Turning my guitar amp into a PA speaker

  • Thread starter Thread starter thebigcheese
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thebigcheese

thebigcheese

"Hi, I'm in Delaware."
My band is a two piece. As you might imagine, that makes it very difficult for us to have guitar, bass, and drums going at the same time. However, the guitarist has a Jam Man that he bought with the intention of allowing us to have more than just guitar and drums when we play live. The problem with that is that if we just run it into his guitar amp, we sort of limit the possibilities to just his guitar. However, I have a Crate XT65R amp that I don't use much anymore and it does a fairly good job of reproducing sounds. It is certainly not the most ideal PA speaker, but as far as guitar amps go, it's pretty neutral. So, what I would like to do is have the Jam Man run into that amp all the time so that we can include bass and secondary guitar parts in our live shows. I foresee a couple problems with that, which is why I'm here.

1) It's open backed. As I understand it, bass cabs should be closed. Can I just nail some wood to the back, or should I build a new box?
2) There are some rattling noises that sound like they might be coming from the amp. I've done a fairly could job of isolating the amp from the box by using Dynamat, but what else can I do? If I'm going to have to build a new box for the speaker anyway, should I just make a new housing for the amp, too?

Are there any other problems you can think of? I mean, it won't give us the most kickin' bass ever, but it should be adequate for gigs where we don't have access to a full PA system.

Edit: I should add that normally for live situations, it is me on drums and him on guitar/vocals.
 
It's not a bass amp. Having said that, try it first without doing anything to the amp. Then tape or clamp a piece of plywood to the back to see if you like the change. Just experiment with duct tape before you start reconstructing something.

I expect that the amp will not like to get a bass signal, particularly as your speaker is not a bass speaker, which has a cone designed for a throw far longer than a guitar signal will provide. You have a 12" guitar speaker; I think you could blow the thing in a heartbeat. It may also conflict with percussion in a mixed signal. But if the gain is low, it might be a stop gap solution.
 
It's only going to run bass and guitar signals. Drums would be live. The speaker is a 12" speaker, so it ought to be able to reproduce bass frequencies fairly well even if it's not designed specifically for bass. But I will definitely experiment. They key thing at this point is not spending money :p
 
thebigcheese said:
It's only going to run bass and guitar signals. Drums would be live. The speaker is a 12" speaker, so it ought to be able to reproduce bass frequencies fairly well even if it's not designed specifically for bass. But I will definitely experiment. They key thing at this point is not spending money :p
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Give it a shot - its a time honored tradition in this game. Just keep the gain down until you know where it wants to be. I do run bass through my PA from time to time, so try it.
 
Don't forget that in the late '50s and early '60s it was very common for a single amp to have a couple of different instruments plugged in, and amps were seen as jack-of-all-trades things rather than being targeted specifically towards a single instrument. As Treeline said, it's a time-honored tradition. :)

That said: don't nail a piece of wood to the back of a combo amp to close off the cabinet. You'll lose the primary path of cooling air and overheat the amp.

If need be, you can - as you suggested - separate the amp and the speaker, and you can try a closed-back configuration. I wouldn't expect any amp to sound great for all things but it might sound reasonable. No harm in trying.
 
You can try it but don't be surprised when it sounds like ass and you blow the speaker. Your best bet would be for you and your band mate to pool your gig money and purchase a couple of powered PA speakers.
 
Man save your speakers because they aren't going to handle the low end of the bass.
you can get this PA for 4 hun and it is a god one, we use it a lot for small gigs and the sem 715 speakers are very nice.
 
Yeah, I just tried it with the amp out of the cab and it still makes the rattling noise, which leads me to believe that at the necessary volume, I will kill the speaker. Unfortunately, I do not have $400 to spend on a PA system. I think one active speaker would be plenty, as long as it's got enough power to make the bass heard/felt.
 
thebigcheese said:
Yeah, I just tried it with the amp out of the cab and it still makes the rattling noise, which leads me to believe that at the necessary volume, I will kill the speaker. Unfortunately, I do not have $400 to spend on a PA system. I think one active speaker would be plenty, as long as it's got enough power to make the bass heard/felt.
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you are going to pay almost as much for a good active speaker as you would that PA. go to www.musiciansfriend.com and type in phonic in the search bar, they have other PA systems for less money.
Or Try Craigs list, you may find something there or hit a few of the local pawn shops; you can find some good deals on music gear in pawn shops.
just a few thoughts.
 
Yeah, they have another Phonics system for $200. I found a Crate system on Craig's List for $250... bah. Time for a band meeting :p
 
As a last ditch effort, are there any mods I could make that would let me use the amp? For instance, swapping speakers or something?
 
how about some of these?
you will pay the same amount for a set of speakers.
 
An alternative- buy a used keyboard amp. For instance, there was a Crate KX-80 on the Atlanta Craigs list recently (I think it was the same one I once owned...) for $80. 80 watts, three input channels- each with it's own input jack/volume/eq/reverb control, 15" woofer and horn, closed back. That sort of thing should get you by until you have the cash and need for something bigger.
 
Oh, good idea. Hmm... That would be a good full range amp, I bet.
 
stevieb said:
An alternative- buy a used keyboard amp. For instance, there was a Crate KX-80 on the Atlanta Craigs list recently (I think it was the same one I once owned...) for $80. 80 watts, three input channels- each with it's own input jack/volume/eq/reverb control, 15" woofer and horn, closed back. That sort of thing should get you by until you have the cash and need for something bigger.
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Stevieb beat me to this idea (and it's a good one.) I have a 150 watt Johnson keyboard amp (found at a pawn shop for $50) which we mainly use as a powered monitor for our drummer, something simillar should work for the purpose you described.
 
I went to GC to see what they had and to try stuff out, and it seemed like the best value was this:
http://pro-audio.musiciansfriend.com/product/Harbinger-APS-15-Powered-PA-Speaker?sku=609806
They only had the display model left, so I got it even cheaper (or the same price after a performance plan, really). It seemed to me like getting 200w was a lot better than 80w from a keyboard amp. I wish it had reverb like some of the keyboard amps do, but maybe I can just convince my bandmate to get a reverb/preamp stomp box or something, if they make those.
 
Some little mixers have on-board reverb- and you will need a mixer, anyway.
 
stevieb said:
Some little mixers have on-board reverb- and you will need a mixer, anyway.
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Not for what I'm planning. It will just have pre-mixed stuff coming out of the Jam Man and probably vocals, too, so the basic mixer on the speaker will be plenty. We can live without it, and if we play larger venues, they'll probably have it anyway.
 
thebigcheese said:
I went to GC to see what they had and to try stuff out, and it seemed like the best value was this:
http://pro-audio.musiciansfriend.com/product/Harbinger-APS-15-Powered-PA-Speaker?sku=609806
They only had the display model left, so I got it even cheaper (or the same price after a performance plan, really). It seemed to me like getting 200w was a lot better than 80w from a keyboard amp. I wish it had reverb like some of the keyboard amps do, but maybe I can just convince my bandmate to get a reverb/preamp stomp box or something, if they make those.
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man that is a great deal for a 15" powered speaker!
180 watts and a 5 band graphic EQ...Not bad at all
how does it sound?
 
Well, I mean, it's certainly no reference monitor, but it dishes out a fair amount of bass and will certainly do what I need it to do, especially since I can tailor my mixes to it for optimum impact.
 
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