Bi-Amp Signal Flow

[garryH]

First off, I play bass in a 3 piece rock band, doing mostly classic (harder) stuff like AC-DC, Aerosmith, Zep, etc. and just looking at various ways to thicken up the sound, especially during guitar solos. I've been lurking here for months, and have searched many a thread for various reasons and have gotten many answers.

Thanks to many of you, probably way too many to count.

I have a question about a bi-amp setup, as I am still not 100% sure about the how the signal should flow. I already have most of the equipment I need, if not all. I have 2 Hartke power amps, a 2000 & a 7000. For cabs I have a GK BLX 115 and a GK BLX 210. I also have a spare x-over I can use if needed, a Rane AC-22.

I have a pedal board with a MXR BOD, Bass Big Muff, a Boss CS-3 compressor, a Boss CE-5 chorus and a Crybaby Wah used only occasionally.

I am looking for that nice clean bottom, with maybe the octaver coming in the 115, and the rest of the effects going into the 210s.
Right? That seems like what I've read most here.

Again, my question is basically about the signal path. I get confused about where the signals get split and crossed over.

Is it: Bass -> Pedal Board -> X-Over - Amps -> Cabs ?

Or does the signal get split coming from the pedal board, i.e. 2 cables (paths), one to the low end one to the mid-hi's?

Or maybe I still don't quite get it, which is why I had to break down and ask the experts here.

Oh yeah, and how does an LS-2 fit onto this concept, if at all?

And should this have been in the AMP forum section?

[bongomania]

There are several ways to do this sort of thing:

bass --> effects --> two amps --> two cabs

bass --> two effects chains --> two amps --> two cabs

bass --> crossover --> two effects chains --> two amps --> two cabs

bass --> effects --> crossover --> two amps --> two cabs

All are legitimate, depending on what you're trying to achieve, and what gear you have (or want).

A Boss LS-2 fits into the first and second of those options, but not the 3rd and 4th. It's a splitter, not a crossover.

There are some pedal-sized crossovers (not too common or cheap or proven though, in most cases) and there are loads of rackmount crossovers.

[garryH]

thanks bongo... so I guess I was on the right track.

Will the crossover automatically push the bass octaver into the low cab, or should I use 2 outputs from my pedal board (line 2 in your diagram I presume) to push only that effect into the lower cab?

I guess my main goal is to get a nice clean bottom, and if the octaver is engaged get that down there too, and then a nice midrange tone on top where I can also send the other effects (if they are used, mainly the Bass Muff occasionally) to fatten up the sound.

[SteveMcB]

As Bongo has noted, there are a number of ways to do this. I will add a further way to his list which is something like:
Bass > crossover > highs to effects, lows dry > mixer (eg. LS2) > amp

I went on a similar quest to you for biamping. I ended up hunting down the (cheap, out of production) Peavey BAC-2 Biamp Bass Chorus. I've seen them go for as little as $10 US on ebay, and it provides an instrument-level crossover in solid, pedalboard-friendly form. Since then I've used it regularly in a variety of setups, mostly taking the form of either:
Bass > BAC2 > lows to clean bass amp, highs to effects and into guitar amp

or

Bass> BAC-2 > lows dry and highs via effects > mixer (behringer MX400) > amp.

Both of these setups have worked really well for me with 4, 5 and 12 string basses.

Steve

[bongomania]

A crossover will split your signal into two (or more) ranges of frequencies. It does not care what signal you're feeding it, whether it's an effect or whatever. If some portion of the output of the octave pedal is in the low band of frequencies, then that portion will go out the low band output. If some portion is in the high band, then that portion goes out the high output. You set the crossover point--typically there is a knob or switch for that.

Whether those bands are clean, fat, or whatever else depends on any other processing you do. Simply splitting the signal with a crossover won't guarantee anything like that. All it does is allow you to treat or amplify two section of the signal separately.

Another option I forgot to mention before:

bass --> effects --> preamp that includes a crossover --> two-channel power amp --> two cabs.

But it sounds like what you want is to split the signal right after the bass, before any effects. So you need a pedal-sized xover that can operate at "instrument level" rather than the much higher "line level" that is expected by rackmount xover units. Then you would either run the two pedal chains to two separate amps/cabs, OR use a pedal-sized mixer (like the Boss LS-2) to recombine the paths into one full-range signal, and then just feed one amp and one cab.

[garryH]

Hey Steve .... That sems like a good idea, but I guess the Peavey BAC-2s are getting harder to find. There are none currently on eBay. Manufacture on the BAC-2 stoppped in 1993 (read somewhere), so that would be 16 years ago.

And thanks again to to you Bongo. You've given me a lot of good ideas to explore.

I don't really have a preference on how I get this done, as long as I can get a clean tight bottom with some thickness on top.

I bet I'm not the first to say that. :-)

[rcubed]

I'm running two amps with my current setup. I'm using both the dry and effect outs on my MicroPOG. I prefer having the full frequency range going through each signal chain and then EQing my amps to emphasize frequency ranges.

[garryH]

I could probably try that as the Bass Big Muff has a dry out / effect out configuration.

EDIT: Actually I misunderstood what you were saying there rcubed.

So do you have 2 lines coming from your pedal board and then sending one line to each amp?

[SteveMcB]

BAC-2's haven't been easy to find for a long time - I don't think they sold a whole lot! I set up ebay to email me with new peavey pedal listings, and they came up every few weeks. The problem was actually that none of the ebay sellers wanted to sell to someone overseas. I ended up buying from the TB classifieds, where they also pop up from time to time. Keep an eye out and you would find one (if you decide that a pedal-based approach works for you).

IIRC the BBM doesn't have separate outs for dry signal, as with most pedals with a dry signal blend or internal crossover, it mixes the signals back together internally within the pedal.

Steve

[garryH]

You are right Steve about the BBM...

From the manual:

In Dry mode, the original dry signal from your instrument is mixed with the output
of the distortion circuit. The level of the Dry signal is constant and will not change as
you turn the Volume knob up or down. This allows you to set the level of the
distortion effect against your dry signal.

[rcubed]

That's the dry mode with the switch that does that. There is an actual dry output jack that passes whatever the input signal is without effecting it. The BBM could easily be used for a bi-amp rig.

[garryH]

Cool... good call rcubed. That's what I thought until I looked at the online manual this morning. Then I read too much. With not enough coffee.

Now, could you explain how to do that? I think I am a little dense on how to make this work.

Would you run all "effected" signals to one amp through the BBM "wet out", and all the unaffected signals through the BBM "dry out"? Would there be 2 signal lines coming from your pedal board and then sending one line to each amp?

This is where I am getting confused. As you can probably tell.

[WaldoNova]

I'm not sure how your pedal board is set up but if you put the Big bass muff 1st in the chain with the wet signal running to the rest of your effects(except the BOD) into the 210 and the dry running to the BOD into the 115 you would be all set (if you liked the sound of having the BBM 1st in line). If you don't (liked the sound of having the BBM 1st in line) then get the LS-2 and split the signal.

[garryH]

Hey WaldoNova... it'd not setup yet because I'm still trying figure out the best way to do this. So I am open for experimentation.

I'll try this tonite and see how it goes.

[rcubed]

Originally Posted by garryH

Cool... good call rcubed. That's what I thought until I looked at the online manual this morning. Then I read too much. With not enough coffee.

Now, could you explain how to do that? I think I am a little dense on how to make this work.

Would you run all "effected" signals to one amp through the BBM "wet out", and all the unaffected signals through the BBM "dry out"? Would there be 2 signal lines coming from your pedal board and then sending one line to each amp?

This is where I am getting confused. As you can probably tell.

Yep, you could do that.

I run the effected out of my MicroPOG to a VT Bass and then out to the amp. The dry out goes through the rest of my pedal board and out to a different amp.

[garryH]

I'll try that tonight too. Thanks.

[chrisisnotevil]

I've been recording, and while experimenting did something very similar with an EHX Stereo Pulsar, One half going to some dirt pedals and a tube amp, the other straight to another amp, then blending them by ear. Worked great! Ended up using an ABY switcher instead on the track, with the same signal path pretty much, I don't think they cost a bomb if the BBM thing doesn't work out.

[Snakeman1066]

GaryH

if i were you i would run true full range stereo

i run this way

bass...phaser, Wah, OD, Dark Boost Fuzz, Sansamp into Hartke LH500.....into a 4 ohm 4x10

Bass...Octave, Chorus, Sansamp.....into Hartke 3500 into a 4 ohm 1x15

and then i mix amp/cab levels depending on song

but i also have an a/b/y and a loop switch in the mix so both cabs can get all effects if needed...

I play a lot of Stoner/Doom/Sludge and find this setup lets me put a lot of bootom back in during my super fuzzed out offerings...

hope that helps

[garryH]

thanks snakeman. I got some ideas from your layout.