[tomb]

Quote:

Originally Posted by Ryuichi /img/forum/go_quote.gif I bought a starving student amp a while back, and it does something a bit strange. Sometimes with a fairly low level input, I hear humming that grows in volume until it pops (sounds like an arc) and the humming goes away. It will also 'pop' when I tap the amp with my finger and the humming goes away. Any idea what is happening? I don't know much about tube amplifiers.

The starving student can build up a charge on the signal ground for some reason - we suspect it has something to do with the power supply or the heater-biased mosfets. The problem is worse when the ground "sink" is not very big/good. Whichever it is, the pop is the sound of the charge dissipating - which makes the hum go away.

You might check all of your connections and the connectors on the case - make sure they're all tight and have good ground connections.

 

[Shayla]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif The starving student can build up a charge on the signal ground for some reason - we suspect it has something to do with the power supply or the heater-biased mosfets. The problem is worse when the ground "sink" is not very big/good. Whichever it is, the pop is the sound of the charge dissipating - which makes the hum go away. You might check all of your connections and the connectors on the case - make sure they're all tight and have good ground connections.

Will do, thank you! Sometimes the volume control doesn't do much with the right channel, think this is just a solder joint or bad pot?

 

[ezzieyguywuf]

Anytime my ground plane moves, I hear it in my headphones. Is this normal? Also, I have a distinct hummmmm in the amp. Its not super loud, but definitely noticeable in quite parts of songs and when no music is being played.

All of my ground connection are made with a bolt, not solder. Could this be the problem? i.e. I put the wire through a hole, then a bolt through the same hole and clamp it down with a nut.

 

[the_equalizer]

Quote:

Originally Posted by ezzieyguywuf /img/forum/go_quote.gif Anytime my ground plane moves, I hear it in my headphones. Is this normal? Also, I have a distinct hummmmm in the amp. Its not super loud, but definitely noticeable in quite parts of songs and when no music is being played. All of my ground connection are made with a bolt, not solder. Could this be the problem? i.e. I put the wire through a hole, then a bolt through the same hole and clamp it down with a nut.

Certain level of hum in a P2P build housed within a non-metal, non-grounded enclosure is normal, as the wiring is somewhat exposed.

Also, the tubes are exposed and that also induces a bit of hum (try holding your hand hear the tubes, and you'll hear the hum grow in intensity).


cheers!

 

[bhjazz]

Finally got some shots of my P2P MHSS. I've sure been enjoying it. I posted a while back that there seemed to be some channel imbalance, and I found it was very much due to my tubes. No matter. I had fun working on this P2P build. Been a long time since I've done one. Anyway, here are some shots.

Here's the completed build. I used a Context Engineering case, and turned it 90 degrees so I could get some space to work with on the inside. And I thought it looked kindof cool this way.

I had to drill the access holes along the seam of the case, which meant bolting the unit together and dremeling out the excess. This turned out to be far more time consuming than I expected.

As for internals, geez, it's, well, P2P. I tricked out the star ground, used Solens on C2/C4,and tucked resistors and parts away where ever I could.

There is lots of power to spare, and I like it. The sound, as others have said, belies it's price tag. I have no hum, buzz, or squeals, just great music. I continue to dig through the web searching for backup tubes, which have all increased in price to about $10 each. Charming.

This is definitely a keeper!

 

[hellomoto]

Hello,

I found 2 19J6 tubes on the internet, at a fair price for France.

They are Raytheon 19J6 tubes. Both are vertical D getters. Will it be ok, and are this tubes good?

Thanks!

Antoine

 

[Juaquin]

Should be fine. It's been suggested that RCA was the only real manufacturer of those tubes anyway.

 

[nullstring]

IDK, my CBS tubes look very much different than my RCA tubes.
CBS tubes have square getters and I prefer them over my RCA tubes.

 

[tomb]

I'm sorry to report that AMB has posted a new update on his Gamma 1 web pages. There are reports of the Starving Student damaging that DAC as well as Aliens and Bantams. So, a word to the wise ... just in case.

 

[hellomoto]

First, thank you for your help.

I have two last questions.

First, about the components: will I have to modify some components because of the Raytheon 19J6 tubes with vertical D getters? I also would like to know if they are upgrades I can do using other parts, not to expensives. I tried to read the Beezar page on this, but couldn't understand a word, and so in the topic...

My second question is about the enclosure. I'd like to buy a nice aluminium case, but I have only basic tools (i have a preety powerful drill) and i'd like to know if it was hard to dril the enclosure to make holes for the tubes and jacks... Maybe is it possible to buy custom enclosures?
What size would be the best (i'll use by me, so it can be big)

Thank you very much for your help!!! it is very useful!

Antoine

 

[manaox2]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif I'm sorry to report that AMB has posted a new update on his Gamma 1 web pages. There are reports of the Starving Student damaging that DAC as well as Aliens and Bantams. So, a word to the wise ... just in case.

You had some experience with that as well I think I remember. Are there any tips maybe to help prevent this?

 

[tomb]

Quote:

Originally Posted by manaox2 /img/forum/go_quote.gif You had some experience with that as well I think I remember. Are there any tips maybe to help prevent this?

Don't ever disconnect/connect the DAC while the Starving Student is on.

 

[manaox2]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Don't ever disconnect/connect the DAC while the Starving Student is on.

Got it.

 

[tomb]

Quote:

Originally Posted by hellomoto /img/forum/go_quote.gif First, thank you for your help. I have two last questions. First, about the components: will I have to modify some components because of the Raytheon 19J6 tubes with vertical D getters?

Yes the radiation from those particular getters will require some lead lining inside the case and special dark glasses when you are listening. ... NOT!

Seriously ... of course not! A 19J6 is a 19J6. There are some who profess to tell a difference in sound of one tube vs another, but they all work just the same in the circuit.

Quote:

I also would like to know if they are upgrades I can do using other parts, not to expensives. I tried to read the Beezar page on this, but couldn't understand a word, and so in the topic...

You can try different film caps or electrolytics. There are some very nice Nichicon Fine Gold that will fit the bill that you can purchase from Handmade Electronics. I believe Mouser is carrying some now, too, but I'm not exactly sure on that.

As for the film caps - the sky's the limit. I'm not sure how much difference you're going to notice, though. The parts selection we made on the SSMH PCB website is about as good as it gets.

Quote:

My second question is about the enclosure. I'd like to buy a nice aluminium case, but I have only basic tools (i have a preety powerful drill) and i'd like to know if it was hard to dril the enclosure to make holes for the tubes and jacks... Maybe is it possible to buy custom enclosures? What size would be the best (i'll use by me, so it can be big)

Check into the Hammond 1455-series cases. They're aluminum, but you can whittle them with a sharp knife. Drilling is not much of a problem. I've found that a Greenlee punch is best for the tube holes. Some people do well with hole saws, but I've never had any luck with them.
Quote:

Thank you very much for your help!!! it is very useful! Antoine

 

[n_maher]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Don't ever disconnect/connect the DAC while the Starving Student is on.

Has anyone explained what exactly is going on that is so unique to the SSMH design that causes the issue? I read both your comments and Ti's and while there is anecdotal evidence to support that something is going on it seems like that something should have a more complete explanation. If you point me in the right direction I'll take it up with Pete.