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

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So uh, what's the second cab for then? No one else notice there are two of these in a few of the pics? 

 

Gypsy Danger needed Striker Eureka to defeat the category 5 Kaiju.

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So uh, what's the second cab for then? No one else notice there are two of these in a few of the pics? 

 

"First rule in government spending. Why build one when you can have two, twice the price."

 

Wanna take a ride?

 

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So uh, what's the second cab for then? No one else notice there are two of these in a few of the pics? 

 

I was going to ship the other one to your house so you could check it out but it wouldn't fit in the USPS large flat rate box. Guess I'm stuck with both of em.

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I was going to ship the other one to your house so you could check it out but it wouldn't fit in the USPS large flat rate box. Guess I'm stuck with both of em.

Well, now that I have teh dimensions, I'm shooting you some packaging to load 'er up in. Be on the lookout. 

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"Now all I need is to get 2 M-Force modules to power the M.A.U.L.'s"

And use one on the first two drivers and the other on the second two, use DPC and DSP to get rid of the different behavior of the drivers because of the OD arrangement, decrease considerably the THD and IMD while you're at it. Now that should definitely happen!

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Ricci....what does the response look like with the access panels removed? (Basically, what does it look like as a straight up vented cabinet).

 

Also, have you looked into driving the front/rear drivers separately and then adding delay to get them more in phase?

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You know the sad thing...If I really did strap another K20 on one, It would gain 3dB of headroom at maximum. Hardly worth it. 

 

^^^^^

THIS.  I know that here at d-b we deal with pretty informed folks, but most ppl would think that adding this much wattage would net more than 3dB.  

 

JSS

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Ricci....what does the response look like with the access panels removed? (Basically, what does it look like as a straight up vented cabinet).

 

Also, have you looked into driving the front/rear drivers separately and then adding delay to get them more in phase?

 

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.

 

post-5-0-18517300-1469627805_thumb.png

 

I doubt delaying the pairs of drivers individually will do anything good. This will then cause them to load the common vented section in a delayed manner. I would also be required to use 2 amps or at least a pair of amp channels to run it that way. If the amp doesn't have internal DSP it would require separate signals for the amp/s. On a bass maker this industrial strength I'll only be running bridged amps on it. Most of the top end and excursion related differences are simply due to the acoustic loading of the drivers into the short horn path. DSP cannot change that. Some delay relative to each other might possibly make some improvements in the combined output but the complications and potential negative effects introduced into the vented section make me doubtful it'd be a net gain.

 

Now if this was a different design with separated back chambers for the drivers that could be an interesting test. I wonder if it could improve the driver behavior with the 21Ipal system I had designed and perhaps make the excursion profiles line back up.

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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

I found this part to be particularly brilliant when I was playing with your Hornresp model. The slot loading adds so little volume gain everywhere above 18Hz! No front chamber ports needed. Sure it ruins your response above 100Hz, but that huge 12" rear chamber port already did that, so nothing lost. The extra sensitivity means this setup could easily be wheeled outside (with a crane) for PA use. Plus, when you equalize it to flat (or downward sloping curve like most will do) the upper band distortion gets stupid low. All of the upper band distortion spikes caused by out-of-band resonances vanish!

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Josh, fascinating read on the M.A.U.L. I have one big question. So this cabinet is a 6th order bandpass and a horn hybrid, where the bandpass boosts the low end and the horn boosts the upper end. Does that mean unlike a vented cabinet, the driver's sound below the knee of the horn is still in phase with the horn, and the output below the knee is the same as a sealed cab?

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I found this part to be particularly brilliant when I was playing with your Hornresp model. The slot loading adds so little volume gain everywhere above 18Hz! No front chamber ports needed. Sure it ruins your response above 100Hz, but that huge 12" rear chamber port already did that, so nothing lost. The extra sensitivity means this setup could easily be wheeled outside (with a crane) for PA use. Plus, when you equalize it to flat (or downward sloping curve like most will do) the upper band distortion gets stupid low. All of the upper band distortion spikes caused by out-of-band resonances vanish!

 

Exactly. I was sort of surprised too when I stumbled on that arrangement. Something like this isn't made to blend with mains at 150Hz anyway so the jags above the SW range don't matter to me a bit. I'll make that trade. I'm most likely going to be using a steep 80-90Hz low pass anyway. I would love to try the pair as the LFE channel of an outdoor theater. That would be fun.

 

 

Josh, fascinating read on the M.A.U.L. I have one big question. So this cabinet is a 6th order bandpass and a horn hybrid, where the bandpass boosts the low end and the horn boosts the upper end. Does that mean unlike a vented cabinet, the driver's sound below the knee of the horn is still in phase with the horn, and the output below the knee is the same as a sealed cab?

 

 

Below the vent tuning the system acts just like a regular old vented cab. Excursion spikes quickly and output drops off. The short 4ft horn section really only loads above 60Hz however it manages to provide gain over a direct radiating arrangement over a very large bandwidth. In this case what we have are a 70 lb, 19" deep driver crammed into what is functionally a 155L vented cab tuned to 15.5Hz :rolleyes:  multiplied by 4. It still behaves like a vented system below tuning but since the airspace is so undersized for the tuning and there are 4 drivers worth of displacement to burn through it takes a huge amount of voltage to push the drivers too far, even well below tuning. Of course these drivers can't actually bottom out due to the magnetic braking effect of the opposed gap...But if they could be it'd still take a lot of amplifier to get there. I don't think the K20 can. Maybe an 8Hz burst or something.

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BTW I wanted to note to everyone that there are a few things about the current version of Data-bass that result in some typos or odd information. Some of the information is entered via a drop down menu and the options available are limited. An example is voice coil diameter for the drivers. The drop down does not have an option for a 4.5" coil or even a 2.5", both fairly common sizes. (Yes I know that the SI HT-18 has a 2.5" coil for the hundredth time!) They show up rounded up to the next size. Another example is the system type. We do not have bandpass as an available choice at the minute. That is why this is listed as a horn even though it's closer to a 6th order bandpass truly. This is also why the 19 RF is listed as an 18". 19" isn't a choice currently. All of that will be fixed when the next DB comes around at the end of 2023 when Kyle gets finished with it. :D

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Below the vent tuning the system acts just like a regular old vented cab. Excursion spikes quickly and output drops off. The short 4ft horn section really only loads above 60Hz however it manages to provide gain over a direct radiating arrangement over a very large bandwidth. In this case what we have are a 70 lb, 19" deep driver crammed into what is functionally a 155L vented cab tuned to 15.5Hz :rolleyes:  multiplied by 4. It still behaves like a vented system below tuning but since the airspace is so undersized for the tuning and there are 4 drivers worth of displacement to burn through it takes a huge amount of voltage to push the drivers too far, even well below tuning. Of course these drivers can't actually bottom out due to the magnetic braking effect of the opposed gap...But if they could be it'd still take a lot of amplifier to get there. I don't think the K20 can. Maybe an 8Hz burst or something.

 

Sorry I wasn't being clear. I was talking about the short horn section for the upper bass. My mind was blown with the idea of combining horn and 6th order band pass to gain up high and low (except for the middle). In vented systems the driver is essentially useless below tuning because of the 24dB/oct drop off from the vent being out of phase with the main driver below tuning. So, in order for this hybrid to work, it must mean that the horn section augments the >60Hz, but below the knee of the horn it does not reduce output (in comparison with a sealed cab of the same size) like a vented/bandpass enclosure would below their tuning point. That was the big idea I wanted to confirm. 

 

If that's true, it seems like a no brainer to do a short horn in a large vented enclosure to get a boost up high from the short horn and down low from the vent. 

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If that's true, it seems like a no brainer to do a short horn in a large vented enclosure to get a boost up high from the short horn and down low from the vent. 

 

I don't disagree that it seems like a no brainer now, though I'm not even close to an expert on subwoofer design; if it isn't sealed, I'm pretty much not interested but that's personal.  But funny how it always takes a master to point out something that others then say, oh yeah, that makes perfect sense now.  Put more succinctly, Josh Ricci is the man!

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If that's true, it seems like a no brainer to do a short horn in a large vented enclosure to get a boost up high from the short horn and down low from the vent.

It's a very efficient approach. In pro audio, the Dynacord Alpha B3 is using a ported sub with a straight horn, almost same dimensions as MAUL and it gets up to 60% efficiency over 55 hz to 85 hz from some regular 18 inch EV drivers.

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Man..... your going to force me to drive to down for a demo if you keep going at this rate..... Its only about 2 hours one way lol....  I was already tempted as crap when you posted those Chase subs for sale (which my buddy ended up buying)......

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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

 

I doubt delaying the pairs of drivers individually will do anything good. This will then cause them to load the common vented section in a delayed manner. I would also be required to use 2 amps or at least a pair of amp channels to run it that way. If the amp doesn't have internal DSP it would require separate signals for the amp/s. On a bass maker this industrial strength I'll only be running bridged amps on it. Most of the top end and excursion related differences are simply due to the acoustic loading of the drivers into the short horn path. DSP cannot change that. Some delay relative to each other might possibly make some improvements in the combined output but the complications and potential negative effects introduced into the vented section make me doubtful it'd be a net gain.

 

Now if this was a different design with separated back chambers for the drivers that could be an interesting test. I wonder if it could improve the driver behavior with the 21Ipal system I had designed and perhaps make the excursion profiles line back up.

 

Hi Josh,

 

That looks like quite a fun and highly effective design you've brought to life... so long as you have others around to move it.  :o

 

Thanks for posting the with/without for comparison.  For those curious about using such design, this is ultimately what determines if you've done something useful with the front chamber.  While trickier to compare, as it requires a bit more back/forth adjustment in models, matching either the SPL or excursion at a few frequencies in the loading range let you know if you are just gaining sensitivity (still worthwhile) or if you are also seeing some useful acoustic loading.  I've played with many variations on this sort of 4th/6th order loading, and you can almost always get a smoother result from sort of front pathway than a classic chamber w/small port, and you don't suffer from the huge mess caused by a small port's dynamic behavior in the upper bandwidth nor the out of band peaking... as your simulation shows.  

 

You also hit on the other benefit with such high motor strength woofers in your later post about the under-sized ported box.  With a little creativity in the chamber size, length, and tapering it is easy to push some of the upper bandwidth efficiency down into the heart of the operational range and achieve a response which would require a very heavy or hard to build woofer.  Using 2 woofers at different offsets along the chamber can also help stagger notches and any resonant issues with the front pathway.

 

Thinking back, I believe the pro subwoofer cabinet Acoupower put together to demonstrate their woofers used a higher tuned, non-opposed variation on this design.

 

Congrats on the results aligning with predictions and how well it appears to have come together.  I know how much planning and head scratching must have gone into bringing this to life! 

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Sorry I wasn't being clear. I was talking about the short horn section for the upper bass. My mind was blown with the idea of combining horn and 6th order band pass to gain up high and low (except for the middle). In vented systems the driver is essentially useless below tuning because of the 24dB/oct drop off from the vent being out of phase with the main driver below tuning. So, in order for this hybrid to work, it must mean that the horn section augments the >60Hz, but below the knee of the horn it does not reduce output (in comparison with a sealed cab of the same size) like a vented/bandpass enclosure would below their tuning point. That was the big idea I wanted to confirm. 

 

If that's true, it seems like a no brainer to do a short horn in a large vented enclosure to get a boost up high from the short horn and down low from the vent. 

 

I see what you are saying now. It's really no different than a 6th order bandpass or back vented scoop type cab. Yes the upper section only loads down to a relatively high frequency but below that point the drivers are loaded into the vented portion so it controls excursion and there's no issue with loss of control of the drivers. The response of the 2 sections are in phase above the lower tuning and below the upper section so you also get some amount of gain there.

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Hi Josh,

 

That looks like quite a fun and highly effective design you've brought to life... so long as you have others around to move it.  :o

 

Thanks for posting the with/without for comparison.  For those curious about using such design, this is ultimately what determines if you've done something useful with the front chamber.  While trickier to compare, as it requires a bit more back/forth adjustment in models, matching either the SPL or excursion at a few frequencies in the loading range let you know if you are just gaining sensitivity (still worthwhile) or if you are also seeing some useful acoustic loading.  I've played with many variations on this sort of 4th/6th order loading, and you can almost always get a smoother result from sort of front pathway than a classic chamber w/small port, and you don't suffer from the huge mess caused by a small port's dynamic behavior in the upper bandwidth nor the out of band peaking... as your simulation shows.  

 

You also hit on the other benefit with such high motor strength woofers in your later post about the under-sized ported box.  With a little creativity in the chamber size, length, and tapering it is easy to push some of the upper bandwidth efficiency down into the heart of the operational range and achieve a response which would require a very heavy or hard to build woofer.  Using 2 woofers at different offsets along the chamber can also help stagger notches and any resonant issues with the front pathway.

 

Thinking back, I believe the pro subwoofer cabinet Acoupower put together to demonstrate their woofers used a higher tuned, non-opposed variation on this design.

 

Congrats on the results aligning with predictions and how well it appears to have come together.  I know how much planning and head scratching must have gone into bringing this to life! 

 

 

Thanks Mark.

 

Yes...Much head scratching and cursing. Mostly over how to fit everything together. Think I started on it almost 4 years ago and settled on the bastard 6th order type maybe 2 years back. Time flies. Whipping up a simulation is the easy part! I thought about contacting you to discuss things a few times because I knew you had some experience with unusual bandpass loadings.  

 

Agreed about using some sort of slot or horn loading up top versus a port. Those are the same conclusions I came to. A positive expansion also gives a chance to use a bit more area at the exit than possible with a port which can help keep airspeeds down while also avoiding issues with the internal vent opening placement and loading. It was also easier to fit this type of short expansion than a vent in a space starved design like this one. Overall it was a win/win.

 

I remember Acoupower. Always wanted to mess with some of their drivers. I remembered their pro audio designs as 4th order with the crazy huge port flares? It has been a long time since I looked at those. I'll have to check out this Dynacord Alpha B3 Paul mentioned as well. Yet another company I've never heard of. I must really be slipping lately.

 

On a side note your buddy Jeff is starting to sell me on slim profile slot ports.

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BTW I wanted to note to everyone that there are a few things about the current version of Data-bass that result in some typos or odd information. Some of the information is entered via a drop down menu and the options available are limited. An example is voice coil diameter for the drivers. The drop down does not have an option for a 4.5" coil or even a 2.5", both fairly common sizes. (Yes I know that the SI HT-18 has a 2.5" coil for the hundredth time!) They show up rounded up to the next size. Another example is the system type. We do not have bandpass as an available choice at the minute. That is why this is listed as a horn even though it's closer to a 6th order bandpass truly. This is also why the 19 RF is listed as an 18". 19" isn't a choice currently. All of that will be fixed when the next DB comes around at the end of 2023 when Kyle gets finished with it. :D

 

 

2017

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