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Guitar amp question (bear with me)

lucas303

lucas303

Mar 11, 2019
3,582
7,433
NH
#1
Splitting a bass signal and sending it to both a bass amp and guitar amp is obviously nothing new. Some of my favorite bass players do exactly that, in various configurations (using crossovers, separate outputs for each pickup, etc.). What I'm totally unclear about, however, is how one goes about picking the guitar amp. I can't imagine a salesman would be cool with me plugging a bass into a guitar amp and potentially blowing the speakers with the low frequencies, so it would seem trying out guitar amps at a store would be difficult at best. I also don't play guitar at all, so it's not like I can draw on any experience with guitar amps from that perspective. So how would someone in my position choose a guitar amp to play bass through? (For the sake of discussion, let's limit this to guitar combo amps.)

For context, I'm currently building a fEARful 15 sub. I envision using the crossover in my Peavey Max preamp to send the lows to a power amp and then the sub, and the highs straight from the preamp to the guitar combo amp. So, no, I'm not talking here about running the bass signal full range through the guitar combo amp. And I'm also not talking about losing out on the lows entirely.
 
#3
How high can the Peavey do the split?

Are you intending to use the guitar amp preamp? You'll need some serious level control on the high out on your bass preamp to do that.

50w should be plenty.

I cobbled together a triamp system for laughs. The top was a little 5W 10'' guitar tube combo. 210 for mids and 15 for lows. It sounded nothing special but fun to try.
 
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#4
Downunderwonder said:
How high can the Peavey do the split?

Are you intending to use the guitar amp preamp? You'll need some serious level control on the high out on your bass preamp to do that.

50w should be plenty.

I cobbled together a triamp system for laughs. The top was a little 5W 10'' guitar tube combo. 210 for mids and 15 for lows. It sounded nothing special but fun to try.
Click to expand...
The Peavey's crossover goes from 100 Hz to 1k Hz. I think the fEARful isn't meant to go above 800 Hz or so anyway, so I think the range of the crossover should be fine.

Care to elaborate about the level control issue if using the guitar amp's preamp?
 
#5
lucas303 said:
The Peavey's crossover goes from 100 Hz to 1k Hz. I think the fEARful isn't meant to go above 800 Hz or so anyway, so I think the range of the crossover should be fine.

Care to elaborate about the level control issue if using the guitar amp's preamp?
Click to expand...
Preamp out signals are generally set to drive power amps. That's an awful lot more juice than instrument level input on the front of guitar amp is expecting.
 
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#7
How clean do you want the highs to be? If headroom is not an issue, even 15w tube combo's will be plenty of power.

I have a live recording where I'm sending my full signal through to both my bass and guitar amps. Granted it's through some dirt that attenuates the lows a bit, but I had zero issues with gig volume. Its also only for a short bit of a track as well.

I know it's a recording, but it was from a gig pulled off the soundboard. The guitar amp was mic'd for the recording only, the sound guy said he never sent any signal from it to the PA since it was always loud enough as is. This was with gain and master up only about 50-60%.

Not saying I recommend doing that regularly with the full signal, but I'd imagine it would have little issue with 1k+. The combo I used is a Vox night train which has a 16ohm greenback.
 
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#8
Thanks all. @Downunderwonder 's comments have me thinking twice about this approach. Now I'm thinking about possibly just finding a bass cab that is more mid-focused and pairing that with the fEARful. I'm not even done building the fEARful yet, though, so I'm in no big rush to decide.
 
#9
lucas303 said:
Thanks all. @Downunderwonder 's comments have me thinking twice about this approach. Now I'm thinking about possibly just finding a bass cab that is more mid-focused and pairing that with the fEARful. I'm not even done building the fEARful yet, though, so I'm in no big rush to decide.
Click to expand...
A 15/6 with the hot 6 and pad for solo duty will sort you right out.
 
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#13
Downunderwonder said:
Preamp out signals are generally set to drive power amps. That's an awful lot more juice than instrument level input on the front of guitar amp is expecting.
Click to expand...

@Downunderwonder is making a very important point, that I will get to in a minute.

Years ago, I biamped an SVT and a blackface Fender Twin Reverb loaded with JBL E120. I ran the pre out of the SVT into an Orban 672A that looks like this:
upload_2020-11-21_1-45-43.jpeg


The Orban has a variable HPF and LPF that can be configure to work as a 12db/octave crossover. I ran the crossover at 200hz because that is the lowest possible knee for the LPF.

(This relates to @Downunderwonder 's comment): Because the input of the Twin was instrument level and the output of the Orban was line level, I had two problems. 1. It was difficult to avoid overdriving the front end of the Fender Twin, and resulting distortion was not pleasant. 2. The Signal to Noise Ratio was pretty bad...essentially the level of background hiss was much higher than desired.

At this point, I believe it would be possible to devise a work around and build some sort of resistor network to pad the signal down enough were the guitar amp can deal with it.

As far as which guitar amp to chose. IMHO pretty much any guitar amp will work if you can find a way to resolve the signal mismatch problem. The problem is not selecting the amp, it's making sure the speaker is up to the task. Most guitar speakers can't handle much power below 100hz, but if you are using a crossover you can manage this problem, although you may have to set the crossover to 150hz or 200hz, depending upon the capabilities of the guitar speaker.

FYI the JBL E120 in my Twin could handle almost the full-range clean power of the amp (about 85W) as long as I did not turn the bass control up above about 4. The speakers had no problem at all crossed at 200hz.

What most people:
Typically people who run a bass amp and a guitar do not biamp, even though many of them call it biamping. The reason I say they are not biamping because they don't use a crossover. Instead they run there bass into the front end of both their bass amp and their guitar amp. I call this multi-amping. The old school way of creating an HPF to protect the guitar speakers is to simply to turn the bass control down, however IMHO an actual HPF sounds a lot better because it does not scoop at the low mids like a bass control does.

Before I bought my SVT and Orban, I ran Ric-O-Sound from my 4001. I ran the neck pickup to a Yamaha B100-115 combo, and I ran my bridge pickup to the Twin loaded with the JBLs. Supposedly the bridge pickup of the 4001 has a tone cap to roll of the extreme lows. This was a very nice sounding rig IMHO, but not as nice as the SVT and Twin run in true Biamp mode.

If you have some bass speakers with decent mids and a power amp, I suggest experimenting with those, before you go down the rabbit hole with a guitar amp.
 
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#15
lucas303 said:
Splitting a bass signal and sending it to both a bass amp and guitar amp is obviously nothing new. Some of my favorite bass players do exactly that, in various configurations (using crossovers, separate outputs for each pickup, etc.). What I'm totally unclear about, however, is how one goes about picking the guitar amp. I can't imagine a salesman would be cool with me plugging a bass into a guitar amp and potentially blowing the speakers with the low frequencies, so it would seem trying out guitar amps at a store would be difficult at best. I also don't play guitar at all, so it's not like I can draw on any experience with guitar amps from that perspective. So how would someone in my position choose a guitar amp to play bass through? (For the sake of discussion, let's limit this to guitar combo amps.)

For context, I'm currently building a fEARful 15 sub. I envision using the crossover in my Peavey Max preamp to send the lows to a power amp and then the sub, and the highs straight from the preamp to the guitar combo amp. So, no, I'm not talking here about running the bass signal full range through the guitar combo amp. And I'm also not talking about losing out on the lows entirely.
Click to expand...
Well, you run a guitar head into a bass cab. Like a rectifier, into the top half of a fridge, and your bass amp into the bottom half of the fridge.
 
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#17
There are two Peavey Guitar amps that will handle bass very well. I've used both with my six string bass. Both of these amp will need a speaker change from stock. My favs are Celestion Pulse, WGS HM75, or McCauly.
Vintage - Peavey Pacer (100SS series) combo. This amp can handle bass no probs.
Modern - Peavey VYPRY 75. Lots of effects that sound good and track bass well.
 
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