if your ambient temp is not over 25-30C you can gt away with less.
25C above ambient 25/150= 0.16C/W.
25C above ambient 25/150= 0.16C/W.
For all you/we know, PKI could be residing in Phoenix, Dallas or Taos.
Here i can pick 30 over ambient, few months a year that heatsinks reach 55C ''don't bother me none''.
Here i can pick 30 over ambient, few months a year that heatsinks reach 55C ''don't bother me none''.
One thing to keep in mind when shopping for heatsinks is that the thermal
resistance may be specified for a rise is temperature higher than you want
for your application and you need to derate things. Conrad has a nice
example here:
Conrad Heatsinks - Technical Details
resistance may be specified for a rise is temperature higher than you want
for your application and you need to derate things. Conrad has a nice
example here:
Conrad Heatsinks - Technical Details
Thanks for the comments and link. I see, for +55-60 I will need a 1.1-1.2 multiplier.
Oh, I thought that it should be in my location. I am in Washington DC area, so It is about +30-35(max) hottest temp.
Oh, I thought that it should be in my location. I am in Washington DC area, so It is about +30-35(max) hottest temp.
Nope.
55 degree heatsink temperature minus 30C is 25 degrees above ambient.
Derating factor for 25C is about 1.38
Another reason for picking as high above ambient as possible.
From 30C to 25C above ambient leads to a heatsink with a 20 percent better thermal resistance spec. On top of that goes nearly 4% extra, due to the decreased efficiency.
1.20 times 1.04 is close to 1.25 , which means that going from 30 to 25C above ambient leads to a heatsink that is more than 1/4th larger.
(why some commercial Class A amps have switches on the front panel to alter bias, a couple can switch between 25%, 50%, and 100% of the nominal Class A output level)
55 degree heatsink temperature minus 30C is 25 degrees above ambient.
Derating factor for 25C is about 1.38
Another reason for picking as high above ambient as possible.
From 30C to 25C above ambient leads to a heatsink with a 20 percent better thermal resistance spec. On top of that goes nearly 4% extra, due to the decreased efficiency.
1.20 times 1.04 is close to 1.25 , which means that going from 30 to 25C above ambient leads to a heatsink that is more than 1/4th larger.
(why some commercial Class A amps have switches on the front panel to alter bias, a couple can switch between 25%, 50%, and 100% of the nominal Class A output level)
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Thanks a lot! I just looked this page on my phone. Did not look the text -- just formula. Embarrassing. Wow couldn't imagine that someone needs specs for 80c above ambient. I will reestimate h-sink size taking into account these. Thanks again! 🙂
Heatsinks are manufactured primarily for other than audio duty. For most applications, dissipation at an elevated temperature level is practical.
There's not an international accepted standard for thermal resistance numbers.
Some measure dissipation at a specified temperature, as Conrad does with the 80C mark (others at e.g. 100C)
Other manufacturers take temperature at different dissipation levels, e.g. Fischer in Germany.
Makes a difference.
Getting everything right the first time, every time, is rather dull.
Hello folks,
I am picking up PSU caps for my aleph 5 and would appreciate if you help me to chose!
I have these options (going with approx. 47k uf per channel):
1) http://search.digikey.com/us/en/products/ECE-T1VA473FA/P10629-ND/272769
2) Personally I think of these Uni. Chemi-con's (parameters are great, but they are cheep. Anything wrong with them?): http://search.digikey.com/us/en/products/E36D500LPN473TD79M/565-3327-ND/2095941
Or if these chemi-con's are good, go crazy and buy 4x100k uf per channel:
Digi-Key - 565-3298-ND (Manufacturer - E32D500HPN104MDA5M) And these are 105C which is good for class A.
What do you think? Thanks!
I am picking up PSU caps for my aleph 5 and would appreciate if you help me to chose!
I have these options (going with approx. 47k uf per channel):
1) http://search.digikey.com/us/en/products/ECE-T1VA473FA/P10629-ND/272769
2) Personally I think of these Uni. Chemi-con's (parameters are great, but they are cheep. Anything wrong with them?): http://search.digikey.com/us/en/products/E36D500LPN473TD79M/565-3327-ND/2095941
Or if these chemi-con's are good, go crazy and buy 4x100k uf per channel:
Digi-Key - 565-3298-ND (Manufacturer - E32D500HPN104MDA5M) And these are 105C which is good for class A.
What do you think? Thanks!
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Try BrianGT Boards at chipamp.com -> order -> scroll down to bottom of page. They are cheaper, more flexible (daughter boards).
Thanks! This one? — Aleph through-hole PCB set - 2 x Main Amplifier PCBs- 4 x Output PCBs. Is these some universal boards? Are there only 4 Outputs? I need 6, Are you sere it will work for A5? Sorry for these stupid questions 🙂.
there is 3 tansistors pr output board. (aleph30) but just ask him and you can get 4 ekstra output boards. then you have for aleph60 🙂
it is a set for 2 channels.
you can build any aleph out of this boards.
it is a set for 2 channels.
you can build any aleph out of this boards.
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the boards are good. i have aleph2 and P1.7 from him. very nice robust boards.
they are a little expensive. but he also send out service/owner manuals that is no longer on pass labs's website.
they are a little expensive. but he also send out service/owner manuals that is no longer on pass labs's website.
PKI--
The screw-top capacitors are bulkier but more convenient than snap-ins if you think your layout will be changing. If you have the money and the space, screw-top caps are a good choice.
The screw-top capacitors are bulkier but more convenient than snap-ins if you think your layout will be changing. If you have the money and the space, screw-top caps are a good choice.
Is it better to use say 4 47,000uF caps. in the power supply or 2 100,000uF caps.?
Does anyone have a link to the Aleph 5 power supply or can one just use a F5 power supply with a 25v transformer instead of a 18v transformer?
Like PKI, I'm curious which transformer is needed for a Aleph 5.
Folks, need your advice now, please!
This is the time to decide: single stereo enclosure vs two mono blocks!
Please look at the photos, isn't it too packed inside if I go with stereo enclosure? Should I go with mono blocks, or it looks fine to you?
This is the time to decide: single stereo enclosure vs two mono blocks!
Please look at the photos, isn't it too packed inside if I go with stereo enclosure? Should I go with mono blocks, or it looks fine to you?
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.
How big are those heatsinks? And what transformers did you wind up buying? They look like Anteks, which model?
I would suggest 2 monoblocks because you will have more internal room for assembly, and you won't be trying to make holes for speaker posts and IEC and the RCA jacks in a section of heatsink.
I would suggest 2 monoblocks because you will have more internal room for assembly, and you won't be trying to make holes for speaker posts and IEC and the RCA jacks in a section of heatsink.
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