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Post subject: Re: My Fender Deluxe plays Bb
Posted: Tue Sep 04, 2012 5:54 pm
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When you say B-flat, I assume (I know.... don't assume) you mean one-half step down on open B-string? This is a rather high frequency ring. I would not suspect the usual things, except maybe, a microphonic input tube.

Rotate the 12AX7's from V1 to V2 (clean to drive) and see if the ringing follows the tube.

If the ringing stays with the clean channel, you may have some sort of instability going on. One that pops up as soon as the tubes get nice and toasty.

As a side note... Early 2010-11 TungSol RI 12AX7 are noted for noise, after a few months of use and abuse. All sorts of noise issues. Ringing, static, early ugly OD. This just happened in a few of each batch. You may want to try another 12AX7, if you have one.

I keep old RCA 7025 pulls just for this reason. As I know these are stone quiet tubes that perform to a known standard, nearly all the time. And as much as ppl love to swap out tubes, I rarely see dead tired RCA 7025's. (Hint, hint... EBay gazers).

If this solves the issue... I'd search for a good, new 5751.... Or that good pull 7025. Raytheon 12AX7A can be excellent pulls, too.


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Post subject: Re: My Fender Deluxe plays Bb
Posted: Tue Sep 04, 2012 6:07 pm
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That might be a good idea BMW2002Ti, but keep in mind that only half of V2 is used for drive channel, and the other half is always in the circuit for clean and drive channels.

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Post subject: Re: My Fender Deluxe plays Bb
Posted: Tue Sep 04, 2012 6:46 pm
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Aspiring Musician
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shimmilou wrote:
Of course, tubes are the usual suspects. I would suspect preamp first, although it could be output. The tubes are covered too for 90 days.
The amp is just over six months old so I'm afraid that the 90-day warranty on the tubes has long expired.

BMW2002Ti wrote:
When you say B-flat, I assume (I know.... don't assume) you mean one-half step down on open B-string? This is a rather high frequency ring.
Actually it's two octaves higher. The Concert Pitch of the humming/buzzing tone is the second B-flat above Middle C which on the guitar sounds at the 18th fret on the 1st string.

As for the rest, I'm afraid that most of it is way above my head. Sorry, still a newbie when it comes to tube amps, especially anything on the inside. Regarding the noisey tubes, you mention "Early 2010-11 TungSol RI 12AX7 are noted for noise" but the stock tubes for my FDR are listed as:
  • Three Fender Groove Tube GT12AX7 (099-4005-000)
  • Two Fender Groove Tube GT6L6B (099-4401-*02)
Are these also prone to noise?

Thanks & Cheers!
BM.

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Post subject: Re: My Fender Deluxe plays Bb
Posted: Thu Sep 06, 2012 7:17 pm
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Aspiring Musician
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Two days later and the High Bb is making frequent apperances. The general consensus is faulty tubes so I'll take it in for servicing and if it turns out to be something else then at least it's under warranty.

Beside the current thread on this topic (viewtopic.php?f=13&t=74983) I seem to remember an older one with suggestions on lower gain tubes for the Fender Deluxe but can't recall the member who posted.

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Post subject: Re: My Fender Deluxe plays Bb
Posted: Thu Sep 13, 2012 10:18 am
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Aspiring Musician
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Epilogue:
shimmilou wrote:
Of course, tubes are the usual suspects. I would suspect preamp first, although it could be output. ...
Just got the amp back from the shop and it turns out that shimmilou was on the money. The culprit was a faulty preamp tube which was replaced and all appears to be well.

As to the high Bb and the intermittent nature of the ringing tone; probably all symptoms of a dying tube.

One thing I've learned from this experience is that I REALLY need to crack the books and figure out how things work on the inside of an amp or at the very least learn enough to be able to change tubes on my own.

You guys are a great help!
Thanks and Cheers!
BM

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