Tube Tester, New Tubes and disapointment.

MLGrado

MLGrado

New member
Joined
May 23, 2015
Messages
5
Location
Knoxville, TN
Hi all. New to the forum.

I caught the tube bug, and caught it hard. I started with a tube amp back in February. Initially rolled in new production tubes. Then came the sickness when I bought my first NOS tube. Since then, in the last 3 months, I now own probably 150 vintage tubes. Some NOS, most others are likely used a little bit.

This week came my first tube tester. When you come into possession of 150 tubes in such a short amount of time, of course at least some of those are impulse purchases, or eBay auctions you never thought you would win with your lowball bid. Getting rid of a few to recover some of that cash was/is in order. Hence the tester. Gotta know what I am selling people. It has already saved me from listing a couple duds that still sounded alright, but were apparently marginal at best.

The most interesting thing though, is what I saw on the tester when I put on my almost brand new JJ Electronic EL84 tubes. I have two matched sets of 4. Two, since I felt my first set was prematurely wearing out. Now that I have tested them, my suspicions of early death are confirmed.

My integrated is Cathode biased, which is apparently pretty hard on tubes. I didn't suspect that things would be this bad after only a couple hundred hours! Sure enough, of my 8 EL84 tubes, 3 of them are already toast. Two of them test low on emissions, the third tests fine initally, then slowly falls off back into the 'replace' zone of the tester meter.

I have put at least as many hours, probably more on the Vintage Sylvania Black Plate EL84 tubes currently in the amp. The test meter says those tubes are still strong and robust, in spite of being used in a Baldwin organ before they came to me, and being subject to my marathon listening sessions that can last 8 hours or more.


I have always felt that the new production tubes in my possession from JJ and New Sensor sounded just fine. Looks like their durability and longevity is what may be questionable.

What are your experiences with the quality of new production tubes?

Thanks!

Andrew
 
MLGrado.......First, welcome to AudioShark.

Lumping New Sensor's tubes into the same category as JJ tubes is a mistake. JJ Tubes have a reputation for being short lived when compared to other tube manufactures of the same type. Some of JJ Tubes products don't even measure up to the original specification for operating perimeters, such as their 7591 tubes, but that is another story.

New Sensor's Gold Lion reissue tubes have proven themselves to be reliable with excellent longevity. I have rolled many tubes through a number of tube preamps and power amplifiers over the past four years or so, everything from new reissues to NOS tubes and used tubes. By and large the Gold Lion tubes from New Sensor in Russia offer some of the best performance to cost I have come across.

Good luck with your tube rolling and used tube purchases. It can be rewarding or it can be frustrating. Used tubes are always a crap shoot. By the way, what tube tester are you using?
 
I picked up locally a simple EICO 625 basic emissions tester. It has been freshly gone over and calibrated. Eventually as funds become available I would like to step up to a mutual conductance tester so i can test for triode match in preamp tubes.

I have several New Sensor tubes. I like them. Despite the language, I was lumping all New Production tubes together, generally speaking. I only have personal experience with the JJ failures, but I suppose I have been biased by the considerable 'purist' disdain for anything other than vintage. It is good to hear that my experience with the JJ's isn't necessarily indicative of all new production tubes.
And as far as buying used tubes goes, I have been able to obtain some outstanding tubes at low prices. But not without also investing into a number of 'duds'. Certainly NOT trivial in number. I have maybe 8 or 10 tubes sitting in my reject box. They may have tested just fine for emissions, balance, shorts, etc... but they fail the noise test miserably, and are of no use in a hi-fi amp.
 
MLGrado.......It is always a gamble when purchasing used tubes, especially on eBay.


1366318976_rolling-dice.jpg
 
There's always a chance too that your Eico tester isn't quite what it's purported to be.
 
Double-D said:
MLGrado.......It is always a gamble when purchasing used tubes, especially on eBay.


1366318976_rolling-dice.jpg
Click to expand...

When I acquire tubes via eBay, I communicate my interest in evaluating the tube(s) for AC and DC balance across all triode sections as well as assessment for noise and microphonics, using an Amplitrex AT1000. Should the evaluation not satisfy my criteria, I require assurance the tube(s) are subject to return for a full refund. If these provisos cannot be agreed upon -- I will seek alternate vendors. I just returned a quad, today, to China.
 
c1ferrari said:
When I acquire tubes via eBay, I communicate my interest in evaluating the tube(s) for AC and DC balance across all triode sections as well as assessment for noise and microphonics, using an Amplitrex AT1000. Should the evaluation not satisfy my criteria, I require assurance the tube(s) are subject to return for a full refund. If these provisos cannot be agreed upon -- I will seek alternate vendors. I just returned a quad, today, to China.
Click to expand...

Did the postage cost more than the tubes? :)
 
A LOT of people have reported reliability problems with JJ. I myself experienced reliability issues with JJ. Cathode bias doesn't automatically mean shorter life. It depends on who engineered the design. As an engineer, I investigated the pros and cons of cathode versus fixed and I use cathode bias almost exclusively, the exception being the GU50 which, for the most part, does not lend itself to cathode bias very well. if you are handy with the soldering iron, you can solder in a 1-ohm power resistor to each cathode. Measuring the voltage across said resistor will tell you the milliamps of current. Then you can figure out if excessive current is flowing.
There are Russian tubes that sub in nicely for the EL84 and will probably last a lot longer. I would use those, or the NOS tubes. I mention the Russian tubes in case you are cost-conscious as NOS can be spendy.
The tubes in organs tend to be rebranded tubes. For example, in the Conn organs I cannibalized a few times, there were black plate 12V6 tubes (same thing as a 6V6, but with 12-volt heater). I have been using an amp daily many hours a day for years with those 12V6 tubes and they STILL sound great. I haven't done the math, but they have a lot of hours on them. I got them used and nearly all of them tested OVER 100% on my tester which I'm told tends to underestimate the life left in the tubes (so that the tech can sell more tubes to the unwitting customer).
I prefer the 6V6 (12V6) to EL84, and an amp designed for one can run the other if you change the socket and change the cathode resistor. their power output and drive requirements and voltage requirements are very similar. IMHO, the 6V6 (12V6) sounds better. The EL84 with good tubes DOES sound good in ultralinear mode, though. I wouldn't use them any other way.
 
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