| MEGA-amp |
I am close to finishing one side of a monoblock for my aleph 2's.
12"H x 19.5" W x 2.28" Fin height. I am contemplating changing the design to an Aleph 1.2, I think the heatsinks may be big enough. Your thoughts?
JH |
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| MEGA-amp |
| steel construction |
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| moe29 |
i think those sinks will have a hard time dissipating 300 watts...
From looking at the Aleph 1.2 service manual it looks like about
346 sq. in. of heat sink for 1 channel.
You've got 234 sq. in. with 2 heatsinks. If you could add another
heatsink like you're using, it would work for 1 ch of Aleph 1.2 |
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| MEGA-amp |
To be honest i've never listened to a Class A amp, so I dont know what 100W will do. From what i've read and followed here on the forum, i believe it will be fine. The only thing i have to compare to is an old pionner sx-1280 which is 185W@8. Just wondering if its possible to move up. Once its built i'm sure replacing fets would become bothersome if i chose to go to 1.2.
I think i'll keep it the way it is, just flirtin with the idea. Moe, I saw your Alpeh 2, great work, are you happy with the sound of it
The above pics, depict just one side of a single monoblock, total heatsink area per channel is 468 sq. in.
Thanks,
JH |
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| MEGA-amp |
The stock Aleph 1.2 has 346 sq. in. of heatsink per channel. I have 468 sq. in. per channel. I believe I should be fine going up to Aleph 1.2. Would anybody object to that?
Many thanks,
JH |
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| kilowattski |
Mega-Amp,
Just a question out of curiosity. Why didn't you use a piece of longer aluminum L bracket to connect your heatsinks together? The aluminum bracket can also be cut easily on a woodworking power chop saw with a carbide tip blade. I was also curious why you drilled all the way through the heatsink instead of most of the way and tapping the holes? Then you wouldn't see the holes in the heatsink. Was it because the heatsink base was only about .25" thick? Just curious. Keep up the good work and show us more pictures as you go along. |
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| Netlist |
| quote: | Originally posted by MEGA-amp
steel construction |
Compared with your feet your sinks look huge :D
Keep them coming ;) |
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| Mark A. Gulbrandsen |
According to M&M Metals specs my heat sinks are 103 sq inches per inch of extrusion of which each is 6" long. I have 6 sinks per Aleph 2 and this gives me a total of 3709 sq inches of heatsink if I'm calculating this corectly.
6.250 X 6.250 X 0.500 Base thickness and weighs 7.550 per foot. Rated at 0.6 deg C/W |
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| moe29 |
JH,
I wasn't counting the fin size into the sq. in. formula. Just heatsink
size. Fin size is about the same for your sinks and aleph 1.2
So i still think you're short.
I did notice that the Aleph 1.2 service manual says 500 watts of
dissipation compared to 300 watts for the Aleph 2. Either way it's
a lot of heat to dissipate. Nothing would be worse than spending
the time and money to match 12 fets X 2 for each channel, and
then have the amp run too hot!
but maybe i'm not being enough of a Fearless DIYer :) |
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| Nelson Pass |
Unless you really need the power, I have always found the
Aleph 2 to be the most neutral of the bunch. The 1.2 seems
to be slightly over the top, and it's much better to have a
nice heavy bias on an Aleph 2 than a parsimonious bias on
a 1.2 :cool: |
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| MEGA-amp |
kilowattski, the brackets are solid steel with stainless steel machine screws, I didnt feel the need to go the length of the sink, for one mono block i used up 84" of steel brackets, this project is starting to get expensive. As it is, its very strong. As for the base thickness, its actually .28" to be exact. I didnt want to deal with threading holes, breaking taps, plus I dont really mind the screws in the sinks being visible.
When I was doing my calculation, I was just measuring flat surface area, not the fins, oh well, i'd like to go for Aleph 1.2, but I'm sure I wont be dissatisfied with the 2.
You know what they say about people with little feet, they wear little shoes;)
Thank you,
JH |
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| moe29 |
JH,
I didn't mean to put you off of what you were going for! If you
want an Aleph 1.2, go for it!
I shouldn't post on 2 hours of sleep... |
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| kilowattski |
| quote: | | I didnt feel the need to go the length of the sink, for one mono block i used up 84" of steel brackets, this project is starting to get expensive. |
I know what you mean. My wife thought that my woodworking hobby was expensive until I got into DIY audio. |
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| SI |
Hi MEGA-amp, I was wondering if you can send me some info on the Heat sinks(cost and availibility).:hot:
Thanks. |
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| MEGA-amp |
SI,
I ordered them through M&M metals. They have great service, great people, no minimums. http://www.mmmetals.com/
For my project I used 8 pieces (4 per monoblock). The total cost was $650 w/shipping. I had them do the black anodizing, which in retrospect, I should have not done that to save cost. I would have saved probably around 70 bucks. A local metal shop can anodize them cheaply.
JH
M&M Model# MM10928 |
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| Sandy H. |
The sinks MEGA-Amp posted are !very! sweet pieces. The sinks I bought off of Ebay a while back are nice, but not as good as those for high dissipation.
Mine are 7 3/8" wide x 13 1/4" tall with a 1/4" base thickness. The total fin height (including base) is only 1 5/16", which is a significant change from the M&M product. The fins are spaced at 1/4" and there are a total of 21. They are black anodized and have 24 pre-tapped holes for some other device.
They are a significant compromise compared to his sinks. I bought 8 also, hoping for 4 per monoblock of Aleph 2 (3 mosfets per sink). It is, from what I gather, a pretty borderline application and I may have fallen victim to the too little heatsink bug.
But, I paid around $130 shipped from e-bay. In the end, MEGA-Amp will end up with a super sharp Aleph 2 and I might end up with a much smaller Aleph, due to my oversight.
I suggest looking for surplus (not exclusively e-bay), but also really compare specs and dimensions. They looked huge to me until I saw a real Pass amp. They look pretty small now. . .
Hopefully in 3 or 4 months from now, I'll be able to post whether or not they are sufficient for an Aleph 2 or not, but that project is still gathering the last few components.
Sandy.
Sandy. |
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| Mark A. Gulbrandsen |
I'm shocked that they were that much as mine ran me only 340.00 un-anodized for 12 sinks. Mine is a far more complex extrusion than the typical flat back sink is. I wonder what gives on this.....?
Mark |
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| MEGA-amp |
I ordered 8 pcs of the above, they gave me 9. It was about 70 lbs of aluminum. When I was shopping around for metal, most places had 1000lb minimums, or some sort of minimums based on weight. Availability of an extrusion or lack of, raises the cost as well. I dont know what the case was with mine, but M&M gave me the lowest quote.
JH |
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| Brian Donaldson |
The large flat panel sinks may not seem as complex, they are much more difficult to extrude because of the asymetry. They want to curl and warp as they come out of the die. Extrusions like Mark's are basically radial and more forgiving.
I bought 8 feet of an extrusion that is 7" wide and 2" deep with 17 fins of alternating lengths 2",1",2" etc. for about $450.
Made 2 Aleph 2's that burn 450 watts at 165 deg. I usually back the bias from 5 amps to 3 or so unless I have friends and beer over.
Letting the temp slide too high has it's cost. I need to buy another 100 ifrp244. Reliabiliy suffers greatly at 180 deg from 55 volt rails and 7 amps of bias. |
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| Mark A. Gulbrandsen |
Brian,
Then yours may work more reliably, longer using the sinks I bought. Although the sinks are more work to incorporate into a chassis they sure are extremely efficient and I see why amp manufacturers used them in early Class A power amps. It may ahve been the largest stock sink that was available a few years back.
Mark |
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| Brian Donaldson |
Mark,
Your extrusion was very tempting. The small base with fins radiating off in all directions is the most efficent design, but I wanted something that would more easily fit into a more traditional sized rack. But you can't possible put 2 of the 75 pound heaters in a rack. They would melt the plastic buttons and face off of the SACD player.
Here's what I'm using for my ugly, noisey, attic mounted big *** Aleph X. I was told that it could disapate over 1 KW with forced air. It's 9" x 12" x 3" |
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| SI |
| Mark, how about posting some pictures of your heat sinks:D |
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| Mark A. Gulbrandsen |
Ok, here ya go. These were brought on line Christmas Day, a year ago last Christmas. I've been so busy listening plus there has been a somewhat continous stream of locals that saw the post back when I got them running that have also been over so they remain un-anodized, and no front panel. This is going to change though in the near future as I am planning a serious PS upgrade to 1KVA toroids from my 680KVA units plus a CRCRC filter bank. So they will be torn down, things re-machined to accomodate the bigger tranny, and capacitor bank and relocate the driver board elsewhere plus a front panel and top cover....then over to the anodizer for hardcoating the black heatsinks and chassis parts and a hard coated pewter front plate. I prefer hard coating as its far more scratch resistant and not all that much more expensive then plain anodizing.
I literally built these on my kitchen table! I did all the machining on Saturdays and in the evening at work on our shop.
Mark |
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| Mark A. Gulbrandsen |
here is a layout shot fomr size comparison. The toroid is 680 va and thats Brian GT's pcb in the shot for size comparison. The statement these sinks makes is definately one of high power and heat:hot: !
Mark |
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| SI |
How about a link. I'm building my very first Aleph 2's, for that matter my first any thing, So I'm no expert on this, But shouldn't the tranny be as far from the I/O as possible. In other words would it be better if you were to swap places between the PCB and the Tranny in your layout.
Are you mounting the fets right on the heatsinks?
They are awsome.
SAAD// |
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| jewilson |
Mark,
I have a bunch of those types of heat sinks however I’ve never used them. I always though that the middle channel was meant for mounting some kind of Stud SCR, high-powered diode or transistors.
Since the channel is narrow, I just never used them. Therefore, I wonder how well they will work since you have only conducting heat through narrow flats of the fins. I though the part you are using was just meant for mounting to a chassis.
Let me know how they work out for you, maybe I'll use mine or dumb them.:) |
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| Mark A. Gulbrandsen |
Here's how I mounted my devices..... inside the shallow end of the channel. Those turret terminals are about 35 cents each and make things a bit more solid and are very convenient. If you need any let me know.
The outer banks terminated back to the center sink and then went to the driver board. This way all the output stage connecting wires were basically the same length.
Mark |
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| jewilson |
Mark,
Dumb me; I should have realized that you did not sink the sinks just to the chassis fins.
That looks good, that must have been a real hassle trying to get the parts in there. Those turrets are really worked out well, or they 4/40 or 8/32 threads.
Yea could use some.
:) |
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| Coulomb |
Well if someone wants to organise a US Contingent to this Group Buy I am trying to get going, then I could arrange a drop ship from the vendor to one US location for reshipping.
The prices are excellent and the more I buy the better the price should get. Take a look at this thread for drawings and pricing. Remember the pricing is in Canadian dollars so for a rough conversion to US multiply times 0.7.
Sorry for the spam guys.
Anthony
http://www.diyaudio.com/forums/show...&threadid=29816 |
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| tomchaoda |
While I am waiting for my Aleph 2 PCBs and GP cases to arrive, I made my preparation in a journal type of report. I would like to share it with you and also pls feel free to comment the contents. I did the preparation based on my previous journal of Aleph 5.
Here's the link:
http://www.penguinlovers.net/audio/aleph2_proj.html
If you don't have a boardband net, e-mail me and I will e-mail you entire files in a zip.
Thanks,
Thomas |
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