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Old 16th May 2011, 06:49 PM   #81
qusp is offline qusp  Australia
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hehe welcome, you have some reading to do if you ask this question. not the case, although i'm almost certain the answer is no, but i dont think even the obscenely large cases Papa has been playing with lately, will house and cool 5 x f5 with integrated power supply for all.

are you aware of exactly how much heat 5 class A power amps will put out at idle?. you will need minimum 1.5-2kva of transformers, 300000uf capacitance and also, just to make sure you understand the nature of the f5, in 5.1 it will sound amazing, but a standard f5 is generally 25-30wpc, while dissipating considerably more than that again into the heatsink. not really what people usually think of for a home cinema.

now if you are cool with that and you are ready for the custom case needed, have the skills and are prepared for many many hours of planning before you even order your first part, then great power to you and dont forget pictures.
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Old 16th May 2011, 07:33 PM   #82
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As I said, I'm new here. I knew those large heatsinks on Class A designs are not for looks! But, judging by your comments, clearly this would not be a place to start my DIY hobby. Thanks for your help.
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Old 16th May 2011, 07:42 PM   #83
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yikes , clockwise or ccw depends on which way he installed the pots !!!!! right now unless he uses a meter to zero them first he has a 50% chance of smoke or no smoke .

you can zero the pots by using your meter across r3 & r4

cheers Woody
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Old 16th May 2011, 07:51 PM   #84
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Thanks, I'll use R3 & R4.
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Old 16th May 2011, 08:28 PM   #85
6L6 is offline 6L6  United States
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Quote:
Originally Posted by gsindela View Post
But, judging by your comments, clearly this would not be a place to start my DIY hobby.
Actually, it's a great place to start the hobby... the F5 is a great amp, easy to build, simple to diagnose, and sounds fantastic. Many people have cut their teeth on this amp, with great results!

It is a truly great project, which is why it's so popular.

But if your requirements are for multi-channel only, there might be a different project out there for you. For example, a 5-channel chipamp might be more appropriate.
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Old 16th May 2011, 09:13 PM   #86
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Isn't it also possible to bias the F5 lower (so it doesn't need so much heat sinking -- but at the cost of some SQ), so it's more of a class AB amp?
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Old 17th May 2011, 04:30 AM   #87
6L6 is offline 6L6  United States
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Don't lower the bias, instead use a fan or two. Moving even a little air on a natural-convection heatsink makes a very big difference.
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Old 17th May 2011, 09:53 PM   #88
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I have to agree with 6L6 on this one.
Fan idea preaty good mosfets sound better at hi bias.
(At least the Tosh I have tried)

As I am planning on dubling the boards on a single heath sink I got a simple controll made up with parts you may have already if building the F5 that may came handy.

I have tried CPU fans and even the noisy ones are silent at 1/2 off V nominal

Just set pot for fan to start tiking over at wanted C the hotter the faster.
and it only start up when you want to so no long time waiting for temperature/ offset to stabilise.


I am Not shure about the next bit could some one cek the math please?
On the other hand you may decide that your normal listening level is quite low
say for example 6 V
6V / 8 (?) homs speaker impedence = 0.75 A The amplifier will stay in class A up to 4.5 W.

I have 4 homs speakers and 32V rails at the moment I have dubled the number of mosfets and current bias is set at 3A

I have decided on a listening level of 12 V and therefore 12/4 = 3
3X12 = 36 W class A

It will pump out much more than this as it leave class A.

One thing I have noticed sound is better at hier voltage.
Don't get me vrong F5 is already realy good but at 32 V rails is a bit more open a bit faster attack.

So fans are worth looking in to and you could use 2 in series and skip on the LM317 bit of the drawing
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Old 19th May 2011, 06:48 PM   #89
6L6 is offline 6L6  United States
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Bksabath, with as much heatsink as you have, are the fans actually required? Just curious.
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Old 19th May 2011, 08:40 PM   #90
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Quite right
And not at the moment

But would you realy think that she let me keep the mule in the livingroom for long especialy in our litle UK cubiholes.

Not all can afford mannors so

Option 1 separate suply and 2 small towers

2 as option 1 but balanced (pulling 3 A at 32 V X 4 quadrants = 384 W dissipation )

Option 3 as option 1 but By amp 2 towers 1 for left and right speaker but 2 F5 in each
384 dissipation

Option 4 as 0ption 3 but 2 balanced F5 = 700 W dissipation

now we are talking cpu fan X3 in series tiking away at 70 %

This based on 12 V class A requirment on 4 Homs Puke speakers so 3 A bias.

Option 5 6 and 7 no worth mentioning and off topic

At times I do sound to put it mildly whakooo but is just my brain running away and asking the next question even before the first one was answered.

By the way is it wort the effort?

Yes absolutley the mule sound fantastic just cant get enough of it
Even started buiing the same copy of records I already have becose the old ones are a bit worn and then having to look for the same all over again because the original Shanakie sound a milion time better than the CBS pressing.

And this with a questionable MC pre and a SS1 Akay duda.
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