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Ampeg PF800 - no sound through cab

Discussion in 'Amps and Cabs [BG]' started by Tommy GL, Jun 30, 2020 at 7:23 AM.


  1. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    Hey TBers, this is my first post requesting some assistance so any help you can offer is appreciated.

    Head powers on and works fine with headphone plugged in and cab disconnected. When I plug in cab and unplug headphones, I get no sound through cab. I know the cab and cable is good as I have other heads to test them.

    Anyone run across this issue?

    I have no warranty, so no option to return.
     
  2. bass10bfb

    bass10bfb Prophet Low End Provider Gold Supporting Member

    May 5, 2011
    Newport, TN.
    Could you give some more info please? What type of head and cab? Are you for sure using a speaker cable, and not an instrument cable for connection? What kind of bass, and is it active or passive?
     
  3. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    Ampeg PF800 with PF115LF cab with speakon to 1/4 cable. I am using speaker cables for sure.

    I am using a musicman stingray 5hh, active.
     
    bass10bfb likes this.
  4. bass10bfb

    bass10bfb Prophet Low End Provider Gold Supporting Member

    May 5, 2011
    Newport, TN.
    Hmmmmmm..... Have u tried changing the 9 volt battery in the bass? I am just guessing at this point trying to help out.
     
  5. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    Appreciate it. Yes, guitar has new battery. The guitar works fine.
     
  6. bass10bfb

    bass10bfb Prophet Low End Provider Gold Supporting Member

    May 5, 2011
    Newport, TN.
    I have played a lot of gear over the years, but never played the PF models from Ampeg unfortunately, so I just don't know much about them. Hopefully someone else can chime in and help out.
     
  7. bass10bfb

    bass10bfb Prophet Low End Provider Gold Supporting Member

    May 5, 2011
    Newport, TN.
    @JimmyM I know you are an Ampeg guy. Have you ever ran into an issue like this?
     
    HG1180 likes this.
  8. Does your cab have SpeakOn inputs? If so use a SpeakOn to SpeakOn cable wired +1 > +1 and -! > -!. Phone 1/$" cables don't have the power handling the amp needs. IIRC your amp is permanently in bridge mode which means that both the positive rail and negative rail of your speaker cable are driven by a separate power amplifier module. Damage will occur if your phone plug barrel contacts a ground.
     
  9. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I have not, although I suppose the potential is there. First off, let me start with the obvious questions...

    You ARE turning off the head before you unplug the phones and plug in the cab, right?

    You aren't leaving the speaker cable dangling from the head while you have it unplugged from the cab, right? You should always disconnect it from the head, not the cab, for headphone usage.

    That's about the extent of my knowledge of these things. But you are always welcome to contact Ampeg TS.
     
    bass10bfb likes this.
  10. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    I already tried connecting my other cab (GK neo 115) using speakon to speakon and still nothing. Headphones continue to work.
     
  11. How is your SpeakOn cable wired? There are differing versions.
     
  12. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    Hi JimmyM,

    I always turn it off before disconnecting or connecting anything. When using headphones, I power unit off, disconnect speaker at head, connect headphones, then power it back on.

    I have a GK MB500 that works the same way when I use headphones and never had this problem.
     
    JimmyM and bass10bfb like this.
  13. lyonaudio

    lyonaudio

    Apr 16, 2019
    France
    The PF-800 appears (according to the manual) to have a 1/4inch speaker output. Try a 1/4" to 1/4" speaker cable. Maybe there's something wrong with your amp's Speakon output.
     
    bass10bfb likes this.
  14. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    Lyon, I need to run to store to buy a 1/4 to 1/4 speaker cable. I only have a 1/4 to speakon and speakon/speakon cables at the moment.

    Paul, not sure how speakon is wired. When I got cable at GC, I told them what equip I had and they sold what they thought I need.
     
  15. lyonaudio

    lyonaudio

    Apr 16, 2019
    France
    That's your problem right there.
    You're trying to use an Ampeg amp and cab with modern things like "Speakon" connectors.
    It's just ain't right.
     
    Killing Floor likes this.
  16. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    The pf800 has both speakon and 1/4 Jack's.
    The pf115 cab has only 1/4.
     
  17. lyonaudio

    lyonaudio

    Apr 16, 2019
    France
    Hence the problem...
    Your speaker cab doesn't want, nor does it need, any fancy-ass stuff like "Speakon."
    A 1/4 inch was good enough for your dad, so 1/4 inch should be good enough for you.
    (Don't ask your Mom's opinion.)
     
    Pulverizor likes this.
  18. Tommy GL

    Tommy GL Supporting Member

    Jan 24, 2020
    Seattle
    That pf115 cab with only 1/4 jack has been hooked up to 4 different heads via 1/4 to speakon cables and never had an issue.

    In fact, that cab has been paired with my GK MB500 for a while now with no problem and that head only has speakon connections. That's why I had the 1/4 to speakon cable.
     
  19. In Dad'd time there were no 500-1000W amplifiers. The 1/4" phone plug was designed for telephone operator switch boards. Operating conditions were about 48V at about a couple of hundred milliamps. They are not capable of handling the power of these modern Class D amps.

    I'm surprised that these amps have Phone sockets as I would not have thought they would pass safety considerations.
    .
     
    Tommy GL and Aqualung60 like this.
  20. lyonaudio

    lyonaudio

    Apr 16, 2019
    France
    Class D be damned. If a 1/4 inch was good enough for an SVT with 8x10 cabinet, or a Mesa 400+ with two 1x5 cabinets, it ought to be good enough for you.
    (Mumble, mumble...)
    :hyper:
     
    PillO and birminghambass like this.

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