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Deluxe Reverb RI help

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  • #1

    Deluxe Reverb RI help

    I am experiencing a fairly pronounced hum in my Deluxe Reverb and would really appreciate some suggestions. I replaced and biased the power tubes a few weeks ago, but the hum is new. The hum is loudest using the first input of the reverb channel, which is the input I always use. The hum is reduced significantly when I use the second input of the reverb channel. If I disconnect the reverb it has no effect on the hum. If I plug into the normal channel, the hum is much less, but it is somewhat louder in the first input vs. the second input of Channel One. Varying the volume affects the volume of the hum. I swapped out all of the preamp tubes and they all seem to be OK, no impact on the hum.

    I tried cleaning the input jack with no improvement. Any ideas? Can I assume that the imput jack needs to be replaced?

    Thanks,

    Lamar
    Tags: None
  • #2
    First thing I'd do is check to see if the amp is using cheap SOVTEK 12AX7WA tubes and if so, try replacing them... this amp seems to hum easily with those preamp tubes.
    Bruce

    Mission Amps
    Denver, CO. 80022
    www.missionamps.com
    303-955-2412

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    • #3
      If I plug into the normal channel, the hum is much less, but it is somewhat louder in the first input vs. the second input of Channel One.
      This caught my eye. What does the amp do with NOTHING plugged into it? If the hum cares what jack you use, it sounds like it is coming in from outside.
      Education is what you're left with after you have forgotten what you have learned.

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      • #4
        Deluxe issue

        I have checked my cables with a tester and they are good. But without the guitar plugged in, no hum. One possibility; my main guitar (Heritage 535) is at my guitar tech for some work, so I was using my LP back up, which I seldom use. But I did try my '57 gibson acoustic cf 100e with a P 90 and it had the same hum. I did notice that the LP had greater hum depending on the p/u selection...perhaps it is the axe?

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        • #5
          The test I use is this.
          If the "hum" volume reduces evenly as you rotate the guitar's volume control from full up to zero then the noise is being picked up by the guitar. Give that a try and let us know what happens. Is the sound really a low "hum" or is it more like a "buzz"? I ask this because I think of excess noise as different categories. Each can be a clue to a different problem. Hum vs Buzz vs hiss.

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          • #6
            Originally posted by Tom Phillips View Post
            The test I use is this.
            If the "hum" volume reduces evenly as you rotate the guitar's volume control from full up to zero then the noise is being picked up by the guitar. Give that a try and let us know what happens. Is the sound really a low "hum" or is it more like a "buzz"? I ask this because I think of excess noise as different categories. Each can be a clue to a different problem. Hum vs Buzz vs hiss.
            Actually, the sound could be better described as a buzz rather than a hum, I guess. Also, the preamp tubes that I have are a mix of fender/electro harmonix that came with the amp, along with two nos upgrades. And yes, the sound reduces evenly as the volume control is rotated. The preamp tubes are a couple of years old, but this particular amp only sees about 10 hours of moderate volume per month. I replaced each tube with a new one to test, and this did not affect the buzz.

            thanks

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            • #7
              OK. So it seems that the amp is not at fault in this case. At least the noise being picked up by the guitar is the major contributor to what you are hearing. You may want to verify that the grounds in the guitar are all up to par. Nearby poor grade light dimmers or other equipment can radiate nose that the guitar will pick up. Therefore, another location in the building may not be as noisy.

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              • #8
                Tom, I believe that you are probably correct, I think the problem lies in my guitar. What threw me off was the fact that I also tried my 50 year old acoustic which has a P-90 in it and it had a similar buzz too. I don't have any light dimmers in my studio, and I tried plugging the amp into my Furman AR-15 voltage regulator and sound conditioner which did not help.

                Part of my diagnostic problem is that both of these guitars are rarely played as my main axe is with my tech.

                Anyway, sincere thanks to all for your time and thoughts. Next week I will have my regular guitar back and will see if the problem continues. I also ordered some tung-sol (new) preamp tubes to make sure that my "test" preamp tubes are good.
                Thanks again,

                Lamar
                After Midnight Blues Band

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