First Watt F5

For the three and more legged things
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colin.hepburn
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Post by colin.hepburn » Mon Oct 15, 2012 3:02 pm

Nick wrote: If you want I will find you the chap I bought the devices from.
Yes pleas nick that would be Handy
I can get the F5 boards from Diy audio shop I had hoped I could have got a set of the semiconductor from the shop as well would make sense to supply then with the boards as an option
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Post by Nick » Mon Oct 15, 2012 3:36 pm

The diyAudio user is h_a

My mistake, he is from Austria
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colin.hepburn
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Post by colin.hepburn » Mon Oct 15, 2012 4:58 pm

Nick wrote:The diyAudio user is h_a

My mistake, he is from Austria
OK thank you nick
Found him
Right one more bit of advice required if that’s ok pleas
Heatsinks Pair
For one F5 amp which Conrad Heatsinks would you pick from?
1. MF35-100 Flat C/Watt for 80 °C rise Thermal Resistance 0.28
2. MF35-151 “Flat C/Watt for 80 °C rise Thermal Resistance 0.21
http://www.conradheatsinks.com/products ... 0_350.html
Or the smaller MF30-1F-75 Flange Thermal Resistance 0.37

http://www.conradheatsinks.com/products/single_f.html
Or would you pick a different spec from the range
Thanks
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Post by Nick » Mon Oct 15, 2012 5:55 pm

Well, the idle current is 1.3A, 24v, so thats 31W a device, or 62W a a side. If you aim for a device temperature of 45C or so, and 25C ambient, thats 20C, So that would mean you are looking for a 0.32C/W heatsink, So from that list I would go for the 0.28C/W one. But remember the amp sounds best with the devices hot, so using too large a heatsink is to be avoided. If its a bit cool, you can always nudge the current up a bit if you use a 300VA transformer as that will have loads of spare capacity.
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Post by Mike H » Mon Oct 15, 2012 6:52 pm

Ah yes FET's are another pail of whelks altogether :D
 
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Post by pre65 » Mon Oct 15, 2012 6:58 pm

Mike H wrote:Ah yes FET's are another pail of whelks altogether :D
Yes, and I'd be pale if I noshed a bucket full. :wink: :lol:
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Post by colin.hepburn » Mon Oct 15, 2012 7:21 pm

Mike H wrote:Ah yes FET's are another pail of whelks altogether :D
OK thanks nick
Yep the Transformer I have is indeed a 300VA 18-0-18v
Do I get the feeling you guys are tiring to steer me way from the F5 idea then :) :shock:
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Post by Nick » Mon Oct 15, 2012 7:27 pm

Cant say about anyone else. I am suggesting that some of your suggested money saving decisions may be a mistake (IMHO). Using the power supply and amp boards and transistor sets makes it a much simpler build and removes a number of things that could go wrong.
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Post by pre65 » Mon Oct 15, 2012 7:34 pm

Colin, if you get the Australian heatsinks what are you using for a case ?
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colin.hepburn
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Post by colin.hepburn » Mon Oct 15, 2012 8:31 pm

Nick wrote:Cant say about anyone else. I am suggesting that some of your suggested money saving decisions may be a mistake (IMHO). Using the power supply and amp boards and transistor sets makes it a much simpler build and removes a number of things that could go wrong.
Well yes
I am just looking at what’s involved in the F5 project at the moment see if it’s viable for me to build it as I don’t want to go down the same path as I did with the valve amp I feel I went the wrong way there
Right So far the F5 pcbs and psu Boards from the diy audio shop
http://www.diyaudio.com/store/amplifier ... oards.html

Matched Semiconductor sets from chap in Australia if he still does them
Heatsinks from Conrad
I find this confusing to work out so I always think go for the biggest to be safe but was just tiring to shave some cost of shipping and would prefer the flanged version MF30-1F-75 for an easier build but this one maybe to small @ Thermal Resistance of 0.37

PSU TX I have already 300VA 18-0-18
So biggest cost is heatsinks and maybe psu caps
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colin.hepburn
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Post by colin.hepburn » Mon Oct 15, 2012 8:38 pm

pre65 wrote:Colin, if you get the Australian heatsinks what are you using for a case ?
Well case build would be based on the retailed F5 and the one nick and most others build using the heatsinks as the back bone of the case yes I know it’s easier to say than do but how hard can it be to drill some holes and bolt it Together :) :shock:
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Post by pre65 » Mon Oct 15, 2012 8:49 pm

If you use the Modus case that Nick linked to it's got the heatsinks already there. :wink:
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colin.hepburn
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Post by colin.hepburn » Mon Oct 15, 2012 9:01 pm

pre65 wrote:If you use the Modus case that Nick linked to it's got the heatsinks already there. :wink:
Good point mist that one need to check shipping cost on that
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Post by Nick » Mon Oct 15, 2012 10:14 pm

Yes, that was the point I was trying to make, the modushop case is complete and the heatsinks are just fine for the F5. Peters boards do not use flange mounting, even though the Pass originals did.
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Post by Mike H » Tue Oct 16, 2012 12:04 am

Not at all trying to put you off FET's Colin, I like 'em :D
 
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