Truckstop Posted April 21, 2012 Share Posted April 21, 2012 Hello all, Need a bit of advice please! I've bought a 115 cab for next to no money as it just stopped working one day. I was wondering how to test the components to work out what needs replacing. Basically, the back panel has 2 1/4" jacks and 2 speakons (no db adjusters or attenuators). The sockets are all attached to a basic looking board and off the board there is a blue wire and a white wire that run to the speaker. The speaker looks to be ok, no burns or tears but who knows! There is absolutely no sound coming out of it at all, not even a hum! Apparantly, the cab was used with a head far too powerful for it and the original owner suspects that it just fried the electrics somehow. Any thoughts would be helpful, I'll put some photos up later! Cheers Alex Quote Link to comment Share on other sites More sharing options...
dannybuoy Posted April 21, 2012 Share Posted April 21, 2012 If the wiring from the terminals to the speaker look solid, maybe try connecting a small 9v battery to the speaker terminals to see if moves? Any tweeter or crossover network involved? Quote Link to comment Share on other sites More sharing options...
Monckyman Posted April 21, 2012 Share Posted April 21, 2012 As above. Remove the driver from the cab, and test directly from the batt to the speaker terminals (with a bit of gash cable). The cone should give a slight bump and move a little when you dab the positive terminal with the cable. No movement means A/your coil is fried and is solid, and won`t allow movement(you can test this also by laying the speaker magnet down on a table and gently pressing with both hands to check for smooth movement. Any friction is a bad thing!) B/your leader cable (the really thin stuff that connects your cone to your terminals)has detached from the cone or terminal. This happened to me recently on a Tannoy Berkely studio monitor. I thought the cone was fritzed and I sent the bloody thing to Tannoy in Glasgow for a recone and they found the tired cable! Good luck! Quote Link to comment Share on other sites More sharing options...
Truckstop Posted April 21, 2012 Author Share Posted April 21, 2012 Cool, will report back with my findings. Thanks for the help! Truckstop Quote Link to comment Share on other sites More sharing options...
Truckstop Posted April 22, 2012 Author Share Posted April 22, 2012 So, I did the 9v battery test and there is movement and a little 'pop' from the speaker so this means it's working? If that's the case, then I need to either replace the input jacks or the circuit board that connects all the jacks/speakons to the speaker wires or bodge something together so that I can just run the cab off one input. Because my Ampeg PF-500 has only one speaker output, I'd have to daisy chain my cabs together anyway so this 115 only really needs one input jack? It wouldn't affect the ohmage or the wattage it can handle, right? Once again, any help is gratefully received! Truckstop Quote Link to comment Share on other sites More sharing options...
Truckstop Posted April 22, 2012 Author Share Posted April 22, 2012 Right, I've just soldered the speaker directly into one of the 1/4" jacks and all is good! Lovely rich Ampeg tones! Truckstop Quote Link to comment Share on other sites More sharing options...
Monckyman Posted April 23, 2012 Share Posted April 23, 2012 Truck, that`s good to know your drivers are ok, but what circuit board are you talking about? Is there a crossover in there? Also, your PF has 2 speaker outs, one on 2/4" Jack and one on NL2 spekon. Doesn`t matter whether you daisy chain both together or use a cable to each from the amp, the ohms will remain the same. Personally, I like two individual cables from the amp, because if the one feed cable goes, then both cabs don`t go down. Happy days. MM Quote Link to comment Share on other sites More sharing options...
Truckstop Posted April 23, 2012 Author Share Posted April 23, 2012 The circuit board, on closer inspection, simply linked all the jacks and the speakon inputs to the speaker wire socket. No crossovers etc to be found. I imagine they did this just to keep everything tidy to make it easier to build. It's only a chinese built Ampeg after all! Anyway, I'd always thought that it was bad practice to use both the 1/4" and the Speakon at the same time to run two cabs. Is this not the case? So if I have two 8ohm cabs, they each get 250w because the head's running at 4ohms (the full 500w available)? And this won't change whether they're connected parallel or in series? Thanks for your help mate. This is the first time I've ever exposed myself to the world of cabinets properly. Always been too afraid before! Alex Quote Link to comment Share on other sites More sharing options...
dannybuoy Posted April 23, 2012 Share Posted April 23, 2012 The two outputs of your amp, or the two inputs on the cab are all wired in parallel so you can either plug them both into the head or chain from one cab to the other, doesn't really matter. Glad you got it sorted! Quote Link to comment Share on other sites More sharing options...
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