My baby is HOT!!

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My baby is hot ,very hot too hot for me.:hot:
I can't even touch her.
Perhaps she need a bigger......:bawling: ...heatsink??
OK anyhow:
¸TEST A5 monoblocks (without exotic parts- resis., semiconduct., caps.ect) in sort-of test enclosures.
- PCB own design
- Heatsink dimensions 30 X 12 X 4 cm
PSU:
- 2 X 35A/200V Bridge
- 2 X 27 V 350W Trann. + CL 70
- 2 X 50kuF this moment without Pi filter ( 2,2mH)
- 2X 36 V Rail
Power Mosfet resistor:
- 2 X 2,2 Ohm 2W Noninduct. parallel ( 0,575 V )
Output resistors:
- 8 X 1 Ohm 1W Noninduct. parallel.

Tomorrow I will check HS. temp with termometer and find possible oscilation with scope!

:cannotbe:
 

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sinks do look a little small... put a fan on them or find a bigger
sink. FET spacing looks to small too. It would be nice if you had
2 more sinks just like that... split your fets between them with
more spacing...

the quality of your work is very nice though!

heat sinks... can never be too big!!


good luck,
m.
 
On some tests I did last year on heatsinks I found a fan would improve the heatsink perfrmance by a factor of 6. Yep, six times as good. I have dumped as much as 350 watts :bigeyes: onto a 100mm x 100mm sink with a 90mm fan going full blast, but that was really the outer limits.
 
Yeah, of course. Fans are awesome. But more importantly I see a lot of designs on this site with the transistors all in a line. This is a huge waste of the heatsink's ability. Space them evenly on the surface of the sink, and you will get much better performance.

The transistors in the picture above are WAY too close together. Most of this heatsink is wasted.
 
jwb said:
Yeah, of course. Fans are awesome. But more importantly I see a lot of designs on this site with the transistors all in a line. This is a huge waste of the heatsink's ability. Space them evenly on the surface of the sink, and you will get much better performance.

The transistors in the picture above are WAY too close together. Most of this heatsink is wasted.


I did some testing with thermal calculation software and there almost no difference in placing the mosfets when you have thick enough back plate (>10mm will do) . There was only a 4 degree difference between the mosfets in placing them in line and all spread around... hardly worth the trouble in wiring, buy more heatsink to compensate this!

I did some measurements on my running Aleph 4 and there is almost no difference between the left, the top the back and bottom when all is in balance after 60 minutes of running... All is hot! :)

Ofcourse his mosfets are a bit too close and his heatsink look too small...

Edwin
 
Nice amp!

too bad its too small.
I would explore the fan possibility, since your amp is so cute!!

I myself did a aleph 5 with more sinks here is a pic

only two of the sinks are getting hot by the fets.

the final temp is about 50ºC or so, after a few hours.
 

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Circlotron said:
On some tests I did last year on heatsinks I found a fan would improve the heatsink perfrmance by a factor of 6. Yep, six times as good. I have dumped as much as 350 watts :bigeyes: onto a 100mm x 100mm sink with a 90mm fan going full blast, but that was really the outer limits.


Use fan is good idea. I made lot of measuring with fan cooled heatsinks. The most interesting was one IRF530 with 70W dissipation on 125*125*50mm heatsink:nod:
The biggest problem is the noise. But there is solution for it: use 12V fan with 6-8V, even 3-4pcs. of them. With this condition there is no noise, and the fan can coll down Your heatsink with some 10-15 degree!

Sajti
 
Fans & Heatsinks

I've got a fan running over the right side of my amp (Mccormack DNA .5). There's a definite difference in the temp of the right side sinks vs. the left side sinks. Is this difference cause for concern? Any possibility it may be affecting right channel vs. left channel performance?

Thanks,
Bob

PS - the McCormack doesn't run hot at all, it's just that it's inside a cabinet where airflow is always a good idea.
 
Hot baby!!

Guys, thank's for ideas and suggestions :nod:
I would explore possibility to substitute transf. with new one - intent to use for A3.
Than I will pull-out 2pcs. Power Mos. from PCB and replace:
- Pow. Mos. resistors with 0,47 Ohm.
- R17 with 1K5 Ohm
- R19 with 47K5
- R 21 with 820 Ohm
Similar like a Aleph3 value.
I intent to keep Balance input configuration.
I HOPE :confused: that Heatsinks than will be suitable.

Pls for coment!!:scratch:
Thanks in advance,
jazzy
 
oh You amp must be hot like boiled tea cup.

I have zen v4 run in 1.3a and heatsinks are 2x 44X16cm x 4mm tall

and after 30-50min it run hot that I can touch hand only 2-4seconds. also get hot back side and up side wals, which is from aliuminium too.I place transistors very carefuly, bigest heater q1 has most space, q2 a ;little bit litter, and q5 small place in anlge of heatsink. result heatsink warms in all areas together flat.


nelson says that temperature must rise only to 30cesius! my is 50-80 for sure! should I use cooling fan? if any replies, please to email, thanks..
 
Why dont you get a few heat strips. I got a few of these one shot things. Basically a sticker that has a thermometer built in and goes black when the set temperature is reached. They come in a variety of ranges mine go from about 70-100 i think but tell you if anything is truly getting too hot.

My dad also bought home a PCR machine from work. This unit is just a thing that heats up and cools down little wells in a machine for biological work. Needless to say it tells the temp the plate is heated to and I set up to heat to 90 degrees and then put my hand on it as it heated up. Its surprising how intollerable we are to heat, I can usually pick up, tollerate, eat hotter things then most ppl. I had to remove my hand when it got to about 50 degrees, this was from a warm up. Now your amp may not be getting as hot as you presume just because you cant touch it for that long. Remember Mosfetts are good up to a max of 150, if your heatsink was at 100 then the devices maybe at 130 and still within acceptable limits. If the sink was at 100 then you would remove your hand WAY before two seconds, in fact you would burn ureself probably.

Also its only a problem on devices lifetime if they heat up cool down heat up cool down often as all the bits in a semi will expand and contract differantly, etc and cause problems, a bit like freeze thaw weathering. A class A amp should have better reliability then a class B as it remains at a constant temperature. Ofcourse this may not hold if the deviced are very close to their max limit.

I dont have any proof on this etc and am only speculating from things that I have read in the past.

Matt
 
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