got's a problem
- Thread starter beandip
- Start date
The Golden Boy
Fleecy Sweaterologist
Re: got's a problem
I honestly don't know, but this is what I found...
From: http://aga.rru.com/FAQs/general.html
My tubes glow blue - is this OK??
There are two reasons a bottle (!) may glow blue.
Have a careful look. If there are patches of blue glowing on the glass, probably with fairly sharp edges, it's due to electrons missing the anode and hitting the glass instead, making it flouresce. (Most of the tube envelope may even glow. -ed) Quite pretty, and you can play for hours, moving the patch with a magnet... (Don't electrocute yourself!) This kind of glow is common with beam tetrodes and is completely harmless. (This type of glow is by far the most common. -ed)
However, if there is a fuzzy blue glow in the space in the bottle (inside the plate, or streamers coming out -ed) it's due to traces of gases in what should be a vaccuum. The valve has gone soft. Bad news for the valve as ions will bombard the cathode, shortening its life. Also, the trace of gas can break down leading to an internal arc. A soft valve set will sound slightly different, especially in amps without feedback, as the presence of ionised gas affects the transconductance and secondary emission. (This is fairly rare. -ed)
-HTH
For additional information, see the Blue Glow in Tubes FAQ at
http://members.aol.com/larrysb/blue_glow.html
or a couple of documents transcribed from old tube manuals at
http://barney.webace.com.au/~electron/tubes/blueglo.htm .
My tubes glow orange or yellow - is this OK??
This is not only normal, it's a requirement of tube operation. This glow normally comes from the tube's heater, or filament, which heats the cathode so that the tube conducts properly. If you don't see this, and your amp doesn't seem to be working properly, check the amp in the dark (some tubes, esp. Sovtek 12AX7LPS tubes) have a filament glow which is very difficult to see. If you still aren't sure, let the amp warm up for a few minutes. Then, place a fingertip near each tube in turn. If the tube is not hot, the filament is burned out and you need to replace it.
NOTE - be careful; even a brief touch to a hot tube can burn you badly enough to cause blisters.
My tubes glow red - is this OK??
First, read the orange glow question above. Is the color you're seeing orange, coming from the top and bottom of the tube's "guts"? If so, you're OK.
BUT... if the plate, or any part of it, especially in a power tube, is actually glowing red (even a faint red) shut the amp off at once and find out what the problem is. Otherwise, you will certainly destroy the tubes. You could also destroy other parts of your amp, resulting in a huge expense to repair it. Take the amp to a good tube amp tech, or start asking question in AGA, if you think you want to learn how to work on things yourself.
I honestly don't know, but this is what I found...
From: http://aga.rru.com/FAQs/general.html
My tubes glow blue - is this OK??
There are two reasons a bottle (!) may glow blue.
Have a careful look. If there are patches of blue glowing on the glass, probably with fairly sharp edges, it's due to electrons missing the anode and hitting the glass instead, making it flouresce. (Most of the tube envelope may even glow. -ed) Quite pretty, and you can play for hours, moving the patch with a magnet... (Don't electrocute yourself!) This kind of glow is common with beam tetrodes and is completely harmless. (This type of glow is by far the most common. -ed)
However, if there is a fuzzy blue glow in the space in the bottle (inside the plate, or streamers coming out -ed) it's due to traces of gases in what should be a vaccuum. The valve has gone soft. Bad news for the valve as ions will bombard the cathode, shortening its life. Also, the trace of gas can break down leading to an internal arc. A soft valve set will sound slightly different, especially in amps without feedback, as the presence of ionised gas affects the transconductance and secondary emission. (This is fairly rare. -ed)
-HTH
For additional information, see the Blue Glow in Tubes FAQ at
http://members.aol.com/larrysb/blue_glow.html
or a couple of documents transcribed from old tube manuals at
http://barney.webace.com.au/~electron/tubes/blueglo.htm .
My tubes glow orange or yellow - is this OK??
This is not only normal, it's a requirement of tube operation. This glow normally comes from the tube's heater, or filament, which heats the cathode so that the tube conducts properly. If you don't see this, and your amp doesn't seem to be working properly, check the amp in the dark (some tubes, esp. Sovtek 12AX7LPS tubes) have a filament glow which is very difficult to see. If you still aren't sure, let the amp warm up for a few minutes. Then, place a fingertip near each tube in turn. If the tube is not hot, the filament is burned out and you need to replace it.
NOTE - be careful; even a brief touch to a hot tube can burn you badly enough to cause blisters.
My tubes glow red - is this OK??
First, read the orange glow question above. Is the color you're seeing orange, coming from the top and bottom of the tube's "guts"? If so, you're OK.
BUT... if the plate, or any part of it, especially in a power tube, is actually glowing red (even a faint red) shut the amp off at once and find out what the problem is. Otherwise, you will certainly destroy the tubes. You could also destroy other parts of your amp, resulting in a huge expense to repair it. Take the amp to a good tube amp tech, or start asking question in AGA, if you think you want to learn how to work on things yourself.
The Golden Boy
Fleecy Sweaterologist
Re: got's a problem
The other one looks like I'd expect a tube to look. The thing is you're going to want to make sure those tubes are at least somewhat matched. Get that one checked and make sure the tube you get to replace it is somewhere in the neighborhood. Or spring for a "matched" NOS set from a reputable dealer.
OTOH, I've heard of good 6v6 tubes being made nowadays...
The other one looks like I'd expect a tube to look. The thing is you're going to want to make sure those tubes are at least somewhat matched. Get that one checked and make sure the tube you get to replace it is somewhere in the neighborhood. Or spring for a "matched" NOS set from a reputable dealer.
OTOH, I've heard of good 6v6 tubes being made nowadays...
The Golden Boy
Fleecy Sweaterologist
Re: got's a problem
In your case- if you've got 2 GE tubes in your amp and you replace one with a new GT- that's fine as long as the remaining GE tube tests out the same as the GT tube.
Remember the amp is a push pull type thing- current goes through one tube, then the other- the idea is that you want the tubes to respond similarly- hence being "matched." Matched tubes doesn't necessarily mean 2 old RCAs, or 2 GTs, just that the characteristics of the two tubes are similar.beandip said:
In your case- if you've got 2 GE tubes in your amp and you replace one with a new GT- that's fine as long as the remaining GE tube tests out the same as the GT tube.
