bad preamp tube?
pglbook
Posts: 2,226
A week ago, while warming up my amp and preamp, I noticed a high pitch ringing sound coming from the right speaker (even when I had the volume control knob of the preamp turned all the way down). It was not too loud but definitely noticeable. It had never done that before. The sound did not start when I first turned on my system but appeared some time later during the hour warm-up period. It lasted only 10 seconds or so and then disappeared and the system played fine the rest of the day. The sound resurfaced again last night while playing a Sam Rivers jazz CD; I could hear the high pitched ringing sound over the music. Again, it was not present when I first turned on the system but showed up about an hour or two into playing music. It lasted about 10 seconds and went away. And the system played fine - for the next 3 hours - the rest of the night without my hearing that sound again.
I am thinking that it could be one of the preamp tubes going bad. Would a bad tube make that sort of sound? How can I tell if a tube is going bad?
I have 3 tubes in my Eastern Eelectric MiniMax preamp - two 12au7 tubes and a rectifier tube.
Any other thoughts on what might be causing that sound?
Thanks.
I am thinking that it could be one of the preamp tubes going bad. Would a bad tube make that sort of sound? How can I tell if a tube is going bad?
I have 3 tubes in my Eastern Eelectric MiniMax preamp - two 12au7 tubes and a rectifier tube.
Any other thoughts on what might be causing that sound?
Thanks.
Post edited by pglbook on
Comments
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Unless you have a tester the only way to know is put another tube in there that you know is good.
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Unless you have a tester the only way to know is put another tube in there that you know is good.
Thanks. I plan to swap out one of the tubes today.
The ringing sound just came from the right speaker so am I correct to assume that I should just swap out the right 12au7 tube of the preamp (there is a 12au7 in the right and middle position and a rectifier tube in the left position)?
Or would it be preferable to swap out both 12au7 tubes?
The nice thing about the EE MiniMax is that it does not require matching 12au7 tubes. Makes for great tube rolling possibilities.
I have read that rectifier tubes rarely go bad so I will start with the 12au7 tube(s) and go from there. -
swap the tube locations and see if the noise follows the tube.Amplifiers: Norma IPA 140, MasterSound Compact 845, Ayre v6xe, Consonance Cyber 800
Preamp: deHavilland Ultraverve 3
Dac: Sonnet Morpheus 2, Musical Paradise mp-d2 mkIII
Transport: Jay's Audio CDT2 mk2, Lumin U1 mini
Speakers: Rosso Fiorentino Volterra II
Speaker Cables: Crystal Clear Magnum Opus 2, Organic Audio Organic Reference 2
Interconnects: Crystal Clear Magnum Opus 2, Argento Organic Reference 2, Argento Organic 2
Power Cables: Argento Organic Reference, Synergistic Research Foundation 10 and 12 ga.
Digital cables: Crystal Clear Magnum Opus 2 bnc, Tellurium Q aes, Silnote Audio Poseidon Signature 2 bnc
Puritan PSM156 -
I had a similar situation and when I swapped channels it followed and got noticeably worse. Put in a new tube and all is well.Gustard X26 Pro DAC
Belles 21A Pre modded with Mundorf Supreme caps
B&K M200 Sonata monoblocks refreshed and upgraded
Polk SDA 1C's modded / 1000Va Dreadnaught
Wireworld Silver Eclipse IC's and speaker cables
Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)
There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus -
Rectifier tubes almost never go bad, like others have said....swapping out tubes would be the first thing I'd do...I plan for the future. - F1Nut
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I'll also suggest cleaning the pins. Many tube issues can be remedied my a good pin cleaning. Use a mild grit sand paper or steel wool and they De-Oxit.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
I swapped out the right 12au7 tube and played music for 4 or 5 hours yesterday and everything was fine. Time will tell but it seems like that solved the problem.
Thanks to all for the feedback. -
I'll also suggest cleaning the pins. Many tube issues can be remedied my a good pin cleaning. Use a mild grit sand paper or steel wool and they De-Oxit.
H9
Thanks, Brock. That is a good idea about cleaning the pins. -
I'll also suggest cleaning the pins. Many tube issues can be remedied my a good pin cleaning. Use a mild grit sand paper or steel wool and they De-Oxit.
H9
I've found stainless steel brushes very good for this. My stainless steel brush is 1" wide and 3" long does a great job. I then use a old tooth brush that i put De-Oxit on and run over the clean and shiny pins. It leaves just enough to cover the pins completely. -
afterburnt wrote: »They didn't speak a word of English, they were from South Carolina.
Village Idiot of Club Polk -
Eventually they all go bad. Depending on how the tube is used in the circuit will depend on how long they last. I've had folks tell me that the mullard rectifier tubes never go bad I kind of find that hard to believe myself.
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If a rectifier tube is going bad often something is wrong with the amp or preamp. Rectifier tubes do wear out but they usually outlast the other tubes in the gear they are in.
