Merry Christmas Sir Rothacher
"Somehow it makes me feel better knowing the Dude is out there....."
This is a great idea ! It would fit perfectly since the heatsinks I’ve used in my ‘Pass’ chassis are very similar to the size of the Dell cpu cooler. One could fix the pcb just beside the cpu cooler and then use 3 flying leads (2-3 inches long) to connect the Mosfet. I’m not very good w mechanics so I tend to use the KISS principle...lol
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I discover another problem.
My input power dc range from 21V to 24 v .
when i set the bias current of 1.8 amp at 21V dc but when the dc input is 24V, the bias current is about 2.4 amp. the heatsink is too hot at 2.4 amp .
Any suggestions to solve the problem ?
I am contemplating this
120W 19V 6.15A Charger Adapter Lenov (end 4/21/2020 3:44 PM)
will a regulated dc solve the problem ??
My input power dc range from 21V to 24 v .
when i set the bias current of 1.8 amp at 21V dc but when the dc input is 24V, the bias current is about 2.4 amp. the heatsink is too hot at 2.4 amp .
Any suggestions to solve the problem ?
I am contemplating this
120W 19V 6.15A Charger Adapter Lenov (end 4/21/2020 3:44 PM)
will a regulated dc solve the problem ??
You'd have to figure why your DC supply varies this much.
Perhaps a better quality 24v supply and back off the bias a little to keep heat sink temperature down.
Maybe you need a step-up/step-down transformer to keep your AC balanced?
Something like this: 1200W 120V Power Conditioner Automatic Voltage Regulation AVR AC Surge Protection 4 Outlets (LC1200) | Tripp Lite
24V implies (for 8ohm load) about 3.0 to 2.7A of idle current; any less is a waste of voltage.
The resulting 72 Watts of heat is a LOT to get rid of with ordinary heatsinks, even fans.
Cutting down to 19V (the Dude's original plan!) suggests 2A-2.1A of idle current and a much more manageable 40W of heat to get rid of.
Don't run 24V!!
19V is only 2dB less maximum output than 24V. If you are clipping, 2dB "more" is not going to cover your hunger for power.
If you "must" run 24V, be ready for heroic cooling. More even than a 200W AB amplifier, because a 200W AB amp will have many output devices, this only has one; spreading the heat around allows less heat-spreading mass in the mounting surface.
The resulting 72 Watts of heat is a LOT to get rid of with ordinary heatsinks, even fans.
Cutting down to 19V (the Dude's original plan!) suggests 2A-2.1A of idle current and a much more manageable 40W of heat to get rid of.
Don't run 24V!!
19V is only 2dB less maximum output than 24V. If you are clipping, 2dB "more" is not going to cover your hunger for power.
If you "must" run 24V, be ready for heroic cooling. More even than a 200W AB amplifier, because a 200W AB amp will have many output devices, this only has one; spreading the heat around allows less heat-spreading mass in the mounting surface.
Use a simple CRC filter to loose a bit of the voltage. A 2.2 ohm resistor will drop 5 volts with this current. It will generate about 10W. Take a 20 W version or better: buy a couple of cheap 3W and combine them (that is what I did).
You will clean up the voltage too.
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There are always advantages and disadvantages to every approach.
Having said that, analog supplies are usually quieter than switching supplies.
The difference is lessened the higher the circuits PSRR is.
IIRC, the ZEN 5 had a near 0 PSSR and required a regulator, and would not be a good candidate for a switching supply without the regulator.
The MOFO has a very high PSRR due to the low output Z of the follower and the high local feedback.
To me this would be the least likely candidate for an exotic supply.
As always, it would not hurt to experiment.
As always YMMV.
Pass DIY Addict
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I have had good results with Dell branded power bricks. I'm using a 19v 12A Dell brick for my MoFo amp and it works great. Same with my ACA amps. I've purchased a few $10 power bricks from China that have long since been tossed in the trash for too much physical and electrical noise. The key is to purchase SMPS that are known to the audience here, otherwise you are on your own in terms of quality and problems. The more recent Meanwell supplies seem to perform well.
There is much less guesswork in a linear supply. It always works and is nice and quiet.
There is much less guesswork in a linear supply. It always works and is nice and quiet.
Pass DIY Addict
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It's a Dell GA240PE1-00 that is rated at 19.5v, 12.3A, 240w. My MoFo draws about 120w and it gets only mildly warm. It is also nice and quiet.
The plug is a 7.4 x 5.08mm male jack. You'll need the appropriate female jack to accept this plug. I purchased a few of these:
7.4 x 5.08mm Female Jack. The fatter end fits into a 1/2 or 5/8" plastic wire clamp that can be fastened with a screw.
An image of my build is here.
The plug is a 7.4 x 5.08mm male jack. You'll need the appropriate female jack to accept this plug. I purchased a few of these:
7.4 x 5.08mm Female Jack. The fatter end fits into a 1/2 or 5/8" plastic wire clamp that can be fastened with a screw.
An image of my build is here.
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Pass DIY Addict
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Yup, no problems at all using one PSU for both channels. Of course, you can splurge and get one for each channel. Either way, it'll work great. I was skeptical at first that the wire from a single female jack would handle the current draw from both channels but it's fine. The wire doesn't get warm at all.
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Pass DIY Addict
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Sorry that I don't have a source for you. I found three of them at a local flea market over the span of about 3-4 months. They were originally 10" long and I cut them down to 5" chunks. Two for my MoFo, four for my Aleph-J. I keep looking, but haven't found any more lately. With 3A bias on a 19.5v supply for the MoFo, those sinks bake off ~60w of heat each with only a ~30c temp rise. I'd love to get my hands on more!
Received my FD841 and they both work.
Since I bought them used (15 usd for 2) I wanted to check if the liquid in the heat pipe did not evaporate. I simply lay them on the side and used my heat gun to heat up the bottom copper plate. Within about 1 min all the fins from both heatsinks got warm and the heat distributed equally over the entire heatsinks fins. Once I closed the heat gun I quickly touched the bottom copper square and it was barely warm..maybe 40C. These units seem very well engineered.
I’m a happy camper
Eric
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what do you think about the "balanced MoFo" presented here? No need for output coupling cap.
Mosfet amp transformer output - The Paper Horn by Inlow Sound
Mosfet amp transformer output - The Paper Horn by Inlow Sound