tube fanatic Posted December 5, 2016 Share Posted December 5, 2016 No discussion about tube rolling is complete unless getters are included. Some ascribe such magical properties to the lowly structure that prices for tubes containing one shape getter over another can be beyond absurd. I've seen discussions in which some claim that they can hear differences in getter configuration in rectifier tubes! To help clear up some of this, I've attached an excerpt from an article featured in vol. 18/#6 of the Tube Collector (with permission from the association president) which explains what a getter is used for. Sorry for the picture, but I don't have a scanner (as all know, I'm thoroughly modern.......). Maynard Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted December 5, 2016 Share Posted December 5, 2016 OK gentlemen, I "get" what a getter does, and how it functions, but your two posts above do nothing to further your "arguments"....The photographed page explains (in part) what a getter is supposed to do, but doesn't say anything about the various shapes, sizes, locations, etc, that people either swear by, or swear at, and how they do or do not affect the performance of a tube. Nor does the statement regarding plate color further the discussion as to whether one color is/is not any better than another? Do you subscribe to the same argument regarding plate structure, smooth or ribbed, long or short? If I take your statements on pure face value, I guess it means that you don't care about these things, and that they don't matter. I can't imagine that's true, so I'm interested in your responses. Hope you have a fine day. Quote Link to comment Share on other sites More sharing options...
EMRR Posted December 5, 2016 Share Posted December 5, 2016 Isn't it also amazing that the first production version of any tube is virtually always sold as 'the best', commanding the highest price with claims of the best sound? How can it be? It can't. Audio mind memory is one of the most easily fooled human aspects, and when combined with any differences at all, makes an untangle able voodoo stew. One can easily trace many vintage tube prices today back to particular print article cork-sniffings in the 1990's, and with quite of few I've seen I can recall the tubes they liked best also happened to be the same brands that would show up on your door step that same month if you ordered from Antique Electronic Supply. Order next month and write the article then, the product and article results would be different. None of this is canonical, it's just not possible. Any one tube from a manufacturing batch will display differences from others in the same batch, which you can possibly hear and measure. Ever put 100 new same batch tubes on a burn-in jig, and then take the current readings for matching? I have, many times. Like many production items, there's a region in which most will fall, but the extremities of that common region may vary by a large margin. Then there will be 10-20% that fall outside of that common grouping, and appear to be totally different beasts at birth. It's fun to theorize about, but there are no definitive statements. It comes down to the individual tube, and whether YOU like the job it does in the PARTICULAR amplifier. Quote Link to comment Share on other sites More sharing options...
Schu Posted December 5, 2016 Share Posted December 5, 2016 My preference has been for long plates over short ones... why? Who knows... in my humble O, they way to tell is to try it. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted December 5, 2016 Share Posted December 5, 2016 15 minutes ago, EMRR said: Isn't it also amazing that the first production version of any tube is virtually always sold as 'the best', commanding the highest price with claims of the best sound? How can it be? It can't. Audio mind memory is one of the most easily fooled human aspects, and when combined with any differences at all, makes an untangle able voodoo stew. One can easily trace many vintage tube prices today back to particular print article cork-sniffings in the 1990's, and with quite of few I've seen I can recall the tubes they liked best also happened to be the same brands that would show up on your door step that same month if you ordered from Antique Electronic Supply. Order next month and write the article then, the product and article results would be different. None of this is canonical, it's just not possible. Any one tube from a manufacturing batch will display differences from others in the same batch, which you can possibly hear and measure. Ever put 100 new same batch tubes on a burn-in jig, and then take the current readings for matching? I have, many times. Like many production items, there's a region in which most will fall, but the extremities of that common region may vary by a large margin. Then there will be 10-20% that fall outside of that common grouping, and appear to be totally different beasts at birth. It's fun to theorize about, but there are no definitive statements. It comes down to the individual tube, and whether YOU like the job it does in the PARTICULAR amplifier. Much common sense above. As far as getters and sound they have nothing really in common. I personally suspect most people realize that..the getter type or placement is an easy way to identify some tube brands and approximate production time frame... 1 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted December 5, 2016 Share Posted December 5, 2016 The take home message seems, not to buy into all the claims on the color being emitted, the type of getter, etc. These are just characteristic of the tube type and material. A blue glow may be prettier than the orange but, the change in SQ is really based on the amp design/execution, tube quality, etc. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted December 5, 2016 Share Posted December 5, 2016 1 hour ago, NOSValves said: One can easily trace many vintage tube prices today back to particular print article cork-sniffings in the 1990's Oh, cork-sniffings.....now we're talking about a subject of which I have a modicum of knowledge!! No doubt in my mind that just like many other types of audio voodoo (like cable risers and boutique capacitors ), that there is much bullshit associated with, if you will, boutique tubes....Which I suppose begs the question....(Everything else being equal, such as circuit, etc) What actually does make up a "high quality" tube? Is it the manufacturing of the glass envelope that is better or worse than others? Is it the type of metal used in the internal construction, the shape, location and size of the getter? I understand the "whatever sounds good to you" line of thinking, but really, there's more to it, yes? Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 5, 2016 Share Posted December 5, 2016 24 minutes ago, jimjimbo said: What actually does make up a "high quality" tube? Is it the manufacturing of the glass envelope that is better or worse than others? Is it the type of metal used in the internal construction, the shape, location and size of the getter? This isn't the answer you want, but check out how the tubes manufactured by Bendix "Red Bank Division"...specifically the one's manufactured for missile use. These tubes IMHO, are high quality, industrial strength, made for war vacuum tubes. 6094 is an example, which (I think?) is the 6AQ5 equal, with a nine pin base. Kittleson? of vacuum tube valley had/has an article regarding the 6094. I think there is a 6l6 variation as well. These tubes to me are the peak of vacuum tube technology, which was the '50's. I have a Bendix rectifier, a equal to 6X5 or some such...58XX... The tube is built like a tank, and it doesn't resemble it's equal in any way with regard to construction. A massive cathode, with a 45 second heat up time. Most tubes are around 11 seconds or less, depending on whether it's indirectly heated or directly. There is information probably still floating the net regarding Red Bank Bendix tubes. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 5, 2016 Share Posted December 5, 2016 3 hours ago, wdecho said: Of course every aspect of tube making should be as good as possible at the price point projected but from my limited understanding the cathode coating is one of the most important. Very important for longevity. Nothing like buying a expensive vacuum tube for big cash from a specialized small company, only to have the tube lose most it's emission after 1000-1500 hours. Weak improper filament/cathode coatings? Maybe a tube specified for use beyond it's capability, boiling off the coatings even quicker? Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted December 5, 2016 Share Posted December 5, 2016 It's worth mentioning that all tube amps don't have a standby switch and need a warm up period of 30-40 seconds. I know preamp tubes last a long time. For power tubes like the EL 34, KT 88 and 300B,how many hours should you be able to get out of them? I know on my first tube amp, the tube will still good after 3 or 4 years. Quote Link to comment Share on other sites More sharing options...
EMRR Posted December 6, 2016 Share Posted December 6, 2016 The average audio amp does not require a standby switch, it is a myth. Cathode stripping only occurs at much higher voltages, such as those found in broadcast transmitters. OTOH, a tube amp left on standby for long periods of time will damage tubes, as the filament heat releases electrons from the cathode yet there's no B+ on the plate to attract them, so the vacuum gets filled with strays. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted December 6, 2016 Share Posted December 6, 2016 Great discussion...this is good stuff Quote Link to comment Share on other sites More sharing options...
Schu Posted December 6, 2016 Share Posted December 6, 2016 Does anyone have an opion or link to difference in sound characteristics based on tube design... for example the difference between a el34,el37,kt77 and 350b for instance? Quote Link to comment Share on other sites More sharing options...
Wolfbane Posted December 6, 2016 Share Posted December 6, 2016 8 hours ago, derrickdj1 said: It's worth mentioning that all tube amps don't have a standby switch and need a warm up period of 30-40 seconds. I know preamp tubes last a long time. For power tubes like the EL 34, KT 88 and 300B,how many hours should you be able to get out of them? I know on my first tube amp, the tube will still good after 3 or 4 years. Depending on the hours on these tubes they may be slowing degrading the sound you hear at a rate of continuous audio decline not you cannot perceive. Tubes in my experience die in two ways either suddenly in a flash of bright light or very slowly until they're equally gone. A good quality tube tester and regular testing of in service tubes is one way to avoid tube audio issues. Quote Link to comment Share on other sites More sharing options...
muel Posted December 6, 2016 Share Posted December 6, 2016 10 hours ago, jimjimbo said: Oh, cork-sniffings.....now we're talking about a subject of which I have a modicum of knowledge!! No doubt in my mind that just like many other types of audio voodoo (like cable risers and boutique capacitors ), that there is much bullshit associated with, if you will, boutique tubes....Which I suppose begs the question....(Everything else being equal, such as circuit, etc) What actually does make up a "high quality" tube? Is it the manufacturing of the glass envelope that is better or worse than others? Is it the type of metal used in the internal construction, the shape, location and size of the getter? I understand the "whatever sounds good to you" line of thinking, but really, there's more to it, yes? Couple of thoughts... my definition of "high quality" would be one that sounds decent and lasts a long time. They do sound different so there is the taste factor. It's also about synergy. I love Telefunkens in my Scott but I won't be installing them in my VRD's again anytime soon. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted December 6, 2016 Author Share Posted December 6, 2016 Another aspect which must be considered for tube longevity is filament voltage. Given that much equipment is made to operate over a wide line voltage range (typically 105-125V), it's possible for the tube filaments to run at more than 10% above their rating. This definitely can shorten their life. It's a good idea, for those technically inclined, to pop out one tube and measure the AC voltage across its filament pins. My recommendation is that if the voltage is higher than the filament rating under your highest line voltage condition, buy a variac and use it to drop the line voltage to ensure correct filament voltage. Although this is likely to reduce the B+ a bit as well, it should not be an issue at all. If anything, the slightly cooler operation of the tubes will increase their longevity even further. Many users of tube audio gear prefer running the equipment at the low end of the recommended line voltage range all the time. As to standby switching, I agree with EMRR that it is not needed in typical audio equipment. Cathode "poisoning" from having only the filament powered for long periods is a real phenomenon. But for those who want stand-by switching, it's an easy matter to use a high value resistor across the switch to allow a low level of B+ to be present all the time to absorb the electrons generated by the cathode. Closing the switch restores full B+. Maynard Quote Link to comment Share on other sites More sharing options...
EMRR Posted December 6, 2016 Share Posted December 6, 2016 Even better than a variac might be one of those AC voltage stepping transformers which has 5 volt steps anywhere from 75 volts to 130, then you have a clear idea of the effect, versus a continuous control that's easily moved to the wrong place (how'd that get turned up to 130?!?!). Given that tubes have a filament range spec rather than a hard requirement (6.3's spec is 6.0-6.6), I have to wonder if definitive studies have been done about the life difference of 6.1 versus 6.5, etc. I can't recall ever seeing mention in any literature. Stability is critical with burn-in jigs when any sort of tube matching is to be done. Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted December 6, 2016 Share Posted December 6, 2016 1 hour ago, EMRR said: Even better than a variac might be one of those AC voltage stepping transformers which has 5 volt steps anywhere from 75 volts to 130, then you have a clear idea of the effect, versus a continuous control that's easily moved to the wrong place (how'd that get turned up to 130?!?!). Given that tubes have a filament range spec rather than a hard requirement (6.3's spec is 6.0-6.6), I have to wonder if definitive studies have been done about the life difference of 6.1 versus 6.5, etc. I can't recall ever seeing mention in any literature. Stability is critical with burn-in jigs when any sort of tube matching is to be done. Doug, is the studio still up and running? I ran across a couple of web pages about EMRR. Quote Link to comment Share on other sites More sharing options...
EMRR Posted December 6, 2016 Share Posted December 6, 2016 Yes, it is. You can imagine I turn on a LOT of tubes on a regular basis. 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.