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ZOD Audio M.A.U.L. Test Results and Discussion

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Infrasonic    149

I've got a ton of people asking about this type of cab for various apps end I just don't have time right now. Once I get some bandwidth opened back up I'll start working on finishing my 21Ipal music version and hopefully have time to work on a few others.

 

And you thought things were bad after the Gjallerhorn came out...

 

:P

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Ricci    637

And you thought things were bad after the Gjallerhorn came out...

 

:P

 

Right.

 

Think I'm going to work on getting my Palehorn plan finished and modify it to work better for the more commonly available drivers like the 21DS115,21sw152 and the 21nlw9000 and also pro 18's rather than the Ipal. Also planning to get my Skhorn thingy completed and probably offer those plans too. Probably going to attempt to modify that to work with drivers a little more attainable than the Ipal as well. Then I might work on something that'll work with more common drivers in a more HT type app, build a little simpler and still remain compact. Probably be another year to get all of that done.

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Ricci    637

In other news I retested a few things with a 2ohm nominal impedance using a single channel of an SP2-12000 instead of the bridged K20. Basically a Torpedo 6000 plate. I'll be posting it soon. Short version is that the K20 will operate into 1 or 2 ohm per channel but the long term power is limited quite a bit by the current demands. 4ohm or higher per channel is where that amp really does its best work and can use the crazy output voltage. The Torpedo 6000 SP amp is a current monster into low impedances. It'll be interesting to see how M.A.U.L. cab 2 tests out with both channels of the SP2-12000. Looks like the K20 might get significantly out powered with the long term sweeps but might still burst a bit more.

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Kyle    62

Its really amazing how much power you need to max out a sub for a short term sweep or burst, but the flip side is if you keep driving at those levels you'll destroy the drivers. Reminds me  of car audio SPL competitions :)

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DrWho    1

Hey Mike good to see you around these parts.

 

I didn't check response with the hatches removed. I can at a later date. We can sim it easily though so I've attached that. Illustrates why I was going with this cab style quite well. Get the benefits of a big vented cab near tuning, use the upper section to turbo charge the mid band and upper bass near crossover. Add a side order of potentially lowering the amount of driver noise and distortion over the target bandwidth by having the drivers inside the cab versus direct radiating.

 

attachicon.gifM.A.U.L. vs Regular Ole Vented.png

 

Coming back to this original conversation.....

 

Have you read this article?

http://www.elpee.info/Documenten/KlipschVervorming.pdf

 

It's a bit math intense, but I've always been more interested in frequency modulation distortion versus other forms of distortion. Lowering amplitude modulation distortion does in fact also reduce frequency modulation distortion, but there is a doppler distortion limit to frequency modulation.

 

My question (that I've slowly been answering for myself since my initial post in reference here), is as follows:

Does FMD get reduced by horn-loading the top-end of the response?

 

My conclusion is that the doppler effect induced distortion stays the same whether the front wave is horn-loaded, or just a classic direct radiator. Reducing the high frequency amplitude of the driver (for the same resultant SPL due to the horn loading) results in the same relative amount of modulation distortion. Even post EQ. It's intrinsic to the motion of the LF drive unit.

 

The conclusion is that we want to minimize the low frequency excursion requirements for a given SPL. Increasing the number of drive units increases the total radiating surface area which is the classic way to reduce low frequency excursion for a given SPL. Venting the cabinet is a next step, but it increases excursion above and below the tuning frequency. The Q (steepness) of the vent tuning can augment that a bit....I've long wanted to do a really low Q vented design and take advantage of the power handling of the voice coil over a wider bandwidth. I've not see a way to model extreme port flaring in any of the tools however. Then there is the tapped horn, which has a profile similar to that of a vented cabinet, but it can be made to be quite different. The full blown horn loaded approach is the best, but with lower frequencies we never have enough space to make a proper sized horn.

 

All that to say, I think it would be interesting to create an excursion per SPL metric - and maybe even make a plot of that versus frequency. The reason for this is that many of these drivers have very linear amplitude behavior at lower SPLs. It's only near the limit that things start to round off. However, frequency modulation distortion is always there - even if the drivers are perfect. I gotta imagine that many of these builds are getting extremely close to that Doppler Induced FMD limit.

 

If we agree that merit is of interest, then we can also go one step further and divide that metric by the number of drivers being used.....this would highlight the acoustic benefit of the specific alignment rather than highlighting the brute force approach of using multiple drivers.

 

 

All that to say....I wonder if the Othorn and Gjallerhorn aren't more impressive from a speaker alignment perspective. If you look closely at your sim data, you'll notice that the front-horn is offering some benefit over the vented cabinet at the lower frequencies. It's not much, but only a few dB at lower frequencies is a big difference in FMD....

 

 

Thoughts? Am I crazy? This came to mind in light of the "accusations" about SPL drag racing. For me personally it's never been about SPL drag racing, but about that acoustic efficiency that brings about lower distortion from the system. It just happens to be the case that high efficiency and low distortion tends to bring about very large SPL capability.

 

Or maybe you're after that SPL drag racing? Nothing wrong with that I suppose.

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SME    201

I really don't think Doppler distortion matters at all for subwoofer frequencies.  The lower you go, the slower you go, if you keep excursion the same.  As such, I don't think there is an inherent advantage to building a system with low excursion, in an absolute sense.  I think it's more important to build a system that can create a lot of SPL without requiring excursion to get so high that it contributes a lot of distortion.  This is not exactly the same thing.

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lukeamdman    153

 

Thoughts? Am I crazy? This came to mind in light of the "accusations" about SPL drag racing. For me personally it's never been about SPL drag racing, but about that acoustic efficiency that brings about lower distortion from the system. It just happens to be the case that high efficiency and low distortion tends to bring about very large SPL capability.

 

Or maybe you're after that SPL drag racing? Nothing wrong with that I suppose.

If you're referring to my comment above, that was just a joke/jab at other "SPL drag racing" comments about this board in the past. Not a serious comment at all.

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Ricci    637

Back from the dead...

I finally have the last 4 drivers for the second cab and have been slowly installing them. I should hopefully have the 2nd one ready to plug in late tonight. I am not looking forward to moving everything out and putting these back in the corners. I have to pull the first one back out of the corner, pull the hatches and a couple drivers and rewire it the same as the second too. Lift with the legs...

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Infrasonic    149
1 hour ago, Ricci said:

Back from the dead...

I finally have the last 4 drivers for the second cab and have been slowly installing them. I should hopefully have the 2nd one ready to plug in late tonight. I am not looking forward to moving everything out and putting these back in the corners. I have to pull the first one back out of the corner, pull the hatches and a couple drivers and rewire it the same as the second too. Lift with the legs...

Hope you will have some help with that! :o

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Ricci    637
16 hours ago, Infrasonic said:

Hope you will have some help with that! :o

Didn't quite get to all of that but #2 is ready to plug in a speakon cable and rip at least. I won't be moving all of that by myself like I did last time.

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Ricci    637

MAUL 2 is in place and the rest of the BIG stereo is back together. Next step is a few days tuning crossovers, delay and EQ until it sounds right. After that I want to make some amplifier changes.

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Infrasonic    149
41 minutes ago, Ricci said:

MAUL 2 is in place and the rest of the BIG stereo is back together. Next step is a few days tuning crossovers, delay and EQ until it sounds right. After that I want to make some amplifier changes.

Nice!

Ooo! What amp changes are you thinking of doing? :D

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chrapladm    46
7 hours ago, Ricci said:

MAUL 2 is in place and the rest of the BIG stereo is back together. Next step is a few days tuning crossovers, delay and EQ until it sounds right. After that I want to make some amplifier changes.

What does the BIG setup consist of other than subs?

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Ricci    637
On ‎7‎/‎22‎/‎2017 at 0:04 AM, chrapladm said:

What does the BIG setup consist of other than subs?

I've mentioned it a few times before. A pair of JBL 4675C's. The 2226H drivers out of the double 15" (4508A) bottoms I sold off and replaced with AE TD15M-4 drivers with the Apollo upgrade. They are wired in series. The big 2360A "butt" lenses still have the 2446H CD's on them. Those sit on top of the MAUL's. It is a tri-amplified stereo system run from a Peavey mixer into a DCX2496 which provides processing and routing to the amps. The current amps are a 20 year old Mackie M1400i on the 2446H drivers (Run from about 600Hz up.), a Crest 8002 powers the TD15M's which run about 80-600Hz roughly and a single SP2-12000 currently has a MAUL on each channel running <80Hz. There's no surround sound and I never replaced the old projector after it died a few years back so there is no video right now either. It's just a mammoth stereo or PA as needed. It's nothing special but does the job.

Eventually I planned to swap out the 2446H's for some BMS coax's or something Be and probably change the lenses too. Now I'm having thoughts of doing something different for the mids and highs entirely. Try to roll my own Synergy's or other design? Not sure what yet. I'll probably upgrade the amps first. Eventually I'll put my K20's one on each Maul and move to SP's at the house so I won't have to deal with fan noise at home anymore. I want to get a newer amp for the CD's. Only class AB or H for those though. I still don't think class D is quite as good for HF. I might just go with an A500. The power requirements on the CD's is almost nothing even at ear splitting levels.

The room is in an old rundown, warehouse / factory, in a ghetto part of town. Myself and the other musicians I work with, have been renting there for 8 years or maybe more. The whole building just about is rented out to musicians, artists or people needing storage. The outdoor test spot is right out the backdoor. The room itself is a shotgun shaped space about 18ft x 15ft x 36ft. Roughly 10,000cu ft. I'm guesstimating and could be off some, since I've never actually measured it. Walls are double carpet hung over sheetmetal and studs with main building supports in there too. Flimsy and leaky as hell but the carpet hanging from the walls and the directivity of the horns actually keeps the space relatively dead. Every surface in the room except for the garage style door and the ceiling are covered in carpet. The room is over the basement level, but the floors are 4 to 5 inch thick cement type material over timbers, so it will shake some, but not easily like a suspended floor in a house. It takes a bit more energy. Ceiling is the same deal. Back wall is a brick interior wall with carpet over it. The back ground noise level is high usually of course. There are no placement options really as the room is jam packed with equipment of all sorts. It is not ideal and there are all sorts of acoustic and structural issues that color the sound. For one my drums usually sit directly in front of one side of the stack. Thankfully the horns are 8 or 9 ft off the floor well over top of them and the bass just goes around, so most of the sound ends up in the right place regardless. None of that matters really because that's not what it's about in there anyway.

 

 

20170720_183943.jpg

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chrapladm    46
12 hours ago, Ricci said:

.......

 

20170720_183943.jpg

Thanks for the reply. I was looking at a lot of used equipment for my setup and so I was curious to see what you had. I cant afford the stuff I want right now so I am looking at a few cheaper options to at least get me started. Nice to see a 001 series still in action.

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MemX    94

@Ricci's idea of 'nothing special' differs somewhat from my own  LOL

 

If you just want to get rid of all that old junk, I can find a home for it ;) :D

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