It is currently Fri Apr 18, 2014 1:10 pm

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: Dead preamp tube?
PostPosted: Sat Oct 15, 2011 9:26 am 
Offline
User avatar

Joined: Fri Oct 14, 2011 6:55 pm
Posts: 17
Location: Montreal, Quebec, Canada
Hi everyone,

I recently put a Tung-Sol 12AX7 in the V1 position of my JSX head. Everything was ok until I decided to test the outcome of putting it in various positions.

When I tried to remove the tube from V1, it was very difficult. The tube was stuck in there. I finally managed to get it out and put it in V2.

Powered up the amp, and I was getting no sound at all. I switched it to V3 (which is the fx loop and active eq I think) and I was getting sound. But as soon as I engaged the FX loop, the sound was gone.

Do I have a faulty tube? I see its filament light up a bit but not as much as my other preamp tubes.

_________________
Be someone


Top
 Profile  
 
 Post subject: Re: Dead preamp tube?
PostPosted: Sat Oct 15, 2011 10:35 am 
Offline
User avatar

Joined: Fri Jul 24, 2009 5:38 pm
Posts: 1386
Location: Columbia, Tennessee
that tube has a spiral filament encased in the plate structure, it won't glow as brightly as other tubes. That being said, there is a problem with Russian made spiral filament tubes when used in cathode follower positions. V1 is not a cathode follower. But I am unsure of the other positions in your amp. Many times, particularly with Mesa amps, the tube will fail almost immediately when placed in a cathode follower position (as in V4 in my Heartbreaker, for example).

Hope this helps.

_________________
When Gibsons are outlawed, only outlaws will have Gibsons

Si Gibsons proscriptae soli proscript habebit Gibsons


Top
 Profile  
 
 Post subject: Re: Dead preamp tube?
PostPosted: Sat Oct 15, 2011 11:45 am 
Offline

Joined: Sat Apr 17, 2010 2:54 am
Posts: 433
If V1 was the last position that worked, have you tried it there again?


Top
 Profile  
 
 Post subject: Re: Dead preamp tube?
PostPosted: Sat Oct 15, 2011 10:52 pm 
Offline
User avatar

Joined: Wed Dec 03, 2008 11:44 am
Posts: 520
I would try it in V1 again and see the result.
I believe V3 is the Cathode Follower stage in the JSX (maybe Enzo can confirm). One time I put a Sovtek LPS in the V3 spot of my JSX and the tube failed almost immediately.

I didn't care for the Tungsol 12AX7 in V1 of my JSX. It was too bright and a little noisy.
The absolute best I've found to use are JJ ECC83S's in V1,V2,&V3 and a Russian tube in V4, either a Sovtek or EH.

_________________
PEAVEY JSX
PEAVEY 6505
LANEY GH50L
ENGL FIREBALL 100
SOLDANO AVENGER
MARSHALL JVM 210H
MESA SINGLE RECTIFIER
VHT PITTBULL ULTRALEAD
MARSHALL JCM800 2203KK


RANDALL CS 2x12
MESA STILETTO 4x12
KRANK REVOLUTION 4x12


Top
 Profile  
 
 Post subject: Re: Dead preamp tube?
PostPosted: Sun Oct 16, 2011 8:23 am 
Offline

Joined: Fri Sep 12, 2008 3:10 pm
Posts: 25918
Location: @ Mountain Retreat [Cincinnati Ohio]
Tubes can & will fail.......

IF you purchased tube new request exchange.

Tube manufacturers generally provide 60 day warranty.

_________________

PAF Classic Series Tube Kit.......Created By Classic30inCincy
Majic Mojo Tradename..........Created By Classic30inCincy
Graduate Of Joe Friday / Dragnet School Of Correspondence
Doctorate Degree Diplomacy From Royal Order Possum Lodge


Top
 Profile  
 
 Post subject: Re: Dead preamp tube?
PostPosted: Mon Oct 17, 2011 6:02 pm 
Offline
User avatar

Joined: Fri Sep 12, 2008 10:24 pm
Posts: 5896
Location: Lansing, Michigan
There is no cathode follower in the JSX. The only stage with a cathode at any voltage to speak of would be the phase inverter, and that shouldn't be near enough to trouble any 12AX7 model.

The tube was probably damaged. Try a different tube, grab one out of another amp if you need to.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 16 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group