Why is mixing cab sizes a bad idea?

[two fingers]

I've heard that you shouldn't mix cabs, but why is this?

I would have figured that using a 1x15 and a 2x10 together would give you a warm low end from the 15 and a tight top end from the 10s, but I guess this isn't the case.

Bass cabs are much more complicated than driver size. It's all about physics (not all of which I fully understand myself).

Here's what I do know.

1) Driver (speaker) size alone has little to nothing to do with how boomy or bright a cab will sound. The same cab won't necessarily sound brighter with tens in it than it will sound with a 15. That's a myth. Don't buy into it. A 410 cab can be tuned to be very boomy and a 15" cab can sound very bright.

2) Phase cancellation CAN occur when dealing with cabs that aren't designed to work together. This means that two cabs will literally sound thinner and worse than either of them alone. Cabs CAN work well together if a) they are designed to do so (like Mesa Subway cabs for instance) or b) you just happen to get lucky. But, if you're going with "b", it's a crapshoot. A GK 15 and a Carvin 210 might sound glorious together. They may also sound like garbage together.

3) Piwer distribution. Much like the myth that 15s are more boomy sounding, there's also a myth that they can handle a ton more power than smaller speakers. This is also false. So, if you stack a 4 ohm 410 and a 4 ohm 115 cab under a 1,000 head, that 15 is gonna get hit with 500 ways right by itself (if you get crazy and crank it). That sucker is gonna a blow.

Short version. It isn't AUTOMATICALLY a horrible idea to mix cabs. But it MOST LIKELY is.

 

[agedhorse]

Thankfully, doing the punk band in a van thing, I only ever had to worry about 3 guys amps, a drum kit, and a few HSC's of instruments - and a bin liner full of disgusting underwear (helps prevent shifting ).

Has a guy come in with his (rack) effects unit packed in a dirty laundry basket one time, made him hook his own unit up to the house PA. I wouldn't touch it, eeeew.

(He said he couldn't afford a rack case)

 

[ThisBass]

Simple you use the driver specs when you develop the system specs. They are related, but not the same. I am confident you know this far better than I do.

Some manufacturers advertise their cabs with the "raw" driver specs.
I think its understandable in practice use cause any additional research of power handling for small series production kills the margin.
I ain't be stupid enough to belive in "rough" RMS numbers

 

[ThisBass]

Bass cabs are much more complicated than driver size. It's all about physics (not all of which I fully understand myself).

honestly do you talk about woman?

 

[Brad Johnson]

I've heard that you shouldn't mix cabs, but why is this?

I would have figured that using a 1x15 and a 2x10 together would give you a warm low end from the 15 and a tight top end from the 10s, but I guess this isn't the case.

Oddly enough, plenty of bass players are against actually trying things for themselves. So they repeat rigid rules. More power to them but it's not how I'd choose to go through life, closed off.

Mixing cabs can work. No matter what they say. Operative word being "can".

When you're faced with a "rule" like this, consider the source. I'd be willing to bet that most are simply repeating what they've read, with little to no practical experience behind it.

And yeah, you're damned if you do and damned if you don't if you dare even ask. That's just part of the silliness. And over the years I've even been asked not to rock the boat by describing several mixed cab rigs that worked out great for me professionally over the years. People refuse to understand that there is no single gig situation and focus only on what could go wrong, not what could go right.

My favorite is when people are admonished not to even try cabs together that they already own... buy what the "experts" think you should buy.

 

[Al Kraft]

I always found this article very helpful in understanding the basics of speaker power handling: www.eminence.com/understanding-loudspeaker-power-ratings/

 

[Brad Johnson]

Honsetly that makes no sense.
Biamping does not mean you have two amplifiers pushing power to two different cabs.
It rather means that you power one cab low passed with one amplifier and a second cab high passed with another amplifier.

Furthermore it makes no sense that you get a good "distorted" sound with your system while the clean sound sucks.
May be you are missing "loudness" with your clean sound? 1x12 and 1x8 isn't lots of cone surface to get a "loud" clean sound versus distorted sound stuff.

That's a limited take on biamping. There are several other configurations. It's about using two amps, which could be two single channel amp, one two channel amp, etc. Doesn't have to be low and high pass either.

For example you could use a bass rig and guitar rig together.

 

[Wasnex]

We have got lots of dynamic with a signal (peak power) and we have got to consider an average RMS number with any signal.
We also have got a thing that is called transient noise which naturally comes along if a signal envelope does change in level versus time (most of the time the decay envelope) which does "enrich" the spectrum with noise that is hard to predict.

If you read the plots of a cab modelling you have to consider all of the aspects that may happen in real live. Fortunatelly with bass guitar the 2nd harmonic does not suck all the power you can read with a modelling at (for example) 80Hz where cone excursion shows a peaking.
Unfortunatelly the impact of transient noise is rather unpredictable thus the cone excursion below cab tuning is nothing but a "stupd" gues if you look only for the harmonic (Fourier) content of the bass guitar.

I don't think its such as as easy to read the specs for "thermal" and "mechanical" modelling plots to "predict" a realiable power handling for a cab system.

No doubt the answer is very complicated. To my understanding, the power rating changes with driver characteristics, box tuning, and also the expected program material. I am sure you could do a better job with your engineering knowledge than I could with my intuition and a few charts. But I only have to worry about how I will use my gear, which is totally different than what you do as an engineer.

If I wanted to be super conservative, I could just run an HPF and a "look-ahead" limiter that prevents the drivers from reaching either their excursion limits or continuous RMS ratings. I believe all of my drivers carry a continuous RMS rating with a 6dB crest factor; so this should be a conservative setup.

 

[Brad Johnson]

One of my favorite rigs broke so many rules it wasn't funny. A Bag End S15- coax 115 and S12X coax 110. Both 8 ohms, different efficiencies and while I doubt they were designed to work together, they did. With a Markbass Little Mark II. Different power handling and efficiencies, neither one should've been able to handle the rated power of the head.

I try stuff. I know, crazy concept.

 

[Al Kraft]

Mixing cabs can work. No matter what they say. Operative word being "can".

When you're faced with a "rule" like this, consider the source. I'd be willing to bet that most are simply repeating what they've read, with little to no practical experience behind it.

I have over 40 years of experience as an engineer and musician and completely agree with you. The only caveat I would add is that if you cannot audition the different cabs you want to combine and have no one you trust to give you any information, you will likely get more of sure thing piking from cabs that were designed to work together or buying a second identical cab. I'm basing that on both technical understanding and personal experience, but recognize I'm still only a single data point, albeit one with more than 4 decades of lessons learned behind me.

 

[Brad Johnson]

I have over 40 years of experience as an engineer and musician and completely agree with you. The only caveat I would add is that if you cannot audition the different cabs you want to combine and have no one you trust to give you any information, you will likely get more of sure thing piking from cabs that were designed to work together or buying a second identical cab. I'm basing that on both technical understanding and personal experience, but recognize I'm still only a single data point, albeit one with more than 4 decades of lessons learned behind me.

Agreed. I will say that cabs that weren't designed to work together, for instance two different brands, can still work together. Agreed, no guarantees on the results... but that is true of single cabs too.


Another thing that gets me is that doubling a cab is considered the only way. As if one cab can't complement another different one. On my Bag End rig the coax 110 added something the coax 115 didn't have and vice versa.

 

[Wasnex]

Some manufacturers advertise their cabs with the "raw" driver specs.
I think its understandable in practice use cause any additional research of power handling for small series production kills the margin.
I ain't be stupid enough to belive in "rough" RMS numbers

Hartke uses proprietary drivers though.

 

[ThisBass]

No doubt the answer is very complicated. To my understanding, the power rating changes with driver characteristics, box tuning, and also the expected program material. I am sure you could do a better job with your engineering knowledge than I could with my intuition and a few charts. But I only have to worry about how I will use my gear, which is totally different than what you do as an engineer.

If I wanted to be super conservative, I could just run an HPF and a "look-ahead" limiter that prevents the drivers from reaching either their excursion limits or continuous RMS ratings. I believe all of my drivers carry a continuous RMS rating with a 6dB crest factor; so this should be a conservative setup.

Limiters don't protect from overexcursion. These tools never did it and they never will do. Its nothing but a myth that limiters do protect anything a woofer from beeing abused.

You are right that the program material characteristic is very essential for the "power handling"
Metallica songs strain the loudspeaker in a very different way (thermal and mechanical) than Beethoven or J.S.Bach

 

[Munjibunga]

I did search but all I found was "it's a terrible idea" but never why or examples from people who have tried it. I would try myself but i don't have the cabs, or the momey to waste on a sound I might not like.

I've tried that exact combination - Eden D-115XL and D-210XLT. Suct. Sold them both although the 210 was pretty good by itself. Also, 15s don't necessarily provide good bottom - I've had better results with all 10s.

 

[Wasnex]

Limiters don't protect from overexcursion. These tools never did it and they never will do. Its nothing but a myth that limiters do protect anything a woofer from beeing abused.

A regular limiter cannot respond fast enough. But, a "look-ahead" limiter uses digital processing time to sample the input and apply the limiter to the output before the peak can pass. With an appropriate HPF and a correctly configured "look-ahead" limiter you can absolutely prevent over excursion.

 

[ThisBass]

One of my favorite rigs broke so many rules it wasn't funny. A Bag End S15- coax 115 and S12X coax 110. Both 8 ohms, different efficiencies and while doubt they were designed to work together, they di. With a Markbass Little Mark II. Different power handling and efficiencies, neither one should've been able to handle the rates power of the head.

I try stuff. I know, crazy concept.

meant as supplement, different efficience does not mean the "system" was different. In easiest case it means nothing but different cone surface

 

[ThisBass]

A regular limiter cannot respond fast enough. But, a "look-ahead" limiter uses digital processing time to sample the input and apply the limiter to the output before the peak can pass. With an appropriate HPF and a correctly configured "look-ahead" limiter you can absolutely prevent over excursion.

How much of bass amps do really delay the signal for about 20msec to "look ahead" the signal?
If I remeber correctly the RH450 delays the signal for 15 msec to look ahead and "compress" the signal for more of output.

edit,
personally I think its a good idea to delay the signal for processing aims but, likely the bass community tries to refuse the benefits.

 

[Wasnex]

I've tried that exact combination - Eden D-115XL and D-210XLT. Suct. Sold them both although the 210 was pretty good by itself. Also, 15s don't necessarily provide good bottom - I've had better results with all 10s.

IMHO the D115XL is and sounds nothing like the D210XLT. As far as 15s go, I think Mesa PH115 and GK RBH115 sound fantastic.

 

[Wasnex]

How much of bass amps do really delay the signal for about 20msec to "look ahead" the signal?
If I remeber correctly the RH450 delays the signal for 15 msec to look ahead and "compress" the signal for more of output.

I am not aware of any bass amps that currently do this (but I am not an industry insider). I have some old speaker processors that do it.

 

[Al Kraft]

In terms of easy to use and easy to find tools, I find a variable HPF can be your friend when it comes to helping bass cabs survive higher power levels without over-stressing drivers. It's not a guarantee against stupid, but is does provide a lot of help IMO/IME.