heatsinks from conrad.. wich amp can they be used for

[wuffer]

i was thinking of using this http://www.conradheatsinks.com/products/double_f.html the MF30-2F-151.5 for en stereo amp in the future.. but wich aleph can it be used for...
it should be a stereo amp
is there any other places where i can buy heatsinks online with a visa card???

[wuffwaff]

Hi,

the heatsink will have around 0,3°K/W at 30°K temperature rise. So if you want your heatsink to be 50-55°C you can dissipate 30°/0,3 = 100watts.

This will be a very small Aleph stereo amp for example an Aleph 3/30 with 1A bias wich is really not enough or a mini-A. You will need at least two of those heatsinks for a stereo amp!

William

[hifimaker]

Hi Wuffer,

You need to apply a correction factor of 1.4 to the Conrad rating to compensate for the right operating range.

.30 * 1.4 = .42 C/W

These heatsinks make are great for about 60 watts, mono A60 or stereo A30.

Unless you really need the flanges, the flatback models have a thicker base and better C/W rating. Personally I'm using the model MF35-151.5 at .21C/W (corrected to .29 C/W), for a stereo A30.

BTW, the Conrad build quality is beautiful. They are also black powder coated and will turn purple over time.

Good luck,

-David

[wuffwaff]

Hi David,

sorry to disagree but a stereo Aleph 30 doesn´t dissipate 60 watts and a mono Aleph60 doesn´t dissipate 60 watts either. (A30 100watts/channel, A60 155watts/channel)

I already added a bit to the Conrad specs (at 80°C temp rise) so if1.4 is the right faktor it will be 0,35°K/W

William

[jleaman]

Originally posted by wuffwaff
Hi,

the heatsink will have around 0,3°K/W at 30°K temperature rise. So if you want your heatsink to be 50-55°C you can dissipate 30°/0,3 = 100watts.

This will be a very small Aleph stereo amp for example an Aleph 3/30 with 1A bias wich is really not enough or a mini-A. You will need at least two of those heatsinks for a stereo amp!

William

I agree on this for a mini a'' You might need a fan to cool these sinks if you do a stereo aleph 30. The mini a's are not a cold running amp..

[hifimaker]

I agree with wuffwaff and jleaman. I should have mentioned that I'm using 2 of Conrad's larger mf35-151.5 heatsinks for my stereo Aleph30, with good open ventilation. One heatsink per channel.

I could be a bit optimistic and may need to back off on the bias or add a fan.

I also left out the word NOT. They will NOT turn purple over time since they are not anodized, but powder coated.


-David

[jleaman]

Originally posted by dw8083
I agree with wuffwaff and jleaman. I should have mentioned that I'm using 2 of Conrad's larger mf35-151.5 heatsinks for my stereo Aleph30, with good open ventilation. One heatsink per channel.

I could be a bit optimistic and may need to back off on the bias or add a fan.

-David

This is funy.. I have yet to find the resistor that i have to change to bring up the bias on the aleph Mini -A id like to push them a little Brian said o could leave the reistor out and it would be full bias.

My plann is to have a switch to have full open bias and then to have it not full bias.

[wuffwaff]

jleaman,

try changing the resistor that is connected between the base of the small transistor in the current source and the plus side of the 220uF bootstrap cap. Leaving it out gives max bias, if this is not enough try lowering the source resistors.

William

[jleaman]

Originally posted by wuffwaff
jleaman,

try changing the resistor that is connected between the base of the small transistor in the current source and the plus side of the 220uF bootstrap cap. Leaving it out gives max bias, if this is not enough try lowering the source resistors.

William

The only reason i ask is so i dont kill thes amps

what resistor R13 ?

[wuffwaff]

Yes, R13

William