McCauley M421 Quad 21" Subwoofer

Bennett Prescott

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Jan 10, 2011
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When long time forum supporter, publishing king, and general Pro Audio Industry guru Mark Herman suggested he would be able to get me a pair of "these crazy McCauley super subs that you have to hear" I naturally expressed interest. At the time I had a little too much on my plate, but I let the idea germinate in the back of my head until I thought we were at the right point in time to start Test Drive up, something Mark and I had been discussing ever since it was apparent SoundForums.net was going to be successful. Mark put me in touch with Daniel Casado over at McCauley so we could talk.

On the phone with Daniel, I explained what the idea behind Test Bench was going to be and expressed interest in having the M421s in time for the 2011 SFN Expo. I was warned about two things: Don't try and use this subwoofer in too small a room, and make sure there is nothing to rattle off shelves. The former doesn't really make sense to me, but as someone who is used to big low end I have experienced the latter and expected to experience it with a sub claiming 1m calculated output of 155dB! I assured Daniel that I would be using the M421, which he was going to supply a pair of along with Lab.Gruppen FP14000 power and associated cabling, in all sorts of rooms as well as outdoors. Satisfied, apparently, Daniel and I made shipping arrangements to deliver the cabinets and amplifiers to Asbury Audio in New Jersey, a company I do a lot of work for and a company in a convenient location to move the cabinets on to other providers once I was done playing.

Screen shot 2011-06-22 at 5.18.14 PM.pngTo familiarize you, the M421 is an approximately 23"x72"x44" cabinet weighing 486lbs. A beast to be sure, but I was promised it would be an easy two man move. Casters are attached to the rear of the enclosure, generous handles are provided all around, and the sides are covered in "interlocking skids" that appear to be teflon or some other slick composite material. The paint, they call it "weather and wear resistant ProCoat™ polyurea hybrid finish", is excellent... rough, but not so much it takes your skin off. The skids keep most of the wear off the paint, and the finish seems to take a lot of abuse. The damage from the box's trip up from Texas is all chunks of wood removed, not much finish damage.

Inside the box are four 6" voicecoil 21" cone neodymium magnet drivers "custom made for McCauley by another company". I am familiar with the driver from "another company" that these are based on, and it is absolutely state of the art. Each is capable of eating up 6KW peak power according to the input panel on the subwoofer. The same input panel claims 2KW AES power, and the spec sheet says 3KW. The whole box is rated for 12KW continuous, 24KW peak so I guess the 3KW per driver number is the one to take seriously. In any case, the box can (and probably should) take power from the largest amplifiers on the market today. The drivers are arranged isobarically, and then coupled to an "FEA optimized acoustic transformer", or a horn to you and me.

Frequency response is claimed as 20Hz - 85Hz -3dB, and 16Hz to 120Hz -10dB. That is an extremely impressive specification, and achieving those sorts of numbers passively even in a box this size is a Big Deal™. Maximum output is stated as 143dB peak measured at 4m, probably to avoid the effects of the cabinet's size on the measurement. That number back-calculates to 155dB at 1m which is crazy loud. Just one or two of these cabinets ought to be able to handle thousands of people for most any genre, and with that kind of power density scaling up to arena performance is child's play.
 
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Bennett Prescott

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SFN Expo 2011

A few days before the truck was due to get loaded to head up to the SFN Expo I got a call from Steve Petrak, all around great audio guy who leases space in Asbury Audio's shop. "What the hell have you shipped here? These things are enormous!" he said. I figured they had to be pretty big, but still hadn't seen them. Apparently they arrived palletized and somewhat the worse for wear, they had been bounced around enough for their wheels to break through the pallet, and it looked like they'd been bounced off a few other things as well. Fortunately, aside from causing some major inconvenience to the guys unloading the truck, the subwoofers bore only cosmetic damage from their trip up from Texas.

IMG_0016.jpgThat weekend's shows finished up and subwoofers and other gear made it on a truck, which made its way up to CT to rendezvous with me. David Karol and I drove the whole mess up to the Expo and conveniently arrived about 1:00 a.m. day of the show. I had hoped to spend some hands on time with these subs before subjecting them to use in front of other people, but as it was we had enough energy to load in for the next day's events and hit the sack. Cracking the truck door in Westminster, MA I had to agree with Steve, these things are massive. Their height lying down isn't so unexpected, but they are wide and deeeep! Not really surprising given the output and claimed LF response, but definitely the largest subwoofer I've ever encountered. Fortunately, as promised, they really aren't that difficult to move around. They seem to have a relatively low center of gravity, so as long as you keep them on their wheels one guy can easily maneuver them, and two guys can take one from wheels to flat on the ground and back. God forbid you have to lift one, though. I'd be finding 5 other guys.

Day of the Expo, I spent a lot of time running around, meanwhile trying to get the M421s prepped so I could use them with the Tyra Penn band that evening. The problem ended up being that, while McCauley was kind enough to provide big amps in a rack all set to go with an L21-30 inlet broken out to three L5-30s internally, we were in a room with only Edison outlets available and I didn't have an L21-30 female cord end. I was hoping the amps would have removable cordsets, but the plug end is molded and the amp end is hardwired. Unwilling to do major surgery on amplifiers I didn't own, I ended up taking apart the power panel on the rack, scavenging the L5-30 outlets, and hard wiring some Powercon cables to them. Ugly, not something I'd want anyone touching, but it got the job done.

IMG_0026.jpgIn a break between presentations I finally had a chance to power up the amps, plug the subs into an output of the system DSP, and put some music through them. The instructions from the factory were to put a 20-25Hz (depending on how hard I was going to run them) 8th order L-R HPF and another 8th order LPF at a reasonable frequency, say 90Hz. Since I wouldn't use an 8th order filter to save the life of my own mother unless the President of the United States was willing to sign off that the resulting sound was not my fault, I used 4th order L-R.

Playing a test track I was immediately unhappy. Something had to be wrong, there was energy but it was undefined and it had a weird fluttery time domain component. Frequency response was wildly unbalanced, if there was 20Hz coming out of the subwoofers it wasn't apparent to me. The boxes weren't rattling or anything, they didn't sound like they were fighting each other, but they couldn't have been doing things right. Short on time, I broke out Smaart and took a few measurements... Measuring in a medium sized room is never a treat, but I was reasonably sure I had to axe a big hump out of band around 180Hz as well as one in band around 75Hz, plus if I was going to get 20Hz there was going to have to be a big boost down low. The LF rolloff certainly didn't look like it made it to 20Hz, and McCauley's frequency response specs are stated without processing.

IMG_0030.jpgSo I equalized the subs, relatively wide filters, to the best of my ability trying to work around what I could measure as the room versus the loudspeakers. I was sure I'd taken a photo of the laptop screen with both my measurements and the resultant EQ in the lake, but I can't find it now. I only had enough time to get it "close enough" before it was time for the next presentation on stage, and I was still very unhappy. One thing led to another and the next time I got to use the subs was that evening for the band. Soundcheck, and I was fighting the subs. I just couldn't get anything to sound like anything. The energy was there, but it was all mushy... every note played by the upright bassist sounded the same, and the kick drum seemed to just move the air in the room around rather than really thump. My EQ changes were definitely having an effect, but that effect was not making things better.

People started trickling back in from dinner and the band started playing, and two songs in I had to stop them. There was no way that all was right in the world, since I didn't have time to really break them down and look over every component, and since I couldn't even be sure that the room wasn't a total mess, I got a few guys and flipped the subs up and replaced them with three ADRaudio JD21s, a known quantity for me. Instantly all the problems were fixed, the kick drum thumped, the bass sounded musical, and I didn't have to fight the mix anymore. I desperately needed to spend more time with the M421s, preferably outside, and go through them from the ground up so that I could develop an honest and complete opinion. In front of a bunch of other sound folks was not the time and place to do that.

IMG_0024.jpgIMG_0033.jpgWe did, naturally, take them apart... This is the only isobaric horn loaded design I am aware of, and the fact that both sides of the radiator drive the air makes them a very interesting design as well. I have a great photo of Bill Hanley poking around inside. Another advantage of disassembling them was that we could check the wiring. Internal sub wiring seemed to be OK, but I still needed to check the amp rack so the M421s hid in the coatroom until the evening of the next day.

On day two Dave Rat showed up and gave a great talk on his past, present, and future as well as his thoughts on arena scale subwoofer arrays. Since I knew he'd had a bunch of the M421s out to test, I asked him afterwards if he'd take some time to play with ours. Dave, always willing to try and make incredibly loud noises, obliged. While I reconfigured the setup in the main room again and ran signal, Dave setup both subwoofers in the hallway as a sort of gate. Meanwhile he also checked the wiring in the amp rack, which must have been satisfactory as he didn't report any problems to me.

I have a great track I like to play called "Bass, I love you" that has extremely loud notes down to about 25Hz with appropriately quieter stuff happening at higher frequencies. It's a fun test track because you can crank it and the HF stuff is enough to give you something to listen to, and the LF stuff will cause diarrhea. Long story short, I put that track on and cranked the gain to the M421s out of the processor... no signal. So I walked towards the subs to try and diagnose the problem and was about to walk between them when Dave plugged the signal line back in.

IMG_0056.jpgI almost got knocked right on my ass. I've heard some loud shit, I've certainly had my bell rung by higher frequency stuff out of a monitor before. I have never in my life gotten my bell rung at 60Hz. By far the loudest thing I have ever heard, it was a full body experience as both subs unloaded right into me. I was stunned, and the only thing that got me out of the way was Dave running out from between the subwoofers with the biggest grin you can imagine. As Dave said in conversation later that night, they are "game changingly loud".

We turned them down and spent some more time listening. While I was more satisfied with the M421s I still wasn't thrilled. These subs should blow me away! 20Hz at decibel levels in the 150s... I've never heard such a thing! As it was I wasn't experiencing anything I couldn't get elsewhere, albeit there was more of it but it was indistinct. I didn't want to go on because I hated to think how much the venue and lack of time spent verifying the whole system were clouding my perception.

Frequent breaker resets were the name of the game, I don't know exactly how loud we were getting it but any extended periods of fun were sure to pop a breaker. We needed more power, and we needed to get these guys outdoors so that I didn't have to worry about how much of an influence on my opinion the room was having. As it was, while they could obviously get much louder than we were using them they couldn't get that loud and stay on. The amount of output they had on the available power was actually kind of disappointing, either the amps or the subs like to pull a lot of juice and wall outlets are just not an option.

The M421s got put back away, to be a source of fun some other time. As it would turn out, it would be about a month before I got to use them again but this time in much better circumstances and with happier results.
 

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Langston Holland

Sophomore
Jan 13, 2011
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Re: SFN Expo 2011

IMO, Lab shouldn't even offer the FP14000 in the 120v configuration you have. The 208v/240v models I use are the only logical choice with an amp of this output capacity. These amps are not auto switching or user adjustable, you have to order them with the voltage configuration you want.

I'd love to get my hands on one or two of those subs for a month or two. :)
 

Bennett Prescott

Just This Guy, You Know?
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Jan 10, 2011
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Colt's Neck High School Graduation

IMG_0254.jpgDue to a number of unforeseen circumstances it was about a month before I had an opportunity to really take the M421s out again, and for that I apologize. Too many shows where I couldn't be there for the show, or where it was a corporate gig and we couldn't use anything that large. What I needed was an outdoor show, with real power and reasonably large PA, with plenty of setup time, and a band that would be happy whether or not I managed to get the subs to play as nicely as I'd like.

Enter Colt's Neck High School graduation. An event in the middle of a football field 200 yards from any major obstructions, 10 hours from access to the field to the show, top 100 country act playing one song, and power tapped right off a 480v transformer. Audience of about 2,000 spread out over about 200' of throw. 6 per side ADRaudio L2821 flown off lifts, simple 4 mix 5 wedge monitor rig, full analog FOH with all the toppings, beautiful sunny day... I couldn't have asked for a better setup.

While the fork lift was taking all the heavy stuff onto the field, I took apart the amp rack that McCauley had provided. Aside from a few loose-ish output terminals, everything checked out just fine. I took every connection apart, checked it, and put it back together. Then I took apart every NL8 cable (each driver gets its own line back to the amps, cable is 10/8, every pin soldered... this shit could be used to power your house) and checked every connection, all good. The Neutrik NLT8 is used since the sub can take, like, 195+ fucking volts.

IMG_0235.jpgIMG_0240.jpgWhile the arrays were going up, I started cabling FOH and getting power out to the deck. A dedicated L21-30 for the sub amps, and a line right out of the DLP. If I was clever I would have run four lines and done all my verification myself, but we had plenty of time. Setup my Smaart rig, cast stones and read tea leaves to determine my measurement mic location, and I sent some noise down the line. Final check was to have Steve, on deck, turn up one amp channel at a time and make sure that all drivers in both subs measured identically. Never measured a rear isobaric driver alone before, it's kind of interesting, but that's for another thread. In any case, all amp channels and all drivers in both subs checked out 100% in frequency response and polarity. At this point I'm pretty sure it's impossible for me to be doing anything wrong, so I fired up the whole thing and got ready to take measurements to equalize and integrate the subwoofers.

The first step was to take several measurements to take a look at the raw acoustic response of the subwoofers. This is with no EQ or HPF/LPF, not even any delay (aside from that inherent in the DSP). I got a measurement at FOH, equidistant from both subs. One midway between the subs and FOH, slightly off axis. Another well off axis house left. Since all three measurements agreed extremely well I moved on to equalize the subs themselves. (A quick note: All these measurements were taken in Smaart 7 with MTW, 2 second averaging, 1/48 octave smoothing. The mic was at ear height for a seated audience member, except at FOH where it was at ear height for a standing FOH person.)

Screen shot 2011-06-23 at 4.09.23 PM.pngWhat may become apparent to you from looking at the measured response of both subs is... where's 20Hz? The spec sheet says 20Hz -3dB, 16Hz -10dB. Those are extreme low frequency numbers, there are very few boxes on the planet that will even do that and even fewer that are designed to be large scale PA subs. By fewer I mean, like, two that I can think of off the top of my head. According to my measurements, the frequency that is 3dB down from 40Hz is about 27Hz. That's, what, 1/3 octave above 20Hz? 20Hz itself is about 15dB down. Now, this potentially calls into question my measurement system, but I'm also not hearing or feeling extreme LF. To be doubly sure, however, I will bring my freshly calibrated B&K 4007 next time and check my field measurement mic against it, and re-measure the subs. My I/O passes a loopback test no problem, and I can see 20Hz on an RTA if I tap the mic, but I want to be absolutely positive before I go claiming that this is a 30Hz subwoofer, not a 20Hz subwoofer.

To rewind a little, after having been so dissatisfied after the SFN expo I called Mark Herman up and asked if he could put me in touch with someone who has experience processing these subs, someone who I could at least talk filters with and get an idea of what they were doing to get these monsters to play well with others. Mark got me in touch with Alex Moran of Spider Ranch Productions, who has a pack of M421s and uses them regularly. His advice was pretty similar to that given to me by McCauley, 8th order L-R at 25Hz and "shut 'em down hard" at 90Hz. "What about EQ? What do you do for EQ in and out of band?" I asked. Nothing. Nothing whatsoever, just high pass and low pass and you're good to go.

That just doesn't make sense to me. First of all, if the sub is -3dB at 20Hz you don't put a filter with a -6dB point at 25Hz. You put your overexcursion protection filter at, I don't know, like 15Hz or so. You want it to protect the drivers from getting blown out of the box, not cut out all that impressive low end. Furthermore, I'm plainly not imagining that 6dB boost at about 70Hz, nor the out of band spike near 200Hz. Neither of them is any cause for alarm, but they are not subtle and need to be equalized out if the subwoofer is expected to have reasonably flat response! I mean, I like a response that slopes up a little towards the low end, but not 6dB at 70Hz. The out of band thing may be why the extremely high order LPF has been suggested to me twice now. I'd rather just EQ it out and use a lower order filter (I mean, c'mon, 4th order L-R isn't exactly gentle either) so my phase traces line up better between my tops and subs.

Screen shot 2011-06-23 at 4.10.14 PM.pngThat said, since this sub doesn't appear to have a -3dB point at 20Hz, I went ahead and put in the following processing:
  • 25Hz 24dB/8ve Linkwitz-Riley HPF
  • 30Hz Bell, 0.5 Octave, +3dB
  • 70Hz Bell, 0.7 Octave, -6dB
  • 193Hz Bell, 0.7 Octave, -8dB
  • 90Hz 24dB/8ve Linkwitz-Riley LPF
You can see the final response of the sub, with (red) and without (tan) HPF/LPF, in the picture to the right. Not too bad, I might have put a small boost in around 100Hz and widened up the boost at 30Hz, but I hate to use little tweaky filters and that's totally excellent sub response. I chose to align the subs to my mains dead center at FOH (120' away), and all I needed was 3ms of delay and the phase traces lined up perfectly for over an octave on either side of the crossover point. A system integrator's dream.

I then went ahead and had my left hand man Austin run from the furthest audience position to the closest, and I finished equalizing my line array. Managed to get 14kHz to the back of the stands about 200' away, not at all shabby for 6 boxes hung at a mere 20'. Time for some music.

IMG_0230.jpgGood alignment, small power alley, these subs behave exactly as I'd expect. Level wise, these two are definitely enough for this crowd. At no point did I hear them working hard. It was too bright to see the meters on the Lab.Gruppen FP14000 amplifiers, so I have no idea where we were signal wise. Out of the DLP I was sending about as much level as I normally do for subs with 36dB of amp gain, and the Labs are set to 41 IIRC. That doesn't necessarily mean anything, so suffice it to say I had no problems getting plenty of output for the crowd. There is little doubt in my mind that these boxes are extremely loud. Whether that SPL is high relative to their size is something you'll have to decide for yourself, I certainly haven't pushed them hard enough yet to determine that for myself, and I haven't compared them to anything else. At this point I'd feel comfortable taking them out for almost any genre of music for maybe even 4,000 people outdoors, no question about 2K, save really really bass heavy stuff. That is indeed a monster of a sub with monster output.

Even with the enormous horn size, getting in front of these boxes is a visceral experience. They move a lot of air. There is a very small amount of chuffing from the mouth on very high SPL kick hits, certainly not enough that most people with their head 1' away would even notice it, but that should give you an idea of just how much air it moves. The cabinets sound solid, no squeaks or farts that I could hear with moderate abuse. The grille doesn't make any noise, which is a Big Deal™. A little bit of caster rattle but nothing serious, noticeable behind the sub but only a little in front, gone a few feet away. Not unexpected for such a high power box. I know a thing or two about isobaric designs and there is a lot of pressure in that chamber, not to mention at the horn throat. This thing must be braced to high heaven.

Here's a little video I made of the sub making everything around it respond to the music, the LF is clipping the mic in my iPhone a bit but you can hear that it's pretty clean otherwise. When I bend down to get closer you can hear the AGC in the iPhone kick in and the kit totally goes away. I told my iPhone to upload this in HD, so if you select 720P at the bottom right of the video you can blow it up to full screen and get better audio and video quality. Not that this is exactly scientific!


During soundcheck, more power problems emerged. Midway through the last song of a quick 15 minute check (noise complaints already...) the amps popped their breaker on the PD. That's kind of troubling, since we were by no means pounding the snot out of anything. Each amp has a 30a cord on it, running down 150' of 10AWG wire, attached to a 30 amp breaker. Nothing else on that breaker. During the check you could see the analog voltage meters on the PD ducking on kick hits, and the two legs that had subs on them were drawing over 25 amps during kick hits, whereas the leg that just had monitors, FOH, line array, etc was drawing 5A. That's a lot of current. I normally see 25a per leg with a full monitor rig, twice as many boxes, 12 boxes of big subwoofer, FOH, monitor console, etc. Popping breakers for this kind of show is extremely unexpected, and makes me wonder if we can even drive these subwoofers to their maximum output. I will probably have to enable the peak voltage limiters on the amps next time I try and take these out, can't have them shutting their service down mid-show. Now, to be fair, if the PD meters were ducking on kick hits our power can't have been that solid. I would expect tying into a 480v transformer to be pretty good normally, but there was another 150' of 2/0 cams after that, and who knows how far the service had to travel before it hit the transformer. Another variable to eliminate next show.

IMG_0271.jpgI still feel like the sound that comes out of these boxes is a little flat. I've been trying to find a way to describe it, and I think compressed is the best way. It's definitely loud, has good punch, has reasonable definition, but seems like it was run through a mild compressor. Just a little dull, not the end of the world by any means and definitely a reasonable sounding box, but not going to win any awards for sound quality. Whether that matters in the face of bone crushing output is really up to you! Maybe I can get Steve or Jason, who were both with me and spent time making noise through these boxes, to comment on their impressions of the sound quality. I would certainly mix any show on them.

In wrapping up for now, I have no problems agreeing with McCauley that these subs have absolutely huge SPL output. Whether they really do 155dB at 1m is a different matter, I would say they are probably close, verifying that number for real is something I'm not really set up to do. Basing it off other subwoofers I know I don't find it hard to believe.

For such a big box they are also reasonably easy to move around. If deploying them in larger numbers I would definitely want to keep amp racks close, since the speaker cable is enormous. Smaller diameter wire would probably be OK since each pair is only seeing a 4 ohm load with two subs, but it's a lot easier to run 10' of that big ass speaker level cable and an extra 50' of 10/5 attached to L21-30s than it is to run longer speaker cable runs.

As you have seen, however, I have doubts about the LF extension. The processing I ended up with to make them play well is not at all unreasonable, but you can't put in enough boost to make them meet spec. That would be crazy, and cost way too much headroom everywhere. Assuming I don't find out that my shit is all fucked up and my mic happens to take a 6th order dive at 27Hz (unlikely, but I'm open minded) I think the spec sheet does this sub a disservice. The state of the art today is a concert sub that can do a little below 30Hz. There is no doubt that the M421 can achieve that goal, with really only EQ to taste down low.

Screen shot 2011-06-22 at 5.06.31 PM.pngClaiming that it needs no processing gives it a bad rap, since obviously it needs more than just a HPF and a LPF. I have no problem with that, but being told all along that it didn't need EQ made me wonder if I was going crazy. Claiming such a low -3dB point also hurts the sub, since I was expecting to be absolutely blown away and I wasn't, making me doubt this box from the get go. If the -3dB point had been stated as 29Hz that would have been excellent LF extension regardless, easily verifiable in the field, and being able to do that at the box's claimed output capability is nothing short of impressive. The spec sheet for this product raised my expectations to the level that, when I encountered what is actually excellent in reality, I was disappointed. Change that one number and this becomes a great product in my mind. Yes, the sound quality isn't as good as a few other boxes I know, but it is not bad... just not stellar. How well it behaves even at high SPL is commendable, there are very few subs that can actually perform at high SPL. No qualms there.

Fortunately, it looks like there are plenty of shows coming up where I will be there the entire time, and where it would be appropriate to try this product. I am reasonably comfortable with it now, my only real worry is keeping it turned on under heavy use. Perhaps with the amps in the shade and more solid power to the PD everything will be copacetic. I hope so, because I'd really like to nail these suckers and see what they can do, and especially see if they remain well behaved into clip on the amps. So far I have been pleased with their behavior, they are easy to work with. Even with the unique design they behave just like a traditional front loaded sub, no tricks required. Plug 'em in, apply a little bit of EQ, and get going. I'm sure there will be plenty of interest in these boxes, and I hope to be able to pass them on to another interested party by the end of July so we can get more opinions during summer concert and festival season.

P.S. I think based on this post 16,000 characters is probably a reasonable message size limit from now on ;)
P.P.S. If you want to Test Drive and you think it will be easy, the three posts I have in this thread took me about 5 hours to put together, and that was after taking extra measurements and photos in the field.
 
Jan 10, 2011
903
3
18
Abingdon, MD
www.harfordsound.com
Re: Colt's Neck High School Graduation

As you have seen, however, I have doubts about the LF extension. The processing I ended up with to make them play well is not at all unreasonable, but you can't put in enough boost to make them meet spec. That would be crazy, and cost way too much headroom everywhere.

Bennett,
With such a high claimed maximum SPL, would a 6dB or so boost down low really take away that much headroom? If you've got the headroom to spare, why not reach for that extra LF extension? I'd be really curious how the boxes would hold up with that extra boost down low.


Evan
 

Bennett Prescott

Just This Guy, You Know?
Staff member
Jan 10, 2011
10,853
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48
37
Wallingford, CT
www.bennettprescott.com
Re: Colt's Neck High School Graduation

Evan,

I already put in a 3dB boost at 30Hz to try and get the sub to sound a little "bigger". Look at that rolloff. A 6dB boost at 20Hz wouldn't do shit, you'd need more like 15dB to make it to 20Hz. That's totally unrealistic, IMHO. I don't have an impedance meter so I don't know what the tuning frequency of the box is or the resonant frequency of the drivers, but it is just totally done below 30. Maybe if it had a 2nd order acoustic rolloff it could be equalized to get another 1/3 octave LF extension a la Bag End, but that is 4th order easy, maybe 6th order rolloff. Who knows how the box would behave with a big boost down there, as well... might get ugly, might not.

If I have time I will try it, just for kicks, but it's not something I would ever do normally.
 

Jay Barracato

Graduate Student
Jan 11, 2011
1,528
2
38
Solomons MD
Re: Colt's Neck High School Graduation

Bennett,

I am not a low end maven by any means, and probably lack the words to describe what I was hearing, but at the Expo I felt there was a constant "buzz" or resonance that colored the subs output musically. I know we usually think of buzz as a higher tone but what I was hearing was down in the 40-50's. Best I can compare it to is the constant drone of a diesel engine on a boat.

I am not sure if it was the sub producing it or if it was a sympathic resonance in the room (or in my jaw) but there definitely seemed to be a constant under (over) tone that was mostly but not completely masked by the music.

I wonder if this was what you were still hearing or if it cleared up when the subs were moved outside.
 

Charles Harrigan

Sophomore
Jan 11, 2011
188
0
16
Upstate SC
Re: Colt's Neck High School Graduation

I think the room played a big role in my experience mixing those 2 first songs at the convention, but here's my $.02:

When they were in front of the stage, anything i put into the subs turned to mush. I've never had that sort of experience before with any system. I had the string bass in just the mains, and it sounded fine, but as soon as i turned the aux up, it went to mud. The bass guitar just disappeared out of the mix and was replaced with this droning mess, and that was before the kick mic fed back. EQ also didn't help (after I realized that you have to manually engage it on the pro6, which took one song), which leads me to think that it was the room making a mess of things.

Side note: during the SMAART class later that week, when Jamie measured the in room impulse response of one of the JD21s. The second arrival was larger than the first, and the third was as large as the first.

Once they were moved into the hallway, they seemed, to me at least, to be better behaved than they were in the middle of the room. They definitely were loud, went pretty low, but as Bennett said, not as low as I was expecting. I wonder if putting multiples of them together to increase the mouth area would lower the cutoff of the box. Personally i'd like to get 6 together to form one mouth in a field with 6 fp14k powered off a 300A 3 phase variac connected to a 100kW genset..... Like that's gonna happen.


Seems like my review is more about the room than the subs, oh well here it is anyways.
 
Re: McCauley M421 Quad 21" Subwoofer

I guess my question would be, at 500 pounds, 6 feet long, and seemingly using every bit of power from a PLM14K, with response only into the 30hz range, are these subs really worth it? If you had a bank loan to build a rig, do you feel that, acoustically and logistically these subs are better than buying say 4 boxes of a modern high power dual 18". Based on the reviews I would almost think that given the same amp input power you might be better off with 4 big dual 18" du jour just on the merit of having a lot of cone area and gains from more boxes. I'm basing this of course on what Bennett has measured and observed and not spec sheets (because they aren't always the best representation as we see here).
 
Jan 19, 2011
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Re: McCauley M421 Quad 21" Subwoofer

I guess my question would be, at 500 pounds, 6 feet long, and seemingly using every bit of power from a PLM14K, with response only into the 30hz range, are these subs really worth it? If you had a bank loan to build a rig, do you feel that, acoustically and logistically these subs are better than buying say 4 boxes of a modern high power dual 18". Based on the reviews I would almost think that given the same amp input power you might be better off with 4 big dual 18" du jour just on the merit of having a lot of cone area and gains from more boxes. I'm basing this of course on what Bennett has measured and observed and not spec sheets (because they aren't always the best representation as we see here).

I would be interesting to see how these would perform against a block of 4 labsubs or 4 TH115. Both are pretty well known subs among people on this forum :)
 

Bennett Prescott

Just This Guy, You Know?
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Jan 10, 2011
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Re: McCauley M421 Quad 21" Subwoofer

I guess my question would be, at 500 pounds, 6 feet long, and seemingly using every bit of power from a PLM14K, with response only into the 30hz range, are these subs really worth it?
To be fair, the box easily has response into the 20Hz range. It just doesn't have response into the 10Hz range, which is what McCauley claims on their spec sheet. I think making it to 30Hz solid, which it does no problem, is excellent. While having response to 20Hz would certainly be fun, and would make the cabinet really industry leading, the real reason this box is impressive is because of its maximum SPL.

Now, as you suggest, that maximum SPL is only impressive if it's high for the size of the box. Is this loudspeaker bigger than four high performance double 18" cabinets? No, I don't really think so... in fact there are many excellent double 18" cabs maybe only half its size. Is this loudspeaker heavier than four high performance double 18" cabs? No, definitely not. Is this loudspeaker louder than 4 double 18" cabs? Well, that's really the question. I think probably. It is also certainly easier to push into place than four double 18" subwoofers, easier to run power to, and unlike many 18" boxes behaves really well down low at high SPL.

Does this box make sense for arena tours? I bet, it gets a lot of power in one place, and saves time getting subs deployed and then back on the truck after the gig. Does it make sense for regional sound companies? I think so, it's impressive, which separates you from the rest of the herd. Two of them will be enough for many types of gigs. I've certainly spent plenty of time hauling around much less practical boxes that were much less easy to handle. Does it make sense for local sound companies? Probably not. You're never going to move this in your car, maybe your truck, but then what else can you fit in there? You need to be the kind of company that always has access to a box truck, and always has access to stiff 3 phase power.

But, of course, I don't own gear and hopefully never will again, so that's just my opinion and it may not be worth both cents.
 
Jan 11, 2011
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Buffalo NY
Re: McCauley M421 Quad 21" Subwoofer

I'll bet you could boost the entire 16dB & have a flat response without losing headroom. The frequency content of your music and individual sources wont aggregate (ahem) to a big demand at 20Hz. So using an EQ that flatents your response shouldnt eat into your headroom at all..... No?
 

Daniel Casado

Freshman
Jul 1, 2011
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Seattle, WA.
Re: McCauley M421 Quad 21" Subwoofer

I’d like to shed some light on the design intent of the M421 and its applications. I feel there may be some misconceptions about how it’s meant to be used, so I’d like to clear these up.

The M421 was designed for concert/ touring and fixed installation. While generally viewed as a large venue sub, it also has applications in smaller venues where space is limited. This is especially true in contracting where the client or architect has not planned adequate space for subs.

The M421 will replace 4 or more double 18” subs in terms of output, but takes up less space. This translates to an efficient truck pack that yields more available truck space and less occupied floor space in a venue. It’s also significantly lighter than the combined weight of 4 double 18’s.

It’s not difficult to move around, and is faster to load in and out of a venue since there are less of them. It’s also relatively easy to stack two of them. I and one other person have moved them in / out of venues and stacked them many times, and I am not superman.

They do require a minimum of an FP14000 to power, but you would need an equivalent amount of power or more to drive 4 double 18’s. I absolutely agree you cannot run an FP14000 off of a 15 amp Edison. I also agree that the 240V version of the FP14000 works better with the M421 than the 120V version does.

While the M421 can be used stand alone, we also like to mix them with our M88 double 18’s. I suggest routing the M421 and the M88s on separate aux sends and mix to taste. Here are a few real world examples to give you an idea of the ratio of M421s & M88s to venue size. We did a 2100 seat auditorium with 1 M421 placed in the center in front of the stage and two of our M88s per side. We did a concert in a 5000 seat church with 2 M421 placed in the center in front of the stage and four of our M88s per side. In both cases we had more than enough firepower for the venue.

I’d also like to comment on the settings since this was discussed above on this thread. We recommend a 24dB/Octave Butterworth High pass at 25Hz, and 48dB/Octave Linkwitz Riley Low Pass Filter at 85Hz. These settings are routinely used in the field with very good results. I encourage Bennett to try them.

Ryan Mccauley designed the M421. He’ll be posting some more technical information regarding some of the points in this thread.

Daniel Casado
Director
Engineering Support Group
McCauley Sound
 

Bennett Prescott

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More McCauley M421 Measurements

IMG_0344.jpgTook the M421s out again for two gigs in two different venues. Southside Johnny and the Asbury Jukes at the Stone Pony Summer Stage, followed by Kid Cudi the next day in Convention Hall. Set up the usual subwoofers stage left and right as an end-fire array, with the M421s front and center. I drove each set of subwoofers off a separate aux so it would be possible to send any source to either or both. This was fun because it allowed me to play with different subwoofer patterns in this outdoor venue, plus it was an easy way to listen to both sets of subwoofers and play with a "dual PA", trying to get even more output and sonic clarity by putting dissimilar sources in different loudspeaker arrays.

As requested by Daniel, I used only basic processing. Butterworth 4th order HPF at 25Hz, and Linkwitz-Riley 4th order LPF at 100Hz (the XTA DSP I used to process the M421s didn't go any higher than 24dB/oct). I have to admit that I also took 6dB out at about 170Hz, Q of 3. Whether this had any noticeable effect once the low pass was applied I didn't spend much time on, but it made me happier.

Naturally, I wanted to continue to gather more measurement data on these subwoofers. Earlier in this thread I expressed doubts as to their -3dB specification, and I definitely wanted to go through my entire measurement system to ensure that wasn't measurement error on my part. First, I ran a loopback test on my measurement interface to make sure it was behaving linearly. I looked around but I couldn't find any XLR cables, so I used an APB Dynasonics Spectra Ti between my outputs and inputs instead...

Screen shot 2011-07-06 at 6.18.30 PM.png
Looks like any measurement error isn't in my USB audio interface. Next to check my measurement microphone. I brought along my recently calibrated (thanks, Hammer!) B&K 4007 to verify my results and took acoustic measurements of the M421s unprocessed with both my fancy mic and my cheap mic (with the capsule in approximately the same position). I then also took a trace with the applied processing using my cheap mic, and compared to the measurement I took a few weeks before at Colt's Neck High School just to make sure I was getting consistent results. In this next screenshot the red and blue traces are my expensive mic and cheap mic, respectively. The yellow trace is with applied processing, and the green trace way in the background is the measurement I took at Colt's Neck. These measurements are all MTW in Smaart 7, 1/48 octave smoothing, and a 6 second average.

Screen shot 2011-07-06 at 6.15.49 PM.png
I think, based on these measurements, that I am comfortable making a few claims.
  1. At low frequencies (<1-2kHz at least) there is no meaningful difference between a $1,800 microphone and an $80 microphone. (obviously there are durability, temp stability, etc, differences but they are not significant in this environment)
  2. The McCauley M421 has a -3dB low frequency point, before processing, of about 27Hz. That's about 1/3 octave higher than what they claim on the spec sheet.
  3. The M421 has a big ass peak at about 65Hz. Whether this is desirable or not is really up to the user.
I ran with the specified and measured processing all weekend. I will certainly agree that it made the sub more interesting. If I equalize out that approximately 65Hz bump the result is an unexciting subwoofer. It looks a little peakier than it sounds, but this sub definitely generates above and beyond kick drum thump when you turn it up! Even though its 30Hz level is 4-6dB less than its 65Hz level the subwoofer still sounds like it goes nice and low, but it is definitely characterized by that response peak. If you want a subwoofer that sounds enormous you might want to take at least 3dB out of that region, but if you want a subwoofer that sounds like it is going to kill you leave it in.
 

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Bennett Prescott

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Show Time

There is one place where I have no reservations about the M421's stated performance: This box is loud as all get out. We had none of our former power woes over the weekend, and definitely gave the M421s a bit of a workout. I wouldn't say they got ridden hard, but I was definitely seeing the amps built in peak voltage limiter get tapped on kick hits. Unfortunately my clamp meter appears to have given up the ghost, so I had no way to measure current draw. That said, I stand by my statement that two of these things are probably enough for most genres for maybe 4,000 people indoors and 2-3,000 out. They get up and go and take a beating like a man, no complaints with behavior at high excursion.

Saturday's outdoor show was easy, I did the line check on the PM5D and had plenty of time to play around with both subwoofer arrays. It is very difficult to do a comparative listening test when one product has peaky response. I will say that I found the M421s gave an easy and powerful kick drum sound, but I didn't try putting kick in our other subs and boosting 65Hz to see if I could get them to match. I definitely preferred the sound of our other subs for bass guitar, I still think the McCauley is a little smeared in time. The rest of that show was mixed by the band's BE who normally, let's say... doesn't use a lot of subwoofer. He was definitely using more than usual this time, though, and had different sources going to different subs... except for kick which was in both.

IMG_0373.jpgSunday's show was supposed to be outdoors, but got called at 7:30 a.m. for rain and moved down the street to the Giant Concrete Box™, so we got to take down, set up, and take down again that evening. Space is at a little more of a premium there, and the room has nearly an 8 second reverb at 160Hz, so less than ideal but I've been in there a lot so I can manage it all right. I used essentially the same setup as Saturday except the artist wanted a thrust, with the results you see here. Less issues than you might think, probably thanks to generous bracing in the M421s. Monitor world, directly behind one of the end fire arrays, definitely appreciated having some directionality in the subs.

I didn't mix at all this show, but had some good fun playing tracks before check. Running both sets of subs, once you build in room gain as well... I might finally have gotten enough subwoofer. At least until I get used to it.

Band Engineer's only comment was "cut out all that fucking sub harmonic shit". I gave him a -6dB shelf at 45Hz and he was happy. Oh well, it's not like there wasn't plenty going on down there anyway, saying this was a low end heavy act was an understatement. Most things went in both sub sends for this guy, but as a result all the subs were just loafing along while meanwhile, at FOH 80' away, my nose hairs were vibrating so badly I had to sneeze regularly. With the PA running about 105A-Slow I popped in some foam plugs and watched meters for a few hours. BE was having a great time, dancing along to the music, so I figured it was a job well done. The 4,000 screaming teenagers there plainly had a good time, and reminded me why I am glad to not be that age any more.

IMG_0383.jpg
A few other forum members have gotten their ears on these boxes by now, and will hopefully post their impressions. I have some more shows coming up and then Evan Kirkendall has asked to take them out on tour with All Time Low towards the end of the month. That should be interesting...
 

Langston Holland

Sophomore
Jan 13, 2011
222
0
16
Pensacola
Re: More McCauley M421 Measurements

...At low frequencies (<1-2kHz at least) there is no meaningful difference between a $1,800 microphone and an $80 microphone. (obviously there are durability, temp stability, etc, differences but they are not significant in this environment)...

The major differences can be found in the time domain, HF polar response and higher SPL's young grasshopper. :)

Some very old measurements I made of a wedge in my living room, mic at ear level and a soon following second arrival from the ceiling. Three separate measurements were made with capsule diaphragms at identical positions and angles. Notice the similarity between the B&K and Earthworks mics relative to the Midas ECM8000 - particularly in the ceiling arrival and the noise floor that follows.

4007:

30ms_IR_BK4007.jpg


M30BX:

30ms_IR_M30BX.jpg


ECM8000:

30ms_IR_ECM8000.jpg
 

Phil Graham

Honorary PhD
Mar 10, 2011
651
1
18
Atlanta, GA
Re: Processing and voicing

I’d like to shed some light on the design intent of the M421 and its applications. I feel there may be some misconceptions about how it’s meant to be used, so I’d like to clear these up.

The M421 was designed for concert/ touring and fixed installation. While generally viewed as a large venue sub, it also has applications in smaller venues where space is limited. This is especially true in contracting where the client or architect has not planned adequate space for subs.

The M421 will replace 4 or more double 18” subs in terms of output, but takes up less space. This translates to an efficient truck pack that yields more available truck space and less occupied floor space in a venue. It’s also significantly lighter than the combined weight of 4 double 18’s.

Daniel,

Since no one has taken the opportunity to reply to your fairly detailed post, I thought I would give it shot.

The point of replacing four or more standard dual 18s is something that should be highlighted in your body copy. For your customers who consistently produce shows consistently using this minimum quantity of LF, that is a strong selling point. Why not simply rewrite all of the copy to focus on saving weight and truck space relative to four dual 18 boxes?

I’d also like to comment on the settings since this was discussed above on this thread. We recommend a 24dB/Octave Butterworth High pass at 25Hz, and 48dB/Octave Linkwitz Riley Low Pass Filter at 85Hz. These settings are routinely used in the field with very good results. I encourage Bennett to try them.

Daniel, why promote such simple, naive processing for a box that clearly has a response anomaly at 65Hz and would also benefit from some out of band eq. The customers purchasing this class of product are going to have enough dsp available to make both the in-band and out of band corrections.

System tuning and system tuning tuneups are some of my most frequent audio gigs. Many pro sound manufacturers suggest overly simple processing for their LF subsystems. That's good news for me, because I can often make substantial improvements to the LF subsystem behavior and tonality. This is good for impressing my clients.

However, overly simple processing is not good for inspiring my confidence that the aforementioned manufacturers have an idea how to voice and process the remainder of their product lines. While I'm not suggesting adding fancy processing for the sake of processing, if it is necessary for reasonable response call it a spade and have customer's apply it.

In my personal case, McCauley's decision to leave a 6dB+ response anomaly right in the middle of the passband for this particular low frequency speaker virtually guarantees that I won't consider the remainder of the McCauley product line for other projects. I realize other potential customers probably won't feel as strongly as I do, but I feel that there are already enough quality products on the market with reasonable processing for obvious flaws. For new products to be added to my personal list, they should also be accompanied with reasonable processing.

Probably more than $0.02
 
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