The Aleph30 PCB layout

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#164
I'm thinking about using two of these for my PD A30. Any comments? Think it will be enough?

The mounting plate is 12" x 4 3/4" x 5/16", the tunnel is 4.25" tall. 120V fans, which I will replace with 12v's, and add variable speed functionality.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.
 
#165
I may be overly optimistic, but with fans, you might be able to cool both channels on a single sink/fan set. There's a lot of aluminum and surface area there. Moving air buys you a lot.

Just my gut feeling, I can't sustantiate it with numbers.
 
#167
Wow. thanks. Perhaps I will go with one per channel with a super-low fan speed then. I suppose I could do that, then simply add two more if it's getting too hot, or the fans are getting too noisy.

Still thinking about water cooling the whole thing.

Hmm. Have some time to think, as I have other amps to "get out of the way first."
 
#169
I finally got the time and last pieces of stuff to complete the amp. The stuffed boards were laying around for a while already...

The powersupply:
An externally hosted image should be here but it was not working when we last tested it.


It delivers a solid +/- 17.5V Plenty for my power needs (I sit approx 2 meters away from my speakers 92dB sensitive speakers...)
There used to be two more capacitors on there, but I blew them because I had reversed the recitfier bridges :whazzat: :bawling:

The inards of the complete amp:
An externally hosted image should be here but it was not working when we last tested it.

These boards are absolutely perfect designed. Chapeau Peter!!!
I mounted the Fets on copper bars I had laying as the heatsinks are composed out of 4 different sinks.
As you may see I only use unbalanced input at the moment. I have to convert my pre to output balanced. I'll do that later.

DC output is a measly 10mV on both channels and it is dead silent. (I used R0)

Big shouts go to Nelson Pass, Peter Daniel and Jason Leaman

And now back to some more listening.
 
#171
Taco said:
Hans,

Wow, nice looking amp, but I have also a couple of questions 🙂.

1) Are those 500VA Amplimo's transformers?
2) Can those air-coils take the bias?
3) How hot are those sinks?
Click to expand...



Thanks Taco.

No, those are just two 160VA 15V with secondaries in parallel to get 11A current capability, that should do the trick. I had these laying around, and probably replace them later with a beefier piece. This is why I only have +/- 17,5V supply voltage.

I never had any problems with these coils. I used them also in a 4amp biased Zen. They probably are saturated but can handle the current withouth warming up too much. The powersupply does its job perfectly, so at the moment I do not see the need to beef things up.

I am kinda dissapointed in the dissipating capabilities of these sinks (another picture can be seen in post #146). These are 4 heatsinks rated at 0.65K/W according to Conrad (part # 188883 - 89), which combine to 360x200x48mm.
At a roomtemperature of 26 degrees I can only touch the sinks a few seconds before it gets too hot. I need to obtain a proper temp probe.
It won't be long probably before the outside temperatures will drop and thus also the roomtemperature here...

regards, Hans-Willem

An externally hosted image should be here but it was not working when we last tested it.
 
#173
Hanzwillem said:

I am kinda dissapointed in the dissipating capabilities of these sinks (another picture can be seen in post #146). These are 4 heatsinks rated at 0.65K/W according to Conrad (part # 188883 - 89), which combine to 360x200x48mm.
At a roomtemperature of 26 degrees I can only touch the sinks a few seconds before it gets too hot. I need to obtain a proper temp probe.
It won't be long probably before the outside temperatures will drop and thus also the roomtemperature here...
Click to expand...

Hmm, 35 V * 2A (assumed bias current) = 70 W per channel
Guesstimated combined heatsink per channel rating: about 0, 25 K/W
(looking at the manufacturers graph (Fischer Elektronik catalog, SK 53, bottom of page A63) for 200 mm (two on top of eachother) I get 0,5 K/W, so two pairs next to eachother = 0,25 K/W)
Temperature rise should be about 18 degrees.

Strange, that is one of the few heatsinks in Conrads online catalog where the K/W rating actually matches the manufacturers.
Others, like the SK47 for instance (on page A41 in the Fischer catalog or Conrad# 188824) are rated a lot better by Conrad than the manufacturers graph warrants: 0,4 K/W instead of 0,53 K/W for the 150 mm high version, 0,55 K/W instead of 0,7 K/W for 100 mm high version.

Take
 
#176
X-conversion input boards

hello Peter
I have read earlier in this thread that you played with the thougth of making an inputmodule, that would allow one to use two channels of A30 as one channel of Aleph-x - of course using another transformer. Out of pure couriosity (have bought 4 boards ;-) ) - have you abandoned this project ?

Cheers !
Buhl
 
#177
Hanzwillem said:


<snip>

I am kinda dissapointed in the dissipating capabilities of these sinks

<snip>
Click to expand...


That's because you have to mount them side by side to make two of them twice as efficient as one. The rule of thumb is that you have to quadruple the height in order to double the effect of any given heatsink profile. The way it is now, the bottom profile is heating up the top profile.

:bawling:
 
#178
Mad_K said:



That's because you have to mount them side by side to make two of them twice as efficient as one. The rule of thumb is that you have to quadruple the height in order to double the effect of any given heatsink profile. The way it is now, the bottom profile is heating up the top profile.

:bawling:
Click to expand...


True. The datasheet of the heatsink has a nice graph of dissipation capacity per heigth which shows just that. Still the temperature rises more than the calculated 18 degrees from that curve.
 
#179
Do you apply the same wattage to the heatsink as they have used in the datasheet to get their numbers? Heatsinks become more effective with more applied power. Also, there is a difference when you stack two on top of another, rather than having one long piece. Regardless, heatsinks specs are to be considered best case scenario and are seldom correct. The best way is to test the profile for your self 🙂
 
#180
Mad_K said:
Do you apply the same wattage to the heatsink as they have used in the datasheet to get their numbers? Heatsinks become more effective with more applied power. Also, there is a difference when you stack two on top of another, rather than having one long piece. Regardless, heatsinks specs are to be considered best case scenario and are seldom correct. The best way is to test the profile for your self 🙂
Click to expand...

Good point. Probably I am over that wattage in a less efficient area.
I don't have enough resistors to test stacked sinks. However, I have a very reliable A30 fot that purpose 🙂

Thanks for helping!
 
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