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Ampeg pf500 and fender rumble cab, with upgraded legend spks

Discussion in 'Amps and Cabs [BG]' started by Johnw65, Dec 20, 2017.

  1. Johnw65


    Oct 16, 2014
    I have been using a Ampeg PF 500 head and a Fender rumble 4/10 cab. I replaced the speakers with Legends, giving me 600 watts at 8ohms.
    I recently played a gig and had the Amp vol cranked to about 3-4 o clock and felt like I had no power coming out and was hard pressed to get a good clean sound. All other knobs set at pretty much flat.

    Any thoughts? Do i need a new rig?
  2. I played a Rumble 410 with a GK MB500 and had headroom for days. Are the new speakers actually "upgrades?"
    What was wrong with the original speakers?
    NKBassman likes this.
  3. NKBassman

    NKBassman Lvl 10 Nerd Supporting Member

    Jun 16, 2009
    Winnipeg, MB, Canada
    Did you do any checking of the cab size and/or porting before you put the new speakers in? Could be that those speakers don't work well in that box.

    Did the cab sound good with the original speakers?
    Why exactly did you swap them out in the first place?

    There is much more to bass cabinet design than simply speaker diameter and power handling. The electrical and mechanical properties of the speaker interact a great deal with the size of the box and the porting arrangement.
    Last edited: Dec 20, 2017
    Gearhead17 likes this.
  4. mmbongo

    mmbongo Five Time World Champion Supporting Member

    Aug 5, 2009
    If your cab is 8 ohms, that amp is doing good to produce 200 watts or so. So you probably need another matching cab.
  5. I suspect that your “upgraded” drivers are in actuality a downgrade. A driver has to have an enclosure that supports it’s TS parameters in order to work well. You seem to have concentrated your attention on driver size and power handling. Probably the least important factors in driver selection.
    plav1959, Gearhead17 and NKBassman like this.

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