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Epifani rig with... distortion ?!

Discussion in 'Amps and Cabs [BG]' started by varcingetorige, May 9, 2018.

  1. Hi everyone in the talkbass family.

    Just a quick question for you guys, here is my rig:
    - Epifani PS400 bass head
    - Epifani PS410 (4ohms - 800watts)

    I'm pretty happy with my rig 8really happy), but how come that if I pass over noon in the master volume, lets say around 1 I get distortion?

    1. Gain is set properly and do not clip
    2. The cab do not fart/distort at lower volume... nothing strange
    3. The cab is twice the capability of the head in terms of watts so, it should handle all the head power pretty easily
    4. All over no signs of anything broken

    Please advice
  2. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Describe distortion, please.
    What amp settings on bass and mid control?
    Active or passive instrument? If active, what instrument settings?
    Does this happen in all environments?
    Any pedals or effects in signal path?
  3. Great! Thanks for help!

    1. everything's pretty flat on the amp
    2. passive jazz bass
    3. I'll pay more attention about the environment, since I focused this problem at home, where I experiment using high volume as well
    4. no pedals and or fx on signal path, simply straight to the amp
    The sound just get... distorted, a little bit farty
  4. I mean... It does not make sense to me. If something where to be broken it should have the same behaviour not according to the volume.
  5. murphy


    May 5, 2004
    Toronto, Canada
    That might be driving the amp pretty hard....have you tried turning down the bass

    You might need more power to get the volume you want

    Or your speakers or one might be on its way out
  6. Ok, now is the time i'm getting worried...

    I'll try different eq's in a clean situation to double check clearly the bass issue

    You think the amp is not powerful enough for a 800w cab?

    The third option you gave me is too scary to even mention...
  7. murphy


    May 5, 2004
    Toronto, Canada
    I am sorry to scare you

    The PS series is the cheaper version of the UL series...so like all brands that carry a cheaper line....Hartke XL vs Hartke transporter
    Eden vs Nemesis
    SWR Goliath vs workingman series

    The components are a bit less top shelf

    maybe your amp is at its max output when you hit the distortion sound.....I have never turned a master volume up that high on a 400 watt amp....or an 800 watt amp
    Most amps will start to hit distortion sounds at that point....gain structures are complex through each stage of the preamp
    Andy would explain better @agedhorse
    Jim Carr and agedhorse like this.
  8. murphy


    May 5, 2004
    Toronto, Canada
    Is it REALLY LOUD when it starts to distort?

    If not then yes you have a problem....try a different speaker cable first.....instrument cable

    Then try a different speaker cab

    I had the same problem once and it was my instrument cable gone bad

    BUT....also look for creasing in the speaker cone surrounds...happened to all my Eden drivers XLT....and needed recones
    Jim Carr and agedhorse like this.
  9. Thank you very much @murphy for your helpful support!!! I'll evoke @agedhorse as well as you suggest.

    Here below my comments to yours:
    • It's my first time with an Epi rig, so I'm not familiar with its response, but I'm pretty happy with the overall sound of it. I think I'll stick with Epi for quite a while :thumbsup:.
    • Mine, it's a rig which I traded with my old TecAmp Puma combo and I've experience with many other brands including Markbass, GK, SWR and etc. For this reason I'm trying to understand if I got a lemon from the seller or not...
    • When I did traded the rig I did not think to try it very loud, since it is like brand new and everything was working very fine at low to mid volume and from a good guy too, so I did not felt, at the moment, to push the rig to its boundaries.
    • Gain is barely clipping as usual (maybe with this rig I should set the gain ways below the clipping stage?).
    • The PS400 is seriously loud to be a 400watts amp, indeed, but it does not distort (which happens to be more like a cross inbetween distorting and farting) at the end of the scale, lets say around 1, 2 'o clock and it should be a 400watts on top of an 800watts - 4ohms cabinet, so the power should be very well handled.
    • I did try to cut the bass a little bit as suggested and it was a little bit better, but still... I cannot cut the basses, I mean... c'mon, we are not guitar players :D.
    • The cones moves a lot, yes, I've seen them moving quite a bit, but, again, it's an 800watts cab that should handle pretty well 400watts even at full power.
    • I understand the PS it is not a top line, but still an Epi made in USA. It is not a UL, but it should be still a PS, not an EpiFunky :eyebrow: for instance a Markbass traveller it is not at the top of their line and the cones moves quite a bit, but it does not distort/fart if the cab and the amp are balacend like above.
    • I did try a couple of instrument cables and it's the same thing.
    • I should try possibly a different speakon cable or I may try a power jack this weekend to see if it's that, but I honestly doubt it.
    So the basic point of everything is:

    I've been scammed or simply Epifani it's a brand where you should exclusively be hunting for their top line (piccolo/UL) in order to have a normal response?
  10. murphy


    May 5, 2004
    Toronto, Canada
    No no no
    You should be able to be happy with your rig

    Did you check the speakers for creasing? They will sound good until the volume gets loud...and fart
  11. I will in the week end!
  12. Maybe i'm focusing the issue too much on the cab where it could be due to the pre-amp stage that gets overdriven too easily for some reasons? :cautious:

    Anyways I'm using a passive jazz, so it sounds a bit strange, where I've notice that the gain it's pretty reactive.
  13. murphy


    May 5, 2004
    Toronto, Canada
    varcingetorige likes this.
  14. murphy


    May 5, 2004
    Toronto, Canada
    varcingetorige likes this.
  15. Thank you @murphy you are unbelievably kind and helpful. Tomorrow I should be able to experiment a little bit more.
    murphy likes this.
  16. To add a little to @murphy able posts, the 800W rating of your cabinet is thermal or when the drivers begin to melt. What you need to know is the power at which the cabinet runs into it’s excursion limits, that’s how far the cones can safely travel. It could well be that you are driving the cabinet past those limits. How is your bass control set? The higher the bass is set the sooner you get the cabinet to reach it’s limits.

    It could also be that you bought a damaged cabinet. Checking for the creasing that was shown in the photographs is an obvious thing to do.
    Last edited: May 13, 2018
    murphy likes this.
  17. Wasnex


    Dec 25, 2011
    I read the entire thread. It sounds like you are exceeding the XMax of the drivers. This can occur well before you hit the thermal limits of the design, especially if you are feeding the cabinet a signal below it's passband. The 800 watts is most likely the thermal limit. The drivers in reflex cabinets unload below the frequency the ports are tuned too. By unload, I mean there is nothing to prevent the driver from jumping around and destroying itself. Perhaps running an HPF a bit under the cabinets port tuning frequency (Xb) would eliminate the problem. Maybe @Rick James can chime in on how far below the port frequency to set the HPF.
    varcingetorige likes this.
  18. @Wasnex wooow. That's a great answer, but i'm not sure i properly understood what you mean.

    Basically you say that the sound is too full of subsonic frequencies?

    How come that an amp thought to go along with that speaker may overdrive the cab?
  19. Wasnex


    Dec 25, 2011
    Your response indicates you understand.

    The manual for the PS400 shows the frequency response as 20-25khz so the low frequency cutoff of the amp does not seem to provide much of an HPF to protect the speakers below their pass band. Only the amp designer can answer why this choice was made.

    I can't say for certain whether the speaker and amp are functioning properly or if there is damage. In my experience, it is not unusual for speakers to fart out significantly before full rated power is applied, so this does not seem unusual to me. Repeated over excursion will damage the speaker, so best to avoid.

    Many players prefer to add a variable HPF to their rig. The HPF can protect your drivers, tighten up the lows, and also increase your headroom a bit. IMHO it's a really good tool for players who push their equipment to the limits.
    varcingetorige and murphy like this.
  20. Dear @Wasnex, you are absolutely right with your evaluation. It would be funny to have an answer about such a kind of choice in designing the amp, I guess is due to give the player the wider possibilities in matching cabs.

    I did experiment today with the rig and your answer is 100% correct. It is a subsonic matter indeed. Could you please suggest some HPF solutions to add to my rig?

    The drivers move really a lot and distortion occur due to the wide sonic palette of the head compared to the "limited" range of the cab.

    I did check carefully for any crease as suggested by @murphy but the all rig is absolutely in mint conditions.

    The overall sound is really good to my tastes and I would like indeed to keep the config. Also the gain is incredibly responsive and with my passive jazz bass I have to keep it around 9 'o clock or just a little pinch above.

    Thank you everyone for such an help!
    Last edited: May 13, 2018
    murphy likes this.

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