Millett "Starving Student" hybrid amp - Page 165

You also might try a temporary, grounded aluminum foil shield around your tubes, to see if that helps -- or even around one tube would be interesting....

(everything I know I learned on Head-Fi)

Actually that reminds me that the tube sockets I bought have spring-shield things included. The collars on the sockets should be grounded through the chasis. I'll pop those shields on and see if that makes a difference.

EDIT: Worked like a charm! Thanks!

Has anyone found a suitable knob for the pot yet?

450-6010


http://www.pmillett.com/images/starving/rds_1.jpg

Sorry I forgot to specify, does that knob work for the pot provided in the BOM for the PCB Starving Student? I looked at the specs of the pot shaft, but I couldn't seem to find any knobs that matched the dimensions.

It works fine with the orginal bom 50k. The shaft is .24"( i measured it with a caliper) so any .25"( 1/4") knob will work. I just installed it in my case and it works fine.

Where does one find copper foil for cheap? Home depot doesnt have it. I havent tried some stained glass places yet.

Hobby stores aka Michael's in the states. Usually comes with adhesive backing as well.

well my lovley proto board arrived today and gotta say you guys did a great job
bad news was that i lost my pouch with all my parts inside. stupid bus driver wouldnt stop while i was running after the bus like a lunatic

You can find the copper PCB blank board at Radio shack for ~$6-7 I believe.

If you are trying to shield something, steel foil from the grocery store works. If you need it for the ground plane - the above works well. Still, I prefer a star ground. - less confusing and less likely to have a short.

Why is it a problem if the lugs are magnetic? (I hope that's not a stupid question!)

Sometimes good to help clean power, magnets may do negative things for analog flow of a signal. Nickel is also ferrous, so I often tend to avoid it also whenever possible.

Magnetic fields induce current. Technically, if the magnets don't move they don't "create" current, but the magnetic field that is present can also affect existing currents. That's a bad thing since your music signal is a current.

SSMH PCB Proto Success

I spent this evening building up the prototype SSHM PCB from TomB.

It took a full evening, but when I connected it up: lovely music!

I have a few technical nits to pass on to TomB, but the build was completely straightforward. I have not yet tackled the casework -- more on that later.

But in the mean time, thanks to TomB, DSavitsk, and as always Pete Millett for another wonderful amp.


P.S. Of course, the heat sinks are temporary (and hot, by the way). And I'm sorry about the photography -- a lifelong handicap.

One thing I learned doing my compact hybrid build I'd like to share WRT case-mounting devices as heatsinking... Depending on case size + dissipation, you may not like the result. Haven't followed this, so don't know the dissipation here or whether there is already a full, target-case proto using case-mounting as heat-sinking (or even if that's the plan

The main heat-producer in the CTH other than the tube is it's LV reg. I measured its apparent dissipation at about 1.5W (not so much). When case-mounted it brought the entire enclosure to about 50C (albeit, a bit smaller enclosure then this PCB build is shooting for)... I'd consider use of a proper heatsink instead, be it internal (w/assoc air holes) or external. When I did this, the case temp dropped nicely.
It's really personal opinion tho because the components are perfectly happy at such temps even if your hands aren't Just something to think about...

tomb - If you think this post is not applicable here, just let me know.