Tubes are funny things!

[davidallancole]

So, my buddy gave me a Mullard 12AX7 produced back in the 60's last night to try in my Epiphone Valve Junior.  Its got a Sovtek in it currently.  The Mullard had less gain, and with the JFET booster I built to go in front of the amp, the Mullard is way thinner and tinnier than the Sovtek.  Sovtek it will be. 

The price on tubedepot.com for a NOS Mullard 12AX7 is $149.95, $8.95 for the Sovtek.

Anybody noticed this type of thing with "better" tubes sounding worse?

[JKowalski]

The distinction between many tube brands nowadays is virtually zero in terms of quality and everything in terms of brand image, though there are exceptions (closer to ideal values, construction quality, ruggedness).

NOS does not at all mean high end - but people are deluded into thinking they are. Its the whole "everything was better back then" idea that is utterly amazing in how widespread and firmly embedded it is in our society. If it wasn't, it is perhaps possible that we wouldn't even have tube amplifiers anymore... (not debating their vastly different amplification quirks and unique sound but simply giving a nod towards the ability of solid state engineering to replicate it or construct something that sounds even better). That also brings up the point that everyone has their own "sound" they like. Tube amps are so widespread also probably because of the peer pressure effect where pretentious tube amp owners act like everyone else is missing out. I'm sure, no I KNOW, that most guitarists will approach buying a good amp to use with the idea that they will only buy tube even though there might be a SS amp out there that they would absolutely LOVE.


Back to the topic...

Keep in mind people in the audio side of electronics have a very different idea of what "bad" and "good" is. Electrical engineers will look at a part, and determine it's uses based on specifications. If one 12AX7 brand is slightly different (characteristics, ruggedness) then another one, the engineer would see them as two units suited for their individual purposes.

A guitarist or audiophile (there are a lot of parallels) will swap them out into an already built unit without modifying the circuit and arbitrarily decide which one sounds "good" or "bad". The tube labeled "bad" is shunned even though it is perfectly fine and performs admirably as it was manufactured. Remember, the tube is part of a circuit and is not the sole determiner of the "quality" of the amp. While you could certainly do it, swapping out tubes to find the "best" sound is not a correct way (in the engineering sense) to approach a circuit.

On a large scale, the community falls away from tubes that people shunned and then expressed their opinions which spread on and on...

And then of course theres the whole "Chinese manufacturing is terrible, no evidence needed" idea that results in Chinese made tubes always selling cheap.

[davidallancole]

Selling them cheaper works for me.  Buying a NOS Mullard could buy you a whole new amplifier.

[zambo]

when i worked at a reputable supply house I heard a lot of things about chinese tubes and have avoided buying them since then. Are they better now? I got my info from pretty good sources I thought at the time but maybe they are the afore mentioned audiophile snobbish types?? Either way I still think tubes have a sound that cuts through and hits harder than every solid state amp I have tried in live situations. In the home practice arena at low volumes though I still like my peavey trans tube....I just do...dont judge me.

[FlyingZ]

I bought a NOS Mullard from Doug's to test and it now resides in a junk parts bin due to low gain, thin sound, poor harmonics etc. Sovtek are among the best 12ax7 tubes I've used and I will swap them freely with GT.

[petemoore]

  SS output amplification is so much simpler:
  The only requirement to know about loading is: never overload it.
  Tube output amplification may produce distortion transients which occur at high frequency intervals, this can relate to air pressure/speaker suspension...buncha other stuff like volume setting on amplifier, instead of avoiding the parameter or parameters which cause loading or overloading the output, plenty of discussion is relevant only to a very small degree, and the discussion invariably is 90% vague, and impossible to replicate exactly or even closely using real-world hardware...it is always different, in the same way that someone you know, you know differently than the way I know them...has to do with phasing and moon, other stuff like room size, cabinet and surface textures, what speaker, what setting, what pickup.
  It's a little easier these days to get almost the exact same guitar/pickup/speaker/cabinet/amp/..anything else as ____ [but I wouldn't recommend it].
  Load a tube output and it will do this: distort, have frequency response shifts all at input frequencies...complicated.
  Load a SS output and...if the coil doesn't leave through the front of the cone or bash itself to bits trying to exit through the back, you can have the nastiest sounding broken-tone that no-one has use for...ie follow the manual or have the amp with limiter..and just never distort it !  ...simple.
 
 
 
 
     

[wavley]

1. Just because it says Mullard doesn't mean it's not worn out and past it's usefulness, even great tubes go bad, I just replaced Mullards in my Traynor Bass Mate with JJ's for this very reason.
2. Just because it says Mullard doesn't actually mean that it was made by Mullard, it was and still is common practice to re-brand tubes (Groove Tubes is a great example)
3. Everything J Kowalski said.

I've heard Chinese tubes that had the smoothest transition from clean to dirty ever, I've heard Genelex, Mullard, and Amperex stuff that sounded like crap even in the proper circuit.

We got away from tubes because they were terribly behaved and terribly inconsistent.

Of course I LOVE them because I'm terribly behaved and terribly inconsistent.

[Mark Hammer]

1. Just because it says Mullard doesn't mean it's not worn out and past it's usefulness, even great tubes go bad, I just replaced Mullards in my Traynor Bass Mate with JJ's for this very reason.
2. Just because it says Mullard doesn't actually mean that it was made by Mullard, it was and still is common practice to re-brand tubes (Groove Tubes is a great example)

+1

I am of the generation that were regularly sent to the drugstore to buy tubes for the TV.  Many drugstores in the 60's would have a sort of "station", containing a tester, and several shelves of tubes.  You'd test out what you brought with you to confirm its' status, and replace it with something that tested "good".  Customers were trusted to monkey around in the boxes of tubes to find what they wanted/needed.  Possible that tubes put back into the box and onto the stock shelf were the lesser ones, and ended up as "NOS" ?  Sure.

[FlyingZ]

1. Just because it says Mullard doesn't mean it's not worn out and past it's usefulness, even great tubes go bad, I just replaced Mullards in my Traynor Bass Mate with JJ's for this very reason.

It's better right? I imagine any tube would be an improvement over Mullard.

I have heard JJ's in some instances can sound even better then Sovtek and GT (pre or post Fender) but have a very short lifespan. I tried them for a couple gigs and found the harmonics too subtle and swapped back in my Sovtek/GT combo. We are talking preamp I hope, poweramp tubes are a hole other story. JJ's are ok I guess if you're on a budget.

Tubes last a very long time unless severely abused. I ran a gigging amp 15 years without changing a tube, don't believe the salesperson 

[davidallancole]

One of my problems playing a tube amp is the time issue.  I keep thinking, are my tubes dead yet?  Is this what it sounds like when tubes are wearing out?

Flying Z, my initial post was based on the 12AX7 in the pre-amp section of my Valve Junior.

[wavley]

I swapped out the EL84s for JJs, the Mullards that were in it started to sound dull and lifeless compared to when I bought the amp off a guy that was in White Witch.  They sounded really great, but after a few years of me running the crap out of it (the bass mate is an incredible sounding amp when on 10) they were starting to sound tired.

On the advice of the guys on the Traynor yahoo group I went with the JJs after burning up some Sovteks, apparently the JJ EL84 is the only modern production tube that can handle the plate voltage of a traynor.  Which leads us to J Kowalski's point about circuits, designers like Pete Traynor pushed the limits of tubes with his amps to a point that when Phillips changed how they made the 6CA7 without telling him, his amps started popping tubes for no reason.  A tube you may find stiff in an amp may really come to life in an amp running a higher B+, Traynors were designed around Phillips/Mullard tubes and those are the tubes that make them sound REALLY great, I'm running two YSR-1's with their original Phillips 6CA7s, I keep trying new tubes and I keep coming back to nearly 40 year old tubes, although I really loved my Pearl/Winged C Cryovalves until one of them broke on a Brooklyn curb.

I'm fond of the way some Sovtek tubes sound, I love the 12AY7 they make, but I stopped using them because my English Muffin was just eating through them so I use an Ei 12AU7 gold pin and a Telefunken 12AX7 and the combo sounds great.  I have had extreme reliability problems with the stuff coming out of the New Sensor factory and have stopped using them after losing half a dozen sets of EH 6CA7s and my amps are rock solid inside with all the tube life mods.  When I worked at the shop Marshall had to switch from Winged C stuff to JJs because amps were popping tubes left and right, though I think they sound pretty decent I wouldn't trust them.  Currently my favorite new production preamp tube is the JJ ECC803s, it has a longer plate and a spiral filament and the result is low noise and REALLY solid lows and low mids.  I can't really say that I care for the JJ EL34, I like thunderous lows, and it just doesn't have them, I haven't really tried the 6L6.  I haven't heard the new Genelex stuff yet, but considering the price and the fact that it's just another New Sensor tube, I'm unlikely, same goes for the new Mullard branded stuff.

It's all about the right tube in the right circuit, buy a bunch of tubes and swap them until it sounds right, use the ones you don't like for reverb stages and stuff.

[DougH]

I bought a NOS Mullard from Doug's to test and it now resides in a junk parts bin due to low gain, thin sound, poor harmonics etc. Sovtek are among the best 12ax7 tubes I've used and I will swap them freely with GT.

I almost bought one of those $50 Dutch EF86's he had that were supposed to be "holy grail" a few years ago. Then I got a set of 3 very similar to that one from Ebay for $20. They sound good, different than the JJ I already had (which has been shunned in some circles) but none of them are "holy grail", whatever that is. I mean, the amp sounds pretty great no matter what tubes I use, and the speaker has a much more obvious effect on the sound than the tubes ever did. (I have one cabinet for higher gain sounds and another one for "piano-like" cleans with this amp. And I swap those more than I ever mess with the tubes.) In general, I don't judge tubes as "good" or "bad", just "different". As JKowalski implied, most of it depends on the circuit you put it in. Very little of it is absolute, most of it is relative to the application.

That said, I have a black plate 5751 that seems to sound good and have some nice qualities no matter where I use it. And IME, JJ tubes tend to sound a little dark- but that can be good or bad. It all depends on where you use them and what you are looking for.

[DougH]

1. Just because it says Mullard doesn't mean it's not worn out and past it's usefulness, even great tubes go bad, I just replaced Mullards in my Traynor Bass Mate with JJ's for this very reason.
2. Just because it says Mullard doesn't actually mean that it was made by Mullard, it was and still is common practice to re-brand tubes (Groove Tubes is a great example)

+1

I am of the generation that were regularly sent to the drugstore to buy tubes for the TV.  Many drugstores in the 60's would have a sort of "station", containing a tester, and several shelves of tubes.  You'd test out what you brought with you to confirm its' status, and replace it with something that tested "good".  Customers were trusted to monkey around in the boxes of tubes to find what they wanted/needed.  Possible that tubes put back into the box and onto the stock shelf were the lesser ones, and ended up as "NOS" ?  Sure.

Kind of like the Ge transistor thing- a lot of the "good ones" have already been sifted out of the lots. Which is why you rarely ever care about part numbers with them.

Tubes used to be like batteries. When they wore out you went to the store and got some more, making sure they were good before you bought them. No one agonized over "tone" or "3D harmonics", "haunting mids" or even "bias" very much.

[wavley]

That said, I have a black plate 5751 that seems to sound good and have some nice qualities no matter where I use it. And IME, JJ tubes tend to sound a little dark- but that can be good or bad. It all depends on where you use them and what you are looking for.

I have a black plate 5751 and it sounds great in my vibrolux while a bit lackluster in my traynor.  You're right about JJ's being a bit dark, that's why I like them in the traynors because they sound good there.  My fender stuff is RCA, Sylvania, and GE all the way I actually like the Groove Tubes GE 6l6s, I hear they have a reliability problem, I've got two amps with them and can't complain, but my traynor ate one of the GE6CA7 Grooved tube, but it was about the time a lost a component in my bias supply so I can't make a judgment on that.

[FlyingZ]

One of my problems playing a tube amp is the time issue.  I keep thinking, are my tubes dead yet?  Is this what it sounds like when tubes are wearing out?

I spent hundreds many years ago thinking I could hear the bass getting muddy or the high rolling off. Never have I improved the sound of an amp by changing working tubes of the same brand and type.

[davidallancole]

I'll have to remember that.

[amptramp]

A friend of my daughter had a Traynor YVM-66 that was in the process of digesting one of its 6CA7's which had a blue glow internally and was getting red in the plate.  No one was too keen on an exact replacement at $37 per tube locally, so I changed the design to reduce the screen voltage to 150 volts using five 30-volt zeners in series, added plate caps to the pin 3 (plate) connection and ran 6BQ6GT's which I happened to have with the prospect of changing to 6DQ6B's later.  I had to replace an electrolytic that I added in the screen circuit that leaked enormously once the power resistor beside it heated up, but further testing showed that everything sounded just fine.  The 6BQ6 and 6DQ6 use the same bias voltages, so it would just be a replacement with no rebiasing necessary to get from the 25 watts two 6BQ6's can provide to the 35 watts two 6DQ6's can provide.  If you do a job like this, test extensively - the electrolytic problem didn't show up until the amp had been on for about 15 minutes.  Other than that, the Traynor is brick-outhouse rugged, so I expect no further problems.

The cost of one 6CA7 can get me a bushel basket of sweep tubes, which remain plenitful.  The total cost of the rebuild was about $20 plus the 6BQ6GT's which I already had.  The owner was pleased with the amp and I would recommend taking on challenges like this (if you know your way around tubes) for people who get an amp that requires expensive tubes.  Besides, the plate caps look butch and my only regret is that I didn't have a place to add a VR-150 as a screen regulator with its nice pink glow!  Pink was the favourite colour of the girl who owns the amp.

[wavley]

A friend of my daughter had a Traynor YVM-66 that was in the process of digesting one of its 6CA7's which had a blue glow internally and was getting red in the plate.  No one was too keen on an exact replacement at $37 per tube locally, so I changed the design to reduce the screen voltage to 150 volts using five 30-volt zeners in series, added plate caps to the pin 3 (plate) connection and ran 6BQ6GT's which I happened to have with the prospect of changing to 6DQ6B's later.  I had to replace an electrolytic that I added in the screen circuit that leaked enormously once the power resistor beside it heated up, but further testing showed that everything sounded just fine.  The 6BQ6 and 6DQ6 use the same bias voltages, so it would just be a replacement with no rebiasing necessary to get from the 25 watts two 6BQ6's can provide to the 35 watts two 6DQ6's can provide.  If you do a job like this, test extensively - the electrolytic problem didn't show up until the amp had been on for about 15 minutes.  Other than that, the Traynor is brick-outhouse rugged, so I expect no further problems.

The cost of one 6CA7 can get me a bushel basket of sweep tubes, which remain plenitful.  The total cost of the rebuild was about $20 plus the 6BQ6GT's which I already had.  The owner was pleased with the amp and I would recommend taking on challenges like this (if you know your way around tubes) for people who get an amp that requires expensive tubes.  Besides, the plate caps look butch and my only regret is that I didn't have a place to add a VR-150 as a screen regulator with its nice pink glow!  Pink was the favourite colour of the girl who owns the amp.

I'll keep that in mind, I'm always looking for hacked up Traynors as a platform for mods, I don't tend to hack them myself as there are plenty of EL34 variants that will work, I prefer the sound of true 6CA7s, I've had nice 34's and KT series tubes that sound good and all I have to do is re-bias.

[tubelectron]

Hi All,

I service and (sometimes) build tube amps for 30 years (Hi-Fi and musical instrument amplification) : the brand and the condition of the tube are independent matters.

A+!

[petemoore]

  Upgrade from lowest quality tubes taste better and take longer to cook.
  RCA Blackplates, JJ's, TS, Sovtek...all are worth the chefs time to consider, any one of these types can make an amp-cook create great tastes.
  "Those" tubes will make ok-ish spares, nice to have along the way.
  What's wrong with the amp doesn't dwell in it's lack of blackplate barium, more likely it's transformers would be an opportunity for ''weak-point / improvement'', that or a speaker upgrade [from speaker that needed upgraded, kind of a catch 22...*blind 'upgrade?' selections].
  Upgrade once [if just to find out if it was needed], the get unstuck before you have to buy 22 tubes of 5 brands and types to find out "it was the tires, not the driveshaft that wanted for greater smoothness".