Educate me on bi-amping

[sawzalot]

Here’s my advice: just skip it.

I went down this road during the heyday of SWR AND Eden. Back then they pushed the idea that biamping made your bass sound better somehow. I had half a dozen cabinets, worked on finding the perfect crossover frequency, bought different power amps and cabs for the lows vs the highs, all that. One day I hooked up a pair of 4x10s with a simple full range preamp + power amp setup and it sounded 10x better than any of the biamped rigs. That was the end of my biamp experiments. Ultimately it cleared the way to using a lightweight head and the right combination of cabs for the gig. For the last few years I’ve not used an amp at all.

The only reason I see for processing highs and lows separately would be for distortion/etc that you only want applied to the highs. But even then most modern pedals have some way to accomplish that.

Interestingly, PA systems above a certain size ARE effectively biamped systems, with big subwoofers handling below around 100hz and the rest of the PA rig handling everything above. So my favorite is to leave the heavy lifting to the PA, leave the amp at home, and give them a feed from my pedalboard.

 

[Rip Van Dan]

Before you go down this road, you might try some of the many newer higher performance amps and cabinets on the market. My experience is that many of these outperform cobbled together "bi-amp" solutions, some by a country mile. There's a lot to choose from.

@agedhorse, as usual, is right on the money. Back in 1985 when I was working part-time at a music store, it was a big deal when the GK-800RB came out because it had a 300-watt rms main amp for the woofer, and a 100-watt rms amp for the horn or tweeter. Back then most bass amps were 212's, 115's, or 215's and they really didn't have much top end, although you could buy a large horn tweeter to set on top of them like an old "Voice Of The Theater" speaker set-up. To run it you needed a separate amp and a crossover so you could send the desired frequencies up to the horn.

Unless you have a cab that is specifically made to be bi-amped and has both high and low inputs (not just two or three blank inputs), you can really screw up a cab and amp by plugging in both parts (high AND low) of a bi-amped signal into it. @agedhorse could give us the particulars of what happens when you try that, but it's not good! I think a normal cab will treat one of hose as an output and try to send a signal out what is actually a second incoming signal. Not sure that's how it works, but I know it doesn't really work.

Now days, most bass cabs have a tweeter horn or a whizzer cone to handle the high-mids and highs and are known as "full frequency" cabs. If you were to run a bi-amp system where you send the lows to one cab and the highs to another, on a modern full-range cab, you'd be wasting most of the cab that you're sending the highs to because the woofer won't be doing anything. you'll just be using the tweeter. Eden also came out with bi-amp ability when they brought out their dual-powerblock amps the WT800 and WT600. I have the WT500 that's been upgraded to 800 watts bridged, but it doesn't have the circuitry to run bi-amp. It is a dual-powerblock amp though.

It does have two separate power channels and I can plug one cab into one side and a second cab into the other channel in what we call "dual-mono". People often think that is bi-amping, but it's not. Cool thing about dual-powerblock amps is that since it has two discrete power channels, what you plug into one side has no influence on what can be plugged into the other. Each side of mine will put out 400-watts at 4 ohms and I can put two 8 ohm cabs in one side plus two more in the other side if I really wanted to lug around and use four 8 ohm cabs.

 

[ezstep]

Back in the day, I had a LabSeries 1x15 @150 hz on down underneath a Peavey 4x10 with the rest of the sound. Sounded good, back in the day. Took two heads, of course.

Then there was the Peavey TNT under the Peavey 4x10, still around 150hz crossover. Now one combo and one head. Sounded good, back in the day.

My advice to educate you in bi-amping: skip it. Today's amps and cabs are so much better than "back in the day." I honestly don't think you gain very much in volume, especially when comparing the more modern options that we have - possibly not as much. Very heavy, very hard to load in and out again.... In my honest opinion, it's just not worth it.

 

[Downunderwonder]

Clarity and doom tend not to belong in the same room.

What you are asking for is what I used to do in fx with the PA behind the band no vocals no bass amp.

You need an active crossover to work the fx on the highs only and then a blender or mixer to recombine to a single source for amping. This is the way of scaling up to the bigger leagues.

In your case I can see you are inclined to do it all from the stage.

I would use the 210 for your high side with one of the tube amps. Get another cab and a SS amp to run the clean lows. Stand the 210 up tall.

Rolls sx21 split. Lots of ways to run it. You can't put the bass straight into it though.

1, out of SS fx loop to Rolls, high side to front of the tube amp and low side back to your SS.

2 out of tube fx send to Rolls, lows back to SS.

Either way you are at the mercy of your amps to return a satisfactory phase orientation at the speakers that the high end of the low signal isn't a goner when it joins the low end of the effected signal.

Adding fx makes it even more complicated as they can supply the Rolls. You probably have to use front of the Tube amp to get it to drive like you want but you can give it some juice out of the Rolls even without the low end in that signal.

Trouble comes if you want time fx on the drive out of the Tube preamp. You need a line level fx unit and fx loop. And you might well find the phase at the crossover goes to hell if it didn't already.

 

[Downunderwonder]

To get a taste with what you have now at the practice spot you need a crossover and an fx loop in the big amp that you use to run the lows out of the 410. I fear that will turn you to the dark side though and make you a pita to work with forevermore.

 

[MCF]

That is fair. We have come a long way since the late 90s.

What would you consider modern high performance? Markbass maybe? I am totally clueless when it comes to amplification. Just looking for something loud with a little bit of clarity when using an obscene amount of dirt/fuzz.

Mesa WD800.

 

[Bboopbennie]

Mesa WD800 with a TC electronic Triple C Compressor. Multi band compression can work like Bi or tri amping.
Its all about the crossover frequency separation.

 

[tleeitsme]

What you're talking about is not bi-amping, splitting a single source signal (PA, bass guitar, etc.) at a certain crossover frequency into dedicated amps and speakers for lows and highs. This was done in bass guitars in the 70's and 80's, and for most, its time has come and gone with the advent of current technology. Modern amps and cabinets have made it unnecessary these days. I did it back in the day, but would not now.

There are lots of cabinets with several different size speakers in them (PA bins, home hi-fi, lots of bass guitar cabinets) driven off single amps, but these used passive crossovers inside the cabinet (an electronic circuit) that divides and sends the right frequencies to the right speaker inside the cabinet.

Now, some guys may still bi-amp for effects following the technique that you leave your big fundamentals, the low end of the split, unaffected and clean, then use the upper part of the signal for the applied effects (chorus, distortion, etc.). We see this practice followed electronically in some bass pedals, and you can still use your regular amp and cabinets with those.

You're talking more about a split signal (which can be done with any bass, not just Rickenbackers, with a 'Y' cable) where you're split-sending signal to a bass amp for your bass tone, and generally a smaller guitar amp for distortion, from the bass guitar. This would be easier than trying to do this with splitting cabinets off one head, by far, which most likely wouldn't work, two amps work best for this. Sending big bass through guitar cabinets is generally a recipe for disaster at any kind of loud levels: They're generally not built for that.

Now you could do this with a Rickenbacker with the separate outs, but don't get confused by those: Those outputs aren't 'stereo', nor are they after a crossover inside the bass. It's actually an output for each pickup. So you could use the neck pickup to drive a bass amp (the deeper sounding of the two) and the bridge pickup for the guitar amp and effects (the thinner sounding of the two). One bass, two cables, two amps, but you'd have to match the amps so one would not drown out the other.

I'd also advise steering clear of old Sunns or any of the other ancient sleds: Unless they're VERY properly maintained, they were built for a different time . . . . . a long time ago. What slightly different preferred tone you might think you hear would be far outweighed by maintenance headaches for those of us that aren't touring with guitar roadies and electronic techs. I'm old enough to have used a lot of the ancient 'lead sleds' back in my time, and would NOT trade them for modern gear.

Here's one of the 'Rig Rundown' vids from PREMIER GUITAR about Stanley Clarke's touring rig from 2011. SC was running a small Fender guitar amp for a distortion edge on some tunes, and here his tech explains how they did it, right around the 3:00 mark:

Rig Rundown - Stanley Clarke

The two Alembics run off 18v phantom power (those big plug-in cables on the face of the two Alembics just below the knobs), and the 'preamps' his tech is talking about are actually Alembic DS5R power supplies for each bass in the top rack. These have HIGH, LOW, and FULL RANGE outputs, and for one of the amps, they tapped the HIGH output (while still feeding the Ampeg heads simultaneously from the FULL RANGE output) to go to that Fender amp for one of the Alembics. Mic'd up thru the house and monitors, it's 'big enough'. It's similar to the Rickenbacker setup, the HIGH is the bridge pickup, the LOW is the neck pickup, and FULL RANGE is both pickups.

Now most of us don't have the advantage of touring with a trunk full of Alembic gear, but this illustration of the idea is what you want to take away for the best way to do this: Ideally, to feed a signal short of the deep end of the signal to a suitable guitar amp.

There's several ways to do it, and you'll have to decide what's best for you.

AND . . . . . however you do this, MAKE SURE you've got it squared away and it WORKS, every time. The surest way to lose gigs is to show up with some half-ass, only-works-if-I-hold-my-mouth-just-right rig that you're fighting all night long to keep it running. Mess up like that on a regular basis, and you'll be back gigging in the bedroom so fast you won't believe it. Being a pro and green are NOT mutually exclusive, and very few will give you time to grow up on the bandstand. With the real musicians, being prepared is an expected given.

Ok. I guess did understand the ric-o-sound function but I guess was off with what you would call that. If it were 2 independent signals coming from each pickup it seems like that would be "stereo" as opposed running a Y cable or active crossover would just be "bi-mono" since it just 1 signal split? I honestly feel like I am in grade school all over again, I havent learntd this hard in a long time. Please bare with me as I try to wrap my head around all of this new vocabulary/information, its a lot to jump into from previously being a "plug in and play" type of bass player.

After reading all of this I think a trunk full of alembic gear would stress me out more than it would help lol. Definitely something I would have down to an exact science before lugging all that junk around to venues.

As far as my obsession with "lead sleds". I've been bit by the tube amp bug and I got it bad. Like anything else vintage = cool. Tube snobs look down on hybrid amps. Lemmy used a marshall jmc, Geezer used laney, Al used to use matamps. Big all tube guitar amp are kind of a common motif in the only sub-genre(s) of metal I can actually enjoy (theres actually only a handful of motorhead songs I like, but I really appreciate his tone). As far as new tube amps go "reissues" are typically pretty expensive and "not the same" and hybrid amps "aren't cool". Additionally when I was just a wee-lad and just started playing, I met a guy who gigged his b15 all over texas. Of course, talkbass had taught me that old tube amps were a pita and easily breakable. He told me that was a misconception and that as long as you dont bang em around while the tubes are still hot, that it wasnt actually a big deal to gig/transport tube amps. Of course my gigging experience begins at house shows and ends at open mic blues nights so its all hearsay to me and I don't know the first thing about the pains of transporting gear.... the actual weight notwithstanding. I used to deliver gun safes for a living so I know how to move weight smarter not harder. 300lbs worth of amp is nothing compared to 900lbs of steel and concrete lol

Here’s my advice: just skip it.

I went down this road during the heyday of SWR AND Eden. Back then they pushed the idea that biamping made your bass sound better somehow. I had half a dozen cabinets, worked on finding the perfect crossover frequency, bought different power amps and cabs for the lows vs the highs, all that. One day I hooked up a pair of 4x10s with a simple full range preamp + power amp setup and it sounded 10x better than any of the biamped rigs. That was the end of my biamp experiments. Ultimately it cleared the way to using a lightweight head and the right combination of cabs for the gig. For the last few years I’ve not used an amp at all.

The only reason I see for processing highs and lows separately would be for distortion/etc that you only want applied to the highs. But even then most modern pedals have some way to accomplish that.

Interestingly, PA systems above a certain size ARE effectively biamped systems, with big subwoofers handling below around 100hz and the rest of the PA rig handling everything above. So my favorite is to leave the heavy lifting to the PA, leave the amp at home, and give them a feed from my pedalboard.

So I previously had reservations about PAing because of some sort of "tone degradation" I had made up in my head because the bass is being pushed through "all purpose" speakers opposed to ones designed for bass. Guess I couldn't be more wrong.

Also I would be more than open to options on "modern bass pedals". Most IME have been pretty underwhelming. I dont have a single "bass" pedal on my board currently.

Clarity and doom tend not to belong in the same room.

What you are asking for is what I used to do in fx with the PA behind the band no vocals no bass amp.

You need an active crossover to work the fx on the highs only and then a blender or mixer to recombine to a single source for amping. This is the way of scaling up to the bigger leagues.

In your case I can see you are inclined to do it all from the stage.

I would use the 210 for your high side with one of the tube amps. Get another cab and a SS amp to run the clean lows. Stand the 210 up tall.

Rolls sx21 split. Lots of ways to run it. You can't put the bass straight into it though.

1, out of SS fx loop to Rolls, high side to front of the tube amp and low side back to your SS.

2 out of tube fx send to Rolls, lows back to SS.

Either way you are at the mercy of your amps to return a satisfactory phase orientation at the speakers that the high end of the low signal isn't a goner when it joins the low end of the effected signal.

Adding fx makes it even more complicated as they can supply the Rolls. You probably have to use front of the Tube amp to get it to drive like you want but you can give it some juice out of the Rolls even without the low end in that signal.

Trouble comes if you want time fx on the drive out of the Tube preamp. You need a line level fx unit and fx loop. And you might well find the phase at the crossover goes to hell if it didn't already.

Lol that first line made me cackle. I suppose that is technically true, I am not trying to sound like Geddy Lee, but to be fair Al Cisneros and Geezer Butler can be heard pretty distinctively while Pike and Iommi have pretty mids cranked pretty hard. I am not trying to play lead bass here but a distinctive bassline that does more than follow the guitar riff adds a bit of necessary nuance to a pretty simple and formulaic genre.

To get a taste with what you have now at the practice spot you need a crossover and an fx loop in the big amp that you use to run the lows out of the 410. I fear that will turn you to the dark side though and make you a pita to work with forevermore.

I will definitely try to snag that Rolls and see what I can make happen next time we have a rehearsal. Bi-amping is probably a hair too complicated for what it is worth but, barring inconceivable volume/eqing issues, a split signal through a crossover sounds easy enough and will get me to where I am trying to go.

 

[Aidenn7]

Guitar amp and bass amp.. Not really a bi-Amp.. high pass the guitar signal.. Full range on the bass.. You can use two combos stacked.. But use a y switch with a inversion switch..

 

[JW56789]

Ok. I guess did understand the ric-o-sound function but I guess was off with what you would call that. If it were 2 independent signals coming from each pickup it seems like that would be "stereo" as opposed running a Y cable or active crossover would just be "bi-mono" since it just 1 signal split? I honestly feel like I am in grade school all over again, I havent learntd this hard in a long time. Please bare with me as I try to wrap my head around all of this new vocabulary/information, its a lot to jump into from previously being a "plug in and play" type of bass player.

After reading all of this I think a trunk full of alembic gear would stress me out more than it would help lol. Definitely something I would have down to an exact science before lugging all that junk around to venues.

As far as my obsession with "lead sleds". I've been bit by the tube amp bug and I got it bad. Like anything else vintage = cool. Tube snobs look down on hybrid amps. Lemmy used a marshall jmc, Geezer used laney, Al used to use matamps. Big all tube guitar amp are kind of a common motif in the only sub-genre(s) of metal I can actually enjoy (theres actually only a handful of motorhead songs I like, but I really appreciate his tone). As far as new tube amps go "reissues" are typically pretty expensive and "not the same" and hybrid amps "aren't cool". Additionally when I was just a wee-lad and just started playing, I met a guy who gigged his b15 all over texas. Of course, talkbass had taught me that old tube amps were a pita and easily breakable. He told me that was a misconception and that as long as you dont bang em around while the tubes are still hot, that it wasnt actually a big deal to gig/transport tube amps. Of course my gigging experience begins at house shows and ends at open mic blues nights so its all hearsay to me and I don't know the first thing about the pains of transporting gear.... the actual weight notwithstanding. I used to deliver gun safes for a living so I know how to move weight smarter not harder. 300lbs worth of amp is nothing compared to 900lbs of steel and concrete lol



So I previously had reservations about PAing because of some sort of "tone degradation" I had made up in my head because the bass is being pushed through "all purpose" speakers opposed to ones designed for bass. Guess I couldn't be more wrong.

Also I would be more than open to options on "modern bass pedals". Most IME have been pretty underwhelming. I dont have a single "bass" pedal on my board currently.




Lol that first line made me cackle. I suppose that is technically true, I am not trying to sound like Geddy Lee, but to be fair Al Cisneros and Geezer Butler can be heard pretty distinctively while Pike and Iommi have pretty mids cranked pretty hard. I am not trying to play lead bass here but a distinctive bassline that does more than follow the guitar riff adds a bit of necessary nuance to a pretty simple and formulaic genre.



I will definitely try to snag that Rolls and see what I can make happen next time we have a rehearsal. Bi-amping is probably a hair too complicated for what it is worth but, barring inconceivable volume/eqing issues, a split signal through a crossover sounds easy enough and will get me to where I am trying to go.

Obviously, you will have to learn these things for yourself. We all did. There's more than a few reasons why guys like me no longer use the stuff we (and the players you mention) USED to use. I'd only caution that it takes a while to know . . . . what you don't know.

Best of Luck,

JW

 

[Rolling Thunder]

Mesa WD800.

Yep

 

[Nephilymbass]

I have developed some serious GAS for amps recently, which is something I previously gave very little thought. Mostly used ampeg/acoustic/peavey solid-state combos throughout the years, but after recently buying a few tube amps I have developed a whole new facet of my gear addiction.

I have always just played various genres of rock, plug in a muff fuzz and go. Now I have been playing in a stoner/doom group and I read about how bi-amping can help cut through the mix when stacked up against distorted guitar with heavy mids/lows.

Now while I understand the concept, I don’t understand the execution. Is it possible to bi-amp with 1 head through 2 cabs? I assume most people bi-amp with a pedal that has dual outputs, but how does that work if youre trying to keep one signal completely clean? When bi-amping with a rickenbacker (queued up to be my next purchase they are essential doom equipment, no?) using a split cable how do you determine the “high” and “low” signals? Or are they identical and the dynamics boil down to EQing of the amp? I am just trying to not blow a guitar cabinet by feeding it a bass signal the speakers arent designed to support.

Additionally I am trying to figure out the amp configuration. The most common setup I believe is to run the clean bass signal through a SS bass amp, and the high signal through a tube guitar amp. I assume many people run 2+ of the same rig, unless the walls of marshall/orange amps you see at metal shows are just for aesthetics. I believe conventional wisdom says that 15” speakers are better for bass response, and 10” are better for crisp highs but from browsing this forum its clear that no two speakers are created equally regardless of size. So maybe suggestions on what speakers have which characteristics or which prefabbed cabinets are designed for what applications? Ideally I think I would run a musicman sixtyfive 212/210 for the highs and a 100 watt all-tube amp (I have a weber kit but am also on the hunt for a Bassman 100/Sunn 100s/Ampeg V4B) through a 115 cab for the lows.

Any information would be greatly appreciated. Please steer me in the right direction. Especially when it comes to old sunns and guitar amps. I. Know. Nothing. Im sure that is evident already.

Cheers

My advice is if you really want a low/highs Bi amp type setup just buy a 3 way cab that has a good crossover like a fearful/fearless. Or if you’re doing a biamped type sound clean and dirty check out of the several pre amp pedals that have low and high pass filters like the darkglass x series or tech 21 dug pedal. The reason I suggest this is if you play gigs with soundguys that work for the venue it can be a major pain to try to Convince the sound guy to allow you to have multiple signals to front of house and then on top of that there’s no guarantee they will take those difference signals and mix them in a way that you actually like. The same issue comes up with stereo bass rigs. That might not be an issue to you at all depending on the types of gigs you play and wether you provide your own pa or not but for me and the types of gigs I play I’m normally just handed one xlr cable or a single mic (in which case I normally unplug the mic and just use the xlr out. But yeah I prefer to run a full range xlr to front of house and let them deal with Bi amping. PA systems with tops and subs are specifically designed for that

 

[Passinwind]

Wow, thats pretty out there. Good luck with the amp build, I just finished a "simple" kit and it absolutely kicked my butt.

Which kit? I have quite a few years of experience doing this sort of stuff, for me it mostly comes down to how much time and money I feel like throwing at it. I'm more or less taking the middle road this time, using a few commercial bits and pieces and then a few of my own. My own designs are well vetted, but as susual it's all about full system integration, so my butt stands to get kicked a few times too.

I'm a geezer and maybe at the end of my gigging days, but I love the Doom aesthetic and when I was doing sound in a 300 seat club I would have happily just left you and maybe even most or all the instruments out of the FOH mix and said carry on. You may not find that to be typical though, yet another instance of "it depends."

 

[Wasnex]

I *think* I am trying to bi-amp, rather than just use multiple amps. If I am understanding correctly bi-amping is splitting the original signal into low and high frequency signals to be sent to separate amps while "multi-amping" is just sending the same signal to two different amps and shaping the EQ through the amp's preamp???

In theory ric-o-sound is bi-amping, no? Each pickup has its own signal and the bridge pickup is capped to choke the bass freq?

Yes bi-amping involves breaking the frequency spectrum into two frequency bands. The active crossover sends high frequencies to one amp and low frequencies to another amp.

Many speakers have passive crossovers that are placed after the amplification occurs. So you amplify the full bandwidth and then the passive crossover spits it into two bands. Passive crossover have a bit of insertion loss, meaning it burns up some of the energy instead of passing it all to the speakers. This is why an active system is more efficient. Not that it really makes a difference today since power is so cheap. In the old days in was considered a significant benefit of active systems.

FYI. Multi-amping is a more generic term. Bi-amping is a form of multi-amping but it has a more specific meaning.

I would call Ri-O-Sound multi-amping. Ric-O-Sound just involves sending each pickup to a dedicated amp. It is true that the bridge pickup in older Rics has a capacitor to limit the lows, but you don't really divide the spectrum into two frequency bands. One band is full range and the other has a high pass applied. Closer to biamping though.

The goal of bi-amping is often to improve fidelity. With the proper components and tuning, a biamped rig can exceed the fidelity of a passive multi-way design. However most modern passive multi-way designs actually have a lot of engineering to make them sound really good. Most people do not have the expertise and equipment to cobble together a bi-amped rig that will outperform the best passive designs. I have actually been happy with my biamped rigs, but I love tweaking and have dumped quite a bit of money into it.

Multi-amping is often about running a clean and dirty channel simultaneously. When you run distortion full range the lows tend to mush out as you increase the saturation of the distortion. To overcome this, you run two channels, on clean and one dirty. The clean channel helps you retain the nice tight lows.

It's fairly common to use parallel processing with pedals as well. Run one channel clean with a bit of compression and the other with your favorite distortion or OD. Blend the two channels, and then run them in your favorite amp. In this case, the blending is occurring electrically instead of acoustically as it does with a multi-amp rig.

The compression on the clean channel is suggested because compression is a byproduct of distortion. The idea is you want similar amounts of compression in both your clean and dirty channels, so they integrate better in the blending process.

 

[Wasnex]

Ok. I guess did understand the ric-o-sound function but I guess was off with what you would call that. If it were 2 independent signals coming from each pickup it seems like that would be "stereo" as opposed running a Y cable or active crossover would just be "bi-mono" since it just 1 signal split? I honestly feel like I am in grade school all over again, I havent learntd this hard in a long time. Please bare with me as I try to wrap my head around all of this new vocabulary/information, its a lot to jump into from previously being a "plug in and play" type of bass player.

Sorry, We can get a bit too pedantic at times and you are doing just fine. At some point terms mush together.

Ric-O-Sound could be described as multi-amping or stereo in some applications. It's unique because each pickup gets it's own amp which suggests stereo. However, when I ran Ric-O-Sound the speaker were dissimilar, but stack vertically. I would not really call this usage stereo, and Ric-O-Sound does not really create much of a stereo effect in my experience even if the speakers are separated. Also in general you don't want to separate bass speakers in a live environment because it causes undesirable comb filtering.

I also have some amps that have two output sections. They are essentially mono preamps with two power amps, so I would call them dual mono. Some have effects loops so you could use separate processing for each output section. You might start leaning towards stereo or stay with dual mono. Some have separate master volume controls and some do not. This fact would limit how you could use the amp and also might limit how you would describe it.

Anyway hopefully you see what I mean by the "terms mush together."

 

[2tonic]

That is fair. We have come a long way since the late 90s.

What would you consider modern high performance? Markbass maybe? I am totally clueless when it comes to amplification. Just looking for something loud with a little bit of clarity when using an obscene amount of dirt/fuzz.

If you look at @agedhorse avatar descriptors, you'll get a pretty good idea of what he would consider high performance. He's been responsible, to one degree or another, for some of the most popular products discussed on TB, and he stakes his well deserved reputation on every new product he develops.

 

[BrickBatMansion]

All these guys have experience and knowledge.
My version is this:

Bi- amping with a Ric in RIC-O-SOUND is sending the signal from 2 separate pups to 2 different amps.
This is 2 different frequency shapes going to 2 different frequency mouth pieces.

Bi-amping with a MONO bass thru 2 separate amps is what I really call "bi-amping", ie, the bass signal being cut in 2 somewhere in the frequency range, sending the low signal to the appropriate amplification system and the high signal being sent to a different yet equally appropriate amplification system.

I have a GK800 that is bi-amp capable. It has a bi-amp switch and a cross over knob.
Where you set the cross over knob ABSOLUTELY determines where the signal is divided between hi freq and low freq.

I send the low freq 300 watt 4ohm amp to an Ampeg SVT 8x10 300 watt 4ohm bass cab.

I send the hi freq 100 watt 8ohm amp to an Ampeg V-2 4x12 100 watt 8 ohm guitar cab.

I set the crossover knob anywhere between 100 hz to 250 hz depending on how the TOP cab sounds IN THAT ROOM.

I turn the 300 watt amp all the way down and dial in my dream tone on the 100 watt amp 4x12 cab. I put as much mid/treble as I like and then I put as much low into this as I can and still keep it clean.

Now, You are going to put a mic in front of one of these spkrs.

Now , while playing, turn up the 300 watt amp to taste..

BEHOLD!!!!!!!!!!!!!!!! God is REAL!

Now put the appropriate mic on this cab.

Send the 2 signals to the board and explain all this to the sound man.

Threaten the soundman if necessary..

You are now bi-amping thru your amp AND the p.a. thru 2 separate channels of one signal; and it is a wonderful thing.

Is it old School? YOU BET! But is sonic bliss.

If you don't go thru the p.a., you will still sound great.

In smaller rooms I use a MusicMan 4ohm 1x15 and a MusicMan 8 ohm 2x12. Smaller, but equally potent.

I hope this helps.

 

[Bander]

A good way to get into a bi-amp rig imo, is to find any of the classic amp heads that were designed as a bi-amp unit. Once you own one, you will intuitively learn how they work, how to dial one in, and you'll get a feel for which cab works with the high or low pass signal. The Hartke 5000C or 7000C, and Fender BXR Dual 400 are available. The Trace Elliot RAH350SMX or AH600SMX are stereo, and I believe both are also configured to function with crossover controls and high and low pass outputs for bi-amping. I never see these Traces for sale anymore. Here's the high and low pass controls, crossover frequency control and channel balance on a Hartke 7000:

 

[Hypocrite]

I thought bi-amping was the thing for me. Then I bought a Darkglass X7. Done and dusted.

 

[MordBass]

I run an Eden preamp into a Crest CA9. The boom goes to one cab while the top end gets a tube screamer in the fx loop for the upper end. Makes for a really nice grit that sits cozy in the mix without impacting the nuts.