You are only limited to their extrusions, but for most cases good enough for a quick check.
Patrick
Patrick
Once you've built several class a amps, you get to know what size heatsink will dissipate what. Don't really need the math, it can be worked out with your eyes😉
yes ofcourse
and those could have been based on either the experience of others, or calculations
to be honest, just a few years ago it could be really difficult to find a supplier, and info
today, the amount of info and supply is so huge, it makes everything much easier
yes ofcourse
and those could have been based on either the experience of others, or calculations
to be honest, just a few years ago it could be really difficult to find a supplier, and info
today, the amount of info and supply is so huge, it makes everything much easier
yes I do like to state the obvious. Isn't it great how much knowledge there is in this forum alone, let alone the web?
Completed F5 with Dual Toshiba Pairs
Completed today my 3rd F5 with dual Toshiba 2SJ201/2SK1530 pairs with 2SJ74BL JFET degeneration on a CViller 2.0 board. Stock schematic except outputs. +/-24V DC rail, 500VA toroid, massive heatsinks.
Biased up about 1A per MOSFET complementary Pair. Pretty stable. Not very hot. Unbalanced. Single Ended input.
Connected speakers and listened. Pretty strong performance. Has better bass than stock F5. Extremely good resolution and imaging. Overall excellent sound.
Had the option to do cascode at the input stage, but did not want to try too many things in one go.
Amp is dead silent without any input connected. With my preamp connected, there is slight hum. Will go through standard hum trouble shooting and report back.
Will post pictures later today.
Cheers.
Completed today my 3rd F5 with dual Toshiba 2SJ201/2SK1530 pairs with 2SJ74BL JFET degeneration on a CViller 2.0 board. Stock schematic except outputs. +/-24V DC rail, 500VA toroid, massive heatsinks.
Biased up about 1A per MOSFET complementary Pair. Pretty stable. Not very hot. Unbalanced. Single Ended input.
Connected speakers and listened. Pretty strong performance. Has better bass than stock F5. Extremely good resolution and imaging. Overall excellent sound.
Had the option to do cascode at the input stage, but did not want to try too many things in one go.
Amp is dead silent without any input connected. With my preamp connected, there is slight hum. Will go through standard hum trouble shooting and report back.
Will post pictures later today.
Cheers.
What are you doing for heat sinks? I used M&M metals on my standard F-5, which keep it very reasonable, 6.5 inches by just over 12 inches, fins just over 2 inches long, was wondering if these would be sufficient for the dual pair amp you built?
While I usually get matched even for standard F-5, do the 4 outputs on each side require matching I suppose? (Never mind on the matching question, I just saw in cvillers blog they need to be matched.)
Thanks,
Russellc
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don't use force - use a bigger hammer
build bigger amp ;
if you're thinking about amp with +/-100V , you don't need A class amp
it's just insane
build bigger amp ;
if you're thinking about amp with +/-100V , you don't need A class amp
it's just insane
F5 Dual Toshiba Pair - Pictures
Here are the pictures. I have local heatsinks - big profile but not very wide. Therefore cut them and put two of them side by side in a vertical alignment and then connected them up with thick copper flat (which cannot be seen in the pcitures - it is underneath the PCB).
My 500VA transformer seems to be humming a bit. May be because of the current draw or it is a bad piece. I will change tomorrow with a 600VA that I have in another Aleph J and will swap and check.
Here are the pictures. I have local heatsinks - big profile but not very wide. Therefore cut them and put two of them side by side in a vertical alignment and then connected them up with thick copper flat (which cannot be seen in the pcitures - it is underneath the PCB).
My 500VA transformer seems to be humming a bit. May be because of the current draw or it is a bad piece. I will change tomorrow with a 600VA that I have in another Aleph J and will swap and check.
Attachments
Thanks for your gracious help. Yes, it worked out well in the end in terms of turning this around quickly. I had all the components for a while now. Originally I was planning to hardwire the second pair. This board is terrific and elegant. Thanks for a great PCB design.
looks like a good candidate for those who need to use 'double heatsinks' 😉
Anilva, neat and tidy
and I like the 'upside down' mounted boards, placing outputs at lower half of heatsink
I need some help here. My transformer is 500VA, 2 x 18V and caps are 60000uF on each rail in a CRCC config (standard Pass PS schematic). The rail voltages without load measure 25.6V and the transformer is quite. When the dual output F5 boards are connected to the power supply and biased at 1A per MOSFET, the rail voltage falls to 18.4 volts on each side and the transformer hums a little bit, but annoying enough.
Is the rail voltage drop normal? Or is there a problem with the transformer and is getting overloaded? My earlier standard F5 builds had rail voltages around 22v on load and never dropped so much.
I am planning to swap out the transformers and see.
Thanks.
Thanks Patrick. Is the hum a thing to worry about? Was thinking of going back to toroid vendor...
