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View Full Version : Quasi-Sixth Order Series-Tuned Bandpass



JayDubb757
07-18-2012, 12:56 PM
I will be building a box for murph ;
It's going to be a quasi-6th order bandpass for one Boston Acoustics G5 12.
Mobile Enclosures came up with the design.
I ordered the materials today, and will start building this weekend.


http://i45.tinypic.com/2iscnpz.jpg

http://i48.tinypic.com/fx8k10.jpg

http://i45.tinypic.com/2v2wgbd.jpg

http://i47.tinypic.com/dcx5ap.jpg

JayDubb757
07-18-2012, 01:38 PM
Whats the volumes of the front and rear chambers??

NIck


murph ; would have to tell you that, all he gave me was the plans.

murph
07-18-2012, 06:37 PM
Whats the volumes of the front and rear chambers??

NIck

Not going to reveal anything. If you want something of the sort contact mobile enclosures.

kushy_dreams
07-18-2012, 10:23 PM
what kind out goal for output? flat response?

murph
07-18-2012, 10:30 PM
what kind out goal for output? flat response?

Decently flat response from low 20's to low 60's. The chart I have for response looks very promising.

kushy_dreams
07-18-2012, 10:44 PM
When I was running the pair tuned at 31.xx hz they had no problem reaching low but seemed to fall off between 55-60.

CAT MAN
07-18-2012, 10:53 PM
i wanna hear it. and J get with me on my box. ill text you tomorrow i guess

murph
07-18-2012, 10:55 PM
When I was running the pair tuned at 31.xx hz they had no problem reaching low but seemed to fall off between 55-60.

Looking back at the response it seems to extend to about 75 well. The box also is smaller than what my 4th would have been it's only a little over 3 cubes.

---------- Post added at 10:55 PM ---------- Previous post was at 10:54 PM ----------


i wanna hear it. and J get with me on my box. ill text you tomorrow i guess

You will.

keep_hope_alive
07-18-2012, 11:29 PM
cool

Falcons
07-18-2012, 11:42 PM
Mobile designed my box too. Can't wait to build it. It's definately something different from the norm for a trunk build.

JayDubb757
07-21-2012, 01:21 PM
Got the box done. Here's some pics.


http://i45.tinypic.com/1607xf.jpg

http://i50.tinypic.com/33nhglx.jpg

http://i46.tinypic.com/2128eue.jpg

http://i49.tinypic.com/2igirzp.jpg

http://i47.tinypic.com/ao4yfb.jpg

JayDubb757
07-21-2012, 01:25 PM
http://i47.tinypic.com/e84fv8.jpg

http://i45.tinypic.com/72swn7.jpg

http://i49.tinypic.com/2m29nc7.jpg

http://i50.tinypic.com/2dtric4.jpg

http://i46.tinypic.com/20kuhi8.jpg

---------- Post added at 01:25 PM ---------- Previous post was at 01:25 PM ----------

http://i47.tinypic.com/vnf152.jpg

http://i48.tinypic.com/33dgkmc.jpg

http://i47.tinypic.com/qrbvi0.jpg

http://i48.tinypic.com/2dl6x42.jpg

http://i50.tinypic.com/rwjp1i.jpg

double 07
07-21-2012, 01:27 PM
Nice box and SHOP!!!!!

JayDubb757
07-21-2012, 01:34 PM
Nice box and SHOP!!!!!


Thanks man! Not my shop, I just work there. Beats the hell out of building a box at home.

husker77
07-21-2012, 02:16 PM
http://i46.tinypic.com/20kuhi8.jpg


What is going on here? I am curious about this box that is for sure.

JayDubb757
07-21-2012, 03:56 PM
What is going on here? I am curious about this box that is for sure.



Weather striping....The side has to be removable to access the subwoofer, and the weather striping helps the access panel stay air tight and with vibrations.
Will deliver to murph ; today or tomorrow. Maybe he can post a video of the performance of this box...I'm curious myself.

CAT MAN
07-21-2012, 03:58 PM
we gotta do my new one soon

JayDubb757
07-21-2012, 04:01 PM
we gotta do my new one soon



Quit bull$hitting and get your design finished!;)

murph
07-21-2012, 04:06 PM
Weather striping....The side has to be removable to access the subwoofer, and the weather striping helps the access panel stay air tight and with vibrations.
Will deliver to murph ; today or tomorrow. Maybe he can post a video of the performance of this box...I'm curious myself.

Where are we going to meet?

husker77
07-21-2012, 04:25 PM
Weather striping....The side has to be removable to access the subwoofer,

I see, so that is all that square cutout is for? I was thinking it was some kind of pseudo port or something, when I first seen the plans.

wenn_du_weinst
07-21-2012, 04:26 PM
looks built well, also looks like one picky bastard.

JayDubb757
07-21-2012, 04:28 PM
looks built well, also looks like one picky bastard.

picky? me or murph lol

thanks man

wenn_du_weinst
07-21-2012, 04:34 PM
the box, as in temperamental

murph
07-21-2012, 04:40 PM
the box, as in temperamental

How so? Mobile Enclosures designed it so no barking up our trees.

JayDubb757
07-21-2012, 04:48 PM
the box, as in temperamental

Yeah, from what I've read on quasi 6th's, they're either great or horrible.
I think mobile has designed a few though, and the customers seem happy.
I'll be meeting murph in a couple hours and he's bringing the sub.
I'll try to get a vid of it in action.

wenn_du_weinst
07-21-2012, 04:51 PM
Yeah, from what I've read on quasi 6th's, they're either great or horrible.
I think mobile has designed a few though, and the customers seem happy.
I'll be meeting murph in a couple hours and he's bringing the sub.
I'll try to get a vid of it in action.
yeah as long as they are done right they are great, just picky and need a ton of math to get right

How so? Mobile Enclosures designed it so no barking up our trees.

they leave very very little room for error, it has to be designed perfect to work correctly.

double 07
07-21-2012, 04:54 PM
Well I guess we are all going to find out if MOBLE really is "DA MAN" huh?

wenn_du_weinst
07-21-2012, 04:59 PM
from what I have seen before he should be able to pull it off.

JayDubb757
07-21-2012, 05:02 PM
from what I have seen before he should be able to pull it off.


Looks like it might be some port noise though.

J31Rob
07-21-2012, 05:50 PM
Planned and executed in great fashion. Nice work.

kushy_dreams
07-21-2012, 06:42 PM
vids! I'm really glad the sub made it to murph ok, that was my first time shipping a sub...I had nightmares about something bad happening in transit.

JayDubb757
07-21-2012, 09:52 PM
vids! I'm really glad the sub made it to murph ok, that was my first time shipping a sub...I had nightmares about something bad happening in transit.


Had to take off those black things around the motor to get the sub threw the access hole, other than that , everything fit properly. murph ; only gave me a short demo...amp was going into protect.
But from what I heard, it crushes the lows! moves a lot of air, and no noticeable port noise.
Came out really nice.

murph
07-21-2012, 10:06 PM
Amp will not let me set the gain to 4 volts only 5 or else the amp cuts out. :crap:

Anyways for one 12 it really slams on 25-35hz and moves some air. It is impressive but also is lacking too in some areas. Not very happy with the majority of frequencies when punch is involved. (It sounds very hollow) Also frequencies at 50hz and up in rap music at least start sounding hollow and muddy. I think if I were to seal it off the muddiness would leave but I can't do anything about the hollow sounds. Impressed for the most part will play with settings and such to get it as good as possible.

kushy_dreams
07-21-2012, 10:18 PM
***** the amp is cutting out on you, is it used?

ThatChevyGuy
07-21-2012, 10:23 PM
why is your amp going into protect? Would like a vid

murph
07-21-2012, 10:24 PM
***** the amp is cutting out on you, is it used?

Yeah it's used but, that isn't why it cuts out. The amp has a clipping indicator light on it which clearly is off a bit. If you push the amp beyond what the clip indicator thinks is right it shuts down to protect the amp. I have it set the best it will get. The amp blasted for an hour and a half no problems once I reset it. (Barley even warm)

murph
07-21-2012, 11:01 PM
To seal or not seal is the question.

kushy_dreams
07-22-2012, 12:48 AM
like to put it in a sealed box?

murph
07-22-2012, 12:53 AM
like to put it in a sealed box?

No seal it off into my cabin.

mazdakid
07-22-2012, 12:57 AM
What way is the port facing now?
Have you tried other ways?

kushy_dreams
07-22-2012, 12:57 AM
ahh gotcha, idk how that would work. I ran the pair subs and port back, they never sounded hollow but a little boomy on a few songs by the black keys with the most recent box. lows were great down to the mid to low 20s and they seemed to get a little distorted sounding above 55-60hz and roll off hard the higher you went.

murph
07-22-2012, 01:00 AM
What way is the port facing now?
Have you tried other ways?

I moved it tonight facing in the cabin but, it was too late to test how well it played. I will test multiple positions tomorrow.

murph
07-22-2012, 01:09 AM
keep_hope_alive Would you say there would be any benefit in this case of sealing it off?

keep_hope_alive
07-22-2012, 10:21 AM
the problems you're having could certainly be from it just sitting in a trunk where phase interference abounds.

if it were me, and i did a box like this, it would vent into the rear deck, and everything else would be completely sealed off. too late for that here, so the next best thing is to seal it off.

pics of the car what you'll have to do to seal it off? this includes the entire rear deck as well.

murph
07-22-2012, 03:47 PM
the problems you're having could certainly be from it just sitting in a trunk where phase interference abounds.

if it were me, and i did a box like this, it would vent into the rear deck, and everything else would be completely sealed off. too late for that here, so the next best thing is to seal it off.

pics of the car what you'll have to do to seal it off? this includes the entire rear deck as well.

You can get a pretty good view of my trunk in this video skip forward a bit

http://www.youtube.com/watch?v=v5R79sdBemI

keep_hope_alive
07-22-2012, 08:18 PM
you'll have to find a spot for the amp. take the time to screw it in place, loom the wires, and route it well and logically. you want the amp out of the way so you can easily move/rotate/flip the box. hopefully the wires you have are long enough to do that.

when you face it forward, you'll have to make filler panels for the sides and top. that box is blocking a lot of airflow to the cabin. facing them backwards you are going to lose a lot of bass out of the car, that will never make it to your headrests.

murph
07-22-2012, 08:35 PM
you'll have to find a spot for the amp. take the time to screw it in place, loom the wires, and route it well and logically. you want the amp out of the way so you can easily move/rotate/flip the box. hopefully the wires you have are long enough to do that.

when you face it forward, you'll have to make filler panels for the sides and top. that box is blocking a lot of airflow to the cabin. facing them backwards you are going to lose a lot of bass out of the car, that will never make it to your headrests.

That is not my current setup... My wiring is cleaned up and my amp is mounted... I was using that as reference to trunk size.

keep_hope_alive
07-22-2012, 08:50 PM
so how is the amp mounted?

murph
07-22-2012, 11:29 PM
so how is the amp mounted?

It is mounted on the 1/3 pull down seat.

The sound issues have been fixed with some eq tweeking. The box is very sensitive to over amplified or clipped music. If a song is either or I have to turn the volume down a bit to get it sounding right again. (only a hand full of songs)

keep_hope_alive
07-23-2012, 12:10 AM
ok. seat mounting is fine, just be sure if you turn the box around that the surround doesn't touch the amp chassis.

the 1/3 seat is usually driver's side. so if you flip the box around the port is on the passenger side.

to seal it off you can just flip it around. use cardboard to mock up the filler panels, cut them out of 3/4" MDF and experiment with them taped to the box and car.

iamamp3pimp
07-25-2012, 05:30 PM
The build looks like it came out fantastic. do you have access to a TL?

I'd like to see comparisons between this enclosure and a standard ported one.

ancorp
07-25-2012, 06:05 PM
The box is gorgeous. But - what's the difference between this and a regular ported box? I wanted to do something like this for a while with a 15 or a 18 in my trunk, firing up inside the box, and sealed off into the cabin.

T3mpest
07-25-2012, 11:42 PM
2 difference resonance points and barely and octave of response..... K

Moble Enclosurs
08-13-2012, 08:17 PM
Hey guys! Justy wanted to chime in here and answer any questions about this build. :D. It was not easy to get that response considering we were required to stay below 3.5 cubes, but all in all I hope it worked out well, and as far as it having two resonances, that is incorrect, and the octave band is around a full octave, which is not bad for a BP design. The goal we had was an SQL to play around the 20-60Hz range, and the first idea was to utilize a 4th order, but I found that this design style worked a bit better than that as far as output in the lower region.
The design was goaled for an in trunk install, BUT the point of interest on the location of the port was to be facing the cabin, which may or may not have been mentioned lol. But all in all, the resonances in the upper range can very well be fixed by sealing it off, though a lot of this has to do with the end of band operation froma lower tuning and trying to control the phase within a small dimensional space given that quasi 6th orders can require a lot of room. All in all, I stuck with a BP design by request of the customer and though a conventional ported box would have worked very well also, the idea was to crush the lows in this case, with high efficiency, and the way to go with that while keeping control of the driver is with a BP.

That all being said, Im glad that an honest review was done and I am glad that the enclosure came out well! The muddiness mentioned can be tweaked obviously by cutoff points and possibly positioning as the response information was based on a single position alone, so please @Murph keep me updated on that and thanks @keep_hope_alive for the help on that as well! If you have any questions, please let me know :D.

Moble Enclosurs
08-13-2012, 08:23 PM
The box is gorgeous. But - what's the difference between this and a regular ported box? I wanted to do something like this for a while with a 15 or a 18 in my trunk, firing up inside the box, and sealed off into the cabin.

Thanks, and the main difference is the control and efficiency. These quasi designs, which can also be referred to as tapped designs depending on the physical structure, can have great efficiency for the use of lower powered amplifiers. This one in particular was designed around a 500W output. SO, for its output on 500W, I hope that it did its job in that respect. But with the control, the great thing is that the compression can be made quite large for lower tuning capabilities, but still control the excursion from the cross-sectional area of the port along with its length. The longer the port (to a point), the better the coupling with the drivers mechanical parameters in relation to tuning of the compression area and beginning of the line. Other than that, in a lot of cases, which this cannot be argued, a typical ported box can very well give a greater response band. But with that, less control in the lower region as well as a possible high peak in the response (though that can easily be controlled by eq settings as well-since they are to be lowered and not raise) from certain drivers designed for SPL purposes. I hope that helps answer a little bit about it. :D

Moble Enclosurs
08-13-2012, 08:25 PM
Those with doubts or concerns need to understand that this particular design was based around the request of a bandpass-originally a 4th, and within a limited volume for BPs as a total volume---hence the quasi effect being utilized. That has to be taken into consideration when you judge its limitations.

murph
08-13-2012, 08:26 PM
Hey guys! Justy wanted to chime in here and answer any questions about this build. :D. It was not easy to get that response considering we were required to stay below 3.5 cubes, but all in all I hope it worked out well, and as far as it having two resonances, that is incorrect, and the octave band is around a full octave, which is not bad for a BP design. The goal we had was an SQL to play around the 20-60Hz range, and the first idea was to utilize a 4th order, but I found that this design style worked a bit better than that as far as output in the lower region.
The design was goaled for an in trunk install, BUT the point of interest on the location of the port was to be facing the cabin, which may or may not have been mentioned lol. But all in all, the resonances in the upper range can very well be fixed by sealing it off, though a lot of this has to do with the end of band operation froma lower tuning and trying to control the phase within a small dimensional space given that quasi 6th orders can require a lot of room. All in all, I stuck with a BP design by request of the customer and though a conventional ported box would have worked very well also, the idea was to crush the lows in this case, with high efficiency, and the way to go with that while keeping control of the driver is with a BP.

That all being said, Im glad that an honest review was done and I am glad that the enclosure came out well! The muddiness mentioned can be tweaked obviously by cutoff points and possibly positioning as the response information was based on a single position alone, so please @Murph keep me updated on that and thanks @keep_hope_alive for the help on that as well! If you have any questions, please let me know :D.

After lots of tweaking I am quite happy with the box. From 26-36 you would think there is a decent 15 in the trunk or possibly even 2 12's. I forgot to shoot a video but, man I am impressed. It plays the bass guitar very well and sounds very clean. I found the low end output to be better when facing the trunk.

Moble Enclosurs
08-13-2012, 08:35 PM
After lots of tweaking I am quite happy with the box. From 26-36 you would think there is a decent 15 in the trunk or possibly even 2 12's. I forgot to shoot a video but, man I am impressed. It plays the bass guitar very well and sounds very clean. I found the low end output to be better when facing the trunk.
Sweet man! Thank you for the extremely quick response! lol. Im glad you like it. Now, regarding the positioning, the ideal for it being facing the front was to control the upper range, which had some to do with that hollowing you mentioned before, but naturally facing the trunk it will excite the low frequencies even more, so either way I am very happy for you! Thank you also for the honest review and I am glad I had the chance to give you a great box that was very complex to design lol. I had very much fun with it! If you need anything in the future, please let me know man. :D

To the others, I do hope that my explanations helped a bit on understanding the limitations we were working with and that the understanding of the idea of that type of design definitely is a tough one as you all mentioned lol, but all in all a great way to gain low end efficiency!

murph
11-18-2012, 08:44 PM
Moble Enclosurs Just wanted to let you know the box pulled off a 137.4 sealed at the dash.

Moble Enclosurs
11-18-2012, 09:46 PM
Was that a musical average or at a specific frequency? Not bad for a single 12 on 500w designed for music.

Moble Enclosurs
11-18-2012, 09:49 PM
Moble Enclosurs Just wanted to let you know the box pulled off a 137.4 sealed at the dash.
Was that a musical average or at a specific frequency? Not bad for a single 12 on 500w designed for music.

murph
11-18-2012, 10:18 PM
Was that a musical average or at a specific frequency? Not bad for a single 12 on 500w designed for music.

Specific frequency either 32 or 33hz. I probably would have scored louder on music since the sine waves I had were not the loudest they could be without clipping.

Moble Enclosurs
11-18-2012, 11:01 PM
Specific frequency either 32 or 33hz. I probably would have scored louder on music since the sine waves I had were not the loudest they could be without clipping.
Wow no kidding. Dead on with the response graph at that frequency also, if you check the response picture in the prints folder from it :applause:. Nice job man! Not meant for SPL testing, but I am curious to know what it can do with a 0dB digital lossless signal. Anyhow, thanks for the update bro. It means a lot to hear about the progress and results of these designs :D Later!