DIY Headphone Amp #3 - Starving Student Hybrid

PJPro

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Jan 21, 2008
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I'm expecting delivery of this kit in July. Watch this space.

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Starving Student Millet Hybrid
 
tractorboy:
Like: the shiny valves

Dislike: the curtain rail brackets

Yeah, I agree with you. I really wanted to do something with valves but was a bit worried about the high voltages usually involved. The Starving Student is a hybrid and was effectively designed to negate the need for high voltages by relying on integrated circuits to assist with the amplification. This particular variant is PCB based rather than point to point (P2P)and was designed by some of the posters on Headfi based on the Peter Millet original. I did consider the SOHA 2 but this Starvinbg student is a complete kit.

As for the heatsink, some love it others hate it. I'll reserve judgement for now. Clearly, it is easily replaced by a different style like this one....
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Anyway, hopefully it'll make an for an interesting build and sound good too. With a bit of luck, I may even inspire someone else to have a go!
 
Hi PJ. Can't wait for the build to start. A little question, whether you can answer it now or will have to wait until the build is finished to answer it doesn't matter. The Starving Student has two valves and is a hybrid. The valves poke out of the top and there is a large heat sink on it. The Musical Fidelity X-CANS and V8P are also two valve hybrid amps. They come in metal boxes with similar finishes to that seen on the above photo with the ridges in the metal. Both X-CANS get warm during extended listening, but not hot. They do not get as hot as the Rega Mira amp. How hot do you expect the Starving Student to get? Any idea why it appears to need far more ventilation that the X-CANS?

Thanks.
 
My guess would be that the two you mention come in heatsink cases.

I'm not sure how hot the MOSFETs will get but there appears to be amble heatsinking in place. I'll report back once the build is comlete.
 
Look forward to this, mmm valves...

Enjoyed your earlier projects too, great work!
 
Thanks Martyp.

I hope to show others that this DIY isn't too difficult. It adds a whole new dimension to Hifi. And it's much more satisfying listening to something you've made rather than just gone out and bought. You can get decent results for not much money, with not a lot of skill required.
 
idc:I bet that if you build it rather than buy it it WILL sound better!
Agreed. That's why I haven't majored too much on how my builds so far have sounded.
 
PJPro:idc:I bet that if you build it rather than buy it it WILL sound better! Agreed. That's why I haven't majored too much on how my builds so far have sounded.

What does your present setup comprise of? I remember from other posts you are a bit if a headfier!
 
flac->foobar2000->WASAPI->Xfi Extreme Gamer->True Colour Industries Coral->Modded Beresford TC7510 DAC->Lindy Premium Gold->GS Novo->Grado SR80s
 
PJPro:flac->foobar2000->WASAPI->Xfi Extreme Gamer->True Colour Industries Coral->Modded Beresford TC7510 DAC->Lindy Premiuim Gold->GS Novo->Grado SR80s

Had to google half of that to find out what it was!
 
I must admit that Lindy are a bit of an unknown make but I find the interconnects OK...although they were free.

If anyone is interested, find them here.
 
Looks as though the kit isn't coming any time soon. My ETA would be early to mid August.
 
Looks like the kit will be here in a couple of 2 weeks.....not far off my estimate.
 
Well, I received an email stating that the kit was shipped from the US on the 14th August. Not sure how long it's going to take to get here but I'm expecting it to arrive in the next week or so at most.
 
The kit arrived this morning. [Rubs hands]

Hope to start construction shortly, though not this weekend.

It all looks very promising......and I can't remember the last time I heard a valve anything.
 
Err. I've finished this and listening to the amp now. I do have pictures and intend to write up the build. I won't be doing the full works like usual, however, as there is an excellent build thread already out there written by a guy called tomb. He's one of the developers of the kit. I can't post a link as I fear that I would be contravening the house rules.

Use the following search parameters in Google and I'm sure the right thread will be returned:

Starving Student Millett Hybrid PCB Step-By-Step Build Guide

First impressions? Good. Trebles are a bit harsh but I'd expect that to mellow over time.

I'm building up quite a collection of headamps. Expect a super test in the not too distance future using LPro's bat detecting but audiophobe ears.
 
PJPro:Err. I've finshed this and listening to the amp now. I do have pictures and intend to write up the build.

Looking forward to that
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PJPro: I'm building up quite a collection of headamps. Expect a super test in the not too distance future using LPro's bat detecting but audiophobe ears.

Really looking forward to that
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One of the tricky bits about building this amp is preparing the tube sockets. Please refer to the build thread mentioned above for details of how to do this. I used the same method and managed to separate the two halves of the socket without issue (so I've now got two spare!).

I glued to two halves back together again with Araldite. Seemed to work quite well but you do need to be careful not to get glue all over the metals bits. Once the glue had gone off I tried to fit a socket. Damn! It wouldn't fit! I happened to have some rather heavy duty resistors hanging about and used one of the leads from these to free up each of the metal receptacles into which the tube fits. After a bit of effort I managed to free things up but it's still a nice tight fit.

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Prepared LEDs.

For the rest of it, I followed the build thread instructions and didn't encounter any problems. During the build you have to make a choice over the gain required. Initially, I went for the 50K resistors which gave me almost no movement on the volume pot before the music was unbearably loud. So, I swapped them out for the 100K resistors and all was fine.

You can see below the completed PCB which is attached to the lid of the case. The tubes poke up through the lid (you can't see them in this picture) and the MOSFETs are attached to the heatsinks.

It was a bit tricky getting the heatsinks on as the heatsink paste made everything a bit slippy. Also, the allen bolts require imperial keys (which I don't have). I ended up using finger pressure to tighten them.

If you look closely, you'll notice that the MOSFETs aren't actually soldered to the PCB yet! I was just about to do the soldering when I took this picture. You might also notice the insulating pads which insulate the MOSFETs from the case lid.

Oh, and those green capacitors are actually from the Nichicon Muse range. In fact all the components appear to be really good quality given the price of the kit.

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Soldering on the MOSFETs.

The next job was to fit the RCA sockets, power inlet and switch to the back panel and wire them in. Again, I used the heatshrink...makes for a really nice job. The power and switch leads are tightly wound together to reduce interference and the RCA signal cables are plaited using a Litz Braid.

You'll notice that the headphone socket and volume pot is soldered onto the board, so no messing about with wiring.

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Wiring on the back panel.

Here's the final picture of the completed amp. I went with the rather ugly heatsinks to stay true to the design and, to be honest, hardly notice them now.

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The amp has been played for about 50 hours. I sense a real improvement to the harshness of the treble but I might just be getting used to it. There's plenty of well disciplined bass and overall I'm pleased with the performance.

Would I recommend this kit to someone? Absolutely. Unfortunately, they are sold out and may not be available in the future. However, the Starving Student as a design lives on and as an introduction to building valves amps, without the high voltages, it comes highly recommended.
 

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