpower.com/ ("power MOS V",
industrial). Would using a mosfet at say 600 V be
detrimental or does it matter, is the Ohm figure
important or can it vary? I know a higher amp rating
wouldnt hurt, is there a limit at which this matters.
Most of these mosfets are rated at 235-250 W
p-dissipation. I'd like to use the T0-3 Pkg. Is this
better or not, for heat i know it would be more
durable. I also saw a modified schematic with with 4
Mosfets per channel, each pair paralled. I am assuming
in this configuration mosfets should be matched, maybe
not. Is a different power supply recommended when
using more Mosfets in the circuit, or does the use of
more mosfets spread the load, maybe better heat
dissipation? This is my first project, so I am doing
my research, with a limited knowledge about using
substitution parts. My thought is, by using
transistors, and industrial power resistors with much
higher ratings my amp would be extremely durable, and
heat would be less of a factor in performance. I am new in DIY, and so is my knowledge on these subjects. Any info or a link in the right direction may be all that is needed.

-HEPs

[moe29]

HEPs,

If this is your first DIY attempt, i wouldn't reccomend a 50 watt
version of the SOZ. Dissipating 1200 watts of heat is no easy feat.
Not to mention the cost and size.

Look in the X-SOZ thread, on the last page you should see a picture
of my 5 watt monoblocks. That's the size heatsink you need for
just 5 watts. (11"x11")

I don't mean to be a kill joy - or to try to talk you out of building a
SOZ. Do a search on SOZ and read up, there's lots of good info on
the Forum. The Zen (1st one) or the Zen Variation - Part 4 or even a 5 to 10 watt SOZ would
be good starting points. Only because they come with excellent
articles on how to construct and have parts lists that you can fill
without having to look for replacement parts or rare parts. You
have a much better chance of finishing one of these amps and
gaining experience for your future endeavours. You can find the
construction articles for all these amps on passdiy.com

[Brian Donaldson]

If you want that kind of power, you should probibly look toward an Aleph. The active current source decreases wasted power(heat) and it's a little less sensitive to power supply ripple. And it's still a very simple circuit.
Larger, more powerful parts don't make the heat dissapation less of a concern. You'll still need to keep device temp down to a reasonable level, and that means hundreds of dollars worth of heat sink. And it's trully not possible to find enough good looking sinks surplus to dissapate 2400 w (stereo). Expect to pay around $1000.00 for enough extruded aluminum to not start a fire. (unless you want to get tricky with water cooling and use a Mack Truck's radiator!)

[B.L.]

Maybe marriage of SOZ & Aleph current source could be a solution

[Magura]

If you have the real DIY spirit, it should not be a big challenge to get the extruded aluminium nessecery for a 50 watt soz. Look around, youll find my good options at the local scrap metal yard....and im not talking bad looking ones, but simply just used ones that might look like new. Im working on a soz 25 watt myself...my cooling is found between the scrapmetal at a windmill factory :-)

Have fun

Magura