3 chamber dual band pass enclosure! help ! - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th January 2012, 11:09 AM   #1
diyAudio Member
 
Join Date: Nov 2011
Default 3 chamber dual band pass enclosure! help !

Hi

i am new to the diy world, haven't done any diy yet. I have 2 Yugal 10" 8 Ohm, 120 watt woofers (my old amp plays them well on single channel in parallel config. so i will use them in parallel) :-

Qts:0.26
Vas: 290 liters
Fs: 30 Hz
Re: 4 ohm
Le: unknown
Xmax: 3 mm
Qms: unknown
Qes: 0.27
SPL: 94 dB
Dia: 10 inch

I want to make this type of Box for my woofers :-
Click the image to open in full size.
ImageShack® - Online Photo and Video Hosting

and i have calculated this Box for me :-
Click the image to open in full size.
ImageShack® - Online Photo and Video Hosting


as i am new to diy and electronics i don't know whether it will act as per my plans or not !! specially middle section of 80 Liters which i have tuned to 20Hz, i don't know it will produce 20Hz or not but i want to try it, WinISD is showing a Vent Match of 0.25 which is my cause to worry if i select 2 vents then WinISD doubles the port length !! please help me how to solve it !! other two chambers are i think good.

Please help me, this is my first Diy !
someone please correct the photo links !!

Last edited by abhihemu; 17th January 2012 at 06:28 AM. Reason: edited photo links
  Reply With Quote
Old 6th January 2012, 03:38 PM   #2
diyAudio Member
 
Patrick Bateman's Avatar
 
Join Date: Oct 2006
Location: San Diego
Quote:
Originally Posted by abhihemu View Post
Hi

i am new to the diy world, haven't done any diy yet. I have 2 Yugal 10" 8 Ohm, 120 watt woofers (my old amp plays them well on single channel in parallel config. so i will use them in parallel) :-

Qts:0.26
Vas: 290 liters
Fs: 30 Hz
Re: 4 ohm
Le: unknown
Xmax: 3 mm
Qms: unknown
Qes: 0.27
SPL: 94 dB
Dia: 10 inch

I want to make this type of Box for my woofers :-
Click the image to open in full size.%20%20Uploaded%20with%20ImageShack.us[/IMG]
ImageShack® - Online Photo and Video Hosting

and i have calculated this Box for me :-
Click the image to open in full size.%20%20Uploaded%20with%20ImageShack.us[/IMG]
ImageShack® - Online Photo and Video Hosting


as i am new to diy and electronics i don't know whether it will act as per my plans or not !! specially middle section of 80 Liters which i have tuned to 20Hz, i don't know it will produce 20Hz or not but i want to try it, WinISD is showing a Vent Match of 0.25 which is my cause to worry if i select 2 vents then WinISD doubles the port length !! please help me how to solve it !! other two chambers are i think good.

Please help me, this is my first Diy !
someone please correct the photo links !!
It's very VERY difficult to get the tuning on a bandpass right unless you have a way to run an impedance sweep. And if you don't get the tuning right, the sub will sound all wrong. IMHO, this is the main reason that bandpass boxes have such a terrible reputation. If built correctly, they can sound very good, but they're easy to screw up.

If this is your first DIY project, I'd stick with a sealed box. Tapped horns are also less sensitive to mistakes because they're simpler than bandpass boxes. (In a bandpass box there are more variables than in a tapped horn.)
  Reply With Quote
Old 10th January 2012, 04:54 AM   #3
diyAudio Member
 
Join Date: Feb 2004
Location: Los Angeles
Welcome abhihemu! Patrick is correct, it is quite difficult to get tuning correct on a bandpass. Bandpass enclosures purposely are very resonant, and so very sensitive to every dimension. If you build something within +-1mm of every dimension of your simulated box, it will never be exactly as simulated.

I can't comment more, because your images are blank-host is dead or something.

What are your goals for a subwoofer? Is there a certain size enclosure you want? What types of music do you listen to? How loud do you want to play (once in a while showing off, how loud really?)

And why did you choose a 3-chamber bandpass (again, I can't see your pictures so don't understand the actual design)
  Reply With Quote
Old 10th January 2012, 05:07 AM   #4
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
I think the image abhihemu is trying to put up is this one:

Click the image to open in full size.

I recently built a 6th order bandpass that works quite well. I had a Woofer Tester 3 at hand though and was able to do the impedance sweeps and port tuning. This thread outlines my experience:

Help with 4th Order bandpass enclosure for a 15" 600W dual voice coil subwoofer (PA)

col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 16th January 2012, 05:00 PM   #5
diyAudio Member
 
Join Date: Nov 2011
Sorry for late reply ! my monitor fell down to the ground after posting this thread today got a new one.

Thanks for your replies !

@Patrick yeah i have heard it's hard to achieve the desired results in a bandpass, please tell me how should i tune the middle chamber to 20Hz, is it possible ?

@col yeah that's the same image... this is my plan -
ImageShack® - Online Photo and Video Hosting

@head_unit actually i want this box to play deep bass strokes and i usually listen music at 12 O'clock volume , but not more than it...can you guys suggest me any other type of enclosure for 20Hz to 60Hz+ tuning ?
  Reply With Quote
Old 16th January 2012, 05:15 PM   #6
diyAudio Member
 
vacuphile's Avatar
 
Join Date: Apr 2011
Location: Seaside
20 Hz is not realistic with these drivers. 10 inch with 3 mm Xmax just will not pump enough air at that frequency.

The only possibility would be in a closed box with heavy compensation for the roll off at the low end, but you won't be able to play very loud without running out of Xmax. With a BR, you might get to the low 40's, but it would need a very large enclosure, using both speakers in one enclosure about 300 liters. It would be better to build two separate subs, though, because that would facilitate optimal room placement.
  Reply With Quote
Old 17th January 2012, 12:52 AM   #7
mdocod is offline mdocod  United States
diyAudio Member
 
Join Date: Dec 2011
Location: Black Forest, CO
Send a message via AIM to mdocod
Your picture is of a sort of quasai 6th order band pass, with a neat separate baffle loading idea (push pull or whatever it's called that should cancel out box vibration and give the drivers an effectively more rigid platform to work from). I would suggest turning the drivers around so they have their magnets pointed at eachother inside the center chamber, and installing a brace between the magnets of the 2 drivers (careful not to block a vented pole).

The idea of having the 2 outer boxes tuned differently whilst the drivers share a common loading on the the center box is something that I would not suggest dabling in. I'm not even sure if simulation software exists that wold support such a configuration.

Here's a hypothetical 6th order band pass box based on 2 of the drivers you have there....

As you can see, yes, you can tune to 20hz, 20ft^3 on the rear chamber is what it takes to make a 20hz tuning sort of practical/worthwhile for this box type.

As you can see, the design takes a hit on efficiency across the listening range (-6dB) but, if the driver characteristics are correct, the bass region can be produced relatively flat from 20-100hz with the box volumes and tuning shown.

Unfortunately, The Xmax limitation comes in with a vengeance at this point. Xmax limited to about 2W per driver, or about 4.1W total. (see sim).

If you simulate the ports with 4W of input, the port dimensions and air velocity are easy to make an acceptably quiet. (see sim)

At 4W, the system is theoretically good for ~100dB across the bass listening range. Nothing fantastic, but, not terrible either.

The odds of this simulation matching reality with those drivers; probably pretty poor.

The final chart on the right there, assumes no use below ~35hz, a still large but more practical box size, and an Xmax limited Pe of 13W instead of just 4W, the combined improvements in efficiency (+6dB) and Pe result in a full 10dB improvement in output capability.

Eric
Attached Images
File Type: png Selection_089.png (13.6 KB, 33 views)
File Type: png Selection_090.png (13.4 KB, 33 views)
File Type: png Selection_092.png (14.0 KB, 23 views)
File Type: png Selection_093.png (15.0 KB, 22 views)
File Type: png Selection_094.png (14.5 KB, 25 views)

Last edited by mdocod; 17th January 2012 at 01:00 AM.
  Reply With Quote
Old 17th January 2012, 06:20 AM   #8
diyAudio Member
 
Join Date: Nov 2011
Thanks for replying with sims mdocod !

One thing i am sorry for, all the driver details i given in my first post are true except Xmax and Fs (due to scratches in Fs and Xmax part on the back of my woofer), they were my guessings, perhaps Xmax would be double than what i stated i.e. 5mm as that driver sound very well and produces good bass with my 80 liter sealed box. I am new to such details but Xmech for that driver as i see would be 8-10mm. I thought (keeping 3mm Xmax in mind ) that single driver wont be enough for moving required air and so i planned two woofers having one common chamber, but after reading your post i took a visual test (as i am a newbie and cant test it through mic or such things) of that woofer playing in high volumes, now i think Xmax would be 5mm and Xmech would be 8-10mm. I will turn the magnets inside the middle chamber as you suggested. So if Xmax is 5mm than what effect it should have on sound quality ?
  Reply With Quote
Old 18th January 2012, 05:18 AM   #9
diyAudio Member
 
Join Date: Nov 2011
Is there any guideline for minimum required Xmax of a driver of a specific size i.e. 10"/12"/15" for an enclosure having specific volume ? should i buy any other driver which has sufficient Xmax for my planned box (same sized) ? if yes then what should be the minimum Xmax of that new driver ? please through some light on it...
  Reply With Quote
Old 19th January 2012, 07:27 AM   #10
mdocod is offline mdocod  United States
diyAudio Member
 
Join Date: Dec 2011
Location: Black Forest, CO
Send a message via AIM to mdocod
Box sizing is based on Qts and Vas. Xmax has nothing to do with it. Assuming your Xmax "guess" was off, then the simulations hold true minus the couple more dB that the Xmax will buy. If Fs was off, forget the sims, that changes everything.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Three way dual chamber reflex flyingtele Multi-Way 3 30th September 2010 01:26 PM
Dual Chamber Speaker Box suministros Multi-Way 17 20th May 2010 12:23 AM
Dual chamber ported sub? elambert Subwoofers 12 18th May 2005 12:40 PM
How to model a dual chamber ported(Weems) enclosure in WinISD? Please help >> beady Subwoofers 4 5th August 2004 10:14 PM
Dual-Chamber Vented Boxes BAM Multi-Way 9 2nd July 2004 02:37 PM


New To Site? Need Help?

All times are GMT. The time now is 02:56 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2