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Post by edoetsch on Apr 27, 2015 13:25:56 GMT -7
So My KT-45 is getting this ringing/rattling sound on lower notes. Especially an open low E.
I took the back panel off and tapped each tube softly with the plastic handle of a screwdriver and none produced rattling.
Is there a better test to see if there is a microphonic tube or is this just the amp being very loud?
It does not sound like the video below. The sound there is more like feed back or even a note. I have much more of a rattling sound. Like taking a lightbulb and shaking it close to your ear...
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Post by edoetsch on Apr 27, 2015 13:35:05 GMT -7
Nor does it sound like a rubber band like in this video so it must be something else.
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Post by KeithA on Apr 27, 2015 13:42:18 GMT -7
My money would be on the EF86. I have an amp with an EF86 and it rattles at certain frequencies. The tube seems to be working fine sonically, but there is mechanical resonance from time to time.
do you have a spare EF86 you can try?
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Post by edoetsch on Apr 28, 2015 6:13:46 GMT -7
Yes, several. I noticed when my Route 66 got back from the Dr, he had put what looks like silicon around the EF86. Is that a "shock absorber"? Is that necessary on the KT due to volume as well?
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Post by KeithA on Apr 28, 2015 6:57:58 GMT -7
Yes, several. I noticed when my Route 66 got back from the Dr, he had put what looks like silicon around the EF86. Is that a "shock absorber"? Is that necessary on the KT due to volume as well? The rubber bands are indeed for that purpose and I'd say it's a help on any EF86. These tubes are prone to mechanical noise more than others. Some brands seem to be better than others and I suspect new production tubes are more prone to noise than NOS.
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Post by edoetsch on Apr 29, 2015 8:26:31 GMT -7
Yes, several. I noticed when my Route 66 got back from the Dr, he had put what looks like silicon around the EF86. Is that a "shock absorber"? Is that necessary on the KT due to volume as well? The rubber bands are indeed for that purpose and I'd say it's a help on any EF86. These tubes are prone to mechanical noise more than others. Some brands seem to be better than others and I suspect new production tubes are more prone to noise than NOS. The tube in there now is a Dario Miniwatt so I certainly hope it is not the tube. I have 2-3 EF86 replacements (2 Dario's and another) so I'll get around to trying a few of them.
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Post by KeithA on Apr 29, 2015 8:42:07 GMT -7
The rubber bands are indeed for that purpose and I'd say it's a help on any EF86. These tubes are prone to mechanical noise more than others. Some brands seem to be better than others and I suspect new production tubes are more prone to noise than NOS. The tube in there now is a Dario Miniwatt so I certainly hope it is not the tube. I have 2-3 EF86 replacements (2 Dario's and another) so I'll get around to trying a few of them. I believe I have a a Dario in my Prescription Jr and that's fine. I have another amp that I put a new EH tube in and that one rattles! No EF86 is safe!
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Post by edoetsch on Apr 30, 2015 11:59:04 GMT -7
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Post by KeithA on Apr 30, 2015 12:24:43 GMT -7
Yeah, I have an EH tube that I got from the Tube Store (approx. the same $/quality as yours) and that's the tube that rattles like a banshee in my Matchless Lighting clone ! It doesn't rattle always, but there seems to be a certain sympathetic resonance point. That's the reason many people avoid the EF86s....especially in a combo amp.
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Post by edoetsch on May 1, 2015 5:49:31 GMT -7
Yeah, I have an EH tube that I got from the Tube Store (approx. the same $/quality as yours) and that's the tube that rattles like a banshee in my Matchless Lighting clone ! It doesn't rattle always, but there seems to be a certain sympathetic resonance point. That's the reason many people avoid the EF86s....especially in a combo amp. What is the Doc putting in new amps these days is probably the right question. So I tried out several more tubes each with slightly different issues. With the amp cranked more the Wing C EF86 had an occasional "pop at the beginning of a low note" Another Dario Miniwatt was probably the best of the 3 tested. Had similar rattling on low notes to the 1st Miniwatt. So it this point I am thinking it is simply a matter of physical shaking of the tube. I am playing in a basement pushing the amp to noon so perhaps wall reverberations are an issue that might be lessened in a larger or outdoor venue.
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