Adrian R

Interesting story here..

Been experiencing a problem with my MKIII head the past month or so. When I got the head it needed a bit of work, mostly cosmetic. Anyway replaced the old tubes with a fresh set of matched EH6L6s...and biased the amp conservatively around 34mA.. things seemed fine at first..tone was good, punchy, articulate and warm....but..

The amp started to exhibit a humming noise that almost sounded like a ground issue...however all attempts to silence this hum failed...but it was strange as sometimes it would hum, sometimes quite loudly, and other times it almost was silent...I tried swapping out preamp tubes in addition with no success..

Then last night while practicing I noticed the hum was beginning to come back..and this time the overall tone quality was poor...Power was good, but the overall tone was harsh and sort of loose..especially in the lower frequencies..

I then looked at the back of the amp and noticed one of the tube failure fuse's LEDs was softly glowing....I also noticed that all four tubes were lit properly, but valve 3 didn't have that nice, softly lit, ultra-violet glow to it in play mode as the other 3 were. I shut down the amp and pulled the fuse...

The fuse didn't appear completely blown..as the element inside was still in tact, however one end of it appeared to be slightly brown..

I replaced the fuse and fired the amp back up. It didn't burn the replacement fuse, and the LED did not glow again...but the overall tone was still bad and that specific tube didn't seem to glow nicely like the other 3...

I called the Tubedepot and they are sending me a replacement free of charge with the same bias rating....hopefully this was the problem all along..and hope to have this amp up rockin' again!

In nearly 20 years of tube amp ownership this evidently seems to be the first OP tube failure I've experienced!

__________________
Adrian R.
Amplification:
Marshall JCM800 2205
Marshall JCM900 MKIII 2100
Marshall JCM900 Dual Reverb 4500
Marshall MG15 Micro Stack
Marshall 1960A 4x12 Cab. w/75w Celestions
Sonic 2x12 Cab.
MXR Fx.

Guitars:
Gibson LP Standard
Gibson Explorer
Gibson Flying V
Guild DV 6 Acoustic

"Only two tones apply: loud and LOUDER"

MartyStrat54

What do you think the failure rate of JJ's are? You've heard my story before. Any tube can fail, but most of the time they are CP tubes. You got one of the worst kinds. It works for a while and then fails. I'm so glad that you were able to catch it before it trashed your amp.

I know JJ's have been good to you, but it's all about odds and playing the numbers. Trust me...JJ's fail.

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MARTY

2009 Gibson Explorer-Hell Raising Machine
1989 Fender Strat Plus USA
2008 Fender Tele USA
2004 Schecter Elite w/DiMarzio's

TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers.
TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends."
DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker.

Tubes: Let's just say they are NOS that kick ass.

Adrian R

Marty..

You know based on what you have said, and most importantly by what my tech has told me recently..I called the Tubedepot an had them cancel the EH replacement order and replace all four of them with SEDs...My tech and the Tubedepot said that this brand has been the most consistent..

However, according to you all CP tubes suck, with the 'somewhat' exception of SED! So I guess the majority of us who cannot afford NOS are utterly doomed eh? A sobering realm indeed....

I really like that MKIII head...great, high gain tone...and don't want to risk burning it up with shitty tubes! Hopefully these more affordable tubes will last!

__________________
Adrian R.
Amplification:
Marshall JCM800 2205
Marshall JCM900 MKIII 2100
Marshall JCM900 Dual Reverb 4500
Marshall MG15 Micro Stack
Marshall 1960A 4x12 Cab. w/75w Celestions
Sonic 2x12 Cab.
MXR Fx.

Guitars:
Gibson LP Standard
Gibson Explorer
Gibson Flying V
Guild DV 6 Acoustic

"Only two tones apply: loud and LOUDER"

RiverRatt

A pair of SEDs are around $50. A pair of NOS RFTs are around $100 and will last over twice as long and sound better, too. I'm not rich... I'm trying to raise 3 kids and keep food on the table, but I can afford that much.

Check out what the Tube Store says about them:
http://thetubestore.com/nos-el34-siemens.html

jcmjmp

I have a set of EH EL34s in my JCM800, which I run LOUD. Never had any issues with them. They make for a very tight sound overall. I like 'em but they would be better suited to a more modern amp IMO.