6sn7 tubes

732tg

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#1
Hello! Come looking for a little help about 6sn7 tubes. I have a Mastersound Compact 845 amplifier, and I'd like to put some NOS tubes in it to replace the stock Electro Harmonix. Not the power tubes, just the driver and pre-driver tubes. Kinda stuck with Shuguang for the power tubes... Anyways, the pre-driver tubes are 12AU7/ECC82's, and the driver tubes are 6SN7's. Problem is, the pre-driver stock tubes are labelled 12AU7A...the driver tubes are labelled 6SN7GTB. I have a matched pair of NOS Telefunken ECC82/12AU7's- minus the "A" designation at the end. Can I drop these in, or is it a question for the maufacturer? Also, I'm hunting for some NOS 6SN7's- does it matter if they're straight 6SN7's, 6SN7GTA or GTB? What's the difference with these minute designations at the end of the tube name? Am I overcomplicating things here?

Thanks in advance for any advice!
 

VSAT88

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#2
I cannot answer the exact question you have but I can say that in some situations the designation does make a difference. Take for example the OP Tubes on a Kenwood KW 70. One has to watch the designation on those or best I recall there can be issue. A search on the www should reveal manufactures specs and tube pin out and by comparing those you may find out what you need. I have searched for I will be honest I do not think I have ever heard of or dealt with the 6sn7 tube. Want to welcome you here as well so...Welcome. EDIT : Look at this, this may well be the answer you need ... https://www.audiocircle.com/index.php?topic=106191.0
 

mr_rye89

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#3
I wouldn't get too hung up on the designators unless your amp runs the tubes near their limits (plate voltage, current, etc). The Telefunken 12AU7s should work fine. 6SN7s are like an octal 12AU7 on steroids, I think they were designed as vertical deflection/video amps in early TV sets. I personally like the RCA ones or the Soviet 6H8Cs from the plant with the "diamond" logo
 

nakdoc

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#6
I have an assortment of premium 6SN7 tubes, and the industrial equivalents, from an estate I'm helping liquidate. If you let me know what price range you are in I'll see what choices you have. Typically the A designation is for tubes with tighter Gm specs. The 6SN7 variations have more to do with military and industrial specifications, especially tube noise, than any single parameter. Modern amps are often "voiced" for modern tubes. If you do tube rolling be prepared for unpredictable results. Many audiophile preamps are voiced for specific 6SN7 tubes, like the Rayethons and almost always sound worse with lesser tubes installed.
 

mr_rye89

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#9
Maybe his amp blew up? Doubtful. I've abused tubes for many years and haven't burned the house down yet......

I've always wanted to build a transmitter-tube SE amp. The plate voltages are kinda scary though. Ended up building a 300B SE amp instead.....
 
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