I have been making some inquiries about getting some Aavid Thermalloy Profiles for a Group Buy.
In order to make a GB feasible we would need to hit 100 units.
I am considering three profiles and have included the links below. I would have to focus on only 1 of the 3 and only one size to maximize the number of pieces ordered.
They would be Finished and Black Anodized, I am targeting either a 6" or 8" length for these cross sections. The °C/W is .30 per heatsink on these combinations.
I have a quote already on 72545 at 8" Min order 100 units @ $64 USD plus applicable taxes and shipping. FOB Chicago. I may be able to improve the price.
I do not know if there is enough demand at this time for another large Group Buy, we will have to wait and see. I believe the 72545 will be the least expensive option.
72545 x 8"
63340 x 8"
62335 x 6"
In order to make a GB feasible we would need to hit 100 units.
I am considering three profiles and have included the links below. I would have to focus on only 1 of the 3 and only one size to maximize the number of pieces ordered.
They would be Finished and Black Anodized, I am targeting either a 6" or 8" length for these cross sections. The °C/W is .30 per heatsink on these combinations.
I have a quote already on 72545 at 8" Min order 100 units @ $64 USD plus applicable taxes and shipping. FOB Chicago. I may be able to improve the price.
I do not know if there is enough demand at this time for another large Group Buy, we will have to wait and see. I believe the 72545 will be the least expensive option.
72545 x 8"
63340 x 8"
62335 x 6"
pooge said:
I think the Conrad heatsinks were a lot smaller and had a "corrected" rating of .30 where these have an actual .30 rating. They were $40 and the R-Theta ones I did the group buy on were about $50 for an 8" section.
I agree the Aavid are a bit more expensive but you are getting an almost 15" wide heatsink with 2 3/4" fins and 8" in length. This is a massive heatsink!
Anthony
First, out of the 3, I prefer 72545 as well.
I have the Conrad with me. For comparison sake:
Width: Conrad is approx 13.75" (Edge: Aavid, 1")
Base: Conrad is close 3/8" which is 1/8" thicker. (Edge: Conrad, 1/8")
Fin: Conrad is 1.5" which a" shorter. (Edge: Aavid, 1")
Length: Conrad's fin side is almost 6" where the base side is 5.75" (Edge: Avid, 2")
#Fins: Conrad has 35 and Avid has 24. (Edge: Conrad 10 fins)
Based on the above, both should be very close in performance. My Conrad was $55 shipped and tapped but didn't get them until 5 months after I paid and almost a year from the GB was initiated. So, I think it probably broils down to the price and how badly the sink is needed.
I have the Conrad with me. For comparison sake:
Width: Conrad is approx 13.75" (Edge: Aavid, 1")
Base: Conrad is close 3/8" which is 1/8" thicker. (Edge: Conrad, 1/8")
Fin: Conrad is 1.5" which a" shorter. (Edge: Aavid, 1")
Length: Conrad's fin side is almost 6" where the base side is 5.75" (Edge: Avid, 2")
#Fins: Conrad has 35 and Avid has 24. (Edge: Conrad 10 fins)
Based on the above, both should be very close in performance. My Conrad was $55 shipped and tapped but didn't get them until 5 months after I paid and almost a year from the GB was initiated. So, I think it probably broils down to the price and how badly the sink is needed.
Aye there's the rub, is there enough demand for another Group Buy of a honking big heatsink at this tme.
I am looking at buying an 8 Foot bar of this stock for myself, I already purchased a 4 foot bar a few years ago and made a nice enclosure with it.
I cut the bar to 8" lengths and placed two side by side to make a Heatsink 13.92" x 8" with 39 Fins, 36 of which are 2.8" long and on a base over half an inch thick. The weight of the Heatsink is 15 pounds. One 8" section runs cold with a BrianGT Mini A strapped to it.
Such an endeavour takes a lot of machine work though and is not a simple Tap and strap together job for you average metal basher.
65605 x 8"
Regards
Anthony
I am looking at buying an 8 Foot bar of this stock for myself, I already purchased a 4 foot bar a few years ago and made a nice enclosure with it.
I cut the bar to 8" lengths and placed two side by side to make a Heatsink 13.92" x 8" with 39 Fins, 36 of which are 2.8" long and on a base over half an inch thick. The weight of the Heatsink is 15 pounds. One 8" section runs cold with a BrianGT Mini A strapped to it.
Such an endeavour takes a lot of machine work though and is not a simple Tap and strap together job for you average metal basher.
65605 x 8"
Regards
Anthony
Attachments
Just for comparison purposes, this KL-271 extrusion is considered one of the best with about 0.15 C/W from natural convection. It is recommended for the Leach Amp, and you may find more info at that site. There have been a couple group buys for the black anodized ~$65 shipped USA in 2006
http://www.diyaudio.com/forums/showthread/t-56086.html
http://www.diyaudio.com/forums/showthread/t-56086.html
Attachments
LineSource said:
Yes I too like the Seifert Comb series Heatsinks, but they no longer list the KL-273 profile. I like the look of a longer Amplifier rather than the stubby look of an amp with 12" (300mm) heatsinks. I am hoping to get some interest in some thing over 14". The KL-271 was $65 two years ago and my favourite the KL-273 was $125. Prices have most defintely gone up since then.
I think the Seifert KL-271 and the Aavid 72545 are pretty close in real life applications at similiar lengths. I like the 72545 because it gives a deeper look for $65 in today's money.
Anthony
Coulomb said:
Here is the inside of the chassis, note how the extrusions are milled for the lid, same as the back and bottom.
Aelph Chassis
Anthony,
You may have trouble finding enough interest in a sink that wide for a volume purchase. Plus, that thin base just won't hack it, both thermally, and for mechanical reasons of not having a goodly amount of material to tap in to.
The 70165 and 72355 models look better to me, but they do not seem to have much in stock, if any.
You may have trouble finding enough interest in a sink that wide for a volume purchase. Plus, that thin base just won't hack it, both thermally, and for mechanical reasons of not having a goodly amount of material to tap in to.
The 70165 and 72355 models look better to me, but they do not seem to have much in stock, if any.
pooge said:
Yes I have noticed over the years there is hardly any interest in Heatsinks in the 14" to 18" profile.
I am not sure I agree with the ascertation that a .250" base is too thin. For 6063-T5 maximum clamping strength on a 6/32 or 8/32 machine screw is achieved in 3 or 4 turns of a UNF thread. Also a benefit of a slightly thinner base means quicker convection factor in heat flow to the fins.
Now if like me you have access to heavy vertical mill and wish to machine recesses into the extrusion then yes you need .375 to .5 of aluminum to do that. Most builders would be content to strap on a reinforcing cross member and mount the top, botttom, Front and back plates to those as no milling is required. Tapping Aluminum becomes exponentially harder the thicker the material becomes so this could also be an impedament to the average basher.
Anthony
Coulomb said:
I think the primary issue is getting heat AWAY from the semiconductors rather than getting heat TO the fins. The thicker the base plate, the higher the thermal conductivity would be away from the packages to the fins. Conductivity is the proper term, as convention more properly refers to heat movement in the air. (Sorry, not trying to be preachy. Just trying to keep terminology on course.) You will find the better fins to be thicker at their base for this reason. You want thickness in the highest temperature area to move a larger quantity of heat faster.
I have requested a quote from my contact at R-Theta for 8" lengths of 9002 (65605). I requested a quote for standard cuts and mill finish. The mill finish would enable bolting them up for a finished width of 13.9" as depicted in the photo's I posted above.
The 9002 is a very beefy heatsink, as you can see from the drawing I posted earlier. R-Theta make the identical part to Aavid or vice versa.
I have also requested a quote on how to calculate costs to have R-Theta do additonal maching to allow recessed top, bottom and back plates as well as tapping and drilling.
I expect the Heatsinks to be reasonable, the machining I expect would be quite a premium.
My interest is to end up with a group buy for any heatsink that meets the criteria of being beefy enough around 14" or longer at a reasonable price. At that there may still not be enough interest to make it worth while as said once a twice already.
Anthony
The 9002 is a very beefy heatsink, as you can see from the drawing I posted earlier. R-Theta make the identical part to Aavid or vice versa.
I have also requested a quote on how to calculate costs to have R-Theta do additonal maching to allow recessed top, bottom and back plates as well as tapping and drilling.
I expect the Heatsinks to be reasonable, the machining I expect would be quite a premium.
My interest is to end up with a group buy for any heatsink that meets the criteria of being beefy enough around 14" or longer at a reasonable price. At that there may still not be enough interest to make it worth while as said once a twice already.
Anthony
I have an interesting proposition for those interested. The R-Theta 65605 will cost around $26 CAD for an anodized 8" section. I will be posting some PDF's of the Thermal characteristics of this profile with 2 x 18W and 2 x 24W devices on them.
I ran the numbers through the Axe 1a spreadsheet for an Aelph x and calculated out the watts dissipated for 40 watts and 60 watts for a 6.5 ohm load.
I used only 4 Fets (1 Channel), so if you used just two of these heat sinks you could build a Mono chassis of either 40 or 60 watts depending on what temperature you want it to run at.
You could use 2 aside 4 in total for a stereo version, a 40 Watt stereo Aelph x with just 4 of these heatsinks would make a nice little amp that did not run like a space heater.
I can make enquiries about machining, drilling and tapping to make assembly a little easier for the mechnically challenged.
Anthony
I ran the numbers through the Axe 1a spreadsheet for an Aelph x and calculated out the watts dissipated for 40 watts and 60 watts for a 6.5 ohm load.
I used only 4 Fets (1 Channel), so if you used just two of these heat sinks you could build a Mono chassis of either 40 or 60 watts depending on what temperature you want it to run at.
You could use 2 aside 4 in total for a stereo version, a 40 Watt stereo Aelph x with just 4 of these heatsinks would make a nice little amp that did not run like a space heater.
I can make enquiries about machining, drilling and tapping to make assembly a little easier for the mechnically challenged.
Anthony
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