Crossover?

[bassmasta_01]

Alright, so I was thinking the other day, why haven't I seen a crossover to split signal from a bass amp to two separate cabs, like a 1x15 and a 4x10. I have seen and played through quite a few rigs with 15's and 10's, but never seen a crossover to separate them. I'd like to find something, essentially a box with one knob to define the crossover frequency, that can do this while maintaining the same impedance and power levels. Does this exist anywhere? Is there even a market for something like this? Opinions please.

 

[DukeLeJeune]

I don't think what you're describing is practical.

Passive crossovers (the crossover comes after the amp) are designed for a specific frequecy, and usually for the specific impedances and frequency response curves of the drivers involved. Also, the components needed to do a high power handling, low frequency passive crossover end up being fairly expensive. A frequency-variable high power handling passive crossover that works at low frequencies would be quite expensive and quite heavy.

On the other hand, what you're describing could be easily done with an active crossover (the crossover comes before the amp, and you'd use a different amp for each cab). It's done that way all the time in PA systems.

But even it we figure out how to do it, I'm still not sure it's a good idea to divide up the spectrum between a 410 and a 115 bass cab. Often the limiting factor is how much air the woofer(s) can move before fartout, and you'd lose roughly half your air-moving capability by sending the low end of the spectrum to only one cab. How practical this approach would be depends on the specific characteristics of the cabs involved. Note that the most practical division of labor between two separate cabs has already been worked out, and it's what we see in the main + sub format of a PA system.

 

[rpsands]

There are active speaker level crossovers in car audio. Not yet any pro audio ones. eminence does have a speaker level dsp device in the works but it is very specialized as limiter.

 

[Downunderwonder]

The reason you haven't seen it is there isn't any market for it. Your commercial bass cabs are all full range, nobody wants to cart two big cabs to do the work of 1 cab.

 

[billfitzmaurice]

Alright, so I was thinking the other day, why haven't I seen a crossover to split signal from a bass amp to two separate cabs, like a 1x15 and a 4x10

There isn't enough difference in the bandwidth of a 1x15 and 4x10 for this to be worthwhile. It makes no sense to mix fifteens and tens, nor does it make any sense to use more smaller drivers than larger drivers in a system. Using fifteens with sixes or eights at a one-to-one ratio is very sensible.

 

[fingerbun]

There isn't enough difference in the bandwidth of a 1x15 and 4x10 for this to be worthwhile. It makes no sense to mix fifteens and tens, nor does it make any sense to use more smaller drivers than larger drivers in a system. Using fifteens with sixes or eights at a one-to-one ratio is very sensible.

Why so?

My instinct is more smaller drivers is more area is more sound. I get it has to be balanced but why does that imply one-to-one?

Not mixing 15 and 10... I've heard mixes of those that I like. I guess your response will be that's either something in the specific speakers used or my imagination?

 

[Jeff Scott]

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[bassmasta_01]

All very valid points, thank you. I'm not sure I agree with billfitzmaurice about not mixing 10's and 15's.. Many bassists use a 15 and 2x10 or 4x10 cab in their full rig, with good results. Also, I don't think a 1:1 ratio on smaller drivers and larger drivers is very sensible either, because if you have one 15 and one 6 or 8, you won't hardly be able to hear a single 6 or 8 at stage volume because it will be so overpowered by the amount of air the 15 is pushing. If it could be heard, you could only hear in very close proximity to the cab because a single small driver simply can't project as far as a 15.

Also, why is there no market? I understand that bass cabs are full range, but why is it so absurd to want to split up your frequencies between different sized drivers? It's understood that a cab with 10's typically can't produce the same gut-wrenching lows as a 15 or 18. It's also understood that a 15 or 18 can't provide the same quick response as a set of tens. So why is it so illogical to want to send your low notes to a driver that's almost specifically tailored to lower frequencies, and sending your higher frequencies to tens so you get less muddy runs and fills and solos and so forth? There are several cabs out there that have internal passive crossovers to send signals to different sized drivers within the same cabinet that produce great results. But why can't us poorer musicians (pretty much all of us, let's face it) have the same flexibility with our old 15 and 2x10 cabs we have sitting in our basement without having to pay $1,000 or more for a cab?

 

[DukeLeJeune]

I don't think a 1:1 ratio on smaller drivers and larger drivers is very sensible either, because if you have one 15 and one 6 or 8, you won't hardly be able to hear a single 6 or 8 at stage volume because it will be so overpowered by the amount of air the 15 is pushing. If it could be heard, you could only hear in very close proximity to the cab because a single small driver simply can't project as far as a 15.

A dedicated midrange driver is usually just as loud as, if not louder than, the 15" at the frequencies it covers.

As an example, the 15" woofer used in the fEarful is rated at 98 db, and the 6" midrange is rated at 102 dB. As a result, the mid has to be padded down by several dB so that it doesn't overpower the woofer.

Also, why is there no market? I understand that bass cabs are full range, but why is it so absurd to want to split up your frequencies between different sized drivers?

It's not absurd to split up your frequencies between different sized drivers. What doesn't make sense (to me at least) is splitting up your frequencies between two cabinets (1x15 and 4x10) that cover virtually the same frequencies.

 

[crack-boom]

GK 800 RB has a built in crossover

 

[Derek Kiernan]

It's understood that a cab with 10's typically can't produce the same gut-wrenching lows as a 15 or 18. It's also understood that a 15 or 18 can't provide the same quick response as a set of tens.

This isn't true. Driver diameter determines when it'll start beaming - larger drivers perform less well off-axis - but doesn't relate to frequency response. The reason multi-driver speakers often use one larger driver, one smaller, is because it's cheaper to use a single driver with greater surface area (translates to displacement) rather than multiple smaller drivers for the same frequency range. As Duke mentioned, a 6" driver can get quite loud if it's designed to be used from midrange and up, and has superior off-axis performance to larger drivers.

 

[Downunderwonder]

All very valid points, thank you. I'm not sure I agree with billfitzmaurice about not mixing 10's and 15's.. Many bassists use a 15 and 2x10 or 4x10 cab in their full rig, with good results. Also, I don't think a 1:1 ratio on smaller drivers and larger drivers is very sensible either, because if you have one 15 and one 6 or 8, you won't hardly be able to hear a single 6 or 8 at stage volume because it will be so overpowered by the amount of air the 15 is pushing. If it could be heard, you could only hear in very close proximity to the cab because a single small driver simply can't project as far as a 15.

Also, why is there no market? I understand that bass cabs are full range, but why is it so absurd to want to split up your frequencies between different sized drivers? It's understood that a cab with 10's typically can't produce the same gut-wrenching lows as a 15 or 18. It's also understood that a 15 or 18 can't provide the same quick response as a set of tens. So why is it so illogical to want to send your low notes to a driver that's almost specifically tailored to lower frequencies, and sending your higher frequencies to tens so you get less muddy runs and fills and solos and so forth? There are several cabs out there that have internal passive crossovers to send signals to different sized drivers within the same cabinet that produce great results. But why can't us poorer musicians (pretty much all of us, let's face it) have the same flexibility with our old 15 and 2x10 cabs we have sitting in our basement without having to pay $1,000 or more for a cab?

You have a whole lot of misplaced sonic baggage clouding your reasoning. Most of what you "understand" is actually incorrect. Pay attention to what Mr Fitzmaurice and Luke said. 1 itty bitty midrange driver covers one sub driver.

Your goal isn't absurd but you would be paying a couple of hundred bucks for a passive crossover to do the job. If you really want it you can diy it.

I can't promise you will like the result as passive crossovers introduce phase cancellations and reinforcements, a whole can of worms I don't know much about at all. The fearful etc cabs go to great lengths to get it right.

 

[billfitzmaurice]

So why is it so illogical to want to send your low notes to a driver that's almost specifically tailored to lower frequencies, and sending your higher frequencies to tens so you get less muddy runs and fills and solos and so forth?

It's quite logical, but electric bass cabs built with said type 8"/10"/12"/15"/18" drivers do not exist. They're all made with full range drivers.

 

[Passinwind]

But why can't us poorer musicians (pretty much all of us, let's face it) have the same flexibility with our old 15 and 2x10 cabs we have sitting in our basement without having to pay $1,000 or more for a cab?

Because there's still no free lunch. Same as it ever was.

 

[BurningSkies]

Because there's still no free lunch. Same as it ever was.

And this is why cabs like the 153tb, Barefaced and FEARfuls are really a bargain, though the cost more than your standard single 15 or 2x10.

 

[scottfeldstein]

I used to use an active xover to feed my biamp'd Peavey power amp. I then used the top end to drive 2x10 and the bottom half to drive an 18. All speakers were in the same cab, but the 10s were sealed away from the 18, which was ported. It worked well.

I think you gain very little from using different sized cones in a setup that isn't crossed over. That's my belief anyway. These days i'm using all 10s.