Bass Drivers v. PA Drivers

[Old Fart]

Compare and contrast, for me, the differences between these two. My current band is stage cabinet free. We use IEMs and everything goes through the mains and subs.. I wondered out loud whether my sound guy's PA speakers can handle bass. He scoffed and said his 10" and 12" PA drivers are more robust than the speakers in my Berg CN212 cab. QSC K12 speakers have 2000 Watts and my CN212 cab is only rated at 700W, but I was insulted anyway.

My question for him was probably stoopid anyway since the LF signal goes to the subs, which saves the K12s from having to try to produce low, loud frequencies. Protection from LF over-excursion allows those K12s to operate at ridiculous volumes. Comparing the two is apples and oranges. I get that.

But I still wonder what are the similarities and differences. Something tells me I ought not to be ashamed of the 12" drivers in my Berg. Heck....they might handle 2000W just fine if there were no LFs to deal with.

 

[agedhorse]

The 2000 watt rating is total peak and the band limited power to the low frequencies is about 500 watts RMS with significant protective dynamics processing.

Most quality bass amps/cabinets (there are exceptions) are rated using RMS metrics and don't use peak (marketing) power metrics.

Bass speakers very much consider the mid voicing as part of the design attributes, PA speakers that are crossed over using a low pass filter don't consider mid voicing since it doesn't come into play.

There are similarities but also differences.

 

[Wasnex]

Pay attention to the parts in bold:

AFAIK the continuous SPL for the original K12 is 125dB. The OM lists 131dB peak.

Ref: https://warehousesound.com/r/qscK8-K10-K12-KSUBmanual.pdf

AFAIK specs for the CN212

• Power Rating 700W RMS
• Impedance 4 ohms
• Sensitivity 104dB 2.83V/1m

Ref: Bergantino Introduces CN Series Bass Cabinets

FYI 2.83V at 4 ohms is 2W

Calculated SPL at 700W = 10Log(700/2) + 104 = ~129.4dB

 

[Old Fart]

Bass speakers very much consider the mid voicing as part of the design attributes, PA speakers that are crossed over using a low pass filter don't consider mid voicing since it doesn't come into play.

Thank you, @agedhorse

Wait! I care about crossover and mid voicing, even though I do not understand it. What I do understand is that in my (our) craft as bass players we make massive use of "low mids." I think the subs don't help with this (maybe I am wrong but I don't think so). So now the question is whether those K12s and K10s can do an adequate job of handling those low mids.

Which also raises the question of where the crossover is. I still wonder if those K12s (and K10s) can really handle frequencies from 100-120 to, say, 400. Thank you.

131dB peak.

~129.4dB

Thank you, @Wasnex

These seem pretty close but it's far easier to achieve these ear-damaging loudnesses at 1000k Hz or 3000 than at 80. Where bass players make their money.

 

[Old Fart]

I suspect the 12" drivers in my CN212 can handle plenty of Watts at 2000 Hz, and perhaps as much as the drivers in the K12s, but can also handle low mid and LF signals that the K12 drivers cannot. But I dunno. I'm just talking out my @$$

 

[Wasnex]

Which also raises the question of where the crossover is. I still wonder if those K12s (and K10s) can really handle frequencies from 100-120 to, say, 400

The OM indicates the K12's response is -6dB at 60hz and -10dB at 48hz.

Per the No Treble article, response for the CN212 is listed as 40hz. Since no tolerance is indicated I assume this means -10dB (usable response).

So the specs indicate the CN212 plays lower but not by a huge amount.

I don't know how the CN212 is voiced. I assume the native voicing of the K12 is flat as reasonably possible.

 

[monsterthompson]

I have nothing to add here, but I'm interested in the discussion.

 

[Boneless]

PA speakers sometimes carry "midbass woofers", which might sound like an OK specification for bass, but actually isn't. As you noted, PA speakers are usually/often used as "satellites" or in a line array, and are therefore dispensed with reproducing the low end. Midbass woofers are intended to be used from 80-200Hz up to approximately 2.5-3.5kHz, where the tweeter then takes over, with subs handling frequencies below. They would incur overexcursion if used "as is" with a bass guitar signal, and as agedhorse noted, their duty is to reproduce well (efficiently, powerfully and with as little colouration as possible, although pro audio is not as "hi-fi" as true hi-fi) a narrower frequency range. (Some speakers are intended to be usable alone, and they might carry woofers that are a bit more similar to bass guitar woofers, but might sound "dull" in the high mids).

In bass speakers, woofers are not low-pass filtered usually, and the tweeter is merely "added" over the woofer, with high-pass filtering only on the tweeter; it's not hi-fi by any means, but bass amplification isn't hi-fi usually. Reproduction in the high-mids will indeed be somewhat "unpredictable" due to the interaction between the woofer and tweeter (which also depends on the listening position), but this arrangement allows the user to dial in the amount of treble by dimming the tweeter as required. In PA speakers, the high-mid voicing of the woofer is not very important (although it shouldn't be too "non-linear", to make it easier to cross it over with a tweeter).

My opinion on the matter is that bass guitar amplification (and why not, guitar amplification) in many cases would greatly benefit from a more "PA" approach, with flatter response and proper crossovers and tweeters, and with mid/treble voicing taken care of by modelling and/or filtering and equalisation rather than by the woofers themselves. This would come with one big benefit: better polar dispersion, with the whole band, stage and possibly audience hearing the bass a bit more as it should be heard (and also programmability, with the option to tweak the response); on the other hand, this means that bassists need to approach their tone shaping and monitoring differently, since the narrow dispersion of mid-high frequencies of traditional cabinets means that bass players can dial in more high mids than appropriate to benefit from the added definition. I believe that this only works on stages with proper PA support; if an amp is expected to provide sound to the audience, this works poorly (and in fact, when the band's amps provide the sound to the audience, the sound is usually subpar and very position-dependent).

But after all, we are all seeing this trend, with bands investing in good PA speakers and then musicians just plugging in their Kemper or whatever modeller or just a regular preamp/DI into the mixer, and relying on IEMs or other personal monitoring. It is both more convenient and can sound better.

 

[jthisdell]

So an A/B at sound check when you have time. Play through your Berg, then play though the PA . My money is on the Berg.

 

[Stylee Mousse]

The above! Just don't blow stuff up!

 

[jnewmark]

I guess nobody remembers the time when the Carvin three-way PA cab was all the rage here; it eventually led to Greenboy modding it some and then coming up with his own designs. I'm too lazy to dig up the old thread, but it went on for a few years.

 

[Old Fart]

@Jim Bergantino , I wonder if you would care to answer my specific question. If you know the answer. You design/build bass cabs but may not have experience with PA drivers. My question: Are the drivers in your cabinets, which we know to be very high-quality drivers, similar to the drivers in high-quality PA speakers like the K12? Or are they a wholly different animal?

 

[dazmond]

Mr. Agedhorse probably has more knowledge+experience for this particular question than anyone on this site. OP questions are too vague to answer. Speakers are speakers, some have parameters that fit certain applications better than others. PA vs bass cab as a general questions can't be answered completely. If you are still asking about your specific cab and that PA you used, maybe someone will have a more complete answer.

 

[agedhorse]

Read my previous comments within the context of somebody who designed touring level pro audio speakers for 20 years before (and while) designing bass speakers.

 

[Zooberwerx]

I guess nobody remembers the time when the Carvin three-way PA cab was all the rage here; it eventually led to Greenboy modding it some and then coming up with his own designs. I'm too lazy to dig up the old thread, but it went on for a few years.

Here ya go...these are the Carvin LS1503's which I've used for more than 2 decades. No grille logo and the better early (?) components. In for a day-of-beauty and rat fur glue-down. Also, AFAIK, the largest enclosure which can be pole-mounted...they're hefty. IIRC, the mod required a different LF 15" driver and crossover moved from 500 to 630. I was able to do this via an external crossover in tri-amp mode...no discernible improvement in a PA application IME. They're ever-present and go low without breaking a sweat. The enclosures to the left are older Yorkville subs retrofitted with Eminence Sigma 18's. Indoors or outdoors, I have you covered.



Riis

 

[J Wilson]

There will always be a fundamental difference in drivers for bass cabinets and PA bins: Bass cabinet drivers will always be standalone applications (with some allowance for a crossed over tweeter or other high driver in some cases) and PA bins which are designed to work as crossed-over systems in two, three, or even four way splits up and down the frequency range, the various cabs and their drivers optimized for those narrow frequency ranges.

This is often why stacking a 15" bass guitar bin under a 2-10" bass guitar bin, then using a crossover and stereo amp to use the 15 as a sub is often really just not happy. PA bins are built for this.

 

[Boneless]

There will always be a fundamental difference in drivers for bass cabinets and PA bins: Bass cabinet drivers will always be standalone applications (with some allowance for a crossed over tweeter or other high driver in some cases) and PA bins which are designed to work as crossed-over systems in two, three, or even four way splits up and down the frequency range, the various cabs and their drivers optimized for those narrow frequency ranges.

This is often why stacking a 15" bass guitar bin under a 2-10" bass guitar bin, then using a crossover and stereo amp to use the 15 as a sub is often really just not happy. PA bins are built for this.

...but a 1x15" (or 2x12") bass guitar speaker bi-amped with a 2x12" guitar guitar speaker can work wonders. For certain kinds of tone. But the crossover frequency will usually be quite a bit higher than what you'd cross a sub over.

 

[Wasnex]

• There can be quite a bit of variation between two PA drivers
• There can be quite a bit of variation between two bass guitar drivers
• There can be quite a bit of variation between a PA drive and a bass guitar driver
• A bass cab and a PA cab could conceivably use exactly the same driver; however performance and tone can still vary significantly due to differences in the way each cab is tuned

 

[agedhorse]

• There can be quite a bit of variation between two PA drivers
• There can be quite a bit of variation between two bass guitar drivers
• There can be quite a bit of variation between a PA drive and a bass guitar driver
• A bass cab and a PA cab could conceivably use exactly the same driver; however performance and tone can still vary significantly due to differences in the way each cab is tuned

... and how the driver is used and voiced. The voicing choice is VERY important to a bass guitar application and while some pro audio drivers have an acceptable mid voicing, many do not (depending on the tone goals of the designer).

 

[J Wilson]

...but a 1x15" (or 2x12") bass guitar speaker bi-amped with a 2x12" guitar guitar speaker can work wonders. For certain kinds of tone. But the crossover frequency will usually be quite a bit higher than what you'd cross a sub over.

I tried a combination like that once or twice, but on a tight stage, all I heard was first the high pass only, then with no time align, I'd hear this indistinct moaning mumble off the low pass a split second behind it. 20 or 30 feet in front of it would have been a lot better, but I never played any stages that deep. Not to mention FOH would have just LOVED it ! ! So that was that.

Subs for a bass guitar rig could certainly be made, but they'd have to be designed to work together the way PA bins do, and to date, no major manufacturer has seen a potential profit in it, and in an IEM world, and the far better response of modern cabinets, I doubt anyone ever will. You could of course still do it with components from the PA world, but in a world where often PBasses with flats through SVT's can be the default norm, not much market.