Thought about an internal bevel on the tubes that pierce the top plate, but so far I prefer the industrial "power station" thang, and the bevels would create a bright detail I really don't want. It's the size of a desktop amp, but I don't want it to come off as an executive bobble.
The overall width and depth is 6", the height is about 10", w/d 150mm, h 250mm, if you are metrically inclined. You can imagine the size from the rca plugs in the corner of the photo.
The overall width and depth is 6", the height is about 10", w/d 150mm, h 250mm, if you are metrically inclined. You can imagine the size from the rca plugs in the corner of the photo.
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You are welcome
One nice looking Cubie you got there. A lot of work went into it - respect !
It's not a problem if your heatsink can't stand the 0.7A bias - especially if your speakers are 8 Ohms nominally and their impedance doesn't have dramatical drops. Transition from A to AB class happens very smoothly thanks to the square law transfer characteristic of MOSFETs which we enjoy here in full extent because no source resistors are used in the output stage and I doubt that you'll hear the difference between the 0.5A and 0.7A idle current.
Call me stupid, but what prevents the aluminum from sliding down the copper chimneys ?
Thinking that there should be some way to make a God-soab-Zilla heatsink out of freebee copper waterpipe leftovers, likely will take me 10 years to figure that one out, as usual. (if I were to relocate to Bač, I'd been sitting on top of a concrete pole 7/7)
I made thermal epoxy from copper powder and slow set epoxy, 1/3 copper powder, 2/3 epoxy. I have noticed on parts that I epoxied and then further worked, that at the temp where you could not hold the piece, the epoxy would loosen and slide. They hadn't cured as long, and if my sinks ever get that hot, I've got bigger issues.
An idea I haven't used yet, is to get a piece of steel rod, cut into two pieces at a greater than 45deg angle, drill out one half and tap the other half. Run a bolt through the drilled half, threaded into the tapped half. When the bolt is tightened, it should slide and become effectively larger diameter. If it happens to be inside a copper tube or an aluminum one, it should expand that tube. If that tube is inside a hole in an aluminum plate, it should get very tight. If a piece of steel wire is wrapped around the tool, it could localize the expansion to create a circular bulge that could act as a shelf. We'll see if I have to try it. What I did not and do not want, are set screws.
Since it is standard plumbing tubing, there may be taps and dies to allow tapping the tubing and threading the aluminum. Dunno.
If aesthetics allow, there are threaded fittings that can be brazed to the tubing. Not an option here. There are ways to solder copper to aluminum. I was not brave enough to try.
-marsupialx's wheel reinvention center for reinventing wheels.
An idea I haven't used yet, is to get a piece of steel rod, cut into two pieces at a greater than 45deg angle, drill out one half and tap the other half. Run a bolt through the drilled half, threaded into the tapped half. When the bolt is tightened, it should slide and become effectively larger diameter. If it happens to be inside a copper tube or an aluminum one, it should expand that tube. If that tube is inside a hole in an aluminum plate, it should get very tight. If a piece of steel wire is wrapped around the tool, it could localize the expansion to create a circular bulge that could act as a shelf. We'll see if I have to try it. What I did not and do not want, are set screws.
Since it is standard plumbing tubing, there may be taps and dies to allow tapping the tubing and threading the aluminum. Dunno.
If aesthetics allow, there are threaded fittings that can be brazed to the tubing. Not an option here. There are ways to solder copper to aluminum. I was not brave enough to try.
-marsupialx's wheel reinvention center for reinventing wheels.
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Driven by the Aikido pre, it is very nice!!! More authoritative. Delicate, with the delicate music I'm listening to. Haven't rocked it yet. I have a feeling that into Maggies, it's not going to be a gut puncher. Didn't expect it to be. Have some Altec 12" woofer/ horn Voice of the Theater speakers that it will rock. Love it so far!!!
Had a scare. Apparently a wire came loose in the line conditioner (little aluminum box on the power cord). Let out some magic blue smoke, fortunately on the power line before the transformer. There is no longer a little aluminum box on the power line. Cool, I didn't like that solution, anyway. Will be back up and running in no time! Will have a temporary connector until I work out a groovy box with switch, fuse, thermistors and capacitor.
Back up and singing. Listening to Baka Beyond "Migrations". Incredibly three dimensional. Sounds coming from behind me. 360deg sound field. (No speakers back there). I thought that the minimal part count might allow for that kind of information making it through unscathed. The sound of 4 transistors per channel. Freakin' great. If the jfets weren't so dang hard to come by. If the store ever gets them back in, I'll try to stock up.
Updated schematic for using Jfet (BL)
Hi,
Just in case someone wants to use the BL type Jfet I have modified Juma's schematics based on his recommendations given to Marsupialx. There was also some minor modifications along this thread so I modified the schematic a little more. I have also gather here the 200VA power supply schematic for the Cap Multiplier provided by Juma in this thread.
Hope this helps someone.
Maybe Juma should bless the mods before anyone goes ahead..
p.s. Very nice and cool amp Mursupialx, congrats !!
BR,
Eric
Hi,
Just in case someone wants to use the BL type Jfet I have modified Juma's schematics based on his recommendations given to Marsupialx. There was also some minor modifications along this thread so I modified the schematic a little more. I have also gather here the 200VA power supply schematic for the Cap Multiplier provided by Juma in this thread.
Hope this helps someone.
Maybe Juma should bless the mods before anyone goes ahead..
p.s. Very nice and cool amp Mursupialx, congrats !!
BR,
Eric
Attachments
Ahaaa... Panoramic.... Geneeerg, komm mal vorbeiii !
Glad you like it marsu - Maggies are not difficult load, it's just a matter of SPL you can get with that kind of power...
Looks OK.
Input cap is not strictly needed, I put it as a precaution against DC leaking source components.
Yes, the main sink/spreader plate (that the LatFets are attached to) get just the right amount of hot after a couple of hours playing. It is a fairly elaborate set-up, with the ten aluminum chimneys going from the top plate, through the main sink/spreader and then going through the plate beneath. The plate directly above the power supply is pierced (drilled) to allow air to move up through the chimneys. The feet are miter cut to allow air to enter the long copper tubes. I left myself the out of adding a fan, but it doesn't appear I'll need to. I don't know the answer to whether the performance would degrade with other thermal situations. I think I recall Papa saying there is no such thing as having too much heat sink.
The amp is not really powerful enough to drive Maggies. It sounds great, but the spl is too polite for serious listening. It really needs speakers that are significantly more efficient, if you want realistic listening levels. I'm looking forward to attaching it to the Altec Voice of the Theater speakers. I am sure I won't get the magic that the Maggies achieve. What I would ideally want are some kick-butt mini-monitors listened to in the extreme near field. That's my fantasy. A largish treated room with a comfy chair and two stand mounted speakers about an arms length away, well away from reflections. Fairly anti-social, and not currently achievable in my domestic situation. I have other amps in the works that will drive Maggies. It's even a bit much for the F5. I got fascinated with the extreme minimalism and small size, and for not very much money I was able to seriously amuse myself for three and a half months. I may have even learned a thing or two. We'll see. It's only my second power amp.
The amp is not really powerful enough to drive Maggies. It sounds great, but the spl is too polite for serious listening. It really needs speakers that are significantly more efficient, if you want realistic listening levels. I'm looking forward to attaching it to the Altec Voice of the Theater speakers. I am sure I won't get the magic that the Maggies achieve. What I would ideally want are some kick-butt mini-monitors listened to in the extreme near field. That's my fantasy. A largish treated room with a comfy chair and two stand mounted speakers about an arms length away, well away from reflections. Fairly anti-social, and not currently achievable in my domestic situation. I have other amps in the works that will drive Maggies. It's even a bit much for the F5. I got fascinated with the extreme minimalism and small size, and for not very much money I was able to seriously amuse myself for three and a half months. I may have even learned a thing or two. We'll see. It's only my second power amp.
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No, it's just a matter of long term reliability - don't let your output devices work at more than 50-55 degrees Cels. and all will be well.