Ampeg PR 410HLF possible blown tweeter

Discussion in 'Amps and Cabs [BG]' started by subsonicbassist, Mar 10, 2017.

  1. Hey guys,

    I have this cab powered by a Mesa M-Pulse 600 and recently noticed that it had a lot of static, even at low volume. I had previously only played it in a band context, so the rest of the noise likely drowned it out. My thinking is that it is the tweeter, because when I adjust the L-pad on the back the static gets louder or quieter in correlation to which way I spin the dial.

    When the L-pad is off (dialed all the way down, I don't believe it is fully off), the static is a lot more quiet but still present. I am sure it's not the amp as it is almost whisper quiet when on and not connected to the cab, but the minute I plug in the cab it gets super loud. Another possibility is that it could be a bad connection between the amp and the cab somewhere, but I have tried both 1/4" plugs on the amp and the cab, as well as both Speakon connections on the cab and they are all equally as noisy. I took off the L-pad panel on the back and inspected the small light bulbs that are there to soak up any excess voltage, and they both are in pristine condition.

    I'm a bit at a loss here, and because the grill design is different than most Ampeg cabs, I can't figure out how to get it off to take a look at the speakers :( there were 6 heavy duty bolts through it but it still won't budge with those removed, and I'm a bit scared of shaking stuff around or prying it too much (you get this way after working on German vehicles frequently!). Any suggestions of things to try and potentially rule out certain components, or does anyone have experience taking one of these apart? Thanks in advance guys, gotta get this rig ready because she's gonna be seeing the stage soon!
  2. UPDATE: Got the grill off and plugged in without the tweeter connected, and 99% of the buzz went away. Looks like I have what I need :)
    Sartori and Gearhead17 like this.
  3. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    Probably fried the tweet. Should be easy to get a replacement. Or not. I always turn them off anyway :D
    subsonicbassist likes this.
  4. A crackling noise is relatively high frequency. So the noise is diminished when the tweeter is attenuated. And gone when the tweeter is disconnected. This could be because the noise is at a frequency higher than what is being passed to the low frequency driver by the cross-over or higher than the LFD can reproduce. Under this scenario, the noise could be coming from any number of places. You should nail this down before you proceed with the assumption that it's your tweeter.
    Bass 45 likes this.
  5. Korladis

    Korladis Inactive

    Disconnecting the tweeter = definite improvement.
  6. Haha, appreciate the feedback gents! New tweeter should be coming in today so we'll see if it's that, even though my multimeter seemed to indicate the old one was ok, at least resistance-wise :) will update when I find out!
  7. Korladis

    Korladis Inactive

    You ordered another one? Why?
  8. because I already have it apart, they are cheap, and I've blown them before so having a backup is never a bad idea! To summarize earlier posts, the tweeter tested fine electrically but the cab functioned normally with it completely removed. Process of elimination points to the tweeter or some component of the horn assembly (or whatever it's called) being faulty, unless there is another possible issue I have overlooked. If so, advice or input is certainly appreciated :)
  9. Korladis

    Korladis Inactive

    Personally I'd just leave it disconnected.
  10. Yeah, quite a few people are saying that but I really dislike the sound of my bass with it out of the loop... my next cab may not have one though, the voicing on these cabs is a bit odd.
    wyrtti likes this.
  11. shipping is late, looks to be out for delivery today! Will update once I get it :)
  12. Update: was indeed the tweeter. The old looked fine and seemed to have good continuity, but it's been beat on for 15 years and something had to give I guess. Was a $15 part, and took the opportunity to check all the rest of the wiring and clean the contacts. Sounds better than before!
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