Roender's FC-100 prototype and builder's thread - Page 54 - diyAudio
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Old 13th September 2012, 10:27 AM   #531
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by AndrewT View Post
................Limiting the front end maximum output such that the output stage never approaches clipping makes for a better "sounding" performance if you like listening at high powers.
I should add that listening at low powers never allows the amplifier to approach clipping (both current and voltage clipping) and thus the amplifier always performs as designed/intended.

I wish I could remember who said:
"All amplifiers that do not clip and have the same frequency response sound the same."
or words to that effect.
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Old 23rd October 2012, 12:05 PM   #532
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Gentlemen, I am currently performing a group-buy for the FC-100 in the German ANALOG-forum, and I am discussing with the German DIYers,
how a sufficient, low-cost DIY-case for the FC-100 can be built.

We are currently settling on this solution:

Click the image to open in full size.
http://www.abload.de/img/image11ksar.png

Buy two ALU-plates, serving as side-panels, dimension: about 380x140mm, 8-10mm thick.
Connect heatsinks, whatever is available and adequate, for example this one, cut in the middle, resulting in 200x125x40mm:

Click the image to open in full size.
http://www.abload.de/img/kk24sjw.jpg

to the "hot-spot" (where the NJL-transistors are mounted) on the outer side of an ALU-side panel and the FC-100 PCB to its inner side.

I think that this solution will do it - and is low-cost as well.

Best regards - Rudi_Ratlos
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Old 23rd October 2012, 01:16 PM   #533
AndrewT is offline AndrewT  Scotland
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use a thinner side panel, 2mm to 3mm would be sufficient.
Bolt the heatsinks to this side panel.
Mark out where the output devices will sit.

Remove the side panels and cut holes right through, so that the devices can be mounted in direct contact with the sink. Where the side panels bolt to the sinks will give a bit of extra dissipation to the sink and thus the devices will run a bit cooler.

Adding a plate between the devices and the sink does not always result in better cooling.
I think most arrangements with an intermediate plate will actually be worse than without the plate.

BTW,
you are using remote servers instead of attaching.
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Last edited by AndrewT; 23rd October 2012 at 01:19 PM.
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Old 29th October 2012, 05:18 PM   #534
lucylu is offline lucylu  England
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Thanks,,I have been thinking about a case as i will start again on my fc 100,this looks cheap and simple regards john
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Old 29th October 2012, 05:34 PM   #535
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Andrew: I made the experience that the cooling solution that I suggest, does its job very, very well!

Have a look at my construction (attached picture).
I am playing music very loud, for hours, and the 10mm thick ALU-plate does not even get "hand-warm", as well as the attached heatsinks do not!

I applied a layer of thermal grease between ALU-plate and heatsinks and screwed them very tightly together using 12 bolts (per heatsink).

I therefore believe that my construction even is "thermal overkill".
A 6mm thick ALU-plate with heatsinks attached to the hot-spot (where the NJLs are mounted) will do it as well.

Best regards - Rudi_Ratlos

P.S. Lucylu: go on, please!
Attached Images
File Type: jpg Eloxiert 001.jpg (395.9 KB, 666 views)

Last edited by Rudi_Ratlos; 29th October 2012 at 05:37 PM.
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Old 29th October 2012, 08:37 PM   #536
DRZ1 is offline DRZ1  Canada
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Sure it work well. I have always did that on my previous projects.

I am now building a new FC-100, and have ordered a case on eBay, and i think it will be on the limit for the heat sink... Wait and see
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Old 9th November 2012, 02:46 PM   #537
lucylu is offline lucylu  England
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Default Heatsinks

Picked these two 200 x 160 very cheap off ebay ,at last a start on the case john
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Old 9th November 2012, 03:08 PM   #538
AndrewT is offline AndrewT  Scotland
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They look similar to mine.
I have a pair of 250 high by 200 wide by 40mm thick. 20off 30mm fins on a 10mm backplate.
At the full 185mA and supplies at +-42Vdc (quite a bit higher than using a 25Vac transformer) the sinks are too hot to hold longer than about 5 seconds at the cooler edges.
The lower voltage of the standard build and the 160mm high will probably end up at about the same temperature.
The 3pair output stage is very robust and can be very hot and yet still stay within an acceptable, good reliability SOAR.
Don't be too afraid of a sink that is just a bit too hot to hold.

Too hot to touch is a bit hotter.
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Old 15th November 2012, 11:48 AM   #539
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Gentlemen, I have sent you an EMail an hour ago telling you about the mishap (error) in my FC-100 PCB layout.
I have posted a bug-fix ("free-air solder-style") in my EMail.

Another, more professional bug-fix would look like the one in the attached image.
Cut the trace at the position labelled with the pink "x". Drill a new 1mm-hole into the PCB (this PCB is not the MonaLisa !)
directly underneath the cut and solder the lower lead of the MKP1839/1F into this hole.
There may be even "better bug-fixes" (?).

I once more regret for causing you any inconvenience.

Best regards - Rudi

P.S. Affected by this "mishap" are those of you, who regularly drive the FC-100 into clipping.
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Old 16th November 2012, 09:23 AM   #540
lucylu is offline lucylu  England
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Thank you ,no problem regards john
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