silverface champ tube glow

[bennieusmaximus]

hi,tI have a silverface 70's champ and my question isthis.The harder the guitar is played the brighter the 6v6 tube glowes.when the guitar is played lighter the tube goes back to its original glow.Is this normal for a single ended amp,or do I have a problem?The amp sounds fine.thanks for your help.

[stokes]

If you are talking about the plate turning a bright cherry red,then yes,the tube is drawing too much current and will have a short life span.If that is the case you should try a new 6V6.

[bennieusmaximus]

hi,and thanks for your help.the tube only glows brighter when the guitar is played harder like on hard played power chords or hard picked notes.when played softly the tube stays normal.I dont think the plate is glowing hot.its kinda weird.this is the first class a type amp that ive ever had.the first thing I changed was the tube but the amp still does this.the glowing always corresponds with the way the guitar is played soft or loud.More so when the volume is over 5.One more thing,do you know the original speaker impedance of this champ.the oem speaker is missing and I am playing it threw a marshall 1960 16 ohm cab.Maybe the cab impedance is making it do weird things.Just thought of that.

[stokes]

When a signal is passed thru the power tube the current rises,as opposed to idling,or not playing/playing softer,and in this case,it sounds as tho it is going beyond the tubes max rating and causing the redplating.It is possible that the cathode resistor has drifted in value and is no longer "idling" the tube properly,but from here it is hard to tell.The original speaker should be a 4 ohm.With most Fenders a 100% mismatch is considered safe,you are definately outside that "safety margin".

[Steve Conner]

If it's meant for 4 ohms, but you're using 16, that will be the screen grid inside the tube glowing. You may even be able to see the glowing wires if you peek into the top of the tube.

You should probably change back to a 4 ohm speaker, because as Stokes said, this is likely to burn the tube out.

[MWJB]

"When a signal is passed thru the power tube the current rises,as opposed to idling,or not playing/playing softer,and in this case,it sounds as tho it is going beyond the tubes max rating and causing the redplating." 70's SF Champs idle at 20W+ in stock form with a 470ohm cathode resistor, so it lives its whole life beyond the tube's rating.

Glowing gas in the tube, that varies in intensity when the amp is played, is normal.

As stated, a 16ohm speaker load is not normal.

[Jag]

Glowing gas in the tube, that varies in intensity when the amp is played, is normal.

I was thinking along this line as well.

We should probably clarify his issue a little bit by asking what color glow he is referring to and where in the tube the glow occurs.

Is it a purplish or bluish glow that seems to be between the glass and tube sturcture or, as Steve said, are any of the actual parts turning cheery red?

Either way, get that impedence matched up better, as the others have already said.

[bennieusmaximus]

I appreciate all the help on this.The glow in the tube is orangish but it dosent really look like a glowing plate kinda deal,I will probably go threw and check all the resistors anyway.There is not that much to go over on these little guys anyway.