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Hi, Wondering if you could help me figure this one out. I own an Audible Illusions M3a preamp and an AR PH3 Phono stage. Each of these units runs on 6922's.
I've rolled tubes for years in both these units, 6DJ8's, 6922's, 7308's. No problems at all. Tonight I decided to listen to Amprex 6DJ8's in the PH3. Removed Telefunken 6922s, put in the Amprex 6DJ8s, turned her on - warmed up - "Bzzzz", severe distortion restricted volume. Scared the hell out of me, I had just finished cleaning my stylus. But all went OK when I put the Telefunkin 6922's back in. I moved to my AI M3A. Changed the Siemens 6922s to Siements 6DJ8's. Same thing!!! Once again all is OK with the 6922's.
In the spirit of disclosure I should add one point. All week I have been rolling 6922's and 6DJ8's in the PH3's #3 position - think that's called the Cathode Follower. No problems there. This is the first time I put them in the #1 and #2 positions in a while. Perhaps tomorrow I'll try the 6DJ8's in the #3 position but that won't really tell us anything.
I'm stumpted. The 6922's I'm using were stored beside the 6DJ8's. I've used 6DJ8s countless times in each unit over the years. If you were me, where would you look to trouble shoot this one? I've never seen anything like it, have you?
Could this have anything to do with the local power grid at 3am? Ah I'm shooting in the dark. Love to hear what you think, this is wierd.
Thanks in advance for your thoughts. I appreciate it. John
Follow Ups:
A big thanks to each of you. I just decided to follow your advice. Plugged in a pair of Seimens 1961 6DJ8s that started this. I worked them in and out,cleaning the pins. It is just perfect now. (Actually they are warming up as I type this - they are better than perfect)I love it when things are such a simple answer. I'm in heaven these guys sound wonderful. I really appreciate your quick responses.
John
Edits: 01/30/16
tooth picks also work.
While u r at it, thoroughly clean the tube's pins, q-tips with alcohol seem to work ok. By that point I look at the connections for the AC cord, and interconnects, clean them, shoot them with ProGold.
If I remember correctly that unit runs one pair of tubes a little rough, and people claimed, by now very expensive mil surplus Amperex 7308s sound "best"?
bob
"He (R.M. Nixon) was a foul caricature of himself, a man with no soul, no inner convictions, with the integrity of a hyena, and the style of a poison toad." H. S. Thompson
;)
"I know just enough to get into trouble. But not enough to get out of it."
Your pins on the 6922 might be fatter or cleaner that your 6DJ8s. You might need to re-tension your sockets or replace them. The good ol' chinese sockets do not hold up to a lot of tube swapping use as the metals used for the contacts have very little yield strength (think tin).
Sure does sound like it to me too. Tube rolling is interesting and entertaining - and HARD on sockets. Clean them very carefully and clean the tube pins too. Chip is right, the tubes that make the best contact probably have pins that are a hair fatter.
The link below has some good info about cleaning and maintenance. If you use tube gear - especially if you change tubes often, but even if you don't swap tubes a lot - you need to do some maintenance from time to time.
Jim,
I commented on your post years ago and refer to it all the time. Excellent!
And it's not just tubes but the entire hi fi chain can benefit from maintenance.
Not only to prevent anomalies but to get the best sound out of your system.
I've gotten a little lazy lately but usually once a year I dismantle, clean, tension and inspect every point of contact.
And I mean everything:
Binding posts, connectors, switches, controls, relays, fuses and their holders; power cords, receptacles (carefully), sockets, tubes, etc.
I even unscrew connections to capacitors and clean them. (Drained of course.)
It's amazing to see the grime that comes off sometimes.
In my case I can definitely hear a difference in sound for the better.
I inherited this habit watching my father who would always take things apart and clean them before bending to a service call. Of course we're talking the day of tube tvs and radios, analog tuning pots and channel switches. Motor brush contacts in furnaces, vacuum cleaners and washing machines.
Yes, besides my stereo, and sometimes to my wife's disappointment, I've kept some things going past their normal lifetime.
My two son's now also apply the "clean it first" process and have quickly resolved household and more frequently, computer issues at home, work and for their friends.
Sorry to get off topic, but I guess there was a time when universal maintenence was accepted. And admittedly, proprietary, sealed, and I guess digital parts make things less accessible to the DIY'r.
I sometimes wonder if there should be maintenance agreements built into warranties of the high end stuff much like there are for cars.
For non DIY's, perhaps a house call service might be a thought. Hmm... 😊
Cheers!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
I know how to retention 8 pin sockets. How do you do those tiny 9 pin ones? If they get loose I usually just change them. Thanks.
But very carefully. Especially if the socket material is brittle as it may crack or chip.
The 9-pin Belton shown in the photo is easy to re-tension.
I've never had to use anything other than dental picks. I would imagine if there isn't much room to maneuver, one would almost have to resort to sewing needles or something similar that wouldn't accidentally break off between the socket wall and claws.
Cheers!
Jonesy
Ed
"I know just enough to get into trouble. But not enough to get out of it."
Thanks for the info Jonesy!
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