Tubes...more specifically...GT tubes.

[Outlaws]

Preface:
I replaced my EL84 tubes from GT to JJ a long time ago.


So for a long while I have had a slight, and sometimes more than slight, rattle in my Fender ProJunior. I always have written it off as that stupid metal plate the is attached with springs to "secured" the power tubes. This persisted even after swapping out the tubes with new ones.

So I took it off. It still rattles.

Then it dawns on me about somethings I had read online about the filiments rattling and being audiable. Duh. Its the fucking GT 12ax7 tubes. The fuckers sound like I am shaking salt and pepper when I tap on them...and the amp is off..

I yanked out the JJs and shook them like a bitch...there is a bit there too, but no where near as bad.

My SuperReverb is not in the best of spots to do an inspections (I am a lazy sob and don't feel like moving boxes to get to it) so I ask this of you all, do you get this problem? I would like to check my Super, but that fucker is so not even accessible right now I don't want to unless I have a solid reason.

 

[Outlaws]

Ok, I am not that lazy right now.

Just got out the SUperReverb.

All tubes (which happen to be stock Fender GTs) are dead quiet when shaking and tapping. PowerTubes and Preamp tubes.

So, I guess my JJ in the ProJunior might be contributing a little also.

 

[krimson]

sounds like the tubes have gone microphonic.

 

[night'schild]

Tubes are like tires on a car they need to be replaced regularly. I change out my tubes at least every 6 months if not sooner. 12AX7 gt's suck IMHO, all they are is chinese crap. JJ makes great tubes. In most instances microphonics are found in pre-amp tubes and not power tubes. You might want to start from scratch and get all new tubes. Try out this place in my hometown they are great people www.tubesandmore.com

 

[Le Basseur]

12AX7 gt's suck IMHO, all they are is chinese crap.

Are you sure?
Most of the Groove Tubes are very cheap Russian imports (around 50 cents/piece at the factory's gates),the same stuff as New Sensor sells as "Sovtek" and similar to those fancy and overpriced Ruby's.GT switched lately to Chinese tubes (wich are even worst than the Russians in terms of reilability) because of the increasing quality complaints.
Anyway,the Russian factories are doing their job:they produce tubes.The best of them cost a little more but it's a lot of cheap junk out there.And the Russian companies know their interest:they sell this junk for nothing because the demand is combined with grief.The fact that a US-branded Russian tube isn't comparable with a Telefunken from the 50's isn't the Russians' fault (actually,they MAKE such quality tubes and even better,but not for us,suckers ) but to the very poor quality selection of a given US importer.

 

[5150 Musician]

Bob!

JJ's are my favorite tube and Bob is the man to go to for the quality tubes.
EuroTubes.com!
I compared a Peavey Classic 30 with stock tubes in it with a Classic 30 with JJ's in it, and the JJ's made a revolutionary difference. If you want good quality, matching tubes, Bob is the man to go to. With the amount of tubes he gets, he specs them ALL out and categorizes them. Since the specs of tubes are never consistant, he finds tubes that our out of their own spec range that fall into the category of another tube. I can use tubes I never thought I could use in my 5150, but with the tubes he specs, there's KT88's that can be used in my stock amp. (KT88)(6L6)(6L6)(KT88) in the sockets. It's nuts. Once I get my amp rebiased up to the correct mA, I'm definetly going JJ. Also, I'm going to get his premium graded high gain 12ax7's. The thing I like about Bob is that no matter what kind of music you play, hes got the tubes that will fit your amp perfectly.

 

[Whoopysnorp]

JJ's are my favorite tube and Bob is the man to go to for the quality tubes.
EuroTubes.com!
I compared a Peavey Classic 30 with stock tubes in it with a Classic 30 with JJ's in it, and the JJ's made a revolutionary difference. If you want good quality, matching tubes, Bob is the man to go to. With the amount of tubes he gets, he specs them ALL out and categorizes them. Since the specs of tubes are never consistant, he finds tubes that our out of their own spec range that fall into the category of another tube. I can use tubes I never thought I could use in my 5150, but with the tubes he specs, there's KT88's that can be used in my stock amp. (KT88)(6L6)(6L6)(KT88) in the sockets. It's nuts. Once I get my amp rebiased up to the correct mA, I'm definetly going JJ. Also, I'm going to get his premium graded high gain 12ax7's. The thing I like about Bob is that no matter what kind of music you play, hes got the tubes that will fit your amp perfectly.

I bought a mess of tubes from this guy recently, and I can vouch for him. You can tell by reading his website that this man eats, sleeps, and breathes tubes and is full of enthusiasm for tube amplifiers. He can tell you exactly what tubes you need for your amp to make specific alterations to the tone. Plus he emails you personally to let you know once your tubes have shipped.

 

[Thatupstateguy]

Most 'Big Box' type stores, including the online ones sell tubes without really checking for how well they work,.. only that they DO work,.... no balance tests, no filiment tests,... just ship em,... and hope they don't come back,..... in tests done by several Officianados, almost 50% of the NEW tubes bought , meaning the JJs, GTs, Chinese, and Sovteks have issues,.... they found that most vary in gain structure from the .... standard measurements of what they are supposed to be,.....This is mainly the preamp tubes I am refering to,....

By the book, the entire family of 12AX7 tubes, this includes 7025, 12AX7,ECC83, are supposed to be measured at 1.2mA, at 250 volts,with a -2 bias,.... if the tubes at your local shop were tested, they could vary as much as from .7mA, all the way to 1.6mA.
This being the case,..... where you buy your tubes from has a very important bearing on how your amp is gonna sound.....

If you just trust that the tubes you throw in there from your local store are gonna make it sound Soooooo much better because they are NEW, and you JUST got em from Harry the PRO down at the Onliest Guitar Heaven If they end up sounding like crap,.....

Well..... if what was already in there was lets say measured at 1.1mA output,... and you put in say,.... a replacement that measures .9,.... what do you think will happen,......????

Being as the Gain of 12AX7s are 100,...... you do not have to be a pro to hear the difference,.......

If you can,... buy tubes that have been gain tested,... matched, and from a reliable source,...... If you can, buy NOS tubes,.... they are much more consistant, last longer, and sound tenfold better than ANY new production tubes.
There are lots of very reliable sources to get them from,... and even tho they usually cost a bit more,..... you will enjoy playing so much more when the sound is pleasing,... the extra $ is definately worth it....


Steve

 

[AlfredB]

I bought a mess of tubes from this guy recently, and I can vouch for him. You can tell by reading his website that this man eats, sleeps, and breathes tubes and is full of enthusiasm for tube amplifiers. He can tell you exactly what tubes you need for your amp to make specific alterations to the tone. Plus he emails you personally to let you know once your tubes have shipped.

I second (third) this ... Bob Pletek (sp?) is def. the man.

he categorizes EVERY tube and you can ask him to send you hotter or cooler tubes, according to your prefs (cleaner (90) or more distorted sound(105-110)) ... The gain factor is penciled on the carton of every tube ... also he is very helpful answering mails.

I loaded my Sovtek Mig-60 w/ JJs, and now when we jam, nobody wants to plug into my friends Marshall head

best of luck

 

[Reggie]

For some reason my guitar amp (BlueDooDoo60) only likes the GT 12ax7's. I think it has something to do with the DC filament something or other. I tried some ElectroHarmonix's and I got a bunch of hum. I should really change out the GT's but I am afraid to buy some more tubes that won't work in my amp. I do like the JJ 6L6's for power tubes, though. The Svetlana's were nice and clear, but the JJ's sound better in the lower midrange to my ear.
Anyone have any experience with this DC filament hum problem?