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4 string bass thru a guitar amp?

Discussion in 'Amps and Cabs [BG]' started by, Feb 22, 2005.


    Feb 21, 2005
    Will it work fine? My amp is a Randall RM100 head (100 watts) and my cabinet is a ported Genz Benz G-Flex 2x12 which is very dark sounding and puts massive lows for a 2x12 guitar cabinet. The cab is rated at 150 watts (75w x 2).

    So my question is will it be fine when I'm playing bass through it? I am concerned about the tubes and the speakers mainly.

    Oh and I'm not going to use this set-up in any performances at all, just for writing songs (and for fun mostly :p).
  2. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Olympia, WA
    For what you plan on doing, you will be fine.

  3. Ozzyman


    Jul 21, 2004
    Don't push the speakers too hard. Even though, they might have a nice lowend response, they have nowhere near the amount of tolerance that bass speakers have with the Low E and will get damaged. But with low-medium sound levels they should be perfect.
  4. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA

    Feb 21, 2005
    Even though the speakers are rated at 150 watts compared to my amp's 100?

    How about the preamp and power amp tubes?
  6. I recently got back into a band after a five year break ( new job and schooling). I had been playing guitar when I quit. I wanted to get back to playing bass this time around. I got talked into playing guitar again, so I bought new gear for playing guitar. Well our bass player had to quit a week and a half before our first gig ( News Years Eve). So I switched to bass so we could still gig.
    I ended up putting bass speakers in my new 2/12 guitar cab, and reloaded an old Ampeg Portaflex 15 cabinet, and runnining it with a 100 watt Peavey Wiggy head. I figured I would get a bass amp afterwards. Well I got so many compliments on my sound from people I knew and whose opinions I respected that several gigs later I am still running the rig.
    The Wiggy is solidstate so I don't know what a bass might do to tubes, but I am very happy with my setup.
    I know 100 watts is small but we have a big P.A. and a good sound man so I mic the 15.

    Feb 21, 2005
    Hmm... what if I just buy a bass cabinet and pair it up with my guitar amp head if the speakers are the problem...
  8. jayzarecki


    Feb 23, 2005
    san diego, CA
    sure if you wanna damage equipent! you can get a decent fender BXR combo for liek 200-500 bucks!
  9. bonscottvocals


    Feb 10, 2005
    Upstate NY
    A bass guitar won't hurt the amp, not even if you're running tubes. The amplifier itself is going to pass the signal, and it doesn't really care if it's high notes, low notes, whatever. A couple of things you may notice are that you may lose some low end definition due to the fact that the amplifier's overall balance for tone is geared towards the fidelity of a guitar, not a bass. The only danger to the tubes may come from vibration if you're sitting the amp head on top of the cab. Tubes are filaments in glass, much like a light bulb, and the filaments may be rumbled a bit by the low end. And that's the only real danger to the tubes that you have.

    The danger is to your speakers. If you're willing to chance pushing them with the low end that you get from a bass, then you're taking the chance of blowing the voice coil even at lower volumes. Even at its cleanest setting, your guitar amps preamp is not really set up to pass very low frequencies undistorted to the amplifier circuit. A rumbling, open E (or worse, down-tuned E or open B string) is going to distort on the way to the amplifier. No problem, right? The guitar distorts all the time. Well, now we run into the danger to your speaker. This 'clipping' of the signal to your tube gets driven to the speaker's voice coil in an extremely distorted low end signal, and the voice coil and tube go into an 'electronic loop' of sorts.

    This loop is consistant with tube amps, and it's what makes them so much more powerful and allows them to cut through more than SS amps. The problem is that this additive condition is where a really low and distorted signal can bust your voice coil(s) in a split second. You're pushing a Genz Benz Flex-coil, for goodness's sake! That thing is made to take punishment, but just like anything else made to take punishment: it will reach a breaking point.

    If that's your gigging rig, you would do well to invest in a bass cab (at the very least) or an inexpensive bass combo for recording. Heck, for recording, you could buy a SansAmp Bass DI and run right to your board. If it's good enough for Geddy Lee on stage, it's good enough for scratch recording.
  10. NO problem so far as you dont push it too far.

    I was a guitarrist too, and before I bought my bass combo,I was practicing through my 100w JCM 900 Marshall combo, for probably about 6 months...
    it was/is just fine...
    Just dont push it. if you think that the speakers arent reacting the way they should, turn it down a little. also, try to use a compressor or significantly lower the volume for slap... thats the kinda stuff that a guitar amp speaker wont much like... its not used to that kinda stress.
  11. jayzarecki


    Feb 23, 2005
    san diego, CA
    i agree