heatsink calculator
I found this nice little program for calculating thermal resistance while I
was searching for heat sinks for the F5. It will let you know how hot
your going to get.
http://www.frigprim.com/online/natconv_heatsink.html
I found this nice little program for calculating thermal resistance while I
was searching for heat sinks for the F5. It will let you know how hot
your going to get.
http://www.frigprim.com/online/natconv_heatsink.html
If things don't work out you could always attach the mosfets to the heatsinks via a slab of copper. I've never actually done this but other people who are more well informed than I seem to think this works well.
thanks guys. i'm a 5 min. drive from http://www.discountsteel.com/. i've DIYed a few aluminum chassis now with cheap drop cuts and a nice Freud non-ferrous 10" circular blade. so buying a bulk length of aluminum U-channel shouldn't be a problem. McMaster Carr also has some: http://www.mcmaster.com/#aluminum/=3xqk2h. these could be mounted on the flat side of my new heatsinks. i have enogh thermal dope to last me a lifetime.
i suppose i could double up the heatsinks, flat to flat for a total of 8 heatsinks, but i'm building a bridged pair to power my piggy ATC SCM12 and would need x2 the heatsinks. the front-end will be a balanced B1 and Benchmark DAC1. i have CNC baltic birch lying around for a pair of uFonkens that still needs to be glued up as well for the FF85K 3" drivers. i was planning on partnering these with an active subwoofer. bridged would not be needed for the uFonkens though.
i suppose i could double up the heatsinks, flat to flat for a total of 8 heatsinks, but i'm building a bridged pair to power my piggy ATC SCM12 and would need x2 the heatsinks. the front-end will be a balanced B1 and Benchmark DAC1. i have CNC baltic birch lying around for a pair of uFonkens that still needs to be glued up as well for the FF85K 3" drivers. i was planning on partnering these with an active subwoofer. bridged would not be needed for the uFonkens though.
So the sinks arrived today. I could find nothing bigger than this in the whole city, I'm really hoping these are enough for a stereo F5. They measure 10" x 7" and are 3" deep. The larger fins attached to the spines are 2" deep, and the mounting base and the spines are 1/2" thick, and they set me back $60 a pop. Anyway we'll take our chances with these guys and figure things out after that.
An externally hosted image should be here but it was not working when we last tested it.
Thanks for the vote of confidence Uriah 🙂
I'm cooking one with a 30 watt soldering iron to try and figure out what the operating temp will be, Pushed the iron into one of those little round channels near the base. It'll not be totally accurate, but I guess it should be indicative.
I'm cooking one with a 30 watt soldering iron to try and figure out what the operating temp will be, Pushed the iron into one of those little round channels near the base. It'll not be totally accurate, but I guess it should be indicative.
Should be less than 0.50C/W each. (compare to Seifert KL187)
Very pretty heatsinks, i'm almost jealous.
Much nicer to watch in full size : http://www.imgx.org/public/view/full/19239
Very pretty heatsinks, i'm almost jealous.
Much nicer to watch in full size : http://www.imgx.org/public/view/full/19239
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Aww, gee, thanks. I abandoned the test as the thermal transfer was terrible, I'll try the real amps to check it out - once I get my head down and build it up. I now have pretty much everything I need to build it except the solid teak logs for the chassis...
try gluing the thermistor to the drain lead right next to where it exits the package.
Oscillation?
Hi
GOt the F5 working very nicely about a week ago with the generous help of members. The day before yesterday I was hearing a very slight buzz from one of the chassis. Last night it was a bit louder and I thought was coming from the transformer. I tightened down the screw and this morning after 1/2 hour warmup and then listening for 1/2 hour, I noticed it again. Is this oscillation? I don't have any filtering on the inputs. I can install that tonight. Is this coming from the transformer? Thanks
Jan
Hi
GOt the F5 working very nicely about a week ago with the generous help of members. The day before yesterday I was hearing a very slight buzz from one of the chassis. Last night it was a bit louder and I thought was coming from the transformer. I tightened down the screw and this morning after 1/2 hour warmup and then listening for 1/2 hour, I noticed it again. Is this oscillation? I don't have any filtering on the inputs. I can install that tonight. Is this coming from the transformer? Thanks
Jan
I had the same problem recently, and I just loosened the mounting screw, and problem solved
Point is that even a very small and inaudible buzzing can set the whole box in vibration
And THAT can be very audible
Might not be good fore the electronics either
You could try and mount some soft rubbers underneath the trafo, and between trafo and mounting plate, and tighten it loosely
Actually I try to avoid using the metal mounting plate, and use brass screw, but thats a different story
Anyway, as far as I understand F5 may be sensitive to interconnects
Point is that even a very small and inaudible buzzing can set the whole box in vibration
And THAT can be very audible
Might not be good fore the electronics either
You could try and mount some soft rubbers underneath the trafo, and between trafo and mounting plate, and tighten it loosely
Actually I try to avoid using the metal mounting plate, and use brass screw, but thats a different story
Anyway, as far as I understand F5 may be sensitive to interconnects
Sounds like lamination buzzing as the windings heat up. Not much you can do. The better transformers are dumped in a pressure lacquer tank for a few days before being covered and sold.
potting
If that's what it is, I thought it could be fixed by potting. I've never done one myself. But, I think I read somewhere around here that it can be DIY.
However, I don't know specifically what potting material to use or where to get it.
Steve
If that's what it is, I thought it could be fixed by potting. I've never done one myself. But, I think I read somewhere around here that it can be DIY.
However, I don't know specifically what potting material to use or where to get it.
Steve
Member
Joined 2002
I think i might jump in on this bandwaggon 🙂 Might order 2 f5 boards from P-Daniel,
Quesitons tho.
Psu voltage per rail ? I think im running 18V on my mini a's will this work ?
will be good with Mini a's?
Going to use with ribbon tweeter.
Quesitons tho.
Psu voltage per rail ? I think im running 18V on my mini a's will this work ?
will be good with Mini a's?
Going to use with ribbon tweeter.
Not too sure about the 'potting' of a Txformer after the fact. You need to uncover the winding cover sheets and somehow find the right potting compound. I have no idea what that stuff actually is, but it'd need to be something that can't attack the enamelling over a long period and also not become porous or affect the dielectric poroperties of the enamel.
I'm sure a transformer winding outfit could help you.
I'm sure a transformer winding outfit could help you.
