Deang Posted February 15, 2003 Share Posted February 15, 2003 As far as the Telefunken 12ax7 and 12au7 go -- which is preferred? Quote Link to comment Share on other sites More sharing options...
mike stehr Posted February 15, 2003 Share Posted February 15, 2003 As far as 12AX7, smooth plates are preferred. I have smooth plate 12AX7, but not the ribbed ones, so I couldn't give any opinion. 12AX7 and 12AU7 have a different gain/amp factor. Quote Link to comment Share on other sites More sharing options...
Deang Posted February 15, 2003 Author Share Posted February 15, 2003 Looking down the road a ways when money is better. Might like a nice set of 12ax7s for the Scott and some nice 12au7s for the Cary. Quote Link to comment Share on other sites More sharing options...
HDBRbuilder Posted February 15, 2003 Share Posted February 15, 2003 I prefer ribbed plates over smooth...I hate it when I go to cut my steak, and it slides on a smooth plate and sends my LeSueur peas rolling all over the table! Quote Link to comment Share on other sites More sharing options...
artto Posted February 15, 2003 Share Posted February 15, 2003 I have a bunch of 12ax7 (&7025) & (I think) some 12au7 I bought in the late 70's early 80's. Many different brands (Mullard, RCA, Telefunken, GE & some others (& some Luxman branded 12ax7 &12au7 made by NEC. not parting with those). I you need any, let me know. I'll take a look & see what I have in terms of the plate type. By the way, anyone ever come across a 12ax7 made by International or IEC (Japan)? If so let me know. I had those in my first Audio Research SP6 (came with it) & that amp really sang. Never should have gotten rid of it. To this day I've wondered if those specific tubes didn't have something to do with the sweet sound that amp had. Richardson Electronics has (or can get) any tube you need that's still made. Major international tube distributor. I've been able to buy at wholesale from them (min.order$$) Quote Link to comment Share on other sites More sharing options...
Deang Posted February 15, 2003 Author Share Posted February 15, 2003 Well, I don't need any, but would certainly like to upgrade the four 12ax7s in the Scott. I think the Cary uses four 12au7s. Please email me at dean.wescott@wpafb.af.mil so we can have discussion. I have to finish paying Edmond for the Cary, after which I can start thinking about buying some tubes. Got hit with 9 inches of snow last night. My son made $40 shoveling snow. Guess I should have been out there too!! Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 15, 2003 Share Posted February 15, 2003 Dean, When and if you replace those RCA black plates I will take them off your hands. I think your a loon. Those are some great tubes !! Craig Quote Link to comment Share on other sites More sharing options...
Deang Posted February 15, 2003 Author Share Posted February 15, 2003 The Blackplate is a decent tube, it's not a great tube. The RCA Cleartops are much better, and many consider them to be almost as good as the European tubes at 1/2 the price. Even if I end up with new tubes, I'll keep the Blackplates just because it's always good to have a backup set. Quote Link to comment Share on other sites More sharing options...
arfz28 Posted February 15, 2003 Share Posted February 15, 2003 I Just got done switching out my jan phillips 6u8a tubes in my scott 299a with some brand new rca black plates. They sound good, still not broke in with only 2 hours on them though. I have to say there is no night and day differece to me on the switch over.Really I could live with either set of tubes. I have a set of telefucten 12ax7 rib plates comming some time next week. I think if I hear a difference these will tell the tail. I will keep everyone posted on the outcome.Heck if there isnt much difference in sound at least I will have some spare tubes, heck almost enough to build another scott amp.Then I will end up going from spare tubes to anouther spare tube amp. Will this crazyness ever end. LOL. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted February 15, 2003 Share Posted February 15, 2003 Dean, I have a pair of each in my HF-81, I don't think I could tell the difference if I didn't know what I put in last. Maybe the smooth plates are just a bit smoother in back-to-back listening. But, like I said, if somebody switched them on me I don't know that I would notice. Of course, it's debateble whether this reveals more about them or or me. :> Tom Quote Link to comment Share on other sites More sharing options...
mike stehr Posted February 16, 2003 Share Posted February 16, 2003 I have a IEC Mullard 6EU7. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 16, 2003 Share Posted February 16, 2003 Mike, What are you using the 6EU7's in ?? arfz28, What is the history on the RCA blake plates ?? Are they new and test real close to each other ? If so since you have no test equipment take the hum pots and center them as best you can. Which they maybe already centeres. The Jan Phillips 6U8 is indeed a nice tube and does a fine job. Scott did a wonderful job designing this to be a transparent use of the pentode section. The use of this tube in there circuit is completely different then Dynaco and others. Craig Quote Link to comment Share on other sites More sharing options...
arfz28 Posted February 16, 2003 Share Posted February 16, 2003 Craig the rca blackplates are sapposed to be brand new , I got 4 of them, They have the original boxes . The guy tested them and he said they all test like new. What the heck is a hum pot? How do I center them? My DAD has a tube tester that he hasnt used in 25 years, I need to go up there and see if I can learn how to use it, that is if it still works. Looks brand new yet. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 16, 2003 Share Posted February 16, 2003 The hum pots are on top of the Chassis near the 6U8 sockets NOT the ones near the output transformers. To center them you turn then all the way one and then the other and put them half way in between no big deal your not going to hear a night and day difference. Have you ever Biased that amp you really need too ! Craig Quote Link to comment Share on other sites More sharing options...
arfz28 Posted February 16, 2003 Share Posted February 16, 2003 Craig, you talked me through the bais job on this amp about a month ago. Its Dinocasters old amp.So thats what those other two slotted adjusters up by the 2 6u8a tubes are far is to help stop are eleminate hum?Well get this a while ago I noticed some hum and buzzing out of the right channel with the rca black plates in, I tried 3 diffent rca tubes in the right side all 3 have the same hum or buzzing sound. So I put the jan phillips in and no buzz or hum whatsoever out of the right channel.Whats going on here, do I need too adjust those pots like you said, will this eliminate the hum and buzz. Why would switching tubes make the right channel do this? Either somthing needs adjustment or my scott just doesnt like those rca blackplates. Quote Link to comment Share on other sites More sharing options...
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