Received all semis today and Digikey was kind enough to send all 240's and 9610's from the same lot! I've heard that some have had bad luck at getting semi's all with the same date code or from the same batch. Guess I was lucky, but the lady I gave the order to was very aware of what I was after. Thank you Digi-Key!
Brian GT's boards should be here in a day or so.
Now to decide on heatsinks.....I have 10 heatsinks that are 5.5 inches long and are the same as R-Theata # 60060 but I really need 12 of them to go 2 devices per sink. I looked at the surplus stuff at MECI and the giant heatsink there is really a bit too giant and ugly for me. So I called M&M Metals for a quote on 12 (6 per amp) of their MM5060 which would be convection cooled, or 4 (2 per amp) of the MM5047 at 11" long which I would make into a Heatsink tunnel and force cool them. Both of these are off the shelf stuff at M&M and should be more reasonable than calling the other heatsink giants that only cater to you if you're Boeing Aircraft or the sort.
Mark
Brian GT's boards should be here in a day or so.
Now to decide on heatsinks.....I have 10 heatsinks that are 5.5 inches long and are the same as R-Theata # 60060 but I really need 12 of them to go 2 devices per sink. I looked at the surplus stuff at MECI and the giant heatsink there is really a bit too giant and ugly for me. So I called M&M Metals for a quote on 12 (6 per amp) of their MM5060 which would be convection cooled, or 4 (2 per amp) of the MM5047 at 11" long which I would make into a Heatsink tunnel and force cool them. Both of these are off the shelf stuff at M&M and should be more reasonable than calling the other heatsink giants that only cater to you if you're Boeing Aircraft or the sort.
Mark
M&M Heatsink Quote
Got the quote back fomr M&M. Boy these guys are sure nice to do buisness with! Friendly and folk with small orders get the same treatment as those with big orders. Here is the quote as I got it.
"Price for 12 parts of MM5060 is 17.39 each."
"Price for 4 parts of MM5047 is 118.92 each."
"Delivery in 2 to 3 weeks."
Link to them here:
http://www.mmmetals.com/pages/extruded high & medium/high/high_power_extruded_page.htm
Needless to say I am going with the 5060 and using 6 of them per amp. This is less expensive, and a better sink than the surplus convection units at MECO. I guess it'll look like an older Krell(KSA80, or 100, or whatever) when I get done, but what the heck, they were cool looking amps anyaway. But these Alephs will knock the Krell's right off the shelf.
Mark
Got the quote back fomr M&M. Boy these guys are sure nice to do buisness with! Friendly and folk with small orders get the same treatment as those with big orders. Here is the quote as I got it.
"Price for 12 parts of MM5060 is 17.39 each."
"Price for 4 parts of MM5047 is 118.92 each."
"Delivery in 2 to 3 weeks."
Link to them here:
http://www.mmmetals.com/pages/extruded high & medium/high/high_power_extruded_page.htm
Needless to say I am going with the 5060 and using 6 of them per amp. This is less expensive, and a better sink than the surplus convection units at MECO. I guess it'll look like an older Krell(KSA80, or 100, or whatever) when I get done, but what the heck, they were cool looking amps anyaway. But these Alephs will knock the Krell's right off the shelf.
Mark
Way to go!
Nice price and a great product. Congratulations. Did you take into account the effects of temp rise on the transistor when you add isolation pads? Calcs look pretty tight under ideal conditions (minus pads). Add a couple mica pads per heatsink and the heat climbs. Still, this is a route that I'm inclined to travel. Here's a thought: since the drains for the current source transistors and the drains on the output transistors appear to be linked to their groups, respectivly, perhaps one could isolate the heatsink and avoid the use of mica isolation pads.
Thanks for the tip.
John Inlow
Nice price and a great product. Congratulations. Did you take into account the effects of temp rise on the transistor when you add isolation pads? Calcs look pretty tight under ideal conditions (minus pads). Add a couple mica pads per heatsink and the heat climbs. Still, this is a route that I'm inclined to travel. Here's a thought: since the drains for the current source transistors and the drains on the output transistors appear to be linked to their groups, respectivly, perhaps one could isolate the heatsink and avoid the use of mica isolation pads.
Thanks for the tip.
John Inlow
Thats exactly what I had in in mind to do. I don't really see any other way to do it. There will be three sinks on each side of the chassis with 2 devices per sink. Current source on the right and outputs on the left side........
I am also considering some very slow moving servo controled fans at the bottom of each one. But I will probably wait and see how the temperature settles in first.
Mark
I am also considering some very slow moving servo controled fans at the bottom of each one. But I will probably wait and see how the temperature settles in first.
Mark
heatsink isolation`
Roddyama makes a good point regarding heatsink isolation. If the anodizing were nicked or scratched and you were to pick up, or adjust, the chassis with two hands while it's operating, a nasty shock could tarnish an otherwise excellent music listening session. I believe a perforated aluminum cage around the heatsinks would prevent such mishaps.
What do you think?
John Inlow
Roddyama makes a good point regarding heatsink isolation. If the anodizing were nicked or scratched and you were to pick up, or adjust, the chassis with two hands while it's operating, a nasty shock could tarnish an otherwise excellent music listening session. I believe a perforated aluminum cage around the heatsinks would prevent such mishaps.
What do you think?
John Inlow
Hi Mark, John,
I wouldn't exclude the insulator. There is another way to get the heat away from the device faster. Look at this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=5307
Your heatsinks will run a little hotter, but the device will run cooler. That's what counts.
Rodd Yamas***a
I wouldn't exclude the insulator. There is another way to get the heat away from the device faster. Look at this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=5307
Your heatsinks will run a little hotter, but the device will run cooler. That's what counts.
Rodd Yamas***a
Excellent thread!
I'm must read the other forums' offerings more often. I really love the idea of a copper spreader. The added value of a larger mica isolator makes sense as well. I build my own heatsinks by bolting a large bank of fins and spacers together, and now realize that the transistor mounting spacer could be entirely made of copper. Thanks for the suggestion, Rodd.
John Inlow
I'm must read the other forums' offerings more often. I really love the idea of a copper spreader. The added value of a larger mica isolator makes sense as well. I build my own heatsinks by bolting a large bank of fins and spacers together, and now realize that the transistor mounting spacer could be entirely made of copper. Thanks for the suggestion, Rodd.
John Inlow
Peter,
Might need to do some surfin',
Rodd Yamas***a
I've been thinking about this off and on since that original thread. How about taking apart a large metalfilm poly cap. I'm thinkin' at least 2" long and 400V. Cut it open, unroll the conductor/insulator, and cut it to size. We could take the metalfilm side and face it toward the heatsink (with a small amount of thermal grease) to make the best thermal contact possible. We would have our choice of insulating materials from mylar/polyester to teflon. It probably wouldn't be as good as a large, thin mica waffer, but I don't know.
Might need to do some surfin',
Rodd Yamas***a
It looks like a nice product, although the thermal resistance is high along with the price. It's best feature is that it is available.
Here are some interesting heatsink and heatsink related products and information links.
http://atschool.eduweb.co.uk/brownie/heatlink.html
This guy appears to be a clocker so many of the links are for computer related heatsink stuff, but there's enough general information to make the link worth having. The worst part about this type information is trying to buy something you've found.
Checkout the "Power Device" link
Rodd Yamas***a
Here are some interesting heatsink and heatsink related products and information links.
http://atschool.eduweb.co.uk/brownie/heatlink.html
This guy appears to be a clocker so many of the links are for computer related heatsink stuff, but there's enough general information to make the link worth having. The worst part about this type information is trying to buy something you've found.
Checkout the "Power Device" link
Rodd Yamas***a
Peter and others, I think this is a large enough insulator:
Peter's post:
--------------------------------------------------------------------------------
If you'll find large enough insulator let us know. I like that idea too.
--------------------------------------------------------------------------------
Alutronic has them:
http://www.alutronic.de
Elinter has the PDF:
http://www.elinter.ch/pdf/138Waermeleitende Silikonscheiben.pdf
Bottom an page 3 are silicon insulators at 200x200 mm and they also have it by the roll (big enough I hope).
/UrSv
Peter's post:
--------------------------------------------------------------------------------
If you'll find large enough insulator let us know. I like that idea too.
--------------------------------------------------------------------------------
Alutronic has them:
http://www.alutronic.de
Elinter has the PDF:
http://www.elinter.ch/pdf/138Waermeleitende Silikonscheiben.pdf
Bottom an page 3 are silicon insulators at 200x200 mm and they also have it by the roll (big enough I hope).
/UrSv
roddyama said:
I had an idea similar to this one about a week ago (before reading this message)... Went in to work some OT last Saturday, and left after spending most of my time mulling over this idea.... My textbooks are at home.
According to my books, Teflon has an average thermal conductivity (compared to other plastics, that is), at .25 W/m-K. With some algebra, C/W = 157 * t / A where t and A are in inches (Yes, I know I'm mixing units
). McMasterCarr has Teflon film in a multitude of thicknesses down to .002inch. With a .002" think Teflon thermal washer with a TO-247 device (~.45 square inch footprint), the C/W = .7. Add in thermal grease, and I guess C/W ~ 1.0. The benefit is that it's only US$.71 for a 6" x 12" piece from McMaster.I was thinking this idea would be really nice if coupled with the copper (or even aluminum) spreader plate idea in the thread Rodd linked to 7 posts above....
Cheers,
Mark Broker
Aleph2 Schematic
Not to get too far off the current subject, but I was wondering if anyone had a Aleph 2 Schematic that was correct with all connections. I was comparing the Board layout by BrianGT to Mr. Pass's Aleph 2 schematic in the service manuel and could not verify if C10(-ve) was connected to C9(-ve).
I just want to be sure of board layout before I begin my Aleph 2.
Not to get too far off the current subject, but I was wondering if anyone had a Aleph 2 Schematic that was correct with all connections. I was comparing the Board layout by BrianGT to Mr. Pass's Aleph 2 schematic in the service manuel and could not verify if C10(-ve) was connected to C9(-ve).
I just want to be sure of board layout before I begin my Aleph 2.
Thanks Peter - That schematic shows the two 220uF electrolytics connected to the same node. BrianGT's Board does not appear to make that connection - unless I am missing something. From what I understand, many are using his circuit board and are pleased with it.
Any Ideas about the two capacitors in question ?
Thanks,
-Brian
Any Ideas about the two capacitors in question ?
Thanks,
-Brian
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