Millett "Starving Student" hybrid amp - Page 120

If you can get film caps big enough not to have serious bass roll-off, by all means, it's a good idea, just goes against the whole "starving student" thing by price.

I don't have a temp gauge on my dmm, might just use a cooking thermometer though

Ya'll are correct, of course.

However, try purchasing or installing a 150uf to 470uf polypropylene film cap.

Glad we finally got it working Kefka.

Pavel, I love the SSMH inna Linksys concept, but your heatsink is the wrong profile for effect transfer to the air. You are able to get very little natural convection, so even though there is plenty of surface area, it just all heats up and doesnt go anywhere, except by simple radiation and minimal convection from air currents in the room, or at least, this is my guess. Never got too advanced in the relative sciences though, so I could be way off. However, adding grease will only increase heat transfer from the MOSFETs to the heatsinks, so should actually make the heatsinks warmer, not cooler.

Cost, and because Polypropylene caps big enough are huge. Here are some 100uf ones I have, and they are around the size of a 12oz soda can, and most people would still consider the capacitance to be too low for most headphones.
http://img.photobucket.com/albums/v3...rts/1000uf.jpg

Thanks I do love the looks and how it just worked together (everything was pretty much perfect size and shape). So I'm curious why a somewhat smaller pair of heatsinks work better at this than this huge monster? More importantly, is there anything I can do to cool this heatsink down? If it doesn't make much more noise, maybe a fan point to the back... ooh, there's an idea, lets make this into a swamp boat/hovercraft

You need fins that point up, not sideways. When the heat rises, it'll pull from the surrounding, particularly below the sink. The vertical fins gives it free movement without impedance or turbulence.

That said, my sinks get hot too, very hot. I can't recall the exact temperature, but could take another measurement soon.

What Holland said. Ideally, the heatsink would be facing like you had the whole amp on it's side, which might not be a bad test, though I would suspect you could get pretty good improvements from turning it so half of the fins are facing straight up and the other half down. Definitely not perfect, and it wont get a chimney effect at all, but it should do better than now, I think. A fan, even a really slow, tiny one would also make it run much cooler.

I have an idea for a design for this thing but not sure im willing to put in the cash for both amp and everything I want in this thing



I was thinking a remote control line out dock for the ipod, sound reactive LEDs in the two tubes on the side and possibly a built in sub with external speakers (PC speaker style) in the bottom part of the jukebox.

I vote you do it!

That looks amazing! Please post pics if you decide to make it.

Ive done something similar some years ago: Captain’s Quarters » Cowon D2 Jukebox Dock
Compared to the resources and tools I have now its not impossible but still not sure. Living in norway makes getting parts expensive and time consuming

haha - ok - sorry for the dumb questions - i'm still new in this game...but then, why are input caps (on other amps) so low on capacitance (.1-1uf generally from what i can c in the cmoy and pimeta, etc.) - is it because it is a lower level (unamplified) signal? and thus the amplified signal needs a cap with a bigger value?

The output capacitors are there to block DC, however, it will also cut off low freq signals. I'm not certain, but I suspect the smaller capacitances used in the inputs are because the impedance of the voltage buffers are very high, and the cutoff freq is proportional to 1/RC. With a high R, you don't need a large C. Whereas at the output, the R is the impedance of your headphones, which isn't as high, so you need a much larger C to avoid a cutoff freq that's too high (in the audible range).

My understanding of electronics is pretty limited though, so someone else might be able to give a better explanation.

Anyone know the secret to making this amp more Grado friendly?

I am using a 100k potentiometer but the input impedance needs to be much higher due to a large imbalance in the potentiometer. I read about this fix earlier in the thread.

Also there is a hum present that's only noticeable with grados, not my 880. I assume this is normal with this simple of a design.

This interests me as well because even with my Sextett, I never get the volume past 9 o'clock

The best fix seems to be a resistor inline with the input (before the pot). Something on the same order as your pot will drop the signal 6db.

Maybe, maybe not. The last one I made was silent with Grados. What caps did you use in the PS? Upping them to 470u seems to help. Otherwise, if your grounding is less than ideal it can cause some hum. Also, the tubes can pick up noise from nearby components (wrap them in grounded foil to see if shielding them helps). Finally, it is possible that it is amplifying noise in the previous stage that your were previously unaware of.