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Old 21st February 2012, 11:01 PM   #421
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from elliott sound products:
The average performance of a typical heat sink is linearly proportional to the width of a heat sink in the direction perpendicular to the airflow, and approximately proportional to the square root of the fin length in the direction parallel to the flow. For example, an increase in the width of a heat sink by a factor of two would increase the heat dissipation capability by a factor of two, whereas doubling the depth or height will only increase the heat dissipation capability by a factor of 1.4. Therefore, if the choice is available, it is beneficial to increase the width of a heat sink rather than the length of the heat sink fins. Also, the effect of radiation heat transfer is very important in natural convection, as it can be responsible of up to 25% of the total heat dissipation. Unless the heatsink is facing a hotter surface nearby, it is imperative to have the heat sink surfaces painted or anodised to enhance radiation.

The reason for the difference is simply that as the height is increased, the air at the top of the heatsink is hotter than that entering at the bottom. If the fin depth is increased, there is more mutual radiation between fins, and as the spacing is reduced, mutual radiation increases again. Airflow is also restricted because of the smaller physical area for air to pass, since more of the available space is occupied by the heatsink itself.
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Old 21st February 2012, 11:07 PM   #422
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by labjr View Post
What manufacturers are you talking about? I'm not aware of too many that make Class A amps.
Firstly to each their own , my beef is that it's being presented as being cheaper to do, it is not . I have owned class-a amplifiers (200w/ch) it was one chassis ,i have owned mono blocs that weren't class-a. Papa has single chassis class-a amplifiers, currently and in the past, had a few of those too... ( aleph)

Anyway if it was cheaper to do mono's you would see them more, it's not, Also they take up more space and a proverbial pain in the ****. I sold my last set of mono bloc's because of such, i don't have the space for multi-amping with mono's.

To split the boards and do mono's is the most expensive way to do it, just let those involved know that, as it does not matter which way this ends up for me, i can do the 8 boards in a dual mono single case , it has to fit in a 19w x 14hx16d space in my stereo rack ...

Last edited by a.wayne; 21st February 2012 at 11:15 PM.
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Old 21st February 2012, 11:10 PM   #423
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Quote:
Originally Posted by a.wayne View Post
San ,

I increased your numbers in my response, your original post had parts for one mono amp. The heatsinks in stereo is not necessarily 4 times the size and most if not all expressed using fans..
the numbers in the list was for one. the total numbers at the end was for 2 monoblcks. forget about the damn fan. we was talking about IF NOT TO USE FANS!!!!

Even if i had monster heat sinks i would still use a temperature controlled fan for the case and i still say you cannot fit 4 boards , caps, rectifiers and transformer in a 3 inch tall case, so your numbers are off...
with a depth of 20"(500mm) you can fit 2 bords side by side. but you dont need to. IT IS 2 BOARDS pr ch. and you have 2 sides with sinks! is your stereo amp that has to fit 2 boards pr side.
so YOUR numbers are WAY off. not mine. and your stereo amp need 2 PSU boards. my monoblocks only need one.
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Old 21st February 2012, 11:11 PM   #424
skunark is offline skunark  United States
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Quote:
Originally Posted by UKToecutter View Post
Jacco,

Good spot.
How is this..........

Click the image to open in full size.
Killer! That should bring down costs on the PCB a bit. What's the spacing of the fets? Sorry to ask again, but is the universal mounting spec still out of the question?


About the monoblock vs stereo chassis? Monoblocks will be lighter and easier to move, and one would be less likely to have a hernia, so the long run, it's probably cheaper. Even if you looked at the NRE, it's most likely a wash as the stereo chassis will probably need cooling and that added cost will offset some if not most of the cost for the additional aluminum needed for monoblocks. Most will have WAF constraints to deal with first.

Last edited by skunark; 21st February 2012 at 11:18 PM.
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Old 21st February 2012, 11:14 PM   #425
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Quote:
Originally Posted by a.wayne View Post
Firstly to each their own , my beef is that it's being presented as being cheaper to do, it is not . I have owned class-a amplifiers (200w/ch) it was one chassis ,i have owned mono blocs that weren't class-a. Papa has single chassis class-a amplifiers, currently and in the past, had a few of those too... ( aleph)

Anyway if it was cheaper to do mono's you would see them more, it's not, Also they take up more space and a proverbial pain in the ****. I sold my last set of mono bloc's because of such, i don't have the space for multi-amping with mono's.

To split the boards and do mono's is the most expensive way to do it, just let those involved know that, as it does not matter which way this ends up for me, i can do the 8 boards in a dual mono single case , it has to fit in a 19 x 16 space in my stereo rack ...
why the hell do you think aleph2 are monoblocks and not stereo amp? to get it more expensive? NO!!!!!
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Old 21st February 2012, 11:17 PM   #426
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If we cut the traces in the middle of the board, then one half could be used for the p channel and the other the n channel right? If yes, then could we add jumpers in the middle of the board? Those who want the 4 pairs use two boards and jumper in the middle, but those who need need less power could use just one input board and one output board per channel with the n and p transistors.

Does this make any sense?
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Old 21st February 2012, 11:19 PM   #427
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by AudioSan View Post
with a depth of 20"(500mm) you can fit 2 bords side by side. but you dont need to. IT IS 2 BOARDS pr ch. and you have 2 sides with sinks! is your stereo amp that has to fit 2 boards pr side.
so YOUR numbers are WAY off. not mine. and your stereo amp need 2 PSU boards. my monoblocks only need one.
1 p channel pcb, 1 n channel pcb, 1 flatamp /input stage pcb, 1 psu board and from this you get 2 boards/ch ....


Quote:
Originally Posted by AudioSan View Post
why the hell do you think aleph2 are monoblocks and not stereo amp? to get it more expensive? NO!!!!!
ur right , they were 3 inchs tall .............
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Old 21st February 2012, 11:22 PM   #428
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by MASantos View Post
If we cut the traces in the middle of the board, then one half could be used for the p channel and the other the n channel right? If yes, then could we add jumpers in the middle of the board? Those who want the 4 pairs use two boards and jumper in the middle, but those who need need less power could use just one input board and one output board per channel with the n and p transistors.

Does this make any sense?
Yes , but we went from a simply setup that gets more complicated by the minute ...

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Old 21st February 2012, 11:24 PM   #429
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Quote:
Originally Posted by a.wayne View Post
1 p channel pcb, 1 n channel pcb, 1 flatamp /input stage pcb, 1 psu board and from this you get 2 boards/ch ....
i don't know about you. but i'm not mounting frontend board and PSU boards on the heatsinks. only the 2 (TWO) outputs boards. in your stereo amp you have twice as many bord! that was the point here. and same bottomplate to mount PSU's transformers and front-end's!
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Old 21st February 2012, 11:26 PM   #430
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by skunark View Post

About the monoblock vs stereo chassis? Monoblocks will be lighter and easier to move, and one would be less likely to have a hernia, so the long run, it's probably cheaper. Even if you looked at the NRE, it's most likely a wash as the stereo chassis will probably need cooling and that added cost will offset some if not most of the cost for the additional aluminum needed for monoblocks. Most will have WAF constraints to deal with first.
OK... first reasonable response for mono's

So i get my honcho's and we 1,2,3, lift into the rack and never touch again ...of course after all is good and done Stereo amp will weight 30KG
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