#1
Hey guys, so recently during a practice my amp started cutting in and out. It mainly happened on the cleaner channel but then started happening on the dirty channel. After letting it sit, I swapped V1 and V3, and the problem disappeared, then reappeared on the clean channel. Unfortunately, I will not be seeing the amp until Thursday, where I will completely retube my preamps with all my extras.

So on Thursday I plan on swapping ALL my pre amp tubes, if I have the time I would like to roll all of them, if not I'll do a complete swap. I also realize that this could be a Power tube issue, will i be able to pull two tubes and run the amp at half power to trouble shoot?

I'm just trying to get a plan of attack going. Quite the busy weekend with the band and I'm unlucky enough to be amp-less till the day of the show!

Thanks for the help!
Splawn Street Rod
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#2
If you pull 2 tubes you need to run the Ohms different. If you have a 16 ohm cab you will need to use the 8 ohm output of the amp. If you don't have a 4 ohm out on the amp you can not run an 8ohm load. The 16 ohm out put on the amp becomes unused

Know this before you pull 2 powertubes.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
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#3
Quote by Robbgnarly
If you pull 2 tubes you need to run the Ohms different. If you have a 16 ohm cab you will need to use the 8 ohm output of the amp. If you don't have a 4 ohm out on the amp you can not run an 8ohm load. The 16 ohm out put on the amp becomes unused

Know this before you pull 2 powertubes.



Yea I got that! Used to run my DSL at half power. I asked the question because after some quick research I was getting mixed results about this particular head, so I decided to ask myself.

But right now all I got to go on is something tube related. Tried multiple cables, and multiple guitars. Wish I coulda spent more time with it but everything I needed was at my house, and I have to be somewhere that is not my house for a few days. What a time for this to happen
Splawn Street Rod
H&K Tubemeister 5
Line 6 G90 System

Gibson SG Standard
Godin Radiator
Dillion 653 GA/3CT
Seagull Coastline s6
New Music on Spotify
#4
if the problem changed when you swaped the preamp tubes around, it is probably the preamp.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#5
Yea that's what I'm thinking. The problem changed but still stayed there. Going for a full tube swap asap. I'll bring the DSL just in case
Splawn Street Rod
H&K Tubemeister 5
Line 6 G90 System

Gibson SG Standard
Godin Radiator
Dillion 653 GA/3CT
Seagull Coastline s6
New Music on Spotify
#6
Yes, you can run the JCA100H with only 2 power tubes. I used to run mine with the outer pair pulled. It's probably a preamp tube issue though.
Endorsed by Dean Guitars 07-10
2003 Gibson Flying V w/ Moon Inlay
2006 Fender All-American Partscaster
SVK ELP-C500 Custom

1964 Fender Vibro Champ
1989 Peavey VTM60

[thread="1166208"]Gibsons Historic Designs[/thread]
#7
Ok ido not have good news. Swapped every tube, and now it doesn't cut out, but the volume is very low. When it's cranked it sounds like it's at 3 at most. Like bedroom volumes, not opening up. It's weird. Pulled the outside tubes, no change, then did the inside, no change. I have no idea what could be wrong. It is not anything before the amp either. Ideas?
Splawn Street Rod
H&K Tubemeister 5
Line 6 G90 System

Gibson SG Standard
Godin Radiator
Dillion 653 GA/3CT
Seagull Coastline s6
New Music on Spotify
#8
get some preamp tubes
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#9
I had a similar problem with my little Laney Cub10, turned out to be badly seated power tubes. Get some contact cleaner, give the power tube base pins a SMALL spray then refit & make sure they are fully inserted. This worked on mine, but you'll have to try it on your amp to see if it makes a difference.
My Gear:- A guitar, a guitar lead, a guitar amplifier. Or sometimes just an acoustic guitar!
#10
Definitely clean the tube sockets and tube pins with a proper cleaner
Make sure the pin sockets are tight, and not bent/messed up
Are the tubes seating properly and secure after checking those?

Worst case scenario, you might have have accidentally broke a solder joint or pulled something loose inside. I'd definitely check out the tube sockets as I listed above before opening the amp up though
Endorsed by Dean Guitars 07-10
2003 Gibson Flying V w/ Moon Inlay
2006 Fender All-American Partscaster
SVK ELP-C500 Custom

1964 Fender Vibro Champ
1989 Peavey VTM60

[thread="1166208"]Gibsons Historic Designs[/thread]
#11
I'm gonna do as suggested this weekend. If all else fails I'll have to look for a good and reasonable tech in my area and give it a once over.
Splawn Street Rod
H&K Tubemeister 5
Line 6 G90 System

Gibson SG Standard
Godin Radiator
Dillion 653 GA/3CT
Seagull Coastline s6
New Music on Spotify