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Bass into Guitar Amp

Discussion in 'Bass' started by eonblue, Mar 27, 2006.

  1. eonblue

    eonblue Guest

    Serious newbie question. But I always heard that you can damage something by running a bass into a guitar amp. I want to know why? Is it only a matter of the speakers not being able to handle the bass frequencies or can you actually damage something in the head? What if I didn't turn up the amp very loud at all. I just want to see what it sounds like.

  2. StevenColbert

    StevenColbert Member

    It wont hurt it. The only real "difference" is the impedance. But some people will tell you that bass guitars mess up guitar amps. One or two people told me the same thing in the past. But that was years ago and I have since found them to know little else about anything.
  3. eonblue

    eonblue Guest

    So when you say difference, do you mean between bass and guitar speakers or what? Am I to assume that given the same amp settings with both a bass and standard guitar that the bass won't blow the speakers? Given that im not just pushing the speakers too much of course.
  4. cfaalm

    cfaalm Active Member

    I have used an active bass on a Fender Champ. I'm OK when I keep the volume down. Two limiting factors:

    1. It never sounds really deep
    2. You can't raise the volume too much without distortion.

    If it is just to make it heard at home, it's OK. I would not recommend to play a live gig or even a rehearsal that way. There is a reason bass amps exist.

    Ever played guitar through a bass amplifier? Not counting the Fender Bassman of course 8)
  5. StevenColbert

    StevenColbert Member

    I mean that the the only real difference is the magnetic field of the pickups for the instrument. A guitar has different pickups than a bass guitar does. That is where most of the difference is. The votage can vary (depending active or passive) and the total amps are usally close to one another, BUT the resistance is typically much greater on one and not the other.
    Impedance is a type of resistance. So, the impedance is just another "thing" that is different.
    The speakers are "geared" differently, but for the most part are pretty much the same. I would assume that bass speaker coil wires are slightly bigger in diameter. However all amps are UL listed and that UL listing has requirements (for the power section of the amp) not to be greater than the rated wire sizes per the National Electric Code.
    Yes. However you can set it up so it sounds better. Most likely the settings are not going to sound good set the same way for both instruments.
    I played a bass through a guitar amp for years. Hell I played my first bass through my home stereo for a year and a half.
    I almost forgot that til I wrote that. Man that was a long time ago. It never hurt the home stereo either, now that I recall it.
    The main thing is that distortion will be preset (on the odd instrument) because of the differences in impedance.

    Also it will never blow the speakers because all U.S. products are UL listed. The amp that powers that speaker(s) is ONLY rated for the max. load of the speakers. It will sound different, and you will most likely never get a good or great sound from the amp using a bass through it. But if it's all you got. Well it's all you got. I've been there
    But it's not gonna burn the house down or nothing like that
  6. moonbaby

    moonbaby Mmmmmm Well-Known Member

    WHAT?!?!? WTF does UL have to do with the speakers' spider being ripped from the cone from a too-low frequency note pumping the cone? Guitar speakers are designed with a FREE AIR RESONANCE point that is usually an octave or more higher than a bass guitar speaker's FAR!! Go to the Eminence website and read why there are BASS GUITAR speakers and GUITAR SPEAKERS!!! You can probably get by with a guitar speaker at a fairly low volume, but the efficiency and tone will suffer greatly.
    BTW, I am the co-owner of a speaker rebuilding business here(JBL/RCF/
    Eminence/Bose and more). The 2 ways people blow up speakers is by either clipping the power amp driving them or by pushing too low a frequency into them. Also, running bass through some amps with spring reverb tanks will kill the springs! Even when the Reverb control is down all the way, the preamp is still driving the send to the tank! Some designs use a highpass filter to prevent this and to voice the 'verb...some don't!
  7. eonblue

    eonblue Guest

    Ouchies. To make it worse we are talking about a 4000 dollar Diezel VH4. So I really want to be carefull. We are talking about really low volumes here. But the thought that one little slip of the master volume might screw me over is highly disconcerting. Btw, the cab is, in fact, loaded with Eminence custom speakers:)
  8. CoyoteTrax

    CoyoteTrax Well-Known Member

    Moonbaby's right and to further understand the difference between guitar speakers and bass speakers you should definitely read the available material at the Eminence site [Eminence speakers totally rawk BTW].

    To put it plainly, yes you can play your bass through a guitar amp and actually get some decent tones for recording and low level practice sessions. Heck, one of the coolest bass tones you might ever hear comes by plugging your bass into an antique tube driven RTR tape deck with little 7 inch speakers. Very sweet tone for recording. Some of the most beautiful bass speakers ever are only 8 inch cones, but their designed for bass guitar.

    Just remember to keep your volume levels low so you don't blow the speakers and you're cool.
  9. eonblue

    eonblue Guest

    Thank you thank you thank you sirs. If I work up the courage(or ignorance) I might give it a shot. I have actually read that the Diezel heads and cabs push a hell of a lot of bass. I just wanted to make sure I wouldnt damage the head, as I might have to hang myself shortly thereafter.
  10. StevenColbert

    StevenColbert Member

    I dont know WTF it has to do with what your talking about either. I answered his question. He asked for more details. So I replied.
    I still say he will not hurt his guitar amp by playing a bass through it.
    Bottom line. And the answer to his question
  11. CoyoteTrax

    CoyoteTrax Well-Known Member

    But Steven you're telling him that he can crank the volume as high as he wants and it won't blow the speakers, which is entirely incorrect. That's what moonbaby flashed WTF at.

    This sentence in particular is the dangerous one IMO: "Also it will never blow the speakers because all U.S. products are UL listed. The amp that powers that speaker(s) is ONLY rated for the max. load of the speakers."

    Dude doesn't want to blow up his Eminence speakers and he'll absolutely blow them up if he cranks his bass through them at high volume levels.
  12. Nirvalica

    Nirvalica Guest

    your way off. just think about it a little. guitars are made for mid frequencies a little low and a little high. mostly mid. now bass guitars are like what they say, for bass frequencies. now we all know bass frequencies are rough on speakers, more so than mid and treble frequencies.

    so now you said that the amp's speakers are supposed to be able to accept the wattage from the amp. sure, makes sense, but the part your missing is it's made to accept wattage from guitar frequencies. the guitar speakers aren't like Pa speakers, they aren't full range. they are designed for mid frequencies. so let me offer an example of what i mean. tweeters are designed to play treble. say we have a 50 watt tweeter. now if we have a 50 watt amp, whatever we run into it should work, right? lets run a subwoofer signal through the amp and into the tweeter. now let me tell u, i doubt the tweeter will survive.

    look at bass amp speakers. they all have thicker cones, bigger magnets and all around beefier than a full range speaker. they are designed to take the beating that bass frequencies put out. also, the bass speakers aren't designed for high frequencies. note alot of large bass amps have little tweeters to get that, some even a little mid sized speaker to get some nice punch.

    so after this, i say its not good to run a bass through your guitar amp. maybe at very low volumes, but be very careful.
  13. StevenColbert

    StevenColbert Member

    I can hear you. But you just made a point to make me sound wrong, and in the same sentence wrote "play bass through it at low volume". Which is it?
    First you say "Your way off". Then you say "think about it".
    Stop right there. I dont need to "think about it". I've done what he is asking about for years. I am giving an honest answer to a question that I have exp with myself. Have you ever done this? If the answer is no, then maybe you could stand to listen to someone that has, rather than assume any result that is not proven.
    I mean Nobody said "turn it up full blast, tune down to low B, and hammer away with some ultra-low frequencies until you see smoke or the amp stops working"
  14. Nirvalica

    Nirvalica Guest

    the way off part is this....
    and just think about means that guitar speakers and bass speakers aren't basically the same. thats like saying tweeters and subwoofers are basically the same. and no, i have never tried it because i don't particularly want to blow my speakers, but i have a friend that did it, and guess what, he fried his speakers.

    and you did say the amp should be able to handle the bass turned all the way up, which is totally false.

    you can play the bass at very low volumes through the guitar amp, same as you could play a sub frequency very very quietly through a tweeter, but don't turn it up. even if it works, its still not good for the amp and its not recommended.
  15. moonbaby

    moonbaby Mmmmmm Well-Known Member

    Gentlemen, gentlemen!
    Mr. Colbert has, I'm sure by this time, gotten the message....
    There were several mis-statements made and we don't need to re-hash them. Suffice it to say that he probably believes that my tone of voice
    sparked at least some of the fury. Read the related post about "Volume pedals vs Potentiometers"....
    The bottom line here is that there are a LOT of people who get the facts wrong about operating gear. I know this because it is a part of my profession to service that market. And, to be fair to Steve, there have been posts on this very forum touting the virtues of pumping a bass guitar
    through the almighty Fender Super Reverb (gasp!) in a studio situation.
    There is a difference whenever any loudspeaker is barely being pushed or when it is really being pushed, and the difference CAN cause flame and smoke, UL be damned (BTW, guitar amp manufacturers rarely register through UL these days...typically CSL, for legal and $$$ reasons).
    Anyway, unless you're jamming in the bedroom, keep the bass outta the geetars' amp!
  16. Davedog

    Davedog Distinguished Member

    Okay. Now I'm gonna jump in fer a bit. First off. UnderWriters Labratories only test a few out of a thousand units of any electrical device in order to insure that it will not catch on fire if used in the manufacturers intended usage. This is mostly concerned with the transformers,tube sockets(in tube gear), capacitors and the general wiring and lay-out of , in this case, a guitar/bass amplifier. In a self-contained, amp/speaker combo there might be a bearing on this in general type of operation. In a separate head speaker combination, the UL listing will only be on each part and the two will have nothing to do with each other due to the fact that UL doesnt give a crap about what you plug into any amp head whatsoever only that the amp head is safe to plug into the 120 volt source and wont catch fire immediately.

    UL is all about things catching fire......ya see.

    As for plugging in a bass to an open back speaker cabinet, well this is where it can get dicey with very little volume. Speakers that are being excursed to a large part of their throw due to low frequencies greatly benefit from having a sealed cabinet or at least a cabinet that offers resistance to this movement in order to reproduce these frequencies.

    So, at any volume other than barely a whisper, an open backed guitar amp with a bass hitting it is just not going to get it done without some damage. This being said, some of the very best sounding bass tracks I've ever recorded were through an old Fender Deluxe with the original speaker. But these were at a very low volume with a big-ass mic through a lot-a-gain pre.

    I actually use a cheap keyboard combo amp in the studio for bass. I like the EQ curve of this more full-range amp as well as it having a good deep sound and a closed back. Keyboards do go really low...... :!:

    Conclusion: A high end, tight, well built, closed back, guitar cabinet will suffer less damage at low volumes with a bass signal than will a cabinet with the speaker flapping out in the wind...... :wink:
  17. Tommy P.

    Tommy P. Well-Known Member

    Well done gentlemen, well done. Yes, UL (underwriters laboratories) is a an organization, giving its saftey stamp for consumer products that meet and comply to standards that pertain to fire saftey. They make no warranties or claims of added product robustness.

    Moonbaby and Da-Dog, speaks correctly, and I'm sure Mr Colbert is fine with it. Glarring inaccuracies can spark exclamated replies, and rightly so.
  18. eonblue

    eonblue Guest

    God, I don't want to beat a dead horse and I was almost done till Davedog had to drop this on me:

    "Conclusion: A high end, tight, well built, closed back, guitar cabinet will suffer less damage at low volumes with a bass signal than will a cabinet with the speaker flapping out in the wind......"

    The cab in question is a closed back Diezel 2X12.....needless to say its approx. 70 lbs and is builit like a brick shithouse. The reason I asked this to begin with is because I will be recording bedroom level bass and this Diezel is notorious for pushing copious amounts of bass with a standard guitar so I said "Hell, why can't I run a bass through it". That being said, the part that worries me in Davedogs statement is this.

    "A high end, tight, well built, closed back, guitar cabinet will suffer less damage at low volumes"

    Less damage? I don't want to damage the thing at ALL. It would be very nice for me to get a somewhat useable bass tone without damaging my dream amp. Maybe I just need to stop thinking about playing with fire and just be content with THE GUITAR TONE OF THE GODS ehh?
  19. Nirvalica

    Nirvalica Guest

    just record the bass direct into the recorder/computer/mixer
  20. Davedog

    Davedog Distinguished Member

    eonblue....Not to scare you but as I said, the speaker moves a certain distance in its frame in order to reproduce the signal its being fed. While I dont believe you will cause any serious damage with that particular rig at 'bedroom volumes' just be aware that ANY movement beyond the normal operating range of a speakercone is going to add some fatigue factor to its lifespan. I, however, think that for your usage as you have described it, it would be okay in limited doses.
    While some would insist that bass should be direct, theres a great amount of desirability in the tones that are created by a speaker cone. In much the same way as a guitar speaker acts upon the final tone created when played through an amp.Simulators, direct boxes, digital modeling....none of it is the same as the speakers being abused in just the right way.

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