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Post by westcoast on Oct 29, 2023 23:12:20 GMT -7
I recently traded a nice Tele for this 35th anniversary Ghia, and while it sounds absolutely incredible, there is a weird sound coming from it when I play an F# (give or take a half-step) It sounds like lower frequency static mixed with wind whistle. I know, maybe a bad description, but best I can describe it. Doesn’t matter where the knobs are set, or the guitar used. Straight in as well. It’s definitely not tube rattle. Perhaps the speaker? I’ve checked all connections and bolts/screws, tubes etc… everything is seemingly tight…
Apologies if this is not the right forum area for this, just hoping to get some advice. Cheers!
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Post by mrcapers on Oct 30, 2023 2:28:09 GMT -7
I had a strange noise also, but it was a D note. Changed all the tubes, still there. Changed the speaker - sound gone. It was cone cry with the original speaker. I'm using a greenback now, problem gone!
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Post by John on Oct 30, 2023 3:11:26 GMT -7
Try a different speaker.
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Post by westcoast on Oct 30, 2023 17:52:09 GMT -7
Well, it’s not the speaker it seems… I rented a small cabinet, just to see if it happens again, and sure enough it’s still there. Could it be power tubes?
Perhaps switching them around? Not much of an amp tech here;)
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Post by John on Oct 31, 2023 2:56:53 GMT -7
If it's not the speaker, then I would try a different set of tubes.
And remember, the Ghia is a self biasing amp, so don't let anyone tell you it needs to be biased. (and charge you for it) Just pop in a new set. Try to get them 'matched'.
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Post by tumeniamps (Tom) on Oct 31, 2023 3:42:43 GMT -7
I've run into this with several amps over the years, it's always been a power tube.
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Post by scottyc13 on Oct 31, 2023 4:35:23 GMT -7
One way to test the tubes is to play a chord and tap on each tube with a pencil or chopstick and see if you and create the sound. A microphonic tube should reveal itself with this test.
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Post by G'OlPeachPhan on Oct 31, 2023 7:38:12 GMT -7
A troubleshooting method I like to use is to play the offending frequency into a looper pedal so you can set the guitar down and have both hands free. From there, use the eraser end of a pencil or something like that as a damper against the various tubes and other parts of the amp, to see if you can isolate the source of the noise. Also, you might try the amp in a different room to see if the issue persists; There’s been a few times where I’d swear I heard a rattle coming from my amp, and further investigating revealed some object in the room vibrating sympathetically with a certain frequency (ex. drywall or baseboards, drinking glasses in a cabinet, pictures or other objects hanging on walls, etc.)…These are things you may not always notice until you engage in supercritical listening while auditioning a new amp.
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Post by frankie on Oct 31, 2023 9:01:18 GMT -7
One way to test the tubes is to play a chord and tap on each tube with a pencil or chopstick and see if you and create the sound. A microphonic tube should reveal itself with this test. Please don't do this. All tubes will produce at least some sort of sound, and even microphonic ones that may make "more of a sound" might not be the ones that are ringing sympathetically from the note being produced. As in, some tubes can be somewhat microphonic and you'll never even know. In that case, LEAVE THEM ALONE! A mechanically microphonic tube is not electrically faulty!
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Post by frankie on Oct 31, 2023 9:04:24 GMT -7
A troubleshooting method I like to use is to play the offending frequency into a looper pedal so you can set the guitar down and have both hands free. From there, use the eraser end of a pencil or something like that as a damper against the various tubes and other parts of the amp, to see if you can isolate the source of the noise. Also, you might try the amp in a different room to see if the issue persists; There’s been a few times where I’d swear I heard a rattle coming from my amp, and further investigating revealed some object in the room vibrating sympathetically with a certain frequency (ex. drywall or baseboards, drinking glasses in a cabinet, pictures or other objects hanging on walls, etc.)…These are things you may not always notice until you engage in supercritical listening while auditioning a new amp. This is most often the case. The best way is to dampen the tube fully using a thick towel/cloth or an oven mitt. Producing the same note via the looper, then going methodically through each tube using the towel. Also, the room resonance is really a thing. Case in point, at Sweetwater we auditioned the new amps in a meeting room and spend a good hour chasing what we thought was a microphonic tube, was just a rattling TV mounted to a wall in the room that was vibrating from back waves of the speaker combo hitting it. Move the amp to another room, see if you can reproduce the sound. Then follow through with the looper method/towel/oven mitt.
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Post by scottyc13 on Oct 31, 2023 12:36:34 GMT -7
A troubleshooting method I like to use is to play the offending frequency into a looper pedal so you can set the guitar down and have both hands free. From there, use the eraser end of a pencil or something like that as a damper against the various tubes and other parts of the amp, to see if you can isolate the source of the noise. Also, you might try the amp in a different room to see if the issue persists; There’s been a few times where I’d swear I heard a rattle coming from my amp, and further investigating revealed some object in the room vibrating sympathetically with a certain frequency (ex. drywall or baseboards, drinking glasses in a cabinet, pictures or other objects hanging on walls, etc.)…These are things you may not always notice until you engage in supercritical listening while auditioning a new amp. This is most often the case. The best way is to dampen the tube fully using a thick towel/cloth or an oven mitt. Producing the same note via the looper, then going methodically through each tube using the towel. Also, the room resonance is really a thing. Case in point, at Sweetwater we auditioned the new amps in a meeting room and spend a good hour chasing what we thought was a microphonic tube, was just a rattling TV mounted to a wall in the room that was vibrating from back waves of the speaker combo hitting it. Move the amp to another room, see if you can reproduce the sound. Then follow through with the looper method/towel/oven mitt. Good to know, thanks.
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Post by scottyc13 on Oct 31, 2023 13:35:50 GMT -7
In a bit of coincidence, while playing my Z-Plus just now, I heard a buzzing type vibration on certain notes. It sounded like it was coming from the back of the amp. But it was actually the A/C I removed from the window that was near the amp. I covered the A/C with a towel and amp cover and the noise went away.
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Post by adam on Oct 31, 2023 18:57:30 GMT -7
Also, the room resonance is really a thing. Case in point, at Sweetwater we auditioned the new amps in a meeting room and spend a good hour chasing what we thought was a microphonic tube, was just a rattling TV mounted to a wall in the room that was vibrating from back waves of the speaker combo hitting it. THIS! ↑↑↑ I've experienced a lot of this and it feels next to impossible sometimes to identify the source. Sometimes it feels like the cab, sometimes it feels like the cab next to it, and sometimes it feel like a tube. Try moving around the room a lot, have a helper if possible, and sometimes the source of the problem can totally surprise you.
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Post by westcoast on Nov 1, 2023 23:28:27 GMT -7
Thank you all for the advice and insight… this really is a great forum and resource. Been a bit busy around here with a sickly kid and Halloween, but I think I may have isolated the problem. If I press upward on V3 the sound dissipates, so I’m guessing it’s a power tube gone bad. The amp was built in May, but I suppose it’s the nature of vacuum tubes, you never know when they might give up the ghost. I’ve had amazing luck with power tubes to this point.
Don in repairs reached out, so I’ll get in touch with him soon. Again, what a great community, and great customer service.
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