southboundsuarez

Hey Myles, Yes, more specifically my questions regarding tubes... Faced with a growing collection of used and unpaired unmatched tubes,,, How to go about grading and matching them? 1: Is there any visiable physical characteristics to determine the condition or health of a tube? 2: Having a selection of several same output tubes, how can you determine which ones may be closest matching? 3: Can you match by simply installing and measuring cathode current? 4: Would it be pratical to build a dynamic benchtop test amplifier jig to match tubes? What features would you incorporate? 5: Tube testing equipment? Any particular test equipment you recommend or equipment vendors you find attractive? Price Points? 6: Rare/exotic/expensive tubes... Theoretically, if a tube has a broken or compromised envelope, could the interior components be saved/reused/recycled if someone could blow a new envelope and had a vacuum that sucked enough to draw the multiple "TOR" of proper magnitude for the immense vacuum required? (This assumes that the tube was not in service or subject to any current when exposed to air) Could the getters be reflashed?

Thanks Myles for all your good Karma and always "paying it forward" to assist others. When it comes to my interests and hobbies, I can get into it and go on and on! I am fascinated with the subjectivity of tone and the expression of tone through the use of valve amplification technologies. With your knowledge, experiences and contributions that you have made in the quest for tone,,,,, Just saying, that I am sure that I have enough questions and interest in your opinions that you could probably write a book. So if I start getting carried away or what not,,,, I hope someone will let me know "hey dude your hogging the forum" or "just quit now, with bothering the man!" Ok with that above disclaimer above said and without having reached my limit on Questions for Myles, Here's more general material for Myles to ponder and maybe could be helpful for others beside myself..... VINTAGE TUBES? USED TUBES? OLD TUBES? BACKUP TUBES? ECT....... What ways can a person judge and decide if an older tube is still serviceable or worthy? I have been more and more often coming up on old classic used tubes and such. Some old tube brands are in such high demand that prices for even used tubes have become ridiculous! As an amatuer enthusiast and not fully professional service man (person) .... I have fairly rudimentary compliment of test gear, (Test gear is another whole subject!) I don't have a "tube tester". Thinking out loud,, how many modern service guys actually have access to tube testing equipment? Everyone just relies on the tube vendors? What can a person do to test or judge tubes without a tube tester? I have been a bit apprehensive of purchasing tube testing gear for several reasons. First, I dont have enough knowledge about which tester, tests what? Or what needs to specifically tested. Not all testers are the same or useful in what attributes they test. Second, nobody makes a modern tester that can bought brand new. Vintage old equipment that is reliable might be a premium, and reqiure alot of maintence and calibration, plus most are big boat anchors that require shop space too. So short of a tube tester what can someone do to judge or grade the usefulness of tubes? One bigtime scenario that I have come upon is all these unmatched unknown tubes I have accumulated. I suppose its a symptom of my hoarding but I always save my old tubes when I put new ones in. I have one amp that would vibrate and puncture the envelope on just one tube and I ended up with alot of mismatched sets of triplicates before realizing what caused vacuum failure. Expensive when you have to buy a whole set of matched 6550's, relying on the vendor to grade them! (Ok I shoulda bought groovetubes or ruby's that grade and indicate the matched sets! But I am a comparison shopper looking for best deal and at that time unsavvy on how to spec and request a single to match my other triples!) Still am unsure how or what to request when I dont know the exact tranconductance and how current was matched with the other three. We put alot of faith in how the heck these vendors actually match a set sold to us. Dynamically in the amp may or may not be indicative, but if it is working I suppose all else matters not... Maybe that crosshatch mismatch is a good thing sonically and the old crude perception of ones own ears knows best? Similiarly I have a rare old amp that runs exotic expensive quad of 8417's I have numerous single examples and no way to match em other than just measure individual cathode current in amp operation? (Lightbulb moment) . Accumulating tubes and trying to match them, what other way to test other than measure current draw in a test amp? Visual physical inspection? Anything to look specifically for? Am I missing anything when I look at the following things???? I look at the plates, looking for deformation, warpage, signs of overheating. I look at the mica standoff and spacer, making sure the components are secure, I also hold the tube and tap the envelope with my forefinger, feeling if the interior vibrates or rattles and possibly microphonic. I view the silver deposit on the glass around the getters, looking to see how solid the deposit and how opaque and no haziness cloudy or dull flaking for indications of vacuum failure, I also look at the glass for any other evidence of foriegn or dark dirty burnt deposits such as vaporization of the interior components deposited upon the glass. I check that the leads arent broken or arc'd below the plates and where they exit the envelope. Is this sound methodology? Or does it really prove norhing? I hate to place a tube in an amp only to have it be internally shorted and take out my newly built or overhauled amplifier. Its happened before, luckily with just a screen resistor. But would hate to fry a circuit board on say my 74 marshall! My collection of old and desirable vintage tubes is growing steadily. Its interesting and fun to roll some of them through my own amps on the bench as I gain a better appreciation for the subtle nuances and tone traits of various similar tubes. But how can I be assured of reliabilty of the tubes life once I button up the amp and want to put it to use? ESPECIALLY WORRYSOME IS RELIABILTY OF POWER TUBE DISCOVERIES! Even more so is the fact that as I have refined my ear and experience at judging tone, more and more acquaintences look to me for tone and setting up their amps! A big starting point and cornerstone to my toneprinting begins with Vintage and/or NOS premium tubes. Many times my tube precurement must resort to antique salvage used finds of these devices. When used for non-personal gear, and professionally performing gear reliabilty now becomes a liability issue, not just an inconvienence. And...... what to do about all those unmatched singles I have collected? How many single ended amp builds can you have? I got a single ended of every popular audio tube,,, either breadboarded or housed in lunchboxes, tupperware, even inside an old dreadnought... ! Maybe I could build a benchtop test amp thingamajiggy. Could run some dynamic testing? What features would you include on such a project? What would you measure and how could it be incorporated into the test amp? Finally what traits make certain tubes stand out as being exceptional tubes? I have limited experience with a few of those holy grail NOS tubes and some of them were nothing spectacular. A set of Mullards stands out as being very uninspiring. I have others such as a pair of mediocre sylvania bq6c that were relabeled as magnavox that were exceptional sounding. I put those ones aside for safe keeping! Interestingly they had failed my visual screening numerous times because of all the dark burnt looking deposits inside the glass. NOW TELEFUNKEN 12AX7 ECC803 SMOOTHPLATES.... those that I have are the gold standard. I didnt even know how premium they were back when I first had placed them in a Crate Blue Vodoo amplifier and appreciated that they worked best. No wonder why, they are all the hype, at least the few working examples I have. However, I just noticed the bids that some have been getting on Ebay,,,, if thats any indicator of the market, I am very scared! Great tube but not at over $150+ dollars with or without orig box! Also as I proofread I had another question about why I am hoarding numerous tubes with no vacuum? Could they somehow have a new envelope blown and if soneone could draw down a powerful enough vacuum? I know not many places to find that strong a vacuum but, I have crossed that bridge before in the other direction and now have access to 4800-6000psi compressed air! So might not be practical but is it feasible given the tenacity,, could new life come to lets say some ultra premium uber expensive tube examples in which the envelope had failed and breached in air? I just cant seem to throw some things away! So if I havent worn out my welcome what has Myles or anyone else have to say on the subject of tubes, old tubes, used tubes, NOS tubes or just usefulness of tubes in general?????????

Yes, indeed I agree about the iron! That's the route I was envisioning when I mentioned building my own Blackface . A beefier P.S. and a correct OP tranny & choke all ala M.M.! A pair of 6L6GC's throw in a tag board with some orange drops and silver mica caps. Man, there must be a gutted basketcase reissue out there somewhere for cheap!? What ever happened to all the bargain silverfaces ya used to find so plentiful? Well I am going to build something along these lines someday,,, of course probably after everything is said done without compromise and toned how I ultimately would prefer for my own rig.... I likely will end with 6v6's anyways,,,,,, L.o.L. Sure love the loose jangle of some of those Mercury Magnetic output trannys. INDUCTIVE REACTIVE Circuit theory is simply magical mojo to me! How the hell do you simply predict or know that so many hundreds of windings around something spaced so far apart is going to equal that and that is going to be harmonically musical????! Amazing to me and I dont care about all the theory and mathematical formula the experts can show me, all those graphs and phase angles ect.... it isnt science.... it's magic and wizzardry is what I say! Pure witchcraft! I got a tip on some decent RCA grey bottle 6v6 blackplates!!!! Cheap too! And its a girl that has em! Gotta go now!!!!

Well, that answer certainly doesnt increase my confidence running the 6L6 ! Kinda tells me what I think I already know or should know better of.... You convinced me to order some JJ's for this amp. Had I had any 6v6's on hand I would have installed right from the very get go. However once I installed those 6L6's and heard this thing,, I was like WoW! I suppose I will have to build my own take on a 6L6 AB763 with some serious iron aboard it. Normally, I prefer a good NOS 6v6 usually like the RCA blackplates. Seemed NOS 6v6 were plentiful and reasonable, but these days with smaller amps the demand has now exceeded the supply and the price and availibilty are starting to really reflect that. I have been hearing many good things about the JJ's for a couple of years now. I have had bad results with their preamp tubes being very microphonic. I think I will give them another try with these 6v6's though. They sound as if they are quite robust from what I have read. If they have similiar 6l6 sound then for the price its a win win.... otherwise maybe I will hunt down some NOS Brimar Coke Bottle 6v6's and can perhaps roll some recto tubes to get some sag..

Hey Myles, How good of an idea is it to run a pair of Sovtek 6L6GC's in a Fender reissue '65 Deluxe, designed to run 6v6? Do you think that it would be reliable enough to gig weekly, or is it a disaster waiting to happen at the most inappropriate time? In my application the plates of the 6L6 are recieving about 380V and the cathode current is 44mA , for approx static dissipation of 17 watts? The stack has minor mods mainly tone and coupling caps to reduce the brite and slope the treble. No power supply mods, the stock filter caps appear in good condition. I am running the stock OEM tube recto, whatever Fender uses... I also increased the coupling cap to the PI, and I am running a very nicely balanced NOS 12ax7, replacing the stock 12at7 PI My first concern is overstressing the power supply. So far it seems to run fine. I cant help but wonder if that slight but sweet sounding amount of sag is detrimental? My second concern is for the mismatch on the output tranny with the 6L6 and the stock 8 ohm emminence speaker? Is it safe? Definately dont need a failure of this setup in the middle of a performance! But it does sound so very sweet!!! It doesnt appear to be too hot to the touch and is so far so good on the bench and in the living room. Should I be nervous? Or do you think that with regular maintainence I can let this rig hit the road? Thanks Brian