diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Subwoofers (http://www.diyaudio.com/forums/subwoofers/)
-   -   How's This Design (http://www.diyaudio.com/forums/subwoofers/227174-hows-design.html)

justinzane 6th January 2013 09:20 PM

How's This Design
 
I am a total novice, so please do not injure youself falling on the floor with laughter... :rolleyes:

I am, obviously not looking for audiophile perfection, just something that sounds nice at low to moderate volumes for everything from Italian Opera to Sunn O))) and whatever TV and movies happen to get played. I did not include a cross since I was going to play with different butterworth frequencies digitally to see what sounded good. Since it is an open box, I figured that 1/2" MDF would be sufficient, though experience would be welcome.

Thanks!

For those who cannot see links, I've attached the PDF below. [Note that the links have been tested with Chrome and Firefox on Linux. IE will probably cause problems.]

https://www.justinzane.com/static/misc/sub.svg

there is a PDF version here: https://www.justinzane.com/static/misc/sub.pdf

tvrgeek 6th January 2013 10:07 PM

No luck on your picture, so I don't know exactly what you have in mind, but guessing from your text:

Open box is not a viable approach unless you have an old 24 inch Heartely and the box is about 10 feet square. ( This becomes an IB. Not something for a first time build )

The box and the driver have to work as a system. You have a quite reasonable goal. There are many many well published designs that are great for a newbie project. I recommend you start there. One of my all time favorites is the Linkwitz sub. I prefer low Q sealed subs. Others like the extra boom from a ported enclosure. In any case, you need a full cabinet as it works with the driver to be a , ready.... hold on..... loudspeaker system.

Two of my subs are probably close to what you are looking at. One a Dayton Titanic III 10 inch, the other a Dayton RS series 10 inch. Both in sealed boxes of 18mm plywood from Lowes just glued together. Sealed is very forgiving; these speakers both work fine between about 50 and 80 Liters. Stuff firmly with plain old fiberglass insulation. They are driven by the small O Audio plates. My other two are a bit more exotic based on Peerless drivers.

justinzane 6th January 2013 10:33 PM

Please see if it is viewable now. Or try the PDF. Thanks.

justinzane 6th January 2013 11:27 PM

@tvrgeek: I'm doing a transmission line design. The line is about 9.5 ft for a 33Hz quarter wave.

chris661 6th January 2013 11:39 PM

The problem seems to be the website root: apparently www.justinzane.com isn't available.

justinzane 7th January 2013 12:27 AM

1 Attachment(s)
The site is available, just slow. I've just tried attaching it as a PDF since svg images are not supported (!?).

chris661 7th January 2013 11:03 AM

Right.

I can say for a kick-off that it isn't an open box, as its aspect ratio is large enough for it to exhibit quarter-wave behaviour. The pressure in those (at times) will be higher than that of a sealed box.

Have you simulated your design?
It can be difficult to get such designs right at the best of times, but with no simulations to guide you, it might be great, or it might be awful (guess which is more likely).

IMHO, the woofer you've chosen won't be fantastic either. The (very) high Qts indicates a weak motor.
One of these would likely be better. There are many designs (some very bonkers) that use this woofer, but for a start try it in a ~30L cabinet tuned ~30Hz (you'll need WinISD Pro for this).

HTH
Chris

justinzane 7th January 2013 03:03 PM

@chris661: I've tried a couple different ways of modelling using online tools and have gotten mixed results. I use a Debian approved free software (open source, not free like beer) stack and therefore can't use WinISD or any of the other proprietary tools. I have written about creating an open alternative here: http://www.diyaudio.com/forums/softw...ameter-db.html.

As far as the driver goes, it is a cheap driver for a first attempt and was picked based on a number of "models" as the most likely to be useful. I do very much like your suggestion, though. I just might get one for the next project.

tvrgeek 7th January 2013 10:00 PM

Ah, PDF is OK. Large TL. Not the easiest cabinet to get right. There is so much to get right in the back chamber and TL throat.

I recommend starting sealed to understand measuring, simulation, and the plethora of box issues. . Move on to ported and then TL. I have to admit, I just plain don't get the fondness for TL for subs. Just too darn large. When I was in my 20's I had a living room with a 14 foot ceiling and played with a really big TL. ( 20') My small sealed worked better.

justinzane 8th January 2013 05:37 AM

Quote:

Originally Posted by tvrgeek (Post 3315404)
Ah, PDF is OK. Large TL. Not the easiest cabinet to get right. There is so much to get right in the back chamber and TL throat.

I wish I could find more about what to get right. The majority of stuff I've stumbled across regarding TL design leads to M. J. King and I've had trouble getting an intuitive grasp of his work. I've also had no luck on getting advice on porting his MathCAD sheets to something FOSS.

Quote:

Originally Posted by tvrgeek (Post 3315404)
I recommend starting sealed to understand measuring, simulation, and the plethora of box issues. . Move on to ported and then TL. I have to admit, I just plain don't get the fondness for TL for subs. Just too darn large. When I was in my 20's I had a living room with a 14 foot ceiling and played with a really big TL. ( 20') My small sealed worked better.

I'm going to do a few simultaneous things. I've got a long length of Sonotube with a repositionable plug to test various sealed capacities with the given driver. I'm currently lacking a decent measurement microphone, so my measurements will not be useful in comparison to anything but themselves. Even so, they will provide feedback about the basic performance of various enclosure volumes. I've also got a 3" driver and a boatload of 3" and 2" ABS DVW pipe to do some basic tests on various TLs.

For me, the appeal of TLs is the simplicity of the concept. Short of an IB, it "feels" logically clean. Plus, the size of TLs forces a visual design change from the ubiquitous little black boxes (or white for kitchens and Apple junkies) that seems to be everywhere. I am not super creative, but I love the funky TL creations I have seen.

They often are far cruder than traditional multiway builds or sealed/ported subs, but they have a visual impact far greater. Some of the typical sealed designs I have seen here are stunning examples of fine woodcraft, but they are little differentiated from other small art objects. TLs command attention.

As far as measuring and testing go, I am quite used to doing valid and reliable studies on an array of subjects from data networks to chemicals to humans. Speakers are rather simple, so I am only limited by my [lack] of equipment.

And, finally, regarding simulation, please see the post in my sig. Thanks.


All times are GMT. The time now is 06:26 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