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Replacing spitting 6BQ5 tubes

bear-hifi

bear-hifi

Well-Known Member
Hello, I have an older Magnavox tube amp that uses 4 6BQ5 Zeniths tubes. The problem is that two of the four tubes make a spitting sound that is driving me nuts. Anyway, I was looking around to find some new tubes and I came across this ebay auction that says the following.
"All 4 of these used Mullard tubes tested good even though they all have that usual Mullard 6BQ5 "spitting" inside the glass that is pretty typical of these used tubes."

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=73377&item=5750006825&rd=1


So, are the older tubes known for spitting sounds and would a newer tube have less spitting? I was thinking about replacing them with newer 7198s or what new tube could I get that would sound like the Zeniths without the spitting of course?


Thanks
Frank
 
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I'm probably way off here and will stand corrected shortly I'm sure but the spitting you're hearing and the spitting they're talking about are 2 different things.
I think what they are talking about is from the getter and is a visual/cosmetic thing. Your's sounds like a cap job is due, I have one that needs it also. Bob
 
Suspect dirty sockets and pins, or bad connections somewhere. Can you do anything to make it consistently make the sound? A tap here, a wiggle there? If wiggling a tube a bit in its socket (gently rocking, not too far), both causes the sound but somewhat abates it after, it's a bad pin contact. Contact cleaner.
 
Actually it has new caps and its really just one tube thats sounds bad even though they all appear to did it. I moved the really bad tube and the spitting sound went with it to the other speaker. I have cleaned the tube pins and sockets and it did not work. Also moving the amp around and moving the tubes around does not reproduces the spitting sound. :dunno:
 
I saw an adapter the convert’s 6V6 to EL84? I wish I could convert the EL34 to 6V6 because I have lots of those tubes.
 
How about 6AQ5?

bear-hifi said:
I saw an adapter the convert’s 6V6 to EL84? I wish I could convert the EL34 to 6V6 because I have lots of those tubes.
Click to expand...

You mean EL-84 to 6V6? 6V6 is comparable to 6AQ5. It's a lower Pd tube, so to convert you would need to rebias for a lot less current. as well as ensure that max plate voltage etc. was not exceeded -- or at least not exceeded by a lot. :)

But it could be done, I guess. You could use "hole-shrinkers" to mount a 7-pin 6AQ5 socket for the 9-pin... I know you said you have lots of 6V6, but still might be preferable to resocket for 6AQ5, and I can make you a great deal on those! Easier to make an adaptor that goes from octal to 9-pin than the other way around... Punching octal holes might be a pain, so that's why I suggest 6AQ5.
 
Thanks but it sounds like it maybe too much trouble to miss with for now. This what I saw while looking for 6BQ5 replacements.

ADAPTER, YELLOW JACKET, CONVERTS 6V6 TO EL84/6BQ5

P-SAYJ20

This Yellow Jacket converter is a specialized adapter which permits the use of EL84/6BQ5 power tubes in place of 6V6 type tubes. Yellow Jacket converters not only re-arrange the pin locations of the tubes but also provide the necessary current limiting on the screens and cathode. Yellow Jackets block the amplifier's grid bias voltage, which configures the EL84/6BQ5 into a class A self adjusting bias circuit. Tubes are not included. Manufacturer recommends the JJ EL84/6BQ
 
One thing is for sure its gets worst the longer its on! At 1st its not bad but after the 4th song its really bad???
 
Hi Bear, sounds like maybe you need a new set of matched 6bq5 output tubes in your amp I think yours could have seen their better days. Try these sovteks out there is some on ebay in a matched quad right now. Cheeper than NOS 6bq5 tubes and they sound dang good. Type in this number on the ebay search. 3781474104
 
Get a new quad of output tubes and quit running the amp until you get them in there. It sounds like the tube is ready to go perminent short on you which can be death to a output transformer.

Craig
 
NOSValves said:
Get a new quad of output tubes and quit running the amp until you get them in there. It sounds like the tube is ready to go perminent short on you which can be death to a output transformer.

Craig
Click to expand...

Thanks for the heads up Craig!

Frank
 
Drop me a note and if you can wait till the next DAC meeting I will set you up with a couple of quads you can roll and decide what you like. All used so no big price tag. 12AX7s too if you want.....5751s for your edification but you gots to give them back because I just don't have enough.
 
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