Millett "Starving Student" hybrid amp - Page 241

No problem, but I don't understand what noisy means. If I pause and turn the volume close to max, there is no noise, it's completely silent. I connected one more heat sink in the upper side, so I guess now it's ok.
I just was paranoid, not to ruin the tubes, being close to the sinks, but if you're saying it's ok, then Ok it is.
Regarding
Nice job, your amp looks very good.

Anyone knows where to find tubes? I need to have some replacements.

Almost done. The build is but I am having a friend do some lettering and pin striping. Sounds good. The switch in the front is for a selector switch for the two inputs on the back.

Will take better pics when the lettering is done.

I am having no luck with anything diy lately. Every time I opened up my senn pc 350's for the hero-mod I broke a wire. Now, I've had two of those sweet little rca tubes in my possession for less than 24 hours and as i was setting up the socket alignment, I dropped one. You can guess what happened...

This new "hobby" (see addiction) has already cost me way more money than I wanted to spend and now one stupid slip up has cost me my day's sanity.

yikes, I didn't think they were that fragile.

You drop it on concrete or ceramic or something?

I don't think anything would happen if it fell on the vinyl flooring in the basement.

If it hit on the tip ...

what happens if you try to give them juice when the vacuum is lost (only out of curiousity

SSMH Tubes 2nd Last photo

After a number of months without problem, my starving student has started acting up. The problem is that sometimes when starting up the left channel tube will begin pulsating, and through a (cheap) pair of headphones you can hear a popping at about 120-130 bpm (checked with a metronome, not exactly scientific I suppose). I opened it up and I didn't see anything loose or burned (also put in another pair of tubes) but is there anything specific that I can look for?

[EDIT]: Even with the left channel tube removed the problem persists, but the left tube is the only on that pulsates.

[EDIT]: I opened it again and traced through the schematic and found that some wire strands had poked through the heatshrink on one of the left mosfet wires and was touching a wire from the other mosfet. Wrapped it in electrical tape and it is working again. I do suppose that is what I get for my rats nest wiring.

The floor I dropped the tube on was covered with hard vinyl tile. I'm never handling tubes again without something softer on the floor. That tube was probably as old as I am. I'm still mad at myself for that one. The socket screw holes were the last ones I had to drill in the case too.

I sent some business your way tomb so hopefully I can get my first amp project back on track.

Weird. I edited this yesterday. Oh well, I made a pretty good funny that I can't quite remember. Something about midgets...

I just finished my amp.
Seems to be working.. I haven't tried them with anything decent yet though.

First, when I touch my pot, I get a loud buzzing noise. This doesn't happen with my CMOY. any ideas?

Second, how bright are the tubes suppose to get? mine get pretty bright. Brighter than I thought they would.
No where near a light bulb though.

I'd appreciate any feedback
thanks

Grounding issue - although, usually it's more of a hum, not a loud buzzing noise. So, it could be something more serious.

I'd review your wiring. In daylight, you should see a few points of orange tips in the tubes - not really "bright" (assuming you didn't use tube LEDs). The unusual brightness may be caused by an error in wiring that could be letting the full voltage of the power supply to go to each tube's heaters. They should be sharing that voltage in series, along with some drop through the resistors.

Measure the voltage at pins 3 and 4, referenced to this diagram:
SSMH Tubes
If you get something a lot higher than 19VDC on each tube, you have a problem! If it's 19VDC, then the brightness is normal. Note that all tube diagrams are referenced from the bottom of the tube! so if you're looking down from the top of the sockets, reverse this numbering. If you're looking at the sockets from underneath, then it's OK.

TomB, let me give you a kiss for the job you did on this tuto ^^

It seems to come and go oddly.
And it's isolated to the left channel.

I think that it might have to do with the fact that the Pot is hanging in the air right now, suspended by it's connections.. instead of attached to a metal chassis.


I came up with 19V when checking, so I think it's fine.

I would, however, like you to explain how exactly they are connected in series. It seems like they are connected in parallel to me...
Otherwise the ground from one would be connected to the input from the other.

http://www.diyforums.org/SSMH/schema...MH-origPCB.gif
Is there another schematic that connects them in series or something?

You're right - I keep getting mixed up with the Millett MAXes. Those heaters are definitely in series.

In this circuit, there's a voltage divider ahead of the MOSFET, I believe. Drop across the MOSFET takes care of the rest of the voltage drop down to the 19V across the heaters. Dsavitsk will probably have to post a more thorough explanation if you want one, though. I'm just guessing.