[v3nom]

Quote:

Originally Posted by tamasic1 /img/forum/go_quote.gif Ok, finally got around to building it. True starving student as the tubes were the only things purchased.(thanks v3nom) The rest of the parts came from old ups and computer power supplies. Jacks are from a sound card and the pot is from an old stereo. All wiring was done with Cat5E, p2p so I can upgrade parts as I aquire them. Very, very slight hum when nothing is attached to the input but dead silent when the mp3 was attached. I’ve been listening for 2hrs now and its amazing. Thanks Pete and everyone else for all the info and upgrade ideas.

Glad you like the tubes. But my build is completely opposite of a "true starving student" lol. All parts together cost me around $80, it's got a lot of extras

I was thinking of calling it "Starving Stud" or "Super Student" or something to that effect

 

[tamasic1]

adding more goodies to the circuit or case?

 

[smeggy]

That's a great build Tamasic, very cool look too. What are those huge caps in there and can we get a shot of the underbelly of the beast?

 

[tamasic1]

The big caps are Chemicon rated 200v. I used 1000uF for power decoupling and 330uF for the output as those are what I had. I have Rubycons and Nichicons but none close to the values in this project. The bypass caps are PE 250v. Again I had nice PP spares but only a 50v rating. I'll get a underside pic when i go to work on it again today.

 

[Earwax]

I've built SS amps but never a tube amp. This looks like a good place to start. But if I do it, I'd want to totally encase the tubes. How tall are they and roughly how tall would the case need to be to accomodate tube and socket?

 

[Yaka]

off hand the tubes are smaller than my thumb, any socket you choose will not add much height to the tubes. personally i find the look of the tubes much better sicking out of the case than hidden inside

 

[metal112524]

ground is negative right?

 

[zkool448]

Quote:

Originally Posted by metal112524 /img/forum/go_quote.gif ground is negative right?

If you mean the (-/0V) of the 48VDC, yes that will be ground.

Quote:

Originally Posted by Earwax /img/forum/go_quote.gif How tall are they and roughly how tall would the case need to be to accomodate tube and socket?

19J6 tubes dimensions:

 

[penneydude]

Well I finally got mine built, but I have a few issues.

There is a pretty terrible hum (60 Hz-ish, but it sounds like more of a chord than a standard 60 Hz buzz) coming out of both channels when I have the amp switched on, regardless of the volume or what I have plugged in. It was just a hum in the left channel and the right sounded fine, so I did some poking around and noticed that on the headphone jack I had switched the tip and the sleeve (right channel audio and ground), so I put those back where they were supposed to be, but now the hum is in both channels instead of just the left.

Also, when I first turn the amp on I have to wait a minute and turn the power on and off a few times to get the tubes to heat up and light, with a periodic popping coming out of my headphones - it sounds like once a second, maybe a little faster. I also get a really loud pop from the phones (crappy test phones, fortunately) both when I turn the amp on, and when I turn it off. These things would make sense if I had smaller power caps, but I'm using 1000uF Nichicons for C1 and C6, so I don't really get why this is still happening.

If anyone could help shed some light on these issues I would really appreciate it. Thank you!

 

[Fred_fred2004]

Quote:

Originally Posted by penneydude /img/forum/go_quote.gif Well I finally got mine built, but I have a few issues. There is a pretty terrible hum (60 Hz-ish, but it sounds like more of a chord than a standard 60 Hz buzz) coming out of both channels when I have the amp switched on, regardless of the volume or what I have plugged in. It was just a hum in the left channel and the right sounded fine, so I did some poking around and noticed that on the headphone jack I had switched the tip and the sleeve (right channel audio and ground), so I put those back where they were supposed to be, but now the hum is in both channels instead of just the left. Also, when I first turn the amp on I have to wait a minute and turn the power on and off a few times to get the tubes to heat up and light, with a periodic popping coming out of my headphones - it sounds like once a second, maybe a little faster. I also get a really loud pop from the phones (crappy test phones, fortunately) both when I turn the amp on, and when I turn it off. These things would make sense if I had smaller power caps, but I'm using 1000uF Nichicons for C1 and C6, so I don't really get why this is still happening. If anyone could help shed some light on these issues I would really appreciate it. Thank you!

The first thing you must do is check the circuit against your work, be painfully exact about it. This is a tried and proven circuit so the chances are you've made a simple mistake. I know I've done it many times

 

[zkool448]

penneydude, what kind of enclosure are you using? Is the pot grounded or is it isolated from the case?

Regarding your power issue, iirc that is the sign of stutter in the ps folks have reported back then, however the larger caps (470uF and higer) supposed to have addressed the problem (?).

 

[metal112524]

Hey guys, just wanted to say thanks for the help, I got a thumpin' headache. I had been listening to my Brand New, Just Completed, Starving Student and after about two hours I took off my headphones and realized that I was probably listening in the way high 90's. Just wow, It sounds awesome, I could never listen to my Fuze straight this loud. AND I DID IT ALL WITHOUT A MULTIMETER!!!!!

Anyways, I just wanted to give a shout out to the guy that I bought the kit from. Awesome dude, he was the one that finally was able to answer my question about the whole which pin is ground and such. Great guy you can find his kit on ebay for like $60 bucks shipped with tubes and all. Mine got here in two days and he even put a little epistle, which is a nice touch. Thanks extremelighting!

 

[penneydude]

Quote:

Originally Posted by zkool448 /img/forum/go_quote.gif penneydude, what kind of enclosure are you using? Is the pot grounded or is it isolated from the case? Regarding your power issue, iirc that is the sign of stutter in the ps folks have reported back then, however the larger caps (470uF and higer) supposed to have addressed the problem (?).

I'm just using a metal box that I had lying around, tea came in it originally.

Pins 3 and 6 of the pot go straight to the ground, and the metal shaft is definitely connected to the metal box I have everything in, so I think the pot is ok, but I'll check it again. I might end up running a lead straight from the box to the ground too.

I'll go back over the whole circuit again tonight and see if I can find this problem. I thought maybe just based on the symptoms someone could point me in the right direction if they had a similar issue, but fortunately I DO have a multimeter.

(Congrats on the successful build metal, btw)

 

[tamasic1]

Quote:

Originally Posted by penneydude /img/forum/go_quote.gif I also get a really loud pop from the phones (crappy test phones, fortunately) both when I turn the amp on, and when I turn it off. These things would make sense if I had smaller power caps, but I'm using 1000uF Nichicons for C1 and C6, so I don't really get why this is still happening.

I agree with Fred. Carefully go back over your work. I got 1000uf and even with the volume all the way up, when I power on or off there is not the slightest sound. Seriously - dead quiet.

 

[penneydude]

Yep, it was my fault - I forgot to connect the other end of the power caps to the ground, haha.

Noob mistake, but it's working perfectly now and it sounds GREAT! Thanks for your help guys, and thanks to Pete for the design.