SWR Help

Discussion in 'Amps and Cabs [BG]' started by maconbass, Dec 7, 2005.

  1. I own a SWR SM-400S that is running at very low output for some reason. With the volume @ 10 it is still fairly quiet and burned up both of the tweeters in my two Aguilar GS112's (in church). I took it to a service tech and they resoldered here an there and gave it back with the same problem ($200 charge). I took it back to them and they say it is fine and testing at about 220watts bridged @ 4ohms. I stated that it is a 500 watt head. According to them that is a peak figure and not RMS. Is that true? I've noticed that most other amps are rated at RMS. It still makes no sense since I used to run the volume at 2 or 3 and it was plenty loud. Any opinions or suggestions?
  2. vision

    vision It's all about the groove!

    Feb 25, 2005
    Ann Arbor, MI
    Endorsing Artist: MTD Basses, La Bella Strings, and 64 Audio IEMs
    That doesn't sound right...the SM-400S puts out 500 watts @ 4 ohms rms...
  3. a) Make sure the idiots you took it to fix it right this time.
    b) Don't go back.

  4. My 350X puts out 350 watts RMS
  5. MattLplaysBass

    MattLplaysBass Proof that gear doesn't make you a better player Supporting Member

    Apr 23, 2002
    Chicago, IL
    it's 500 watts rms bridged into a 4 ohm load. maybe they are only testing one side of the amp...
  6. They claim to be testing it bridged and say it is just a lower powered amp than others that claim the same wattage. In his words "when Ampeg says 500 watts they actually mean RMS."
  7. I'm not qualified to verify manufacturer's claims, so i'll stick with what I know. Don't listen to what's being said....listen to your amp. You've noticed a drop in output? You're probably right.

  8. BillyB_from_LZ


    Sep 7, 2000
    I'm not that familiar with the SM-400, but does it have a line (mains) voltage switch on the back? If so, is it set to the correct voltage?

    If there's an effects blend knob, is it set to dry?

    Have you tried a short cord to jumper the effects loop?

    If you're using it bridged, are you connecting the speaker cable properly?

    Does it have a tube and if so, is the tube known to be good?

    Is there a mute button that could be depressed or a failed switch that could be in the permanent mute mode?

    Did you try a different power cable?

    Are the fuses all good (inside and out)?

    Has the amp been dropped, left out in the cold, get wet, etc.?
  9. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    South Shore MA
    Could you do a couple of things to help narrow it down?

    1 - Try running the amp in stereo and see if the problem affects both power amps.

    2 - run a signal from the effects out to another amp and see if you get a clean, loud signal. An effects return on another amp would work well for this. This will take the preamp out of the equation.

    The output is 500W RMS.
  10. Thanks for all of the suggestions. They are very helpful. The tube is new, that was my first try and the cabinets are hooked up correctly. However, I have not tried a different power cable or cable from the head to cabinet. I have not been able to find anywhere, in writing, that states the power is RMS to show these guys. I'm disappointed that I blew $200 for nothing.
  11. draginon


    Oct 4, 2004
    call SWR and explain this to them and see if u can ship it to them to get fixed. If not, take it to another amp shop, preferably someone more reputable.
  12. Also, they still have the amp. When I get it back, I will try out your suggestions. It seems to me that they would know these things. I got there name off the SWR/Fender website. I called SWR/Fender today with my wattage question but the person I talked to didn't seem to know much.
  13. There's a shocker.
  14. BillyB_from_LZ


    Sep 7, 2000
    I presume that you have a manual... If not, this one's available online


    I wouldn't think that the power ratings are Peak.

    If SWR wasn't much help, contact Steve Rabe at Raven Labs. He'll know for sure...and might have some better suggestions.

    Make sure that the limiter is bypassed...

    Do you still have the old tube? Did you try a different one?

    Try plugging your bass into the effects return jack and see how loud the amp is then. Make sure you turn your bass' volume down before you turn the amp on.

    Good luck and please keep us posted.
  15. iammr2


    Jun 10, 2002

    To put it gradiously, they're full of bunk. That amp should run about 250 a side at 4 ohms and 500 watts at 4 ohms bridged. Take it to a decent tech and have them check the solder joints at the controls where the board meets the faceplate. Also have them check the Effects input and output jacks on the back. Then take the receipts back to the first guy and get your money back.
  16. Great suggestions guys. You have really come through for me. I will in fact get in touch with Steve Rabes, never thought of that, and also try everything you have suggested.
  17. iammr2


    Jun 10, 2002
  18. The owners manual doesn't state RMS or peak unfortunately. I just looked up Raven Labs and Steve Rabes has retired. Bummer.
  19. Kitsapbass

    Kitsapbass What key is this?

    May 26, 2005
    Bremerton, WA
  20. dalley


    Jul 6, 2005
    Billy, just curious as to what these two suggestions might fix. I might have a similar issue and might want to try these two things.