So, what exactly is this ZOD Audio M.A.U.L? - Page 3 - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 54Likes
Reply
 
Thread Tools
post #61 of 101 Old 07-26-2016, 04:55 PM
AVS Forum Special Member
 
WereWolf84's Avatar
 
Join Date: May 2011
Posts: 1,135
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 399 Post(s)
Liked: 170
is this the ultimate subwoofer? first subwoofer that meet CEA-2010 All Time Max (10-80Hz)?

I guess we have an answer for this question asked by @kutlow few years ago

https://www.avsforum.com/forum/155-di...ester-now.html

Last edited by WereWolf84; 07-26-2016 at 05:48 PM.
WereWolf84 is online now  
Sponsored Links
Advertisement
 
post #62 of 101 Old 07-26-2016, 05:12 PM
AVS Forum Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 21,148
Mentioned: 822 Post(s)
Tagged: 1 Thread(s)
Quoted: 2909 Post(s)
Liked: 3590
Quote:
Originally Posted by Ricci View Post
Nothing magic about it for sure.
...
I wouldn't suggest anyone build a copy. It would be better to adapt a similar style design to the space and dimensions wanted. Different drivers, layout, vent, tune, etc would make more sense. Mine is just a product of the limitations I am dealing with for placement and wanting as much output as possible from it.

may not be anything magic about it, but it is a good design that works.


your second point is really the best way to think about all this stuff. the challenge is that without having skills like you have, most folks are kind of limited to "off the shelf" designs.


this may (or may not lol) be of some value when it comes to port velocity vs. compression.
https://www.avsforum.com/forum/155-di...l#post41118346


just eyeballing some rough numbers, it seems like the zod maul is roughly following a similar model.

Listen. It's All Good.
LTD02 is offline  
post #63 of 101 Old 07-26-2016, 06:02 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,179
Mentioned: 309 Post(s)
Tagged: 0 Thread(s)
Quoted: 3719 Post(s)
Liked: 3686
Quote:
Originally Posted by Ricci View Post

The 12" port did surprisingly well. Some compression and a bit of noise with the high power sine waves at tune but that happens on every vented system I've ever tested. Thought it might compress way worse than it did. There is a huge amount of air moving out of it. Blow your clothes back from 10ft away amounts.
That's one of the reasons I went with two drivers per enclosure, I wanted minimal port noise and compression at high power levels. The other was weight. Definitely worked, but I'm using twice the space per driver as you, so that's a big trade off. Worth it IMO if the space is available. The potential output at these low frequencies (15hz ish) with strong motored high power drivers is just insane with huge enclosures / ports. I've been afraid for my house at times when the amp was barely even lighting up.
Scott Simonian and LTD02 like this.
notnyt is offline  
Sponsored Links
Advertisement
 
post #64 of 101 Old 07-26-2016, 06:27 PM
AVS Forum Special Member
 
Decadent_Spectre's Avatar
 
Join Date: Sep 2005
Posts: 1,518
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 381 Post(s)
Liked: 182
Quote:
Originally Posted by Ricci View Post
Nothing magic about it for sure. Brute force approach in effect. They are going to be fun on Friday nights at beer practice.

Moving it is not that bad. Used a shop dolly with 4" casters. Tip it up and slide it under. Need 2 people though. I can flip it up and over myself but it is definitely not easy. Now lifting it? Better bring a fork lift.

The 12" port did surprisingly well. Some compression and a bit of noise with the high power sine waves at tune but that happens on every vented system I've ever tested. Thought it might compress way worse than it did. There is a huge amount of air moving out of it. Blow your clothes back from 10ft away amounts.

I wouldn't suggest anyone build a copy. It would be better to adapt a similar style design to the space and dimensions wanted. Different drivers, layout, vent, tune, etc would make more sense. Mine is just a product of the limitations I am dealing with for placement and wanting as much output as possible from it.
Agree. Particularly the brute force part. Some pro companies have been also using high power density style subs with high powered amps and hybrids for a while. Years ago I heard 4x Martin ASX in a large club which is a fairly early example of the modern hybrid, the sound wasn't for me though so I passed them over. Klipsch also has a sort of hybrid with the port firing into the horn IIRC. Never saw any measurements or other info though.

I read your post on data bass and your findings are pretty spot on with what I've read/observed over the years, thanks for posting all the info up for all of us to read. Your point about the FLH vs low corner vs size vs sens is particularly true and hybrids such as BP/Horns are one way to keep size down.

All you guys who want something interesting to analyze need to go to db.com and start comparing the sealed RF to this.

BTW if you are using 8x of the RFs in these, what are you using in your sealed cabs at home? Or do you have 16x RFs?
Decadent_Spectre is offline  
post #65 of 101 Old 07-26-2016, 06:40 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,509
Mentioned: 200 Post(s)
Tagged: 0 Thread(s)
Quoted: 5985 Post(s)
Liked: 5114
Josh has a quad dual-opposed sealed XXX18 for his home HT system.

Or maybe he replaced all the XXX18's with the RF's. I forget. It's one of those though.
Scott Simonian is offline  
post #66 of 101 Old 07-26-2016, 07:29 PM
AVS Forum Special Member
 
Decadent_Spectre's Avatar
 
Join Date: Sep 2005
Posts: 1,518
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 381 Post(s)
Liked: 182
Last I heard he replaced the REs with the RFs, IIRC there was a thread about it on db where he outlined why he went with the RFs including better top end.
Decadent_Spectre is offline  
post #67 of 101 Old 07-26-2016, 08:12 PM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,789
Mentioned: 197 Post(s)
Tagged: 2 Thread(s)
Quoted: 1385 Post(s)
Liked: 1999
Quote:
Originally Posted by Decadent_Spectre View Post
Last I heard he replaced the REs with the RFs, IIRC there was a thread about it on db where he outlined why he went with the RFs including better top end.

http://data-bass.ipbhost.com/index.p...cussion/page-1
lukeamdman is offline  
post #68 of 101 Old 07-26-2016, 09:39 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,509
Mentioned: 200 Post(s)
Tagged: 0 Thread(s)
Quoted: 5985 Post(s)
Liked: 5114
That's right. I remember now. Thanks guys.
Scott Simonian is offline  
post #69 of 101 Old 07-27-2016, 12:49 AM
AVS Forum Special Member
 
wlhungdude's Avatar
 
Join Date: Dec 2006
Location: Evansville, IN
Posts: 1,038
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 208 Post(s)
Liked: 265
well crap. time for new glasses. I'd been seeing it as M.A.U.I. and trying to figure out what Hawaii had to do with it.

mods, can we have a 'dislike' button ?
wlhungdude is offline  
post #70 of 101 Old 07-27-2016, 06:59 AM
AVS Forum Special Member
 
Join Date: Jan 2015
Location: United States
Posts: 2,510
Mentioned: 48 Post(s)
Tagged: 0 Thread(s)
Quoted: 1248 Post(s)
Liked: 1934
Quote:
Originally Posted by LTD02 View Post
this one shows roughly the gain vs. ported.



efficiency is a tradeoff. it drops in the 40hz ballpark, but increases dramatically in the upper bass as a result of loading the front of the driver. imho, this is the primary advantage of the design--it allows for using relatively low efficiency, long throw woofers, which are great for maximizing the low end bass, but then it loads them up so they have pro audio like output in the upper bass.

[/IMG]
Oddly enough,

If you look at the efficiency curve and the FR curve, it would be a great design for car audio. As cabin gain kicks in, the deep bass drops off but still is more efficient than a ported box. Still is not as efficient as a horn but those won't fit realistically in a car for most people.

For pro sound, any efficiency gain is great to take the load off the amps with PEQ being standard. Although not as efficient as a FLH or TH, that design would allow more SPL by weight/size than ported so a win.

For PA/block party purposes, that design would be a great option. You can go low when needed but for the main output, the 40 to 100Hz band it really has the efficiency required for general music. This is what Ricci was going for so a different option when scaled to the real world.

Thanks for the info LTD, checking over the design--the four 15's I use in my garage subs won't work with the design. They will remain PPSL ported for their life. I can hit reference levels at 4 meters with "only" 400 watts of power, can't complain too much about the efficiency.

For home use, a pair of SWS15 ported to 18Hz and powered by my XTi1002 is still in the lead. Maybe my wife will want more and buy me a very good table saw and various tools to build a pair of lilwreckers. It could happen.

Now for the dual driver MAUL builds that are stuffed in SUVs to start rolling out. Nobody ever said car audio was sane, after all.... those RF subs are made for car audio.
Scott Simonian likes this.
18Hurts is offline  
post #71 of 101 Old 07-27-2016, 12:37 PM
AVS Forum Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 22,564
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 1756 Post(s)
Liked: 617
Very impressive, Josh!

Curious why with such a large space you placed an emphasis on power density.

Just guessing, but I'd think you could have gotten the same performance with double the volume and half the cost.

Noah
noah katz is online now  
post #72 of 101 Old 07-27-2016, 01:30 PM
AVS Forum Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 21,148
Mentioned: 822 Post(s)
Tagged: 1 Thread(s)
Quoted: 2909 Post(s)
Liked: 3590
Quote:
Originally Posted by 18Hurts View Post


...
the four 15's I use in my garage subs won't work with the design. They will remain PPSL ported for their life. I can hit reference levels at 4 meters with "only" 400 watts of power, can't complain too much about the efficiency.
...

the bl curve that was posted for the 15sws a long while back never really impressed me. however, push-pull would seem to solve both the offset as well as the asymmetrical rolloff in field strength. can you tell if that is actually audible, or do you think it may be one of those theoretical things that isn't so noticeable in practice?

Listen. It's All Good.
LTD02 is offline  
post #73 of 101 Old 07-27-2016, 02:42 PM
AVS Forum Special Member
 
Ricci's Avatar
 
Join Date: Mar 2007
Location: Louisville KY
Posts: 5,467
Mentioned: 163 Post(s)
Tagged: 0 Thread(s)
Quoted: 366 Post(s)
Liked: 877
Quote:
Originally Posted by noah katz View Post
Very impressive, Josh!

Curious why with such a large space you placed an emphasis on power density.

Just guessing, but I'd think you could have gotten the same performance with double the volume and half the cost.
That's just what I do. Can't help it.

No doubt you are right but I don't have double the volume or even 10% more volume.
Ricci is offline  
post #74 of 101 Old 07-27-2016, 04:06 PM
AVS Forum Special Member
 
chrapladm's Avatar
 
Join Date: Mar 2010
Location: Adelaide, South Australia
Posts: 4,766
Mentioned: 34 Post(s)
Tagged: 0 Thread(s)
Quoted: 1099 Post(s)
Liked: 443
Maybe not affordable for some but seems to meat anyones FR. I would only be able to do a pro audio version like four 18IPAL's or four 18XL1800's. BUT I think you could use two RF and still easily beat out the pro drivers especially down low.

Either way this design trounces my dual 21 Hybrid.
chrapladm is offline  
post #75 of 101 Old 07-27-2016, 07:37 PM
AVS Forum Special Member
 
Join Date: Jan 2015
Location: United States
Posts: 2,510
Mentioned: 48 Post(s)
Tagged: 0 Thread(s)
Quoted: 1248 Post(s)
Liked: 1934
Quote:
Originally Posted by LTD02 View Post
the bl curve that was posted for the 15sws a long while back never really impressed me. however, push-pull would seem to solve both the offset as well as the asymmetrical rolloff in field strength. can you tell if that is actually audible, or do you think it may be one of those theoretical things that isn't so noticeable in practice?
My garage subs don't use SWS 15's, they use something a bit more efficient but it has a Qts of .48--too high of a Q for the Maul level stuff. It is rather tough to get a good indication of the ultimate sound quality of the PPSL subs in a garage--they tend to shake the house, the garage door and my tools when up to full power--the cops are not happy either.

My love of the SWS has to do with the insane Xmech of 34 or 36mm--no matter what I don't I won't blow them up. Figure if they work well in a Lilwrecker, my use will ensure a long and happy life.

The only thing I gathered about the Maul design is they need low Qts drivers, just trying to wrap my head around the design and downsides.
18Hurts is offline  
post #76 of 101 Old 07-27-2016, 11:27 PM
AVS Forum Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 22,564
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 1756 Post(s)
Liked: 617
Oh OK, I was wrong to assume that a large space to fill with sound meant there was a lot of space for the subs.

Quote:
Originally Posted by Ricci View Post
That's just what I do. Can't help it.

No doubt you are right but I don't have double the volume or even 10% more volume.

Noah
noah katz is online now  
post #77 of 101 Old 07-27-2016, 11:44 PM
AVS Forum Special Member
 
diy speaker guy's Avatar
 
Join Date: Jan 2011
Posts: 1,416
Mentioned: 42 Post(s)
Tagged: 0 Thread(s)
Quoted: 510 Post(s)
Liked: 524
Quote:
Originally Posted by 18Hurts View Post
The only thing I gathered about the Maul design is they need low Qts drivers, just trying to wrap my head around the design and downsides.
The design is super simple - it's actually almost exactly the same thing as PPSL except this is push push (not push pull) and the drivers in this fire into separate slots at the side instead of a single central slot. I guessed what this design was just by looking at the frequency response and impedance curve before the details were released - it's pretty clear what it is with that limited info.

So... this type of design absolutely does not require low qts drivers, any driver that will work in a ported box will work. If you want it to be really small you need low q and low Vas drivers, but really any driver that will work in a ported box will work if you don't mind large size boxes.

Here's how it works - it's a ported box and it's got a slot load on the front side to boost the high frequencies (up around 100 hz). It's a super simple 6th order bandpass. I've advocated this type of thing for quite awhile to boost the high frequencies if it's needed. Here's part of a post from back in March showing how the front slot works to boost the high frequencies from here - https://www.avsforum.com/forum/155-di...l#post42274633 and there's a bit more in post 109 too, another sim with a longer slot that's a lot closer to the response of the MAUL (the peak is wider, there are more dips and they are much narrower). It's a really simple concept - in this case I was talking about using the slot to boost the high end in a sealed sub but it works just the same if it's a ported sub instead of sealed. It takes about 3 minutes to sim this kind of alignment in Hornresp but you can't do it in WinISD.

Quote:
Adding a slot to a sealed box will effectively turn it into a very high tuned 4th order bandpass (and adding a slot to a ported box will turn it into a 6th order bandpass). There's several 1/4 wave simulator programs you can use to simulate a slot accurately (but not WinISD or similar Helmholtz simulators). Hornresp, TL.spp, Akabak can all sim this.

Below is a sim of a sealed box (top pic) compared to the same sealed box with the addition of a slot (second pic). Third pic is both responses overlaid, the red trace with the 10 db spike is the slot version, the blue trace is the regular sealed box. The 4th pic shows the regular sealed box (the black part) and the red part is the slot that's added. The diagram is not to scale at all. The slot is 70 cm long and cross sectional area is 200 sq cm, roughly equating to a 1.5 x 20 inch terminus which might need to be bigger to keep velocity in check but I'd have to check on that, but for this exercise velocity isn't important. It would be an important consideration if you were actually going to build something though.

The 1/4 wavelength of 123 hz is 70 cm, so the big 10 db spike occurs around 123 hz (not exactly but pretty close). Now you will also notice a large notch in response. That is caused by the wave bouncing off the end of the slot and recombining with the main wave before exiting the slot. That notch could be pushed higher in frequency by moving the driver further toward the closed end of the slot (shifted left in the diagram) but I centered it for symmetry because this is just a slot info session. The frequency the spike occurs at can be changed too, based on the slot length. Ideally the driver should be as close to the closed end of the slot as possible to push the big notch as high in frequency as possible.

In real life the 10 db spike won't be quite that high, the sim doesn't account for internal box losses due to the enclosure being less than infinitely rigid. And the spike is relatively narrow so it will be a lower q resonance than shown and will lose a couple (or a few) db in real life. And the same thing goes for the dip, it won't be as deep in real life for the same reason.

This type of slot is very common in dual driver PPSL (push pull slot load) enclosures where both drivers fire into the slot (one facing backwards) to cancel even order harmonics. But you can use it with a single driver as shown here to get a boost at the top of a sub's passband and it can be especially useful if you have an inductance related severe roll off at high frequencies.


Last edited by diy speaker guy; 07-28-2016 at 12:29 AM.
diy speaker guy is offline  
post #78 of 101 Old 07-28-2016, 12:17 AM
AVS Forum Special Member
 
diy speaker guy's Avatar
 
Join Date: Jan 2011
Posts: 1,416
Mentioned: 42 Post(s)
Tagged: 0 Thread(s)
Quoted: 510 Post(s)
Liked: 524
Usually the only place you see slots like this is with PPSL and the goal of PPSL is usually only to take advantage of the push pull arrangement for the even order distortion reduction benefits (which itself is a dubious benefit, as even order distortion can be quite pleasant). In that case the slot is made as small as possible since the slot is just wasted space aside from the distortion benefits, and it's made as shallow as possible to push the spike in response (and the dip that comes right above the spike) as far outside the passband as possible.

BUT if you want that spike in response, as Ricci clearly did, you can tune the slot to put the spike inside the passband. It has to be a fairly long slot to push it's resonance down that low in frequency but it clearly works as the MAUL demonstrates. The MAUL could have been built as PPSL to get the get the distortion reduction by putting the outside slots together in a central location, but even without the push pull arrangement slots can be used to good effect.
diy speaker guy is offline  
post #79 of 101 Old 07-28-2016, 08:29 AM
AVS Forum Special Member
 
Ricci's Avatar
 
Join Date: Mar 2007
Location: Louisville KY
Posts: 5,467
Mentioned: 163 Post(s)
Tagged: 0 Thread(s)
Quoted: 366 Post(s)
Liked: 877
I'm still running the RF's sealed at home.

Noah,
I'd say I did have a lot of space available but the size these are is the absolute max I can fit. Actually the height went a few inches over where I wanted to be.

DIYspeakerguy,
One reason to use an expanding OD horn type slot is to keep air speeds at the mouth lower than with a straight or negative taper. Also push pull works well with some drivers but isn't very feasible with the extreme depth on the ones I used.
Ricci is offline  
post #80 of 101 Old 07-28-2016, 11:38 AM
AVS Forum Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 22,564
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 1756 Post(s)
Liked: 617
I'm not getting why to add to box size to boost the top of the passband; if you've got enough driver and amp for prodigious ULF how could you not have enough upper bass?

Noah
noah katz is online now  
post #81 of 101 Old 07-29-2016, 12:51 PM
AVS Forum Special Member
 
diy speaker guy's Avatar
 
Join Date: Jan 2011
Posts: 1,416
Mentioned: 42 Post(s)
Tagged: 0 Thread(s)
Quoted: 510 Post(s)
Liked: 524
For the same reason it's ported on the low end - more spl with less power. These particular drivers don't necessarily need a boosted top end like many of the super high xmax drivers but even so, less power to produce the required spl at the higher frequencies = less thermal stress on the drivers. Arguably these drivers aren't suffering that much from thermal stress with the available power available to them, but boosting efficiency is almost never a bad idea. As long as you can deal with the frequency response anomalies (the bump in response and the dips right above the bump) then the added efficiency is a good thing. Whether it's worth the extra cab space or not is a judgement call and directly related to the goals for the design.
diy speaker guy is offline  
post #82 of 101 Old 07-29-2016, 01:07 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,509
Mentioned: 200 Post(s)
Tagged: 0 Thread(s)
Quoted: 5985 Post(s)
Liked: 5114
Not a terribly bad idea for this particular driver.

Examine it's compression charts on DB and see that >60hz at very high voltage levels it will severely begin to thermally compress. More sensitivity/efficiency up high above 60hz only helps linearize it's output across all frequencies and at all power input levels.


Woah. 20,000th post.

Thank you. *bow*

Thank you. *bow*

Stereodude, LTD02 and kingpin111 like this.
Scott Simonian is offline  
post #83 of 101 Old 07-29-2016, 01:22 PM
AVS Forum Special Member
 
desertdome's Avatar
 
Join Date: Aug 2004
Location: Blair, NE
Posts: 3,786
Mentioned: 313 Post(s)
Tagged: 0 Thread(s)
Quoted: 1527 Post(s)
Liked: 1856
Quote:
Originally Posted by Scott Simonian View Post
Woah. 20,000th post.
20,000th post about a $20,000 system (original price listed on data-bass) with 20,000 watts in a forum with almost 20,000 threads! Well done!

Attached Thumbnails
Click image for larger version

Name:	DIY Sub Forum.PNG
Views:	468
Size:	16.8 KB
ID:	1572305  

Ponderosa Theater
High Impact AV
- ISF Level III Video Calibrator, THX-HAA HT3 Audio Designer/Calibrator
desertdome is offline  
post #84 of 101 Old 07-29-2016, 01:33 PM
AVS Forum Special Member
 
Join Date: Jan 2015
Location: United States
Posts: 2,510
Mentioned: 48 Post(s)
Tagged: 0 Thread(s)
Quoted: 1248 Post(s)
Liked: 1934
Quote:
Originally Posted by diy speaker guy View Post
Usually the only place you see slots like this is with PPSL and the goal of PPSL is usually only to take advantage of the push pull arrangement for the even order distortion reduction benefits (which itself is a dubious benefit, as even order distortion can be quite pleasant). In that case the slot is made as small as possible since the slot is just wasted space aside from the distortion benefits, and it's made as shallow as possible to push the spike in response (and the dip that comes right above the spike) as far outside the passband as possible.

BUT if you want that spike in response, as Ricci clearly did, you can tune the slot to put the spike inside the passband. It has to be a fairly long slot to push it's resonance down that low in frequency but it clearly works as the MAUL demonstrates. The MAUL could have been built as PPSL to get the get the distortion reduction by putting the outside slots together in a central location, but even without the push pull arrangement slots can be used to good effect.
Thanks for the clarification DIY

The reason I went PPSL in the garage was to protect the drivers inside the slot from flying everything, put them in balance to eliminate vibration (line arrays use them as stands) and if I got any additional efficiency, distortion reduction--just call it a bonus.

One of the PPSL gurus measured a 2.7dB increase in efficiency over ported when the compression ratio was 3:1 Granted, his drivers were for horns so that compression would never cause any motor issues.

It all becomes gray when trying to classify the Maul--a bandpass/horn...yes but a PPSL ported box could be called that...technically. No, I don't plan on modifying my 175 pound PPSLs in the garage to make them a horn--the juice is not worth the squeeze.

It would be great for PA use, get the maximum efficiency out of available space then EQ to get what you want in the room. Using less electricity to get the same SPL is the name of the game, power costs money and heat is always bad for amps. Every little bit counts.
18Hurts is offline  
post #85 of 101 Old 07-29-2016, 01:36 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,509
Mentioned: 200 Post(s)
Tagged: 0 Thread(s)
Quoted: 5985 Post(s)
Liked: 5114
Quote:
Originally Posted by desertdome View Post
20,000th post about a $20,000 system (original price listed on data-bass) with 20,000 watts in a forum with almost 20,000 threads! Well done!





homeskizzle likes this.
Scott Simonian is offline  
post #86 of 101 Old 07-29-2016, 02:10 PM
AVS Forum Special Member
 
diy speaker guy's Avatar
 
Join Date: Jan 2011
Posts: 1,416
Mentioned: 42 Post(s)
Tagged: 0 Thread(s)
Quoted: 510 Post(s)
Liked: 524
Quote:
Originally Posted by 18Hurts View Post
Thanks for the clarification DIY

The reason I went PPSL in the garage was to protect the drivers inside the slot from flying everything, put them in balance to eliminate vibration (line arrays use them as stands) and if I got any additional efficiency, distortion reduction--just call it a bonus.

One of the PPSL gurus measured a 2.7dB increase in efficiency over ported when the compression ratio was 3:1 Granted, his drivers were for horns so that compression would never cause any motor issues.
Any efficiency gain from a PPSL will be outside (above) the subwoofer's passband unless the slot is quite long, like the MAUL's slots. This is usually by design in PPSL, as the frequency response bump is pushed outside the passband by design. The compression ratio of the slot doesn't really affect the efficiency but it does affect the air velocity and to some extent the tuning. If the slot isn't long enough to put the frequency response bump inside the sub's passband it isn't going to affect the sub's efficiency at all in any way.

Quote:
It all becomes gray when trying to classify the Maul--a bandpass/horn...yes but a PPSL ported box could be called that...technically. No, I don't plan on modifying my 175 pound PPSLs in the garage to make them a horn--the juice is not worth the squeeze.
I don't think it's grey at all - it makes no difference what you call it. It's a 6th order bandpass or a slot loaded ported box. The slightly tapered slot doesn't make it a horn. What the tapered slot does is lower air velocity and slightly raise the slot tuning. If the slot was straight (not tapered) the exit velocity would be higher and the slot tuning (the bump in frequency response) would be a bit lower. The taper is not adding any significant amount of gain - maybe a bit but not much.

Quote:
It would be great for PA use, get the maximum efficiency out of available space then EQ to get what you want in the room. Using less electricity to get the same SPL is the name of the game, power costs money and heat is always bad for amps. Every little bit counts.
Depends on the design goals. The slots take up a LOT of space in exchange for the benefits provided. Bigger is always better from an efficiency standpoint but bigger is the enemy of small packsize, which is usually pretty high on PA goal lists.
diy speaker guy is offline  
post #87 of 101 Old 07-29-2016, 02:18 PM
AVS Forum Special Member
 
rhodesj's Avatar
 
Join Date: Apr 2005
Posts: 2,158
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 600
I read the thread on data-bass, and one of Ricci's requirements for the location the sub is installed is that all the drivers/ports fire from the same side of the box. That pretty much defines the need, and explains why the box volume is spent on the slot rather than the bass reflex chamber.
rhodesj is offline  
post #88 of 101 Old 07-29-2016, 03:54 PM
AVS Forum Special Member
 
Ricci's Avatar
 
Join Date: Mar 2007
Location: Louisville KY
Posts: 5,467
Mentioned: 163 Post(s)
Tagged: 0 Thread(s)
Quoted: 366 Post(s)
Liked: 877
Hey Rhodesj that is correct. Everything has to radiate from one face. That was a big factor.



Quote:
Originally Posted by Scott Simonian View Post
Not a terribly bad idea for this particular driver.

Examine it's compression charts on DB and see that >60hz at very high voltage levels it will severely begin to thermally compress. More sensitivity/efficiency up high above 60hz only helps linearize it's output across all frequencies and at all power input levels.


Woah. 20,000th post.

Thank you. *bow*

Thank you. *bow*

That's a big fat negative captain. What you see is not the driver compressing in this case but the amp current limiting being bridged into a 2ohm load.

Congrats on 20K. What do you win?
Ricci is offline  
post #89 of 101 Old 07-29-2016, 04:01 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,509
Mentioned: 200 Post(s)
Tagged: 0 Thread(s)
Quoted: 5985 Post(s)
Liked: 5114
Oh right. That's cuz you're still using that weak sauce K20.




It's pretty scary that this amp isn't enough! Yikes!

Thanks for the correction. My bad.


Nope. Didn't win anything. Could be set to delay though.... wait one.
Scott Simonian is offline  
post #90 of 101 Old 07-29-2016, 08:07 PM
AVS Forum Special Member
 
Decadent_Spectre's Avatar
 
Join Date: Sep 2005
Posts: 1,518
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 381 Post(s)
Liked: 182
Quote:
Originally Posted by diy speaker guy View Post
The design is super simple - it's actually almost exactly the same thing as PPSL except this is push push (not push pull) and the drivers in this fire into separate slots at the side instead of a single central slot.
Quote:
Originally Posted by diy speaker guy View Post
Any efficiency gain from a PPSL will be outside (above) the subwoofer's passband unless the slot is quite long, like the MAUL's slots.
+ 1

Do note the length of the cab is about 4 feet (rounding it from 47/47.5") and the slot runs the whole length if I saw the drawings right, that means 1/4th WL at 70Hz about and if you compare the maul db numbers to the sealed RF numbers you can see it gains about 3-6db in roughly the 80-90Hz band over 4x sealed RFs (using 4x since the maul also uses 4x RFs) when looking at both burst and long term sweeps, narrow band and reasonable gain.

Josh has mentioned the amp current limiting which can be correlated to some degree with the impedance vs compression, there is a bit of an impedance peak 80-90Hz. Perhaps the loading is down a bit but still useful to 60Hz?
Decadent_Spectre is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off