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Millett "Starving Student" hybrid amp - Page 424

post #6346 of 6756
Quote:
Originally Posted by KimLaroux View Post

I think you'd have better chances asking about those modifications in another thread... I have a feeling you and I are getting off topic here. In order to respect the original design and keep this thread dedicated to it, I think it would be more appropriate if we continued our discussions in another thread.


I think you're okay, this is the DIY section.

post #6347 of 6756

After a very, very long procrastination that began when I finally gathered all the elements, I eventually started building my MSSHA.

 

It has been more work than I thought, but also infinitely more pleasure.

 

Here are the pics of the complete process.


Edited by Oeufdepoire - 1/16/13 at 12:04pm
post #6348 of 6756

For anyone who is looking to build this amp, I have updated the BOM (attached) and also created a Mouser one click to buy project:

 

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=de75dcc795

 

I hope this helps others as it took me a while to go though all the posts and collect all the final parts needed to build the new 12AU7 version.

 

Thanks!

Dustin

 

 

 

12AU7_Starving_Student_BOM.xls 445k .xls file
Edited by dustinsterk - 1/17/13 at 11:07am
post #6349 of 6756

Ewww... Two day after testing the amp for the first time, the right channel just ceased working. I'm stuck, because the problem seems particuliar, and I am ignorant at electronics. Thus, I'm asking help from you electronic gurus.

 

Here's the matter :

V1 belongs to the right channel, and V2 to the left channel. The problem doesn't come from the tubes themselves; I have switched them, changed them, nothing works.

When the tubes aren't plugged in their sockets, I have 48 V of voltage between pin 1 and the ground, for both sockets.

But, with tubes plugged, the voltage between pin 1 and ground, for V1 only, progressively goes down from 48 to 24 V, while the voltage for V2 remains good (48 V between pin 1 and ground). And I have no sound in the right channel.

 

Can anyone help me ? Any piece of advice would be very much appreciated.

 

Stupid me. Unable to figure out the problem, I checked all the solders and made them cleaner. It was just a fraying cable going to the ground that was touching R3's lead to Q1.


Edited by Oeufdepoire - 1/19/13 at 10:23am
post #6350 of 6756

Hi. I am going to build my first tube amp ever. 

I am planning to build Starving Student amp based on 12SR7 tubes. I've collected all necessary parts however I would like to ask you one thing. Is that correct:

 

 

 

Quote:

If you want to build this version, you have to make some small changes - 

 
R1/R7 - 44k
R5/R11 - 4K
R2/R8 - 330K
R4/R10 - 180K
 
You will have to use an octal socket, and here are the conversions from the seven pin socket 
in the original circuit diagram:
 
1,2 -> 6
5,6 -> 2
3,4 -> 7,8
7->3
 
You will also have to ground pin 1 which is for the metal casing.

 

 
Are these the only changes I need to make to the original project from this website? I want to build it in the simpliest possible way. 
Sorry for stupid questions but I am not good with electronic (but not bad with soldering iron biggrin.gif )
Thanks. 

Edited by ProTofik - 1/19/13 at 4:34pm
post #6351 of 6756
Well I spent a very wet and miserable Irish afternoon yesterday building my MSSH as I want it to drive my DT880/600s. I have the electronics all done, but so far I'm not getting any output.

I went for the 19J6 version built on strip board.

I've not had much chance to troubleshoot, but have checked a few voltages and all seem OK. I'm getting 48v where I expect to, 18v on the sources and around 22v on the gates.

Both valves, oops sorry tubes :-) , are glowing nicely and the heatsinks get pretty warm.

I get around 22v on pins 1+2 of the tubes, which seems normal.

I'll take another look later, but does anybody have any ideas that could save me any time? I do realise that its next to impossible without seeing it. I'm not getting anything on the output at all. I have a feeling that its something fairly stupid, as by the time I'd finished the soldering yesterday I was starting to loose all sense of feeling in my fingers:-) .
Edited by DudeMyCans - 1/20/13 at 3:28am
post #6352 of 6756
Quote:
Originally Posted by DudeMyCans View Post

Well I spent a very wet and miserable Irish afternoon yesterday building my MSSH as I want it to drive my DT880/600s. I have the electronics all done, but so far I'm not getting any output.

I went for the 19J6 version built on strip board.
...

 

Where did you find 19J6 tubes?!? If there's more where they come from, I know someone who'll buy them all. biggrin.gif

 

As for your problem, I'm guessing you made an error in the signal path. Verify that the interstage coupling capacitors are connected to the right places. In my build, touching those capacitors introduces a hum at the output. Same thing if I move a metal screw driver close to the signal path. If this is normal for every build, it may be a way for you to narrow down the source of the problem.

post #6353 of 6756
Hi Kim.

I got them off eBay. He was a seller in the US selling NOS tubes. I don't want to pi$$ anybody off but I actually bought 4 as I'm thinking off building one as a wedding present for my brother later this year.

Anyway. Now for the embarrassing bit. (Shuffles awkwardly and looks down to his shoes).

I found the problem with the amp. I was right. It was something stupid and it was the last thing I soldered before I went inside out of the cold....I'd wired the jack socket to the wrong (switched) side. 5 minutes with the iron and its now singing. Well actually Adel is, but you know what I mean.

Sound great. Way better than my Creek that I've been using until now.

There's a very slight hum, only audible when its idling, which I'm hoping will go away when I box it up next weekend and spend more time on laying out the wiring.For now its sat in a shoe box and still sounds great. :-)

I'll post some photos next weekend when its boxed and if anybody wants my sketches for the strip board layout I'll post them as well.
post #6354 of 6756

Looks (and hopefully sounds) nice Oeufdepoire!

post #6355 of 6756

Hi all, i'm new in the forum and even in electronics, and i want to do this amplifier, looking at the schematics, for me, it's a bit difficult, did someone create a pcb sort of thing or a more particular schematics?
Thanks in advance, and sorry for my english, i'm from Italy :)

post #6356 of 6756
Quote:
Originally Posted by KimLaroux View Post

 

Where did you find 19J6 tubes?!? If there's more where they come from, I know someone who'll buy them all. biggrin.gif

Someone PM me if they find 100 or more - we'll do another PCB run, custom case and kits. wink.gif

post #6357 of 6756
Quote:
Originally Posted by tomb View Post

Someone PM me if they find 100 or more - we'll do another PCB run, custom case and kits. wink.gif

Would you be able to do such a large run with 12AU7 tubes? When I had my SSMH I found 12AU7s that were affordable enough, around $5-10. Sure, they're not top-notch quality, but I doubt you'll be able to find so many 19J6s at their old price.

post #6358 of 6756
Quote:
Originally Posted by Ikarios View Post

Would you be able to do such a large run with 12AU7 tubes? When I had my SSMH I found 12AU7s that were affordable enough, around $5-10. Sure, they're not top-notch quality, but I doubt you'll be able to find so many 19J6s at their old price.

No, it would be a different amp.  Dsavitsk and I really went another route in using dirt-cheap tubes with the Torpedo.  It's more expensive, but the 6J6 tubes (the 6V heater version of the 19J6) can be found for $2 a piece and less if purchased in high quantities.  They number into the tens of thousands.  Some dealers may have that many on their own.

 

If you really want a hybrid that uses 12AU7 tubes, I suggest the SOHA II. As always, of course, if you are willing to build point-to-point, then you can do anything you want. 

 

I still have several extra 19J6 tubes and even the Cisco power supplies.  Maybe it's time I tried to sell them. wink.gif

post #6359 of 6756

I went looking on Ebay after the comment. There's a couple for sale, but at outrageous prices. Most listings advertise them has "Starving Student" tubes, and ask 45$ for a pair. It's quite shocking when you think the original design had a total cost lower than that.

 

It'll be quite the day when someone finds a rotten box filled with hundreds of 19J6 in the back shed of an old shop. Gotta keep dreaming, right? rolleyes.gif

post #6360 of 6756
Quote:
Originally Posted by KimLaroux View Post

I went looking on Ebay after the comment. There's a couple for sale, but at outrageous prices. Most listings advertise them has "Starving Student" tubes, and ask 45$ for a pair. It's quite shocking when you think the original design had a total cost lower than that.

 

It'll be quite the day when someone finds a rotten box filled with hundreds of 19J6 in the back shed of an old shop. Gotta keep dreaming, right? rolleyes.gif

Yep.  However, the Starving Student Millett Hybrid PCB kit with custom case sold for $120.  It's extremely doubtful that it could be sold for that again, even if the tubes were still $2.

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