Coytee Posted February 2, 2008 Share Posted February 2, 2008 I've got a KT-88 that isn't 'silver' on the top. My understanding is, when they make these things, they do some kind of 'getter' and when it flashes over to take all the air (or something) out of the tube, it leaves this silver coating on the inside of the tube. I've attached a picture and you can see how one of the tubes is almost glass clear on the top. I've always noticed a tube (which turned out to be this one) that showed a bit more of the red glow from above... Since I had the cage on, I never noticed this difference. Does this infer nothing? or does the lack of the silver mean something? Quote Link to comment Share on other sites More sharing options...
fini Posted February 2, 2008 Share Posted February 2, 2008 Richard, What amp is that? I thought you were the king of Crown? Quote Link to comment Share on other sites More sharing options...
Marvel Posted February 2, 2008 Share Posted February 2, 2008 This might give yo the info you want... http://en.wikipedia.org/wiki/Getter Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 2, 2008 Author Share Posted February 2, 2008 What amp is that? I thought you were the king of Crown? Finster (am I allowed to call you that in public? [:^)]) ... I wear many hats. This is the business end of a McInosh MC-2102 (100x2) that I have and recently took out of system to give my 4 channel dbx amp (BX-3) a whirl. I'm debating on selling it (2102) & am getting all the dust off for picture session. You see... (and this is just between you & me, ok?!!) I've had SET amps, liked them! I've had PP amps and liked them too!!. I also had OTL amps and yep... liked them (probably the most of the tubed variety) and I've also had solid state amps (residential) as well as those commercial "PA" amps, the Crown K2. Some would like to tell you the Crown amps sound like PA amps and suck in the home application. Next time you're visiting your Aunt, I'll show you how/why they're wrong. [Y] Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted February 2, 2008 Share Posted February 2, 2008 I've got a KT-88 that isn't 'silver' on the top. My understanding is, when they make these things, they do some kind of 'getter' and when it flashes over to take all the air (or something) out of the tube, it leaves this silver coating on the inside of the tube. I've attached a picture and you can see how one of the tubes is almost glass clear on the top. I've always noticed a tube (which turned out to be this one) that showed a bit more of the red glow from above... Since I had the cage on, I never noticed this difference. Does this infer nothing? or does the lack of the silver mean something? Richard does the MC2102 have individual bias adjustments for the tubes? If so then check the tube in question's bias setting and if it will adjust to the proper reading then have no worry. mike tn[] Edit: Did a little research Richard and unlike the MC2000 the MC2102 does not have user adjustable bias settings like every tube mac I ever worked on. My guess is the tube is Ok but if you are worried about the tube I can check it for you or you might just run it by Terry Dewick since he isn't far from you. Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 3, 2008 Author Share Posted February 3, 2008 Ok but if you are worried about the tube It's not so much that I'm worried about anything as sonically, everything is fine. I'vve just never seen a KT-88 with so little silver on top (then again, I've not seen LOTS of them) I was just wondering if this is a normal deal or if by its absence (silvering) if that alone might indicate perhaps it was an extra weak or perhaps extra strong tube since it might not have 'flashed over' as strong as typical. Just being curious Quote Link to comment Share on other sites More sharing options...
Wrench722 Posted February 3, 2008 Share Posted February 3, 2008 I saw your add on Ebay. Why are you selling it? Is it because of the tube or just the sound? Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 3, 2008 Author Share Posted February 3, 2008 Actually the reasons are a couple fold. Wife & I are now in stages of making reservations for a trip in May to London, Rome, Naples and Istanbul (among some other stops) This trip was one of the straws that broke the camels back. It's going to be about 3 week venture. Anyone want to stay at my place and "Jube-sit"?? (feeding the dogs will be a side benefit [Y]) The other straws that got this amp in contention for being sold is simply... If I can buy a Crown amp for say, $1,000 and this amp costs $4,000 (using round numbers), does this amp sound FOUR times as good as the Crown? Nope, not to my ears. This amp is currently out of the system as I'm playing with some other amps and frankly, for the premium in price (although I LOVE the looks) I don't know if I can really justify it. So, since I LOVED the sound of the SE-OTL amps I had, I was originally going to sell this amp, buy one of those and pocket a couple thousand in my pocket. Though that still might happen, I also might just keep any proceeds in my wallet for the trip in May and deal with replacing it later. IF/when I do replace it, I will most likely nab an OTL again. All that is a long winded way to say it's not the tube nor is it the sound. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted February 3, 2008 Share Posted February 3, 2008 That clear top tube is probally one of the original tubes that came with the amp. Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 3, 2008 Author Share Posted February 3, 2008 Though I might be wrong, I'm under the belief that they all were the original tubes. I've never really looked at them and always had the cage on (didn't want one of the dogs to slobber nor step in that area) I use to have amp sitting on top of Khorns but when Jubilees arrived, ended up moving it down to floor on top of my large dbx BX1 amp. It wasn't until it was down low that I started noticing one of the tubes was brighter, but not brighter like I had when one cherried out on me, but brighter as though it had maybe a 'hot spot' or as closer inspection has discovered, simply no 'veil' shading the top parts of the tube. If this is a sign of a defect in any way, I'm trying to find out 'now' so I can deal with it. If a clear tube like that is nothing to be worried about, then I don't intend to worry. I just don't want to have a pending problem and because of my ignorance, me sell the amp to someone then have it blow on them. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted February 3, 2008 Share Posted February 3, 2008 tubes that came with getter and now have none left.......hmmm....I wonder what that means Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted February 3, 2008 Share Posted February 3, 2008 tubes that came with getter and now have none left.......hmmm....I wonder what that means The only times that I have seen the silver flash from the getter area of a tube change was: (1) The flash area turned brown because the tube was running to much current and was slowly over heating. (2) The flash area turned white because the tube has a crack and lost it's vacuum. Richard I had a friend call McIntosh when he bought some tubes from them and there was a considerable difference in the Flash Area and their response was it wasn't anything to worry about. Again if in doubt just have it tested by DeWick then you will have piece of mind. mike tn[] Quote Link to comment Share on other sites More sharing options...
Guest " " Posted February 3, 2008 Share Posted February 3, 2008 Prediction....tube has less than 10% life left...tube will flash soon....no getter to counter act accumilated gases...the tube will test fine...just won't last more than about 150 hrs...best case senerio....a fuse will blow...worst case senerio...a resistor could also blow....if you're going to roll the dice.....remove the 6 amp slow blow fuse in your MC-2102 and replace with a 4 amp fast blow fuse......I would rather be wrong than to have you come back next month saying the tube flashed...I would expect a discount if I was buying an amp that had clear kt-88 tubes...it would lead me to think the tubes had 1300+ hrs on them. I use 4 amp fast blow fuses on MC-2102's if I am toruble shooting tube issues. fuses will blow before resistors do. A new Mcintosh tube is 60 bucks from Mcintosh or 66 bucks froma dealer. Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted February 3, 2008 Share Posted February 3, 2008 Prediction....tube has less than 10% life left...tube will flash soon....no getter to counter act accumilated gases...the tube will test fine...just won't last more than about 150 hrs... I would expect a discount if I was buying an amp that had clear kt-88 tubes...it would lead me to think the tubes had 1300+ hrs on them. Hey speakerfritz What are you baseing these predictions on? Have you read information somewhere that you could show me what your describing above? I've done electronic repairs for close to 35 years and I've had experience servicing Tube equipment built from the 1940s to present day (television, stereo, jukebox...etc...). I use to see tube televisions with tubes lasting decades and except for the conditions of the getter flash I mentioned in my previous post there was no way to predict tube life based on the getter flash that I'm aware of. The silver flash on the glass occures when the tube is made and they fire the getter to burn off oxygen/impurties at that time and as far as I'm aware it serves no purpose in estimating tube life. I have read articles were people have taken old tubes and refired the getter to burn of gases formed from normal aging of the tube and thus get extended life out of the tube although I've never tried it myself. I do agree as far as if I was going to worry about it then just spend a few bucks and have piece of mind. mike tn[] Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 4, 2008 Share Posted February 4, 2008 I thought the silver coating on the inside top of the tube was some sort of RF shield sprayed in there. Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 4, 2008 Author Share Posted February 4, 2008 We'll know SOMETHING relatively soon. I took ALL (including the small ones) tubes out of the amp this morning and took them over to Terry. He was dropping what he was doing (working on a pair of MC-75's) to test these and I said not to... I didn't want to cut in front of anything he was doing so I left them with him. He said he'd write on each tube what its nominal number is (I think that is the word he used) and then how it tested. He didn't specifically say but upon showing him the clear tube I got the impression that he thinks it's closer to the end of its useful life rather than middle. (based on the clarity of the top) If I'm going to be selling this amp then I really want to know what's going on and not sell it to someone & have a tube blow right after they get it, even if it means me buying a tube or adjusting their price to compensate for this. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted February 4, 2008 Share Posted February 4, 2008 ""I got the impression that he thinks it's closer to the end of its useful life rather than middle"" Yes...10% left or 150hrs...then flash..plus blown fuse . Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 4, 2008 Author Share Posted February 4, 2008 Terry said he'd write the numbers/values of each tube down. I'll post them here when I get them. Quote Link to comment Share on other sites More sharing options...
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