Millett "Starving Student" hybrid amp - Page 123

thanks for the info, much appreciated Ordered 2 of these NOS 19J6 RCA Vacuum Tube - Valve on eBid.net United Kingdom

anyone know how this amp will compare with my dead Darkvoice 336i?

Infinitely better...it works.

When they say they are "sourcing" a new supply, it means that someone is going to start rummaging through old boxes in a dusty warehouse somewhere

All these posts about having trouble finding tubes makes me think I should order some more while I still can.

newb question time...
Since this is my first tube amp, I'm experiencing something new. I can hear when the tube is tapped or vibrated. For example, I have my amp sitting on my desk here at work, and I can hear myself typing when no music is playing. What can I do to dampen them? I've seen the rubber o-rings for sale. Is that what those are for? Do they work well?

You're experiencing tube microphonics. They can range from as slight as ringing when you tap a tube to a crescendo when you just touch the desktop. The defect is in the tube - the mfr installed the getter slap against the plate or some other defect.

It doesn't mean the tubes are worthless - far from it. Some of the best tubes I've heard have been slightly microphonic. However, if they're badly microphonic, they're almost always useless. Good tube rings can minimize this effect, but they won't entirely eliminate it. They can reduce a strong microphonic tube to one that is less sensitive and listenable. However, there's probably no hope for a badly microphonic tube.

In defense of tube vendors, though, keep in mind that there's no way to test for this, short of installing the tube in an amp and listening to it.

Tube microphonics are not necessarily indicative of a bad tube. They can also be indicative of an oscillating tube which generally means a build issue. Put some stoppers (470R to 1K) right on the grid pins and see if that helps.

Those O-rings probably won't help.

hmmm I have more tubes. I'll try rolling them and see if I notice a difference. It's pretty subtle though, and the amp still sounds good.

What sort of build issues? Is it something I could fix or do better perhaps?
I'm not sure I understand what a "stopper" is. So put a resistor between pins 5 and 6 or a resistor on each to ground? Is this something to test with or is it a more permanent solution?

Sorry for the so many questions. I appreciate everyone's help.

A stopper resistor helps to help keep the tube from oscillating or accidentally transmitting RF.
5&6 are the grids (inputs) of the tube
Attach a smallish resistor to EACH pin (with the body of the resistor as close to the pin as practical), then twist the legs together, and solder input to that. signal in now goes to the twisted legs of the resistors, through them to the tube...

I agree though, it sounds more like a mechanical issue: I would try to reduce microphonics with tube dampers and other little tricks like that. Don't spend too much on these, they can only do so much. mcmaster carr loves you a lot, go buy some thick high temp silicon o-rings in a size that are a snug fit on your tube.

yes - tx indeed for the ebid link - they have a za site as well - so just bought 4 tubes off them...radioera couldn't source the tubes - so had to refund me. The store on ebid that sells them is VacuumTubes - i can see 13 19j6 tubes in total there - so if you need some, hurry...
k

Hi DIY Mates..
I am very interested in "Starving Student".. It doesn't look very complicated and its very cheap to build.
I've just build myself GainClone amp using original Peter Daniel's components and I think that it sounds very good but maybe in the future I'll build this amp to..
There is only one problem. Assembly.
I like to have the assembly instruction before I start building amplifier..
Have someone written the assembly instruction to the Starving Student?
Does it exist?

CHeers,
CHarles

I completed my Starving Student a couple of days ago, using OldKing's case design and BOM. What fantastic little amp! It's a shame the tubes are becoming difficult to find, because this little guy is very musical for the money. It seems to be nice match for my late-production sextets.

A big thank you to Pete for this amplifier, and to OldKing for the BOM!

There aren't any assembly instructions, but it's not hard if you take your time. For many people on this thead, this was their first build, myself included. What I did was take about 5-6 hours and redraw the schematic as a wiring diagram. Once I did that, it was pretty simple.

Just thought I would drop in and say hello. I've been lurking since I came across the Starving Student design a month ago. I built my own a few weeks ago and have been enjoying it thoroughly. Like many others I departed from the "starving" aspect of the design since I'm no longer a student (and thus not starving). It took me a while to figure out how to lay things out since I wanted to keep wire runs short but straight, especially the incoming signals. The result is interesting and I'm really liking the volume knob on the top.

Thanks to everyone who has posted here with all the great ideas and information. Particular thanks to bmw & n_maher for design inspiration and tomb for parts.




Now that I'm hooked I'm trying to decide what to build next.

^Welcome to the club omega
There are many designs to choose from.
Are you looking for another PTP build, or just whatever?
Have you looked at the DIY links and resources thread yet?
Nice SS amp. I like the layout and design.

Thanks digger! For the next possible build I have been thinking about the MiniMAX; not sure though.

Before I get too ahead of myself though I want to determine how to hear the difference between tubes. I have 6 total (all side D getters and are RCA tubes rebranded as Hytron) for my SS amp and I have swapped them in and out and honestly have not been able to hear a difference, aside from the fact that some of the tubes are slightly more microphonic than others. With all that in mind I'm not sure then if I would be able to appreciate something like a MiniMAX over the SS, though I would enjoy building one.

omegamajor, if you like the SS, you will love the MAX...you will be able to hear the difference.