[Gradofan2]

Quote:

Originally Posted by Skylab /img/forum/go_quote.gif Just a question: have you tried cleaning the pins on the tubes with something like Caig ProGold? This has eliminated slight hum for me in several amps I have had.

As well as... gently spreading the pins to fit more tightly in their sockets - but you have to be very careful, or you'll break them out of the glass.

 

[mchang]

I swore I had good tubes, but didn't fix my whine until I swapped in and out two sets of Svets and two sets of WEs. Turned out at least one of my "good" tubes was actually bad.

 

[dhammavijaya]

Can someone do me a favour? Can you switch on your 332, and place your ear 4 or 5 inches from the transformer? Do you hear a hum? What I get through the phones sounds like that. I think I hear transformer hum rather than tubes.

 

[mybeat]

I have hum coming from transformer only if i put my ear really close to it, from 4 inches its dead silent.

Did you try swaping the tubes?
What's your source?
I had a hum problem because of my mic was plugged in the same soundcard as my amp was.

 

[PrTv]

Quote:

Originally Posted by mybeat /img/forum/go_quote.gif I have hum coming from transformer only if i put my ear really close to it, from 4 inches its dead silent.

Same here!

I've to put my ear on the metal casing to hear the faint hum, but 2 inches from the cover is also dead silence.

FYI I'm using Russian 6S19Ps and WE403Bs if that matters.

 

[PrTv]

Today I've just discovered a problem.

The amp hums for no reason.

Like my previous post, I'm using 6S19Ps with WE403B and I kinda like the sound of this combination.

However, this morning I temporarily removed 403B for testing Mullard tubes. After finding Mullard' sound is not my taste, I swapped 403B back, and BOOM! Faint hum on left channel.

It seems my left channel tube that hums as the hum moved to right channel when I moved that tube.

I don't know what caused this problem as that tube performed perfectly fine before being temporarily removed.

This is what I tried
1. spread tube's pins
2. clean the pins
3. apply contact cleaner.

None of the above help.

However, when I swapped another set of tube (Mullard, the sound of which I don't really like), the hum is gone.

Is it possible that one of my WE403B is damaged from removal?

 

[DennyL]

Quote:

Originally Posted by PrTv /img/forum/go_quote.gif Is it possible that one of my WE403B is damaged from removal?

It does seem like it.

 

[DennyL]

My DV332 has so far been without problems. I have done a bit of valve swapping, but so far have heard no hum on the signal or mechanical hum from the transformer. When I was valve swapping with my DV336 I had some valves that hummed, and others that hummed initially, but who's hum faded away after 30 or so hours of use.

 

[magnetiq]

*sigh* I'm getting a bit fed up waiting for the 220v version from Jasmine, even though it was one of the rarer cheaper listings...

..I'm tempted to get one from casque now, anywhere else I can get one?

 

[dhammavijaya]

Quote:

Originally Posted by mybeat /img/forum/go_quote.gif I have hum coming from transformer only if i put my ear really close to it, from 4 inches its dead silent. Did you try swaping the tubes? What's your source? I had a hum problem because of my mic was plugged in the same soundcard as my amp was.

Thanks for trying that. I can hear a hum off mine from nearly a foot away (at night when all is quiet). This will happen whether I have my CD source connected or not. It seems the transformer is the problem rather than the tubes, as I get the hum whichever tubes I use. I have Mullards and Ulyanovsks. It's very faint through the phones, but still annoying. I'm thinking of fitting a resistor in the headphone cable as a solution.

 

[Scottyyy]

I only start to hear a hum when I turn the volume passed 12 o clock, which is way above listening level anyway.

 

[PrTv]

Quote:

Originally Posted by dhammavijaya /img/forum/go_quote.gif Thanks for trying that. I can hear a hum off mine from nearly a foot away

A foot away?!?

If I were you I would stop using the amp immediately and have the amp inspected by some electronic guy. Though I'm not an electronic expert, I can say that I don't think it's normal for a transformer to produce the hum which is audible a foot away like this.

 

[afgeneral]

Quote:

Originally Posted by PrTv /img/forum/go_quote.gif A foot away?!? If I were you I would stop using the amp immediately and have the amp inspected by some electronic guy. Though I'm not an electronic expert, I can say that I don't think it's normal for a transformer to produce the hum which is audible a foot away like this.

It's actually quite normal for inexpensive transformers to hum like this. These are mechanical vibrations of the transformer laminations, and to a certain extent, transformer windings. Transformers are still manually impregnated even with larger/reputable manufacturers -- so they are subject to sample variation. It's easy to fix, though... bake the transformer for 1 hour at 120 degrees Celcius, while hot, dip the entire transformer to a varnish material like Dolphon AC-43 (about 40 bucks per gallon) and air cure for 24 hours.

 

[nor_spoon]

Finally I found a couple of LM Ericsson 403B's. This is the gold pin version. Looking forward to try this tube

 

[PrTv]

Quote:

Originally Posted by nor_spoon /img/forum/go_quote.gif Finally I found a couple of LM Ericsson 403B's. This is the gold pin version. Looking forward to try this tube

Wow, this one looks very promising!
How much did you pay for it?

By the way, how does it fare comparing to WE403B?