JJ 6L6GCs... WTF?

[überfuzz]

Bob p Actually I play with the idea to use the term more general. -Sir did your beef taste good. -Dude, it made my pants flutter. ;-)

[km6xz]

I have heard that expression before and always attributed it to high levels of IM distortion where two audio range waveforms mix for sum and difference waves when passing through a non-linear process. A very low frequency resulting signal, well below the musical range could be generated. Transformers would be the limiting factor however, a 8hz distortion product would see a long of attenuation in the transformer. The tubes would have no problem amplifying anything from DC to 15Mhz or much higher. The impedance of the speaker would be very low at 8 hz. Solid state amps could handle it fine but protection circuits might shut it off when seeing how much current is being pulled by a ultra-low frequency signal seeing a 1 ohm speak Z.
If you want cleaner, tighter, more authority from your base, get rid of any VLF signal content with HP filtering at the front end and the driver stage. It will be louder, and run cooler with more headroom for dynamics.

[Steve Conner]

I associate "pant fluttering" with a low frequency output big enough to flap the fabric of your trouser legs when you stand near the speaker. If the old tubes were worn out and not delivering full power, then the new ones might well bring back the pant-flapping experience.

A SVT with two 8x10 cabinets will kind of do it, but for the full effect you want a DJ playing drum'n'bass on a massive sound system.

[g1]

Some attribute the terminology "pant flap" or "pant flapping bass" to Geddy Lee. He may not have originated the term, but certainly helped popularize it. From an interview he did with Bass Player mag, Dec.88 : " That bottom end from pedals really sounds great in certain halls, it really fills and gives you a lot of pant flap, as we call it. It shakes your pants. Moves a lot of air in the low range,"
That being said, to get maximum "pant flap", I think you would required some vintage '70s wideleg pants.

And I'll go out on a limb here and wager that uberfuzz is talking about a different kind of "pant flutter", the kind that is strictly a male phenomenon.

[Chuck H]

And I'll go out on a limb here and wager that uberfuzz is talking about a different kind of "pant flutter", the kind that is strictly a male phenomenon.

And some might interpret it as the "brown note" effect. Where by the note and it's force are such that one craps ones self... Or at least a flatulent response.

[Chuck H]

FWIW I'm going to add to the bitch list about tubes. I've been through three new pairs of EL34's in my most recent build and every one has failed. Now, before you start accusations about the common denominator I want to assure everyone that the amp is working correctly and the failures are different. First were the Tung Sol EL34B's. Biased correctly and working fine until, after a suitable burn in, the amp was cranked up a bit to clip the power tubes and one tube shorted plate to heater. Then there were the Ruby EL34Bstr's that everyone said were very reliable, consistently good quality and sound just dandy. They were microphonic right out of the box. In a 60W combo you can't play a D note without hash noise and thumping the cabinet sounds like a flabby snare head. And yes, of course I pulled the other tubes to be certain. Last are the JJ E34L's that made a little of that phasey Wooosh-ing sound while warming up. Then a little popping and then seemed fine. But the problem worsened until now all they do is wooosh. This amp hasn't been fired up by the owner more than a dozen times but none of the tubes are returnable under warranty. He doesn't play much. So I'm down the cost of three pairs of EL34's and shopping for new ones I'm starting to think it's not possible to buy a good pair of EL34's anymore.

EDIT: I'm sure I've already mentioned somewhere about all the preamp tubes I've bought new that were bad out of the box. But I'll mention it again. I'm basically a hobby designer that sells his projects. I don't buy many tubes. In the last five years I have bought thirty new preamp and power tubes. Twelve of them were bad. That's a pretty awful failure rate for new product. I can't think of a single other product that could get away with that sort of thing. I've bought from a few different vendors and I've come to the conclusion that they all buy the cheapest batches or lots they can and then don't do much QC like burn in or even plugging them into an amp that actually makes sound to see if they're noisy or microphonic. I've become so touchy about it I actually expect to get hosed when making a tube purchase. Which I now do with the attitude that I can't continue to do this without the tubes so I expect to throw money at the problem until it goes away. With no defined limit on how much time or money it will take. At first I chalked it up to coincidence and figured I just had $h!t for luck but there are two other recent threads here where others are having similar problems. I'm officially beaten! My purchase failure rate is 35%. I'll happily pay 35% more for new tubes. But they'd better F@#KING WORK and I want a decent warranty!

[Chuck H]

Glad you liked it Bruce. Lemme continue a little if I may. The amp in question was going to be shown to Kurt Griffey this evening when Creedence finishes their gig at the Snoqualmie Casino. The Official Web Site of Kurt Griffey. But I ain't got no fish f#@k power tubes for it. Because there are no tube vendors testing their product "I" need to put in three times the work and I still don't have a properly working amp, but I sure as hell have missed opportunities! I'm so happy I could just $h!t myself.

[bob p]

Some attribute the terminology "pant flap" or "pant flapping bass" to Geddy Lee. He may not have originated the term, but certainly helped popularize it. From an interview he did with Bass Player mag, Dec.88 : " That bottom end from pedals really sounds great in certain halls, it really fills and gives you a lot of pant flap, as we call it. It shakes your pants. Moves a lot of air in the low range,"
That being said, to get maximum "pant flap", I think you would required some vintage '70s wideleg pants.

Bellbottoms! That's the ticket.

I think the first guy to get real pants-flap in his 70's wideleg pants had to be Entwhistle. He had the manliest rig of the day, way far ahead of everyone else. He was famous for using arrays of Sunn amps to deliver lots of clean power into enough speakers and subwoofers that he made his bass sound like a Steinway. None of that LF IM garbage that you get with girlie amps. I think he was the pioneer of the wretched excess bass gear. Here's what his simple little rig looked like back in the 70s, when most other guys just used a full stack:

[km6xz]

Then there were the Ruby EL34Bstr's that everyone said were very reliable, consistently good quality and sound just dandy. They were microphonic right out of the box. In a 60W combo you can't play a D note without hash noise and thumping the cabinet sounds like a flabby snare head. And yes, of course I pulled the other tubes to be certain. ..........But they'd better F@#KING WORK and I want a decent warranty!

Did Ruby drop their 6 month warranty? Why not send them back?
Maybe all has changed but when I was buying them in large quantity, an occasional bad tube would fail in a customer unit and Tom would replace it no questions asked.

If they develop power they would pass typical testing by the very few who might be interested in testing, however it would be a pretty rare supplier that is testing for microphonics in power tubes, they test for plate current in a fixed parameter test jig,if at all.

My own experience here is that power tube loose elements is the failure mode, not "fail mode" but failure to be usable yet still meet the only performance criteria a supplier cares about. I never remember getting new power tubes that were micro(bad term, in power tubes to be heard it is Mega-phonic)phonic when buying them over the years, until getting back into it the last two years after a 6-7 year absence.. I guess it was all my fault, I go away for a few years and the whole industry falls apart.

On my own tube sales, which are made in China, and plopping them into a test jig which sweeps anode voltages up to whatever the tube is rated for, or up to 1000volts, while stepping grid voltage per sweep, megaphonic tubes are clearly visible if they are tapped with a pencil. Tubes to 100 watts plate dissipation can be test to their rated spec this way, so a 6L6 or 6550 does not even get the curve tracer warm. It has a pulse mode also so for tubes that might fail without external cooling, they can be tested at high levels for short pulses for each sweep, in that mode peak power equivalent to 1000 watts per tube can be tested before the curve tracer runs out of power supply.
It is interesting to see a СЕД 6550 running peak power of 600 watts single ended in 10us pulse per sweep mode. I have not dared try that on a JJ anything.
I have tried some old Soviet small RF tubes with strange bases that handled 1000 anode volts continuously, while being rated at only 12 watts of dissipation. Their ratings were not for impressing anyone which explains why the well known 6П3с-е was only rated to 250 plate volts but still seem to be the most rugged and abusable "5881, 6L6" tube used in guitar amps. Better still is that they are only about $3. Too bad they are a bit lower gain than some common 6L6's or it would be the logical solution for metal amps survival.

By all reports here and from own experience, new tubes (except the really hard to get СЕЛ), are becoming less reliable by the month. Not good. A distributor could make a name for themselves and compete with the more established ones simply burning in and really testing the tubes, and then warranting them.

Technically, fast testing could be done with low labor cost. A jig would loosely hold the tube in a split cup, upside down, and a mechanism bring a set of conductors arranged in a ring to down to encircle the pins, regardless of orientation, and clamp onto the pins, automatic pin identification would be by polling resistance measurements instantly to determine the heater so all the pin contactors would be instantly assigned the correct connection to the test set which would run parameter test, including microphonics by measuring capacitance change between grid and anode induced by the mechanical vibration of the test jig itself, testing by dynamic signal that covers all ranges from high cutoff bias stepped downward to a cut off predetermined maximum plate current value. A higher heater voltage could be used to get the test time to bring it up to operating temperature, before lowering to rated voltage, so tests could be completed in 4-5 second per tube with no human input. Its actual measurements would be recorded and labels printed for box, individual serial number and tube label with serial and when released by the connector ring and the cup opened to drop the tube to a padded ramp that would divert it to the correct shute for packaging based on gain value, pass-no pass etc.
More than one test jig could be analyzed by a single test computer and switched distribution box. A method of preheating them in a larger array, maybe a wheel which rotating the next tube for parameter tests could speed up the time of test to less than a second is it pre-heated the filament. Even using just the single jig, 15,000 a day could be tested. A small distributor could start by doing it by hand, and charging a little more for the 11 second manual test and as they conquered the market could use this fully automatic system.

[Chuck H]

The design of such a test jig is beyond my engineering and fabricating scope. Maybe Juan wants to tackle it

Unfortunately I don't know if the vendor I bought the Ruby tubes from honors Ruby's warranty. I'll need to check. Because all the tube warranties I'm aware of are thirty to ninety days I assumed these would be the same. At any rate, if I can I will return the Rubys. If I can't I will buy some from a vendor that does honor Ruby's warranty (provided they still have the six month warranty) because they actually sounded better than the others, and at a lower cost.

[J M Fahey]

Thanks for the heads up but such a rig is *way* beyond my abilities, yet I can easily envision a much simpler yet real world tube punisher .... er .... tester: a push pull stage, with an actual transformer to provide a real world inductive load (we want to test resistance to flyback pulses) , with switch selectable proper +V, and screen voltage, driven by, say, 400 Hz squarewave and, of course, adjustable bias.

Similar to gun proofing, where they shoot a 20% extra powder cartridge (pressure variation is exponential, so that translates to , say, 50% or more explosion pressure), I'd test tubes with, say, 20% or higher voltages, plus allowing them to redplate for, say, 20 seconds, etc.

Infant mortality would be very high, but better now than on some stage, Saturday night, in the middle of a solo with 200 people watching.

[Chuck H]

Infant mortality would be very high, but better now than on some stage, Saturday night, in the middle of a solo with 200 people watching.

Or a few days before a delivery deadline with no time to order more tubes!

One hitch is that I'd expect tube warranties to cover only normal use. Would sticking tubes into a test rig that would actually find faults, rather than an amplifier, void the warranty? I haven't been able to find much about what IS and isn't covered. Some of the thirty day warranties indicate "no questions asked" but I wonder if there isn't some clauses like "tubes need to be installed by a licensed business" or "authorized repair center" or some such. I am neither. Not that I can't properly replace tubes, but I can't PROVE that. If I were selling a product like tubes and the person (technically unqualified) wanting to return them because of failure had put them into a newly, hobby built amp that might be something I would clause against.

[bob p]

I hate to say this Chuck, because you're hurting right now and I'm sure that you already know this, but if you're going to run with the big dogs and show your amps to big-name professionals, then you need to keep a good supply of known-to-be-good spare tubes on-hand.

btw, I don't know if you noticed this but I gave you some props in the OTT thread.

[bob p]

continuing the hijack:

John Entwistle Gear | John Entwistle Bass Gear | Whotabs

and the bellbottoms:

[Chuck H]

Yes, well... On the tube inventory note, not mentioned above is the three other sets of used tubes I had on hand. I wouldn't have saved them if they were too old or bad so I thought I had spares. Unfortunately they all fell short of the mark. One set was too microphonic for a combo, one was 6L6's and sounded dreadful with this particular amp and the last pair must have been older or weaker than I thought because one of the heaters died during testing. I get into these situations because I've done some good things for the right people. But I never planned to "run with the big dogs" as it were.

As it happens the appointment was cancelled (as was the gig at the casino). I was told that too much ended up happening for this to be a good time. So I sort of got a reprieve on that one. Now it's a matter of diligently setting up another opportunity. But at least the missed presentation wasn't "my" fault now.

And thank you for the cred on the OTT thread. As a non technical tech I worked very hard to solve for the various snarky issues that EL84's present. It doesn't hurt that I got a big, fat box of them for free and focused on them because they're what I had on hand. Unfortunately I'm down to my last pair I think the OTT is one of the better uses of EL84's I've seen. I spent some time yaking with the rep at the Orange booth at the 2009 NAMM show. They were premiering the Dual Terror. Sweet amp. Mine sounded better Just kidding. But it was really a different strokes thing at that point. I remember being a little put off that they could make such a good and affordable amp when I took such great pains to make mine. The Orange Terror amps are all really good designs. And FWIW the Terror amp circuits weren't known at that time. I didn't copy ANYTHING from the TT. Any similarities are coincidence. As are any similarities between my designs and the TrainWreck circuits. I came up with my topology many years before those circuits were accessible on line. My personal amp, and the same design I proto'ed for Dean Markley at that NAMM show could be characterized as a 15W Liverpool with a little TT thrown in. It's pretty sweet.