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SWR Mo Bass Amp is HOT!!! Ouch!!!

Discussion in 'Amps and Cabs [BG]' started by dugonbass, Aug 8, 2004.


  1. dugonbass

    dugonbass

    Aug 8, 2004
    Just bought an SWR Mo' Bass head which reviewed really well. I used it live for the first time last night and noticed 2 things. First off, with the preamp set right, I slowly turned up the volume knobs for both of the amps and had to go to about 3 O'Clock to get a reasonably lound stage volume. That didn't seem right. Also the amp is in a 4 space case with a power conditioner mounted above it. After a few minutes of playing I noticed the thing was really hot. I bumped into it at one point and it actually burned. I'd guess the 2 are related. Here's what I have:

    SWR Mo' Bass head(supposedly 600Watts @ 8 ohms Bridged)
    SWR 8 Ohm Goliath (4-10) III(takes 700 Watts)

    Any thoughts on what this could be?
     
  2. Raising the volume to 3 o'clock in bridged mono mode seems like a lot,... but I don't know. Are you boosting a lot of low end bass?

    I believe the whole amp chassis is designed to get hot and pull away the heat from the internal components. Check the owners manual.

    My SWR SM 900 gets hot sitting on top of the cab (not in a rack) when running at a good volume, and I always let it cool before packing it away. I believe a lot of people have complained on this forum about SWR amps getting hot, but I haven't heard of any of the amps shutting down or going bad.
     
  3. dugonbass

    dugonbass

    Aug 8, 2004
    I ran the amp pretty much flat. I know it's probably not, but could the preamp tube have any effect on the overall volume of the amp? It doesn't have the sounds or symptoms connected with bad tubes but I'm not sure. As far as the heat I suppose I could get another fan or something but the power thing's freakin me out. thanks
     
  4. inazone

    inazone

    Apr 20, 2003
    Colorado
    I agree.
     
  5. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    What is your pre-gain set at?

    Joe.
     
  6. dugonbass

    dugonbass

    Aug 8, 2004
    I plugged into the Active/Passive in, instead of the active in which the manual said was fine. The gain was at about 1/2 or a little better. The clip light came on only when I really dug in or slapped the lower strings.
     
  7. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    To be honest with you, it sounds like your amp is fine. You either need more power or a cab with bigger drivers in it so you can push more air.

    You said you needed to turn up that high to get a decent volume. Do you mean you were having a hard time hearing your bass or were you having a hard time feeling your bass? My Goliath III is pretty loud and I can always hear it but I am very disappointed with its lack of thump. When I bought it I didn't realized that that's what you need big cones for, the thump.

    So anyways that's why it is going up for sale.

    Now...just a thought. Are all your speakers in phase with each other? If they aren't you lose an incredible amount of bass.

    :)

    Joe.
     
  8. fast slapper

    fast slapper

    Dec 11, 2001
    Fresno, CA
    You need to leave space above the amp for proper ventilation. I experienced the same thing with a Bass 750. I've noticed SWR amps aren't that successful at producing high db's at 8 ohms(or any load).
     
  9. dugonbass

    dugonbass

    Aug 8, 2004
    Thanks Joe, I hope the amp is fine. That means it's me and I can deal with that. I recently bought the cab and I assume the speakers are in phase. I guess I could open it up and see. I guess I'd need to trace the wires and make sure they all go + to + and - to -? Just tried to donate to this forum but they said it was down for a while. Have you ever tried 2 Goliath IIIs together? What do you want for yours?
     
  10. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    A good way to check polarity is to get a speaker cable with only 1 end on it and plug it in. Then take the other end (the wires) and touch them to a 9v battery. Watch the cones and see if they all move the same direction (either all out or all in). If they all move together, they are in phase. Real easy and you don't need to take your cab apart. Unless they are out of phase, then you need to do the 'follow the wire' thing.

    No, I have never tried two Goliaths together. I would imagine they would really roar but I haven't done it.

    I would like to get $450 for the cab.

    You can see it here.

    :)

    Joe.
     
  11. I'm curious...who reviewed the piece favorably? "Cause quite frankly, I haven't seen a single good word on the Mo' Bass...and would tell most to avoid this model like the plague.
     
  12. dugonbass

    dugonbass

    Aug 8, 2004
    I just did a search and found several reviews and couldn't find anything negative about it. Where have you read the - reviews?
     
  13. dugonbass

    dugonbass

    Aug 8, 2004
    I bet you'll easily get that for it. Looks good. I may get a Big Ben(18") to round out the bottom but I'm in the process of shopping a new bass. Looking at a Pedulla or maybe a Modulus.
     
  14. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    I have considered the same thing.

    Good Luck!

    :)

    Joe.
     
  15. If memory serves...going back to its inception, Bass Player gave it a 'ho-hum' kind of review (I don't think Ive ever seen them give anyone a 'bad' review)...essentially stating that you'd be better off buying a separate effects unit and that for its size, it coulda had a bit more in the wattage dept. (headroom) Remember this is going back a few years when SWR first introduced it. I would hope that under Fender, they would be making a concerted effort to improve the model. My first real time experience with one was at my local music store. I asked to try the unit out...and my buddy there said, he'd love to have me try it out if it worked. He told me 2 days outta the box it just quit on him.
    You're not the first I've heard of regarding thermal issues either. If you've got a return policy on it...I'd go over the unit with a fine tooth...and if there's anything that concerns you; excersize your right.
     
  16. amped1

    amped1

    Aug 24, 2002
    I recently had a chance to A/B the Mo'Bass and the SM500 and IMO the SM500 has a much fatter tone and is quieter than the Mo'Bass. The Mo'Bass seems under powered for a 900 watt amp. And yes my Mo'Bass gets pretty hot. I'm saving up for a SM900, but I'll still keep the Mo.
     
  17. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Damned good idea about the fans!

    Joe.
     
  18. dugonbass

    dugonbass

    Aug 8, 2004
    Hi, Been busy all day playing and running around. glad to be back. How do I tell if the amps are biased and what do I do if they are? I played a gig this afternoon at the Sturgis Rally, which is a huge biker rally, and had to crank the amp to get a competetive sound on stage. I did pull it from my rack and it ran much cooler but still didn't have the power it should. The soundman looked at it and said to run the preamp hotter with a little of the limiter on. Seemed to help the volume thing but the clip light was red more than it was green. Well, thanks for the help.
     
  19. Fealach

    Fealach Guest

    Apr 23, 2003
    Gone to a better place
    I had a Mo Bass.. for a couple of weeks. Sounded great, but the band drowned it out, extremely low power. I though 900 watts solid state should be able to come close to the volume levels of the Mesa 400+ I had been using, and it sounded so good at low volumes in the store... 2 Mesa 2X15's, the same cabs the 400+ pushed to deafening volumes, useless with the Mo. Found out later it'd been discontinued, only the preamp was being manufactured still, and I think I found out why. If it hadn't cost me so much, I'd have kept it and ran the preamp section into a power amp.
     
  20. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    Everybody I've ever talked to who have used a Mo Bass has said that it seems extremely underpowered for its rating.

    Personally, I didn't think the effects were that great and like certain pedals MUCH better.