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5e3 shhhhh sound diagnosis

Discussion in 'Shock Brother's DIY Amps' started by Finastbeans, Apr 12, 2012.

  1. Finastbeans

    Finastbeans Tele-Meister

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    Maybe you guys can help me with this. Both channels on this amp work and produce sweet sound. However...

    I get a shhh/water flowing sound noticeably with the normal channel at full volume, and very pronounced with the bright channel as soon as you start turning it up. This happens regardless of whether a guitar is plugged in or not. Here is a video (with no guitar plugged in) so you can hear what I'm saying better:

    http://youtu.be/9Xp65WD_a_E

    I'm guessing that I need to ditch the brass plate, isolate the jacks and pots from the chassis, then put all of the input grounds at a single ground point near the input jack... right now i'm following the weber scheme. I have poked around the leads with the chopstick but that didn't seem to impact the background noise.

    It almost sounds like television static - maybe I shouldn't have gone with the TV front.
     
  2. TheSmokingMan

    TheSmokingMan Banned

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    my guess is grounding at the pots
     
  3. Telenut62

    Telenut62 Poster Extraordinaire

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    Yup grounding issue to me. Double check it, is the first filter cap grounding towards the PT? Try and quieten the bzzz with the MM with one prob on ground touching the signal path with the other on the input jacks onwards.
    Looks a nice tidy build there ;)
     
  4. Finastbeans

    Finastbeans Tele-Meister

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    I would describe it more like a shhhh, than a buzz or hum (see vid). I will try the mm thing tonight and also redo the pot grounds and report back. Thank you.
     
  5. rokdog49

    rokdog49 Friend of Leo's

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    Does it happen all the time or just when you fire it up?
    My DRRI does the same thing when I first turn it on. Others here said it's just stuff warming up.
     
  6. Finastbeans

    Finastbeans Tele-Meister

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    It doesn't go away over time.
     
  7. boredguy6060

    boredguy6060 Poster Extraordinaire

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    i agree that some improvement is possible, no doubt a grounding issue.
    However I didn't hear anything unexpected from a 5e3 with the volume maxed out.
    YouTube videos leave much to be desired as to sound quality, but again I didn't hear anything out of the ordinary.
    We can all pick fly crap out of pepper on one of our builds, but this build looks great and I'll bet it sounds just as good as it looks, personally I wouldn't start tearing it apart just to try and improve it, just play the hell out of it and enjoy, don't drive yourself crazy over something minor as that.
     
  8. Finastbeans

    Finastbeans Tele-Meister

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    Redid pot grounds last night and re-soldered some junctions, didn't seem to help though. I have heard others mention their build is "dead quiet", so I have to assume this isn't normal.
     
  9. Powdog

    Powdog TDPRI Member

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    White noise

    Hi. The power section of the build looks good, but didn't really get a solid view of the circuit. Whooshing noise, or white noise, is usually associated with the circuit path resistors (at lease in my experience). The short view of the guts looks like you used 1 watt metal film resistors. Not my personal choice. Grounding issues usually present themselves as a buzz (again, at least in my experience). I've built a pile of 5E3's, and the first thing I'd do is make sure your preamp tubes are all up to snuff. I've found that Sovteks really suck in the 5E3. If the tubes are positively not the issue, I'd consider replacing all of the metal film resistors with 1watt carbon film ones. Not as authentic as AB carbon comps, but the best compromise between warmth and silence. I hope this helps. Like I said, in my 15 year experience building 5E3's, white noise has always been signal path and plate resistors.
     
  10. Finastbeans

    Finastbeans Tele-Meister

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    Hmmm, most should be carbon film, I used the ones that shipped with the Weber kit. That seems like a good lead though, maybe a check of the resistors in the signal path is in order. I can send gutshots if it will help.
     
  11. Powdog

    Powdog TDPRI Member

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    A gutshot would be great
     
  12. JDO

    JDO Tele-Holic

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    weber sends metal film resistors in their kits. what's odd is i think of metal film being more quiet than carbon film and definitely more quiet than carbon comps. my 5e3 is more quiet than yours. i do get some white noise when fully cranked but not as much as yours. are you using the tubes that shipped in the weber kit? do you have access to some known quiet tubes?
     
  13. Finastbeans

    Finastbeans Tele-Meister

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    quick update:
    - pulled the first tube and the hiss sound goes away
    - swapped in a known good tube in V1 (12AX7 from another amp), hiss sound is still there
    - reflowed solder connections on the input path around v1, hiss sound still there
    - unsoldered tone pot connections, hiss sound is now equal on both channels so it's not a function of the bright channel. it's just more pronounced since there is less bleed off.

    ...I've done something squirrely with the input grounds. the brass plate ground connections were never solid and I initially had issues with them, so I added a terminal strip and connected some of the brass plate connections to the terminal. The terminal is then grounded at the first preamp filter cap ground. At this point I'm thinking that I need to rule out the grounding scheme. I'll have to re-do it with the preamp grounds connected to the chassis near the first input jack, and the controls isolated. My gut actually tells me that the issue is something else - like maybe a bad resistor or cap, otherwise the MM test would have isolated the issue. Nevertheless....

    Thanks for all the support and great info.
    -Mike
     
  14. Finastbeans

    Finastbeans Tele-Meister

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    I originally wired up my jacks as if they were isolated from the chassis. there is a ground wire coming off the speaker jack ground tab to the pt bolt. I need to remove that and see if that loop is causing the noise... Will report back.
     
  15. Wally

    Wally Telefied Ad Free Member

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    I am with Powdog here. I have never heard a 'hiss' or white noise that was the result of a grounding issue. Grounding issues usually result in a hum...at 60hz,ime. I also have never heard a 5E3....or any other amp...that was 'dead quiet' with the volumes pumped up to anywhere near the max. Gain equals noise, ime. HIgher gain equals more noise. WHen I turn an amp up, I am busy playing it rather than listening for gain noise. In fact, I expect the amp to benoisier at volume. IFit isn't it won't be producing the gain I am looking for.
    Thsi is not to say that your amp is as quiet as it can be, but I think looking at the groudning issues is a dead end. I could be wrong...again...but that is my thought on the issue. I also prefer a 12AY7 in V1 in the 5E3 circuit...jsut like the originals used. Lower gain tube equals less noise...and the amp is plenty 'hot' with a 12AY7, ime.
     
  16. printer2

    printer2 Poster Extraordinaire

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    Sounds like the noise floor of the tube. I had a lot of white noise with one tube and swapped it out and the noise was reduced. Try a new tube in the first and the second position.
     
  17. tubeswell

    tubeswell Friend of Leo's

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    What printer2 said. Try a tube swap
     
  18. Finastbeans

    Finastbeans Tele-Meister

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    Thanks, I am using a 12ay7 in v1.. My known good tube was the 12ax7. Removing the loop wires made it just a little quieter but it could be psychosomatic. I think I will just play it for awhile, it does seem acceptable.

    I'm actually really digging the tone and nuance with no pedals at stage volume ... Its the perfect volume next to a drummer in a medium size room.

    Its loud as #@$! in my basement :)
     
  19. FiddlinJim

    FiddlinJim Tele-Holic

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    Not all 12AY7s are made equal.... I've tried a bunch of NOS and used 12AY7s with varying amounts of hiss, mostly unacceptable. I always end up with current production EH 12AY7 in V1 for the least hiss. I use them in my 5e3 and 5f4. I also had a noisy 100k carbon comp plate resistor on my 5f4 that caused a bunch of hiss. I replaced that with a good metal film and the hiss went bye bye.
     
  20. cousinpaul

    cousinpaul Friend of Leo's

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    I had some problems with the jacks themselves on my Weber. They were not the best quality and easily bent. Have you tried, one at a time, plugging into all four inputs? If it quiets down when you plug into one of them, it may be a bad switching jack.
     
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