Tube Preferences?

rockdude326

Active member
Messages
56
So...I'm going to have to replace my recently deceased Electro-Harmonix 12AX7 preamp tubes in my Classic 30.  But, I don't really have a whole lot of experience with tubes or tube amps, so I have a few questions for you guys:

- What are your preferences for brands to buy tubes from? (I've heard several accounts of EHX tubes being dissastisfactory)

- Are there any tubes that are similar or swappable with the 12AX7, and if so what are the differences?

- Where do you usually buy your tubes from?

- Some tube manufacturers claim "low noise" and "darker sound" as differing characteristics, but are these claims valid or are the tubes really just the same as any other ones?
 

TroubledTreble

Senior member
Messages
830
Tubes can be just as subjective to taste as strings or picks. I had a matched set of Ruby tubes that I liked fairly well. But I still find myself searching for that "elusive" sound. What ever that is.

Here is a good place to find some tubes. http://www.tubesandmore.com/

And there used to be a guy in Orlando. I went into his warehouse and he had literally a million tubes. Super nice guy, very knowledgable. I liked doing business with him. I have since moved, and apparently he sold the business to these folks. ( He was getting up there in years ) Kind of a chessy web site and I haven't done business with them but it may be a good place. http://www.vacuumtubesinc.com/

Good Luck!

-TT-
 

-CB-

Senior member
Messages
5,427
rockdude326 said:
So...I'm going to have to replace my recently deceased Electro-Harmonix 12AX7 preamp tubes i

What did you do to 'em?  Deceased?  Ya know, its damn near impossible to destroy a preamp tube running in class A operation as an audio amp right?  That is - it runs as hot, does the same, whether you are playing clean and soft or balls-to-the-walls flat out gettin' it.  Thats because... (ta-da) its running class A... with the same current used (and heat given off) no matter what.

So now ya have me curious.  There should be literally 1000's of hours of use on a 12AX7.  Whats up with yours?
 

rockdude326

Active member
Messages
56
Well...a few reasons I think the preamp tubes are toast.  I bought the amp off the floor of a huge guitar store (probably stupid because it had most likely been cranked many, many times already), and adding to that, I had cranked it many a time myself to keep up with a full on rock band.  Not only this, but I replaced the power tubes because of a crackling noise and had an amp dude look at it and take care of a sort of rattling noise.  He said there were just sorta loose components in there, but he also mentioned I might want to replace my preamp tubes soon.  The noise went away for about a week, but came back.  I hadn't moved the amp at all from where it is in my basement, and I haven't even really cranked it enough to make anything jostle around....so I guess I just assumed the tubes are what's causing the rattling and that they are bad.
 

-CB-

Senior member
Messages
5,427
rockdude326 said:
it had most likely been cranked

I had cranked it many a time 

I replaced the power tubes because of a crackling noise

he also mentioned I might want to replace my preamp tubes soon

in my basement

First - didn't I just tell you, totally truthfully, that it doesn't matter one bit to the preamp tubes if you dime the amp, or let it sit there idling?  Thats correct.  Cranking it has no effect on the life of the preamp tubes.  None, zip, nada.  Thats because preamp tubes run in an operation mode called Class-A.  This means the amount of electricity going thru the tube is constant, no matter if you crank it or not, it remains virtually the same.  They run at a constant current, and constant temperature.

Second - power tubes in most larger amps _do_ wear if you crank it.  Why?  Because they operate in whats called Class A/B mode.  In Class A/B operation the current (or amount of electricity) varies all over the place as you crank it up.  High volume=high current draw, and this will wear the tubes faster.

Crackling noise can be many things.  It can be preamp tubes, directly or indirectly.  And can be other things.

With the amp on and warmed up - and some volume on the amp - and with the tube shields off, try wiggling the preamp tubes one at a time.  Does this make it crackle more?  If so, power down, turn the amp over, and get some "ProGold" spray (available at www.tubesandmore.com)  give each socket a spritz and put the tube back in.  See if that fixes the crackle problem.

If you still get crackling - pull the preamp tube closest to the power tubes.  Turn the amp on, let it warm up and... does it still make noise?  If so its your power tubes.

If you still get noise (when all the tubes are in) then try the ping test, where you flick each tube with your finger tip (like flickin' a booger) to see if the tube itself is doing it.

And finally - in your basement.  Is there a dehumidifier?  Is is damp there?  Dampness is probably the #1 cause of tube amp noise.  It causes things to slowly oxidize - like tube contacts, pots, etc.  Moisture seeps into transformers and even into resistors and capacitors.  A damp resistor will sit there and just sing away until it dries out - which could be never.  Don't keep the amp in a damp place.

And don't go blowing a lot of dough on preamp tubes, when it might be one noisy tube out of the mix.  A bit like replacing all four tires and the spare because you ran over a nail.  Just fix the flat, ya know?
 
N

neilium

Guest
CB's notes above mirror my experiences, for whatever that's worth. Also check for mechanical stuff e.g. loose input jacks, loose sockets, loose speaker connectors, loose speakers. Some amps rely on the chassis for a ground plane, and loose nuts and bolts then = crackle and pop.

As far as replacement tubes, I'm partial to JJ's. People who go on and on about NOS Mullard/Telefunken/Unobtanium have way more money than me, which means I automatically don't like them.
 

jackthehack

Senior member
Messages
5,630
Back to original question; for most applications I prefer GrooveTubes; were I redoing something especially tasty/vintage, might be tempted to pay the $$$ for NOS tubes if available...
 

-CB-

Senior member
Messages
5,427
Hate to say - I'm still doin great with Sovtek/EH 12AX7WA and WB varients.  WB's especially can be good in a bright amp.
 

Roundmidnight

New member
Messages
19
I like the Mullard and Tung-Sol reissues. Have several copies of each tube running in various amps and they sound great with no microphonics and most have been in service for 1-2 years. I did have one Tung-Sol fail prematurely (hash & crackling) but am not willing to write them off yet.

Time will tell.

RM
 

reddart

New member
Messages
17
I happen to like NOS tubes in general, even at their much higher price, their lifetimes are also generally much longer than new production tubes.

That being said, you can buy NOS sylvanias and phillips all day long on Ebay for almost the same price as new production tubes. I really like sylvanias in my superlead.
 

-CB-

Senior member
Messages
5,427
The lifetimes are longer because of two things - one:  they cost more, and two: they cost more

 

-CB-

Senior member
Messages
5,427
I dont think it will last any longer, or shorter than the better quality tubes made today.

You have to remember, the Russians took tube technology past the point where the USA , UK, and Germans did.

You also have to remember that there are lots of total CRAP old tubes out there - NOS  does not mean NOS, nor does it mean even good sounding.  That is, there are so many rip offs in the tube market today - unless you know the folds of the plates by heart (or by comparison) you're really getting a pig-in-a-poke.

And finally - Mikes a great guy!~  REALLY!!!!  I know him.  Haven't spoken to him in oh.. must be nearly 8 years now, but he's a great guy.  As an aside -  Mike (in his infinite good nature) used to come to my High School, where I first started playing guitar.  He was friends with the instructor there.  Well... WE... all thought it was cool, getting to hear and try all sorts of badass effects.  Black Finger, Soul Preacher, etc etc... BIG MUFF (of course).  ----- Time Passes Slowly ----  Years later, here I am, chatting with Mike, reliving some of that, and being one of his dealers (in the day).  Trust me, there's not a phoney bone in his body, he's taken his lumps trying to do the right thing, and somehow... he's making it work.  When EH goes in and says lets do a Mullard "repro" its not just a repro in name.  They try to get it right, as best as they can, with what is available.

And having said that - I'll stick with the WA's and WB's.

Another GREAT tube (if you get a quiet one) is a pre-war EI (Serbia) 12AX7.  Perhaps the smoothest 12AX7 EVER, and I mean EVER made.  But they're prone to noise, which you hear right away, so its easy to cull 'em out (and use em for the Vibrato oscillator).
 

reddart

New member
Messages
17
I agree that the EI's are nice if you get a non microphonic one, and preamp tubes in general have very long lifetimes...powertubes on the otherhand...

I also wouldn't buy a +$100 telefunken or mullard, which is why I suggested sylvanias, although even at $100 a tube, you will go though more cost in guitar strings before the tube wears out.

And yes, it definitely is a risk buying NOS tubes, especially on ebag, you must know what to look for...or sometimes gamble on poor pictures (which will mean lower wining price). I have been lucky, perhaps, but so far I have been happy with better than 95% of my ebag tube purchases.


For powertubes, I've tried almost all of the new production EL34s, and nothing sounds as good as a quad of mullard EL34s, or sylvania 6ca7s in my superlead, period. The only ones that have been close were the Groove tubes mullard el34's. The chinese KT66's sound pretty good vs GEC's, but about ~30% will die very quickly, and the ones that last more than a week start sounding weaker and ratty after a few months of heavy playing. The pair of GEC's I have in my JTM45 are still going strong more than a year. I have not tried the Tungsol or JJ's or the new "Genelex" KT66, but I have been burned and disappointed way too many times with these new production tubes (especially those originating from the slobtek plant) to even bother. These new production KT66's are also not what I would consider low cost either.
 
N

neilium

Guest
Well, if web design is any sort of barometer, I'd keep my distance.
 
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