Microphonic tubes cause ringing. Probably time to replace one or more of the small signal tubes. You can tell which one(s) is the culpert by lightly tapping on the tube, lightly(!).
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I figured that it was "tube microphonics" but didn't know how to go about solving the problem short of buying new tubes. btw, found a site for HAL-O Vacuum Tube Dampers and was wondering if any of you have used these (or other brands for that matter) and what your thoughs are about these products in solving "tube microphonics". Guess damping my tubes might be my first "tweak".
The ringing I hear is low level. Go back to my intial post and you'll see that I only heard this ringing when I "changed my CDs and was close to the amp". Certainly, I'll switch some tubes out and see it that solves the problem, but if it's just "low level ringing" then perhaps dampers might be the way to go. Basically at this point, I'm interested in what results people have had with dampers.
I use NOS because most of the current production is not as good as it "used to be". Good tubes are the best place to start, and Vintage Tube Services is a good place to get good value tubes. Your amp calls for 12AT7's, 12AX7's and EL-34's. I don't advocate touching tubes at all while they're in use. I've used several tube dampers, finding Herbies Hal-O's to be about as good as it gets. You're not going to correct a microphonics problem with dampers. Once they becomes noticable ... time to replace tubes. Fortunately the small signals that you use are widely available. Don't try to be too cost conscious here. Try some used Telefunken smooth plates for 30.00 - 40.00 ea and see what you hear... Give Andy a call at VTS ... you can't go wrong. I buy 80% on mine there. Be careful on auction sites ...
FWIW, my reference to "low level ringing" was ringing not seperately audible as ringing no matter where you were standing, but was a very low level ringing mixed into the main signal. If I can actually hear a tube ring with out touching it, it goes!
Many folks actually prefer this very low level ringing and find it additive, so I guess my answer to your question is that tube dampers can work but whether you like their effect or not may well depend on what you like.
Personally, on tubes in applications where noise and microphonics can be an issue I use tubes tested for low noise and a simple rubber type rings that only cost a couple of bucks. But then I'm both anal and cheap.
YMMV. I'm sure others will chime in and give you further guidance.
Far as I can hear, the "ringing" is occuring at the amp and doesn't seem to be getting into the signal. I checked this out by turning the volume control up (slowly, of course) with nothing playing on my CDP, but with the CDP on, to see if any "ringing" was coming through my speakers. Didn't notice any. btw, where do you get the "simple rubber type rings that only cost a couple of bucks" as I'm somewhat of a believer in the KISS (Keeping It Simple) approach, along with keeping it inexpensive.
I agree with Tvad - tube dampers are no cure for sick tubes. Their primary purpose is to assist healthy tubes in presenting micro details for clearer images. They aren't what you need in this case.
A minor amount of microphonics can contribute to a soundstage appearing slightly larger than normal which on some recordings can be a positive thing. However, when they get to the stage that you are describing, they have gone past the positive effects and need to be replaced.
My amp the 502 uses the 6550 (currently using Svetland) or can use KT88. The 302 on the other hand is the Jolida that uses the EL34. Currently, in the 12AT7 positions I'm using NOS RCA Black Plates and in the 12AX7 positions I'm using Sovtex. Maybe this afternoon, I'll try to pin point which tube(s) is the "ringer". btw, any good suggestion on some good "low noise" tubes? Brashgordon, thanks for the Telefunken suggestion. Was going to get a pair, but the dealer I usually buy from was out of them at the time.
You answer my question, on just how to figure "which" tube is the "ringer", now to find a pencil with an eraser. The NOS RCAs are my "newer" tubes, but nevertheless we'll see what happens. One more thing, do you have a link for TVS? Might try giving Andy a call and see what he's got.
btw, to Everybody
Do appreciate all the info you're giving me. As I said I'm a "newbie" and still learning.