SOZ Temperature

[PedroPO]

Question about SOZ operation temperature:

I built SOZ with the following:

-230V~25-0-25V 600VA toroidal transformer;
-2 x 150000uF Capacitors;
-there is 30.0V+30.0V DC on the capacitor terminals after the circuit is on


I used a 375 x 200 mm Aluminium heatsink from alutronic (PR170) per channel,
and greased all the components including the resistors that are rated at 50W

The temperature at the heatsink after 30mins of operation is about 100ºC!!!

What do you guys think of this?

Will it burn up in a couple of hours? days?

Thanks

Pedro Oliveira
pedropo@mail.telepac.pt

[PassFan]

Pedro:
If you are using only one of these heatsinks you need about three more. Realisticaly you should be able to touch your heatsinks. At 100 deg. C you should be able to cook food on them, forget about touching them. Are they turning red when their hot? I built the same rating that you've got and with the heatsinking that I used my amps weighed in at 45 lbs. apiece. At the temperature yours are running I don't think they are going to last very long. The problem with that, when it happens, unless you have some sort of speaker protection circuit hooked up you might lose a good set of speakers. Be Careful.

[PedroPO]

thanks for the advice!

I actually use one PR170 per channel, but what kind of heatsink do you suggest?

Pedro Oliveira

[PassFan]

Pedro I'm not sure about the size in mm, but if they are a little bit taller than a coke can I used 4 per channel. The extrusion # was 6209 ahamator. They have a web site but I don't know the address. It's under Ahamator or Wakefield if you do a search. My amps ran at about 50 deg.C or a little cooler. Good Luck

[audionut]

when one of those mosfets fails because of the heat, one of two things can happen. If the Mosfet fails open, you will get DC through the speakers, and you will likely burn out a speaker. If the mosfet fails shorted, you can also hurt a speaker, as well as overload the power supply. Make sure you have the amp is properly fused.

[vpharris]

Skippy:

I'm not sure if you were kidding or not when you asked if Pedro's amp was turning red, but that wouldn't happen until it's in the vicinity of 750 degrees C. Aluminum heatsinks would melt before they started to turn red.

I spent a long time in the ceramics kiln business, and we considered that temperature as "starting to get warm."

[AudioFreak]

Originally posted by vpharris
Skippy:

I'm not sure if you were kidding or not when you asked if Pedro's amp was turning red, but that wouldn't happen until it's in the vicinity of 750 degrees C. Aluminum heatsinks would melt before they started to turn red.

I spent a long time in the ceramics kiln business, and we considered that temperature as "starting to get warm."

so i take from that that you are more a white/blue = hot kinda person

[PedroPO]

Can anyone tell me the power of my device, or how can I determine it? the description is on the first thread.

Pedro Oliveira

[ralf]

Hi,

I am building a SOZ to about 50 Watts per channel. An i mis-calculated the Heat-sinks, too.

i`m going to use one Big Heat-sink for each resistor, about 46 pieces 330*165*60 mm.
I have 46 Pieces of 50watts resistors from Dale.
And a big one for the Mos Fets.

This amp will be verry big and heavy !!!- and expensive.

I thing to be finished with it in the middle of this year and will do a dokumentation in the pass sites.

Regards

Ralf

[Variac]

Looking at the graph Fig. 5 on the Son of Zen site, it looks like you
are putting out about a mighty 14 watts/ch

thats about 3 times what most Single Ended Triode amps put out.

I'm aiming for about that output too- but more heatsinks!

Mark