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  1. #1

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    I've owned a Fender Deluxe Reverb reissue since around October 2019 which I bought new. Recently, I started noticing (more frequently) these bursts of crackling noises. I thought at first it was coming from my guitar since the volume and tone knobs were causing some crackling, but I unplugged my guitar from the amp to listen and see what happens. It's not consistent. Sometimes I'd hear it several times within ten minutes, other times it could be on for an hour or more and I hear nothing.



    I'm a complete novice to tube amps and how they work. There is normal noise that raises and lowers with the volume knob and the reverb knob. Sometimes if I turn a knob too fast it crackles.

    How much of this is normal and how much of this is something to be fixed? I'm from Belize, and there's no "amp technicians" down here - so I'm stuck with going off of advice from the internet.

    Edit: Also, periodically I heard this very sharp "click" sound. At first I thought it was coming from the guitar because I had put on new strings, but nope, it's coming raw from the amp.

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  3. #2

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    90% of tube amp problems are tube related
    That sounds like a bad tube. Start by tapping the preamp tubes w a wooden stick like a chopstick or pencil and listen for a pinging (microphonic) sound. Have a new tube on hand to swap it out.
    Turning the knobs and getting scratchy sounds could just be an oxidized pot. Turn the knobs up and down several times quickly and see if it lessens.

  4. #3

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    Woah! The knob thing worked.

    I've been in quite a bit of amp trouble lately, and one thing I CAN say is that I'm definitely learning new thing by the day. Music has certainly taken me in directions I never thought I'd be in.

    I read somewhere online that I'd have to replace ALL the tubes if I replace one.

    I guess, if it is one of the preamp tubes, what would have cause it to get this way?

  5. #4

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    Modern tubes aren't the best quality and don't last like old production tubes.
    You definitely don't need to replace all the preamp tubes if one goes bad, though it's wise to match power tubes ratings if possible.

  6. #5

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    Deluxe what?

    im not an amp expert either but have owned my share of Fenders. Could be that reverb.

  7. #6

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    ^ Highly unlikely, almost certainly a tube

  8. #7

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    Quote Originally Posted by Loreto
    Woah! The knob thing worked.

    I've been in quite a bit of amp trouble lately, and one thing I CAN say is that I'm definitely learning new thing by the day. Music has certainly taken me in directions I never thought I'd be in.

    I read somewhere online that I'd have to replace ALL the tubes if I replace one.

    I guess, if it is one of the preamp tubes, what would have cause it to get this way?

    You can replace preamp tubes one by one and mix brands etc. They are pretty much independent of each other.
    The common practise is to use matched power tubes, so they are often sold in matched sets.
    Today many tube suppliers write the test values on their power tubes so if one tube in a set gets bad, before you feel it is time to replace all of them, you can send these values to the suppliers and then they can send you a tube of the same model that will match the good tube(s) you already have.



    The deluxe reverb has 6 preamp tubes, referred to as V1 (furthest from power tubes), V2, ... upto V6 (closest to power tubes).

    V6 is the phase splitter and your amp will not output any guitar signal without it. (if you are having noise issues you can try to pull it out as a means to troubleshoot).

    In order to try to find a bad preamp tube (given that ony one tube is bad) you can pull the tubes one at time and see if the issues disappear.

    pulling V1 - the normal channel will not work - V1 is the first two gain stages of the normal channel.
    pulling V2 - the vibrato channel will not work - V2 is the first two gain stages of the vibrato channel
    pulling V3 - the reverb effect will not work - V3 is the reverb driver tube.
    pulling V4 - vibrato channel will not work. (put the reveb knob to 0 if you turn your amp with this tube pulled). - V4 is the reverb recovery tube and the 3rd gain stage on the vibrato channel.
    pulling V5 - the tremolo effect will not work (put both vibrato knobs to 0 if you turn on your amp with this tube pulled) - V6 is the tremolo oscillator and driver.
    pulling V6 - nothing will work - V6 is the phase splitter.

    V3 and V6 are both 12AT7 so if you can swap them with each other. (for instance if your tube in V6 position is bad, you can pull your tube from the V3 position and put it into the V6 position and test the amp without reverb)
    The other 4 tubes are all 12AX7 or 7025 (very similar to each other) so you can swap them with each other too.



    if it is one of the preamp tubes, what would have cause it to get this way?
    Sometimes preamptubes just fail without any specific incident or abuse causing it. Inside the tubes are somewhat delicate structures which can fail due to harsh treatment, high termperatures or out of spec electical currents/voltages.
    But preamps tubes can very often last for decades.
    (there is a somewhat widespread believe that touching tubes with bare fingers can lead to oils from the fingers causing the tube to get much hotter but I haven't seen that claim from any reliable source)

  9. #8

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    I had a similar noise problem with Princeton custom 68 reissue and it was a bad preamp tube(reverb). Easy fix!

  10. #9

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    Look at the tubes. If there’s a white powdery coating inside one, it has a vacuum leak and is probably the culprit. A substance called a “getter” is put inside each tube to absorb as much residual oxygen as possible after it’s evacuated during production. This used to be barium, but I don’t know if there are more modern materials. After sealing the tube, the getter is fired to cause it to combine with residual oxygen, and it forms a silvery coating inside the glass.

    I’ve had a similar crackling from an audio amp that turned out to be an output tube. But in a stereo amp, it’s easy to swap tubes from L to R to see if the noise follows suit.

  11. #10

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    Quote Originally Posted by orri
    You can replace preamp tubes one by one and mix brands etc. They are pretty much independent of each other.
    The common practise is to use matched power tubes, so they are often sold in matched sets.
    Today many tube suppliers write the test values on their power tubes so if one tube in a set gets bad, before you feel it is time to replace all of them, you can send these values to the suppliers and then they can send you a tube of the same model that will match the good tube(s) you already have.



    The deluxe reverb has 6 preamp tubes, referred to as V1 (furthest from power tubes), V2, ... upto V6 (closest to power tubes).

    V6 is the phase splitter and your amp will not output any guitar signal without it. (if you are having noise issues you can try to pull it out as a means to troubleshoot).

    In order to try to find a bad preamp tube (given that ony one tube is bad) you can pull the tubes one at time and see if the issues disappear.

    pulling V1 - the normal channel will not work - V1 is the first two gain stages of the normal channel.
    pulling V2 - the vibrato channel will not work - V2 is the first two gain stages of the vibrato channel
    pulling V3 - the reverb effect will not work - V3 is the reverb driver tube.
    pulling V4 - vibrato channel will not work. (put the reveb knob to 0 if you turn your amp with this tube pulled). - V4 is the reverb recovery tube and the 3rd gain stage on the vibrato channel.
    pulling V5 - the tremolo effect will not work (put both vibrato knobs to 0 if you turn on your amp with this tube pulled) - V6 is the tremolo oscillator and driver.
    pulling V6 - nothing will work - V6 is the phase splitter.

    V3 and V6 are both 12AT7 so if you can swap them with each other. (for instance if your tube in V6 position is bad, you can pull your tube from the V3 position and put it into the V6 position and test the amp without reverb)
    The other 4 tubes are all 12AX7 or 7025 (very similar to each other) so you can swap them with each other too.




    Sometimes preamptubes just fail without any specific incident or abuse causing it. Inside the tubes are somewhat delicate structures which can fail due to harsh treatment, high termperatures or out of spec electical currents/voltages.
    But preamps tubes can very often last for decades.
    (there is a somewhat widespread believe that touching tubes with bare fingers can lead to oils from the fingers causing the tube to get much hotter but I haven't seen that claim from any reliable source)
    Woah this was extremely helpful! Thanks! I'll check it out later and see what happens. I'm guessing I have to remove that metallic cap that goes over them? I stupidly thought the power tubes were the preamp tubes and tried tapping them. Both 'p' words I suppose.

    A bit of a different topic, but I've heard people talking about swapping in different tubes for a "different sound". Since I might have to buy new tubes anyways, what's that all about?

  12. #11

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    Preamp tubes named 12a<letter>7 can usually be swapped for each other, to play it save you can stick with just replacing a tube with a tube with less gain but amps can usually also handle higher gain tubes (but it might sound like crap)

    For jazz 12ax7 in the V1 and/or V2 can be swapped for 12ay7 which has a bit lower gain.
    I've also swapped V4 tube for a 12ay7 to get less idle noise (but also less gain and less reverb)

    You can also replace the v3 reverb driver tube with a 12au7 to get a bit less maximum reverb setting but also easier to dial in a moderate amount of reverb.

    People also sometimes replace the v6 phase inverter tube with 12ax7 or 12au7. I haven't tried it myself but it gives different gain and maybe also different character.

    It kind of boils down to just trying and listening. I think it is perhaps more about enjoying the process rather than a necessarily reaching a better end result, which might though come as a bonus.

  13. #12

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    Quote Originally Posted by Loreto
    A bit of a different topic, but I've heard people talking about swapping in different tubes for a "different sound". Since I might have to buy new tubes anyways, what's that all about?
    I strongly suggest that you get it working fine first. Then we’ll discuss “tube rolling”.

  14. #13

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    I had a similar thing happen, albeit in a different amp. In my case it was a 5E3 clone. I found the problem went away when I blew out the big whomping dust bunny that had collected around the input jacks. I should mention I have a cat. Anyway, it's worth looking for easily fixed things creating static or tiny short circuits in the innards.

  15. #14

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    I had a Victoria amp bought used that developed a similar noise. It turned out to be a manufacturing flaw, there was a high voltage small wire inside that wasn't cut short enough, so it caused static and heat that over years had gone through a resistance insulation. It caused a power tube failure. Easy to fix, but difficult to find..

    The same amp had an Italian Jensen in it, and the speaker threads (inside the speaker, not in the speaker cable) were almost cut, meaning it could have blown the output transform.. My point is, it's a good idea to have amps checked from time to time, definitely if buying used, or if you've had them for many years.

  16. #15

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    So I guess the next question too is... Where online can I buy the tubes? What brand should I get? Are all tubes created equal?

  17. #16

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    Okay! So, I tested the tubes, and it seems like the 5th tube (the second one from the right side) made a noise (reverby) when I tapped it with a pencil. From above, that means it's the vibrato tube? I don't use that effect at all, in fact, I turn it off via the footswitch and then never lug it around. The effect is always off (so why does it do anything?). If I just pull it out (until I get a replacement issue) should this fix that humming problem?

    I didn't get the exact crackling noise when I tapped it, but I did hear something through the speaker that didn't happen with any other tube.

  18. #17

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    If you look at the amp from the back side, the tube, second from the right, is the V2 tube. (V1 is to the far right and the left most are the power tubes V7 and V8)

    Tubes can work fine despite being microphonic, so it doesn't need to be the cause of your issues.
    Sometimes you can swap them for the same kind of tube in a different position an then it stops having microphonics issues.

    Just try to pull the tube and see if the problem goes away.
    If it's the V2 tube you will need to use the normal channel (it might sound slightly different because the second halves of V1 and V2 share what is called a cathode resistor, and removing one will affect the current in the remaining one (but the tube can easily handle it), some people do this because they prefer the sound character).

    You can also put your V1 tube in the V2 position to try the vibrato channel.

    One quick way to check if it is a preamp tube at all, is to simply pull all tubes except V6, and the two power tubes (V7 and V8) and turn your amp on.
    If it is still an issue try to replace the 12AT7 in the V6 position with the 12AT7 tube you pulled from position V3, see if that helped.

    (Some recommend being careful with turning an amp on with tubes pulled (especially power tubes), because the voltage on the some filter caps (which ones, depends on which tube you pull) will be higher.
    If the manufacturer cheaped out and used some of the filter caps with a lower voltage rating, this voltage might be above their rating (but they often see a higher voltage during start up of the amp anyway), but according to the DRRI schematic all filter caps in the power supply are rated 500V so you're fine in this amp.)

    So I guess the next question too is... Where online can I buy the tubes? What brand should I get? Are all tubes created equal?

    For guitarists, this is among the big questions:
    - what is the meaning of life?
    - are we alone in the universe?
    - which tubes will bring me to sonic nirvana?

    I usually try to find suppliers with low shipping costs, which are often local or somewhat close. import fees can also be an issue
    I googled that the population of Bilze city is 57 thousand, so it isn't that unlikely that you can buy them in a local guitar/music instrument shop.

    The common current procuction brands JJ, Electro Harmonix are Sovtek are all (generally considered) good and more affordable, but you can spend a lot more money if you're struggling with getting rid of some money
    I've tried paying double and triple the cost of JJs and I'm not convinced I got anything in return.
    Last edited by orri; 01-19-2022 at 05:59 AM.

  19. #18

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    Quote Originally Posted by orri
    If you look at the amp from the back side, the tube, second from the right, is the V2 tube. (V1 is to the far right and the left most are the power tubes V7 and V8)

    Tubes can work fine despite being microphonic, so it doesn't need to be the cause of your issues.
    Sometimes you can swap them for the same kind of tube in a different position an then it stops having microphonics issues.

    Just try to pull the tube and see if the problem goes away.
    If it's the V2 tube you will need to use the normal channel (it might sound slightly different because the second halves of V1 and V2 share what is called a cathode resistor, and removing one will affect the current in the remaining one (but the tube can easily handle it), some people do this because they prefer the sound character).

    You can also put your V1 tube in the V2 position to try the vibrato channel.

    One quick way to check if it is a preamp tube at all, is to simply pull all tubes except V6, and the two power tubes (V7 and V8) and turn your amp on.
    If it is still an issue try to replace the 12AT7 in the V6 position with the 12AT7 tube you pulled from position V3, see if that helped.

    (Some recommend being careful with turning an amp on with tubes pulled (especially power tubes), because the voltage on the some filter caps (which ones, depends on which tube you pull) will be higher.
    If the manufacturer cheaped out and used some of the filter caps with a lower voltage rating, this voltage might be above their rating (but they often see a higher voltage during start up of the amp anyway), but according to the DRRI schematic all filter caps in the power supply are rated 500V so you're fine in this amp.)
    Will try that in a bit! If it IS the problem, can I just swap out the V5 tube for the V2, and all is well?
    If it ISN'T the problem, what can it be? The sound only happens, I believe, when I unmute the standby switch.

  20. #19

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    If v5 is the problem you can just pull it from your amp and not use the tremolo effect.

    If v2 is the problem you can replace it with the v5 tube (and not use the tremolo effect).

    Same with v1 and v4. You can replace them with the v5 tube.

  21. #20

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    I swapped the V2 and V5! Sounds great now! Thanks everybody! Still a little bit of crackle time to time (like when turning on the amp), but I feel like the amp sounds a bit more alive now!

  22. #21

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    Actually, it was still making the noise if I left the bad tube in the slot for the vibrato. I pulled it out and it works much better, but there's still an occasional strange noise from time to time. Is it safe to leave it pulled?

  23. #22

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    Yes, you can safely leave it pulled.

  24. #23

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    I'll upload footage a bit later of some really horrible noise that was coming out of the amp again. Not sure what's causing it. I tapped the tubes again, the one I replaced (that I took from V5 and moved to V2) became microphonic too! So is that the cause again? Is something in my amp just turning these microphonic or did I just miss them from the start? I'm a total tube amp neophyte, so I have no idea what's going on.

    If I play exclusively through the normal channels, and mute everything on the vibrato channel, everything is good overall. Just occasional tubes clicking now and then - though it happens more than I'm comfy with.

  25. #24

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    If your amp has less issues when the vibrato channel voulme is at 0 then there could be an issue with your V2 tube.

    You only need v1 and v6 to play the normal channel so you can pull v2, v3, v4 and v5 and play your amp's normal channel. If your issues get better with that, there is likely some issues with some of the pulled tubes (there can be issues with the tubes regarless of whether they are microphonic or not).


    It could help to clean the tube sockets. You can spray contact cleaner in the sockets and wiggle a tube in and out a few times (there are other methods like using small brushes).