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Aavid Thermalloy Possible Group Buy

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#221
Re: Re: Good job

rebos123 said:
Another vote for a good job! I hope we get the minimum number of orders. I updated the WIKI with my preference for a $65 parts kit.
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Coulomb said:


I could look into supplying panel plugs, they are round, bright, shiny and have spring clips to hold them in place. 😎

Anthony
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Hope and interest. that's what we need! 🙂

Anthony
 
#222
since there seems to be relatively little interest in the small chassis, what about a 5"-6" tall option would use two heat sinks per side? That way, the top and bottom could be reused from the "large" chassis option. I there just might be a contingent of people that would like a lower profile option..
 
#224
luvdunhill said:
since there seems to be relatively little interest in the small chassis, what about a 5"-6" tall option would use two heat sinks per side? That way, the top and bottom could be reused from the "large" chassis option. I there just might be a contingent of people that would like a lower profile option..
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BobEllis said:
6" high would be a good size for a 4 channel sym-a-sym. Oh Geez! another project...
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A change in Heatsink Hieght would preclude the small chassis buyers from participating in the FPE rear panel portion of the group by as that is set at 10". The point of having the small chassis at the same length heatsink was indeed to standardize the rear panel. Unfortunately there would also be an additional setup charge to cut the Heatsinks to a shorter length and a CNC setup charge for a new file to change the drill positions on the shorter profile.

Also affected would be the length of the rails and front Panel which would also affect the pricing for buyers of the large chassis as the numbers would split out to two different groups.

I had considered these variables when trying to standardize on one chassis to maximize the buying power.

At present there are only 2 members looking for small Chassis configurations and no rear panel. We would need a lot more interest in an alternate small chassis configuration to bring the WAC down to a reasonable target price (think another 20 kits).

I will request a quote for 40 x 5" sections.


Anthony
 
#228
khundude said:
I am just looking for heatsinks. I need enough for an F4 and F5 with room for a little extra bias. If I can use a pair of 10" for each, this would be great. Can anyone confirm the sinking I need?
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Essentially you can safely dissapate 30 watts per 10" section, 40 watts at a push if you like to run very warm.

How many devices and how much wattage per device do you intend to dissapate?

Anthony
 
#230
I am going to ask that rkevans and Tube Noob move thier choices from 8" basic to 10" basic. I can supply the 10" in basic and drilled forms without a penalty, but supplying the 8" as well would not be feasible.

For the small chassis builders, no slight intended, I have asked for the quotes on the 5" version, I am expecting 4 of the 5" to be a bit more than two of the 10".

Anthony
 
#231
Icarium said:
Yeah 10 dollars cost is trivial I think I'll go ahead and do that. Okay I think I have all the information for my personal group and then there's the larger group that I'll present to too. I think I can have my group (4-5 people) locked in by end of next week. Probably another week for the others (Another 5-10).

We have some people looking to build F5's which might be interested in this if this will do that. In fact I may get a second chassis for that.. or maybe the F6 when it comes out.
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Any progress on the additional participants?

Anthony
 
#235
I don't mean to be a stinker, but... Why was the choice not made to use 12" or 14"wide, vertical fin material and make one heatsink per side? The small chassis would use a 6" peice and the large a 12" piece. I am just curious what the motivation is for using 4 and still different lengths? I mean, if two were sufficient for a small amp and four for a large, or if two were needed per amp and the length changes, this would make sense. This way the same top and bottom could be used on all amps and save on machining costs for the sink, top and bottom. This is why if you look at commercial amp chassis dimensions, the base area is usually close to the same and the height of the component changes. If you were to do this, you would only need to machine one top and bottom, the heatsink only needs one cut per side to 6", 9", 12", or whatever is needed and the front and back are no different than is proposed in this thread. That is 50% less machining in the top, bottom, heatsinks... Most people are going to want these for FW clones and it would be nice if the small is good for small is good for a stereo FW amp and the large good for 4-channels, not just two with a little more bias.

Also, it is not such a good deal when you factor in that I need 4 compared to 2 Conrad for $100US shipped, and I live in Canada where these are coming from.
 
#237
khundude said:
I don't mean to be a stinker, but... Why was the choice not made to use 12" or 14"wide, vertical fin material and make one heatsink per side? The small chassis would use a 6" peice and the large a 12" piece. I am just curious what the motivation is for using 4 and still different lengths? I mean, if two were sufficient for a small amp and four for a large, or if two were needed per amp and the length changes, this would make sense. This way the same top and bottom could be used on all amps and save on machining costs for the sink, top and bottom. This is why if you look at commercial amp chassis dimensions, the base area is usually close to the same and the height of the component changes. If you were to do this, you would only need to machine one top and bottom, the heatsink only needs one cut per side to 6", 9", 12", or whatever is needed and the front and back are no different than is proposed in this thread. That is 50% less machining in the top, bottom, heatsinks... Most people are going to want these for FW clones and it would be nice if the small is good for small is good for a stereo FW amp and the large good for 4-channels, not just two with a little more bias.

Also, it is not such a good deal when you factor in that I need 4 compared to 2 Conrad for $100US shipped, and I live in Canada where these are coming from.
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As I had said earlier I had considered Conrad Heatsinks and a multitude of solutiions to a multipurpose chassis. It is critical to keep the cut lengths the same to reduce duplicate setup costs at the manufacturer. This also effects the number of front plates and back plates per order and the internal frame lengths. Each change in hieght will affect all these parameters, a change in length only effects the cut length of some aluminum square bar.

As for the value of the Conrad Heatisnk for $100USD delivered, consider that it is 13.77" x 5.96" x 1.88" has 35 fins and wiegh 4.67 pounds ea.

The combination of the two 66449 heatsinks would be 13.9" x 10" x 2.65" has 50 fins and wiegh 14.6 pounds ea. 2 of these Paired Heatsinks would be $125 USD plus delivery.

The advantage you ask? Well 3 times the mass for start, more fins over twice as much surface area for another. I think that, plus the flexibility of being able to use only two of the same profile for a smaller chassis make it far more viable for the intent of this Group Buy.

After all is said and done unfortuantely there will be some members who feel this GB is not for them. I do not have a solution that suits all members, but hopefully it will appeal to enough members to make it worthwhile.

Regards

Anthony
 
#238
BobEllis said:
Just in case you missed it, they rate their sinks at 80C rise. To get a more comfortable 40-50C sink temperature you need to derate by a factor of 1.4 or 1.5.
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Bob,
thank you for reminding those that refuse to read the datasheets and application notes.

And 50Cdegree rise in 28degC ambient gives Ts~78degC and Tc~88degC.

That is some de-rating for the semiconductors attached to that already de-rated heatsink.
And if one device is running 5Cdegrees hotter than the average, then the de-rating for a 150degC plastic package is ~56%, i.e. a 150W device becomes the equivalent to a 68W device before applying the second breakdown de-rating factor (if it's a BJT).
 
#239
AndrewT said:
Bob,
thank you for reminding those that refuse to read the datasheets and application notes.

And 50Cdegree rise in 28degC ambient gives Ts~78degC and Tc~88degC.

That is some de-rating for the semiconductors attached to that already de-rated heatsink.
And if one device is running 5Cdegrees hotter than the average, then the de-rating for a 150degC plastic package is ~56%, i.e. a 150W device becomes the equivalent to a 68W device before applying the second breakdown de-rating factor (if it's a BJT).
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Hey what about my note, I pointed out the mass and surface area difference! 😎

Just Kidding, I want everyone to feel comforatable about what they are committing to will meet thier individual requirements. So the more information we share, the better the end product.

Anthony
 
#240
I was looking at the derating factor for 25-30 degree rise to get to somewhere around 40-50C heat sink temperatures. Nelson Pass is a big proponent of keeping them below 55C - where you can still touch them but not for long.

At 30-35 C the cat will sit on top. At 40C+ she sits next to the amp. So don't run too cool if you want to keep fur out of your amp 😀
 
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