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New 5e3 is Really Quiet

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  • New 5e3 is Really Quiet

    Hey everybody, first post here. My name is Alex, but my screenname has been Kramer for as long as I can remember. Playing guitar has always been one of my hobbies, but rather recently I have become a diy amp and effects enthusiast and have built 4 amps...1 was scraped for another which was later completely scraped. Another was built only to find it had a fatal flaw (the chassis was painted and nothing was grounded properly) and then transfered to a different chassis with a few upgrades. They were all Tweed Deluxe clones, and after I built this one, I wasn't really sure I liked it. So, I started with the modding. This is just my first crack at modding, and I did all of this in one shot. Here's what I have so far:

    - Split Cathode Mod
    - Paul C Mod
    - 16 uF Filter Caps buffed to 22 uF
    - Screen buffed from 250 to 300 ohm
    - NOS 5y3 and 12ay7

    This definitely helped get rid of some of the fuzzies, but I think I still need to tweak and play with the coupling cap values a little more to get it right. Perhaps I will even investigate the addition of a choke, though that would require quite a bit of work to accomplish, but I suppose if it helps marginally I would definitely consider it! Let me know if you built a 5e3 with a choke, and what all went into accomplishing it...I'm interested in your experiences.

    Now, onto the problem. The amp fired up fine on the first try. However, I've never really had this problem, but the amp seems very unusually quiet. Not in the fact that it doesn't have much hum to it (Just about 95% of the hum was eliminated with the star ground anyways ), but it just doesn't sound like 18 watts...at all. I can turn this thing up to half way volume, all the way up...anything, and I can just sit right in front of it without any ear protection. What's also wierd is that when I jumper the channels, it gets even quieter yet. It just thins out and all the over drive goes away then....I've never experienced this problem before! Can anybody try to explain what might be going on here?

    Thanks

    - Alex

    Edit: Does anyone have any voltages for a 5e3? It seems like there might be reliable and definite information somewhere out there, but it has been eluding me...

  • #2
    Hi Alex

    I did a 5E3 for 6V6s or 6L6s last year with a switchable CLC/CRC filter. The thread is around on this forum somewhere.

    In terms of your 'quiet' amp, what are your voltages? that might be a good starting point. Also what type of speaker have you got in it? and what is the Ot Primary Zed etc? Those things can have an effect on volume (as well as things like leaky coupling caps etc)
    Building a better world (one tube amp at a time)

    "I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo

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    • #3
      Thats why I was asking about the voltages, I think I'm going to take some tomorrow and see what it's running. Also, I built a head instead of a combo. Right now I'm running a 2x12 loaded with Celestion AlNiCo Golds in series with a 4x12 loaded with mid 70s G12M BlackBacks. Sounds okay with this amp, but that's what I got to run this thing. I'm using a MM FTDP PT and FTDP 59' (with a single 8 ohm output). Would it be those speakers causing it to be really quiet for some reason? On my other 5e3 I built I ran it through basically the same config only with G12M reissues and it sounded plenty loud. I don't think the coupling caps are leaking since they are all brand new, and I take all the precautions with soldering I can when possible (i.e. using heat sink, always making sure I don't have heat on any one component for a prolonged amount of time). I guess we'll find out if the coupling caps are messed up or not since I'll be trying different values in there anyways.

      Oh, and just a simple question. When you are just taking voltages on an amp, and you put a load on it, does the impedance of the load have to exactly match the amplifier's impedance? I don't have a hot plate or anything, and it would be most convenient to just carry a 16 ohm 2x12 out to my shop than a 16 ohm 2x12 and a 16 ohm 4x12. The amp can only run at 8 ohms...that's just one of the reasons I'm thinking about getting a new output transformer..

      thanks for the help!

      alex

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      • #4
        "Oh, and just a simple question. When you are just taking voltages on an amp, and you put a load on it, does the impedance of the load have to exactly match the amplifier's impedance? " Not when taking "idle" voltages but if you are taking AC signal voltages, then yes.

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        • #5
          I'll put my money on the PaulC mod as the cause of the problem. Increase the 2.2 meg resistor to 4.7 meg.
          WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
          REMEMBER: Everybody knows that smokin' ain't allowed in school !

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