Soundthought Posted October 20, 2002 Share Posted October 20, 2002 Hi all, I accidentally had a pair of 12AX7s instead of 12AT7s in the driver socket of my amp. I've got about 50 hours on them. They are '75 Matsu$hita 12AX7/ECC83. Is it going to cause me problems when I put them in the appropriate preamp sockets? Being that they have been in the power driver sockets for a while. Also, i'm currently running a Philips ECG 12AX7WA preamp tube. Are the Matsu$hitas' an acceptable replacement for these? Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 20, 2002 Share Posted October 20, 2002 Yes to all the above, although it would help if you say the make and model of the amp. Your tubes should be fine. Quote Link to comment Share on other sites More sharing options...
Soundthought Posted October 20, 2002 Author Share Posted October 20, 2002 Hey Mobile. My fault, I meant to add that in there. It's a Jolida JD202A. I meant to swap out the existing pair of Electro-Harmonics 12AT7EHs for some RCA 12AT7/ECC8s. But, I got excited and wasn't paying attention. That's how the Matsu$hitas got stuck in there. Ooops. Live and Learn. Anyway, Wow. There are some serious physical differences in the constuct of these tubes. Is that where the sonic and performance differences lie? Quote Link to comment Share on other sites More sharing options...
powdermnky007 Posted October 20, 2002 Share Posted October 20, 2002 while were on tube newbies... what does rolling a tube mean and why would you want to? Does it matter which pin is in which hole, or can the tube just be stuck in the hole with out worrying? How do you set the bias? can you do that on the tube tester? try not to laugh (out loud at least) at my tube ignorance thanks guys Quote Link to comment Share on other sites More sharing options...
lynnm Posted October 21, 2002 Share Posted October 21, 2002 Rolling tubes refers to trying different makers' version of a tube type or sometimes versions of a tube made by a maker at different times in their production cycle. The term may also refer to swapping essentially equivalent varieties of tubes which vary from the originals in some way but which share the same pinouts and which were designed to perform the same functions. Some here believe ,for example , that unused examples of tubes produced 40 years ago are inherently superior to their modern counterparts and further that NOS tubes built by a given maker were/are superior products as compared to tubes made by its competitors. Thus you will sometimes see members complain that recently made 12AU7's are grossly inferior to the same tube produced 40 years ago by Sylvania,Western Electric etc,( ie. New Old Stock) and see claims that the Amperex or Mullard etc. of the same period are superior to others produced at the same time. On the other hand you will occasionally see the claim that certain currently produced tubes are superior to the NOS tubes. I cannot comment as I don't have sufficient excess funds to play that game. Either opinion may well be correct. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 21, 2002 Share Posted October 21, 2002 You MUST be very carefull plugging a tube in a socket !! It only fit one way period and either will have a key way or one pin missing that determines how it goes in the socket. The reason to roll tubes was covered real well in the post above. Quote Link to comment Share on other sites More sharing options...
prodj101 Posted October 21, 2002 Share Posted October 21, 2002 EEE! if you put it in the wrong way it could ruin the tube! don't want the heater power going to the plate! Quote Link to comment Share on other sites More sharing options...
Soundthought Posted October 21, 2002 Author Share Posted October 21, 2002 Lynnm, So rolling tubes doesn't relate to rolling fatties, it's just slang for interchanging the same tube(s) from different manufactures and/or eras? Cool. I didn't know that. So about rolling tubes. Is it all a matter of personal preference? Are there inherant benefits from particular internal construction? Thanks for the feedback. Quote Link to comment Share on other sites More sharing options...
powdermnky007 Posted October 21, 2002 Share Posted October 21, 2002 When rolling (not a fatty) a tube, are all 12ax7's (or any tube w/ the same #) compatiable? Quote Link to comment Share on other sites More sharing options...
Deang Posted October 21, 2002 Share Posted October 21, 2002 I'm glad it was finally explained, and I've been too embarrassed to ask. Sitting in front of my amp and rolling all my tubes back and forth across the carpet hasn't really been doing much for the sound. Quote Link to comment Share on other sites More sharing options...
Soundthought Posted October 21, 2002 Author Share Posted October 21, 2002 Well Dean, Rumour is that if you roll tubes on deep blue shag carpet for 30 seconds, you allow for a static charge to build up on the tubes interior surface, thus decreasing burn in time due to the increased induction properties of the tubes exterior surface. Maybe it was RED carpet? J/K. Quote Link to comment Share on other sites More sharing options...
dougdrake Posted October 21, 2002 Share Posted October 21, 2002 Would be interested in hearing a response to the earlier question regarding bias. What is it? How is it measured? How is it adjusted? I found that my 3 yr old grandson does a great job of rolling tubes in the bathtub. They can really get to spinning without much friction to speak of. However, they dripped so much on my amp when I put them back in that I had to stop. DD Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted October 21, 2002 Share Posted October 21, 2002 When you get good at rolling tubes, the idea is to do it during a particular tune you are playing and to do it on the beat. This way you can clearly hear the difference that the other tube makes sonically while the music is still fresh in your memory. You have to be fast otherwise the music might fade out before you get the next tube into place. This is easier to do with the miniature tubes because they are not as hot. I use special gloves when I roll the output tubes while running hot. If you are ambidextrous you can roll both output tubes in a push-pull amp simultaneously, although this would be considered advanced tube rolling and is usually only practiced by the very high-end audiophiles who believe push pull is making a comeback. When doing hot tube rolling for SET amps which have only one output tube, I recommend that you have the next cool tube in your other hand ready to be plugged in rapidly as you remove the hot tube with the other hand. And of course with the SET amp it makes a huge sonic difference what kind of gloves you use. Don't skimp, if you are rolling hot tubes with an SET amp, the $500+ special gloves are not really considered that expensive. Some hard core hot tube rollers believe it is better sonically to do this bare handed in which case the correct thing to yell when you grab the hot tube is "Hootchiemammma!!!!!" { prounounced Who-Chi-Ma-Ma! - you prounounce the exclamation point with your grimace} If going for this bare handed, try not to leave greasy fingerprints on the tubes though since this might eventually bake into the glass and look funky, and like with a projector bulb, may cause the tube to eventually crack prematurely kind of like what happened to me, but that is in another thread. -C&S PS: Bias control has to do with heated discussions between audiophiles that become, well let us say, ugly or even violent. The best method can be found in self help books or by watching Dr. Phil or listening to Dr. Laura. I have even seen high-end audio store owners tweak the bias of a recalcitrant prospective customer by giving them a quick twist on their nose. The ones who hate horns have been known to cup their hands over their mouth like a megaphone and yell like you were hard of hearing: "We only sell REAL speakers not HORNS!". The best bias control adjustment for these store owners, besides a kick to their shins, is to remind them how you don't pay sales tax when you buy gear for much less online and have they ever heard of eBay or Audiogon. This makes a HUGE difference in their noise floor and you can almost cut the Blackness with a knife.....so much for bias control. -C&S Quote Link to comment Share on other sites More sharing options...
Soundthought Posted October 21, 2002 Author Share Posted October 21, 2002 HOOTCHIEMAMA! he he. You tube people are nuts. I should fit right in. Seriously. About my Jolida 202A, could I have done any damage to the Amp or tube (Matsu$hita 12AX7), by having it in the wrong socket? Mobile said the tubes "should be" alright. How could they be "not alright"? BTW.Has anyone even heard of Matsu$hita? Thanks again gang. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 21, 2002 Share Posted October 21, 2002 Audioreality, Well actually I don't think you could of hurt the amp but the tube could have suffered some damage !! It all depends on what voltage it drew from the wrong socket and to what plate or grid and so forth. Did the amp play with it in the wrong socket ? Did it sound good ? If it did maybe you stumbled on to the Ultimate audiophile tweak !! LOL !! Quote Link to comment Share on other sites More sharing options...
Soundthought Posted October 21, 2002 Author Share Posted October 21, 2002 Yep, I had the pre-amp tube in the power driver socket. Listened to it for about 20 of the 50 hours I had it playing. I was trying to burn them in. LOL. Sounded pretty good. IMO. Then again, This is the only tube amp i've ever REALLY listened to. Only had it operational for a week, now. So, I'm far from qualified to pass any judgement on sound quality. Who Me? A poineer breaking new ground in tube application? I highly doubt it So should I take the tube to be tested before I pop it in? I've got my gloves on and she's plenty warm. Ha HA Ha HA. Quote Link to comment Share on other sites More sharing options...
Soundthought Posted October 21, 2002 Author Share Posted October 21, 2002 Double post. Quote Link to comment Share on other sites More sharing options...
Soundthought Posted October 21, 2002 Author Share Posted October 21, 2002 Triple post. Geez Louise. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 21, 2002 Share Posted October 21, 2002 I would test them first myself but I have a tester here on hand. The gamble is all yours ! Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 21, 2002 Share Posted October 21, 2002 They really should be fine. Quote Link to comment Share on other sites More sharing options...
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