Buzz's intepretation of Pete Millet's Starving Student Headphone Amp

[BuzzK]

I was selling a bunch of odd tubes and have a few NOS 19J6 medium-mu twin triodes left.

Trying to figure out what they were good for, I discovered Pete Millett's "Starving Student Headphone Amplifier" - a hybrid project using MOSFETs driven by the triodes. Kinda like a NYAL Moscode amp, only smaller.

Here is a link to photos, and from there, complete parts list, schematic, etc. http://www.pmillett.com/starving_gallery.htm

I thought . . . perfect! . . . since I'm now a starving student (paying for 3 in college, 3 cars, etc.) I'll build this.

I found this cute little enclosure from China on eBay for about $15 delivered. It's tiny, and nothing really fits right without some real effort, but I couldn't resist the challenge. The 48V external power supply cost something like 12 bucks delivered from China as well.

For example, I dug up a pair of RCA input jacks from my junk box, molded into a single piece of plastic, that will fit in the holes. I made a standard SPDT switch fit into the aperture (JB Weld is gonna help here), and the power jack will be soldered to a PCB that will be anchored to the bottom panel. I had a small stereo jack that will work in the hole provided, but putting a 1/4" standard jack will require some metal work.

Anyway . . . 'cause I really hate doing my homework, and I have ADHD . . .

 

[BuzzK]

Here is a rough layout . . .

 

[RWood]

Looks great...keep 'em coming. Hunter S. Thuompson would have been proud!

 

[BuzzK]

Yeah, looks like "Gonzo" Audio . . .

 

[Lavane]

Cool! I went the lazy route with mine. Looks to be about the same size. Mine came with some God awful 6j9's I swapped out with some GE JAN's, cant remember the number, but it sounds good. Same thing, tubes driving sand. Its amazing how much they stuffed into such a small box. Hope you have tiny fingers.

 

[BuzzK]

Hope you have tiny fingers.

My wife says I have "Donald Trump" hands. I wonder what she means?

 

[Lavane]

My wife says I have "Donald Trump" hands. I wonder what she means?

Im gonna be watching your build. Mine Is chock full of smd parts to fit everything in the case. Stuffing small chassis is something I have problems with.

 

[Smeed]

I've had one of these for years, it was built by Whiplash audio and I've used it for my AKG K701s. It's a great amp and I've never had an issue with it.

 

[BuzzK]

Parts came in today. Ready to wire.

 

[derekva]

My 'Starving Student' build turned out to be a bit more gluttonous than starving as I splurged on Front Panel Express bits for the chassis (although I did have a 20% off coupon code so it wasn't outrageous). Also found a good use for some Russian mil-spec polystyrene film caps and some Cinch micanol 7-pin tube sockets that had been sitting in my parts drawer since the second 'W' administration. The only regrets I have is (1) I forgot to order some nice wirewounds for the 48V step-down and had to use some vintage 3W films (the reddish brown resistors) that measured OK but may or may not last too long and (2) in hindsight I should have changed the back panel layout to have the DC line in on one side (directly behind the power switch) and the RCA jacks on the other side (directly behind the volume control) as it would have been a cleaner layout underneath.

All things being equal, I think it sounds about 2x better than the original Millett Hybrid Headphone amp I built years ago. Noise floor is much lower and there is an overall lushness that was lacking.

-D

 

[BuzzK]

Still working on the inside . . .

 

[derekva]

Are you sure you will have sufficient 'POEWR' to drive this, Buzz?

-D

 

[BuzzK]

A little acetone will take care of that nicely.

 

[BuzzK]

Well, the acetone wouldn't dissolve it . . . I'll bet it was an epoxy-based ink. So a little sandpaper and a magic marker did the trick (I wanted to erase the erroneous voltage).

Anyway, it's done. Admittedly, it's not my neatest work "under the hood."

I've added a pic of it turned on. The LED matches the color temp of the filaments. Kinda nerdy, huh?

And also a size comparison with my earlier tube HPA (not a hybrid).

Buzz

 

[Lavane]

Very nice. Tou got it all crammed in there rather nicely too.

 

[Kegger]

Nice build Buzz,

Has anyone compared this with other headphone amps? (If so what was your thoughts)