Please help

jb1911 · September 11th, 2004, 09:54 AM

I just put new tubes in my Hot Rod Deluxe and now when I switch from the clean channel to the drive channel, there is a popping noise that I don't remember being there before. I got Svetlana 6L6GC's for the power section, and Electro Harmonix 12at7EH for V3, and 2 12ax7EH for V1 and V2. I don't know if the tubes are to blame or what. Is this normal for this amp?

lonewolf2 · September 11th, 2004, 12:35 PM

did you put the tubes in your'e self

they might need biased
to make them work in unison ,
talk to your'e local amp tech

:D lonewolf2 :D

mechanicdave · September 11th, 2004, 01:53 PM

Put the old tubes back in and see if the pop goes away.
I'm not familiar with the HotRod amps, but the Svetlana tube company has been taken over by another company. The original Svetlana tubes are now marketed as "Winged C". If those are new tubes, they may be suspect to your problem. Dave

skip62 · September 11th, 2004, 10:17 PM

Did the new tubes seem to be tight enough in the sockets? I've heard that if a tube is loose there can be a voltage build up then it will pop. just a suggestion. I'm not that knowledgable about it.

jb1911 · September 26th, 2004, 03:42 PM

Thank's for the help guys. I found out the problem was the EH tubes. I replaced all 3 with JJ's and the popping noise went away completely. All noise went away as a matter of fact. This HRD is now the quietest amp I have ever owned. It's quieter than my Cyber Champ. You can't even tell weather it's on or not till you hit a string. Needless to say, I'm very happy. :D

Big Cookie · September 27th, 2004, 09:40 AM

Quote:

Originally Posted by jb1911

. You can't even tell weather it's on or not till you hit a string. :D

If you can't hear that a tube amp is on or not your bias is likely set very cold.

jb1911 · September 27th, 2004, 04:28 PM

Well, I can't hear too well, I'm 52 years old. Anyway, I have the Svetlana 6L6GC's biased at 70mv. From what I hear, that's a bit hot.

zook · September 28th, 2004, 01:55 PM

If you have them biased at 70ma EACH that is hot. But if you have the pair biased at 70ma that's only 35ma which is cold.

Bias is relative to plate voltage. Use these tables to help.

http://members.shaw.ca/house-of-jim/...as_tables.html

Winnie

jb1911 · September 28th, 2004, 09:04 PM

The Hot Rod Deluxe has a bias point on the circuit board. I'm pretty sure that the reading you get from it is for both tubes together.

zook · September 29th, 2004, 08:15 AM

Quote:

Originally Posted by jb1911

The Hot Rod Deluxe has a bias point on the circuit board. I'm pretty sure that the reading you get from it is for both tubes together.

If that is the case, then bias the pair at double the desired bias from the table.

For example if the plate voltage calls for 40ma then bias the pair for 80ma.

Winnie

September 11th, 2004, 09:54 AM	#1 (permalink)
jb1911 TDPRI Member Join Date: Jun 2004 Location: Chicago area Posts: 92	Please help I just put new tubes in my Hot Rod Deluxe and now when I switch from the clean channel to the drive channel, there is a popping noise that I don't remember being there before. I got Svetlana 6L6GC's for the power section, and Electro Harmonix 12at7EH for V3, and 2 12ax7EH for V1 and V2. I don't know if the tubes are to blame or what. Is this normal for this amp?

September 11th, 2004, 01:53 PM	#3 (permalink)
mechanicdave Tele-Meister Join Date: May 2003 Location: Houston Posts: 330	Did You Try? Put the old tubes back in and see if the pop goes away. I'm not familiar with the HotRod amps, but the Svetlana tube company has been taken over by another company. The original Svetlana tubes are now marketed as "Winged C". If those are new tubes, they may be suspect to your problem. Dave

September 28th, 2004, 01:55 PM	#8 (permalink)
zook Tele-Holic Join Date: Aug 2003 Location: Northeast Kingdom, Vermont Posts: 801	If you have them biased at 70ma EACH that is hot. But if you have the pair biased at 70ma that's only 35ma which is cold. Bias is relative to plate voltage. Use these tables to help. http://members.shaw.ca/house-of-jim/...as_tables.html Winnie __________________ I have noticed that happy people are often evaluating themselves and unhappy people are always evaluating others. -William Glasser

September 11th, 2004, 12:35 PM	#2 (permalink)
lonewolf2 TDPRI Member Join Date: Aug 2004 Location: prescott,az. Posts: 21	did you put the tubes in your'e self they might need biased to make them work in unison , talk to your'e local amp tech :D lonewolf2 :D

September 11th, 2004, 10:17 PM	#4 (permalink)
skip62 Tele-Meister Join Date: Aug 2003 Location: Dallas, TX Posts: 337	Did the new tubes seem to be tight enough in the sockets? I've heard that if a tube is loose there can be a voltage build up then it will pop. just a suggestion. I'm not that knowledgable about it.

September 26th, 2004, 03:42 PM	#5 (permalink)
jb1911 TDPRI Member Join Date: Jun 2004 Location: Chicago area Posts: 92	Thank's for the help guys. I found out the problem was the EH tubes. I replaced all 3 with JJ's and the popping noise went away completely. All noise went away as a matter of fact. This HRD is now the quietest amp I have ever owned. It's quieter than my Cyber Champ. You can't even tell weather it's on or not till you hit a string. Needless to say, I'm very happy. :D

September 27th, 2004, 04:28 PM	#7 (permalink)
jb1911 TDPRI Member Join Date: Jun 2004 Location: Chicago area Posts: 92	Well, I can't hear too well, I'm 52 years old. Anyway, I have the Svetlana 6L6GC's biased at 70mv. From what I hear, that's a bit hot.

September 28th, 2004, 09:04 PM	#9 (permalink)
jb1911 TDPRI Member Join Date: Jun 2004 Location: Chicago area Posts: 92	The Hot Rod Deluxe has a bias point on the circuit board. I'm pretty sure that the reading you get from it is for both tubes together.