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Ampeg PF 50T

Discussion in 'Amps and Cabs [BG]' started by Super Bass, Apr 22, 2017.


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  1. Super Bass

    Super Bass Supporting Member

    Feb 4, 2017
    Alberta, Canada
    I was just curious as to whether or not any other owners are experiencing any hum from their PF 50T amps. Mine hums a bit, nothing that concerns me.
     
  2. lowplaces

    lowplaces Supporting Member

    Dec 20, 2015
    Louisville Kentucky
    Can't advise but I'm thinking of getting one. So ......bump
     
  3. kobass

    kobass Supporting Member

    Nov 3, 2003
    Outside Boston
    I have a PF-50T and the output transformer does hum a little bit (no hum through speaker, just hum from the transformer). As soon as I start playing (even at solo practice levels) I can't hear it. I contacted Ampeg just to be sure. They told me that some hum from the output transformer is normal/acceptable.
     
    Aqualung60 and Super Bass like this.
  4. Super Bass

    Super Bass Supporting Member

    Feb 4, 2017
    Alberta, Canada
    Thanks for the reply! I was starting to think mine was the only one!! The hum is not bad probably similar to yours but mines through the speaker. I do really love this amp though, I kind of want to get the PF 20T now too!
     
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    You can hear the hum and hiss in this video. Note that the hiss changes with the tone settings. Line hum is something else, there are a number of things that can affect that.

     
    Last edited: Apr 23, 2017
    lowplaces likes this.
  6. kobass

    kobass Supporting Member

    Nov 3, 2003
    Outside Boston
    fwiw, my hum varies depending on the bias setting. If I turn the bias setting screw counterclockwise, the hum is reduced. When I set the bias according to spec/recommendations it's at its loudest.
     
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  7. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    It also depends on how well matched the power tubes are. An unmatched set will have more hum.
     
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  8. kobass

    kobass Supporting Member

    Nov 3, 2003
    Outside Boston
    I still have the stock power tubes that it came with. I'm not sure if Ampeg goes to the trouble of matching tubes for these amps, but it will be interesting to see if I ordered a "proper" matched set (from Doug's Tubes, etc.) if that would change things.
     
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  9. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Ampeg specs the tubes that they order to be matched. But you never know how tight their spec is and what can mistakenly get through quality control.

    Other factors such as light dimmers, bad home wiring, a bad tube, and other external influences can all play a roll with line level hum.
     
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  10. Super Bass

    Super Bass Supporting Member

    Feb 4, 2017
    Alberta, Canada
    So the hum from my amp is line hum or the transformer? I have a few other all tube amps that do not hum at all in different places in my house. Can the hum be from the power tubes?
     
  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Some transformers hum. It's often a mechanical hum caused by a vibration inside the transformer. You hear the hum if you are near the amp but it doesn't come out the speaker.

    If the hum is related to the line frequency you often hear 60Hz or 120Hz (or 50Hz or 100Hz if that's your line frequency) depending on the amp design. That can be hum from the heater circuit getting picked up in an audio pathway and amplified. This comes out the speaker.

    If the power tubes are not well balanced, yes there can be a hum. There is a higher THD. There are other causes, a bad tube can hum. The amp can also pick up external noise as I mentioned above. A bad ground inside the chassis can also cause a hum. Some amps are shielded better than others. That can explain why one amp hums in a room and another doesn't.

    Years ago some amps, such as the early Ampeg SB-12, had a power tube hum balance pot. The SVT-VR has one, the CL doesn't. This isn't the same as the heater hum balance pot that you see on many tube amps. The power tube hum balance is used the same way, you listen to the hum while adjusting the pot and set it for minimal hum. This feature balances out differences if the tubes are not well matched.
     
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  12. Super Bass

    Super Bass Supporting Member

    Feb 4, 2017
    Alberta, Canada
    Thanks for your reply!
     
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  13. Super Bass

    Super Bass Supporting Member

    Feb 4, 2017
    Alberta, Canada
    PF 50T PRONEO.JPG Just wanted to post a picture of the PF 50T that started this thread..
     
    lowplaces, gregmari, Spectrum and 3 others like this.
  14. JJR58

    JJR58 "Big Angry Piano" Supporting Member

    Dec 2, 2010
    Queens NY
    Nice combo!!!!
     
  15. Super Bass

    Super Bass Supporting Member

    Feb 4, 2017
    Alberta, Canada
    That Ampeg PRONEO 115 sounds great with the PF 50T!
     
    lowplaces likes this.
  16. JJR58

    JJR58 "Big Angry Piano" Supporting Member

    Dec 2, 2010
    Queens NY
    Oh, I bet it does.
     
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  17. JJR58

    JJR58 "Big Angry Piano" Supporting Member

    Dec 2, 2010
    Queens NY
    The only reason I gave up on the short lived 50t I had was, what I think, was a problem in the power amp section.

    And I can't say for sure that was the issue.
    It's a killer amp.

    Through a 810e.
    It can push it, hard.
     
    lowplaces likes this.
  18. Super Bass

    Super Bass Supporting Member

    Feb 4, 2017
    Alberta, Canada
    While I am loving mine something inside me is afraid of this amp because it is only a few days old! I have had my share of problems with newer Ampeg amps. I just love the sound I get from them... This one is under warranty and I can return it within 30 days if I have to...
     
  19. Nickweissmusic

    Nickweissmusic Knows all intervals from one Fred, to Juan octave Supporting Member Commercial User

    Jan 26, 2014
    San Diego, CA
    I teach lessons and perform live music in and around San Diego CA. Sometimes I even make money doing it!
    if the spkr output is clean, and the DI outputs are clean, you're probably better off keeping it, since the physical noise is inconsequential. No guarantee another copy will be any better. If everything sounds good, it would probably be worth spending bucks on matched, independently spec'd tubes, my understanding is tube production is poor nowadays and it's common to be way off spec out of the box.
     
  20. InhumanResource

    InhumanResource

    Dec 28, 2012
    Curious about that - does it get gig usable volume through the 810e? I play with a pair of 410HE's and a big SVT 6-Pro, but I have more juice than I'll ever realistically need.
     
    Lvjoebass likes this.