I haven't read them. I think you'd do well to consult a textbook. If you studied college physics or mechanics-dynamics, go back to Newton's second law of motion applied to forced oscillation. It's a second order ordinary differential equation which explains how things including woofers move. It explains many other things including the suspension system of your car also for example. Also look a the ideal gas laws which will show you how Newtonian gases react under compression and rarifaction (Boyle's and Charles' Laws.) Theil and Small turned these laws into a cookbook recipe but I like to think about it the way I first learned it. Look at how PV work is done (PV=nRT and P1*V1=P2*V2)
BTW, Villchur's explanation of why it works using a thermodynamic model to explain heat loss was not appropriate (not wrong but didn't really explain it) but it didn't negate the fact that the design is correct. He remarkably got the right answer but his understanding of it was for the wrong reason. Once you understand this concept it will make it possible for you to see the flaws in other designs especially their frequency dependency.
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Thanks for the response, but it's to difficult for me and not enough time to learn about it all.
I'll have to stick to the basic designs.
hadnt thought of that, great advice, will do....thanks
also you may want to use dowels, broomhandle, etc to brace the wings from the lower edge of the shelf/port
![QUOTE]](/community/proxy.php?image=http%3A%2F%2F%5D%5B%2FQUOTE%5D&hash=6887b12fa1072a7feb48d630ff4ff69e)
I haven't been following this long thread, so forgive me if my comment misses the point. I recommend buying "The Loudspeaker Design Cookbook" by Vance Dickason. It is an excellent reference written by a very experienced authority of design - and not too expensive.
Short of that, you need to obtain the Theil/Small parameters for your driver, which are probably available from the manufacturer. Then I recommend one of the many software programs available free on the internet. Here is a super simple one which works online: http://www.mh-audio.nl/CBC.asp
Also: you don't need to understand how subwoofers work to design one if you are using the software. Just do what the software tells you to do.
Also: Don't assume your driver can be used for a sealed box. Vance Dickason recommends using a simple formula developed by Dr. Small (of the Thiel/Small fame) to determine if your driver is suitable for ported, sealed, or either enclosure:
it is:
If Fs/Qes >75, driver is only good for vented/PR enclosures.
If 75>Fs/Qes>50, driver is good for either.
If Fs/Qes<50, driver is only good for sealed enclosures.
Please buy the book, drink a lot of coffee, and enjoy!
Short of that, you need to obtain the Theil/Small parameters for your driver, which are probably available from the manufacturer. Then I recommend one of the many software programs available free on the internet. Here is a super simple one which works online: http://www.mh-audio.nl/CBC.asp
Also: you don't need to understand how subwoofers work to design one if you are using the software. Just do what the software tells you to do.
Also: Don't assume your driver can be used for a sealed box. Vance Dickason recommends using a simple formula developed by Dr. Small (of the Thiel/Small fame) to determine if your driver is suitable for ported, sealed, or either enclosure:
it is:
If Fs/Qes >75, driver is only good for vented/PR enclosures.
If 75>Fs/Qes>50, driver is good for either.
If Fs/Qes<50, driver is only good for sealed enclosures.
Please buy the book, drink a lot of coffee, and enjoy!
Hi,
That's a good start..
Referring to post # 43..44: Here is an example of how to design an AS Sub:
b🙂
Attachments
The truth is there is not a single "box" subwoofer (acoustic suspension, or bass reflex) design out there that does what is described here. If you did an actual THD test of such a subwoofer design a very good one would have at least 10% THD in the 20hz -80hz region. The lowest distortion bass design available is a pure horn loaded design using a driver with a very lightweight cone (paper) and a very strong motor system(magnet). These can be ginormous! The best comprimise is a Tapped horn design. the Hornresp software available free from diyaudio member David Mcbean is an excellent tool for designing these. I recomend designing one yourself because a "best design" is impossible as everyone's priorities are different.
Good reference. It is Qts which matters howevever the real number to be interested in is Qms. This is the mechanical resonance component and Qes is usually quite small. The overall problem can be considered as the superposition of the mechanical and electrical resonances and dealt with separately. The electrical resonance can be considered as a purely electrical problem solved with filter design, either passive or active elements in the chain. The Theil Small cookbook solves the mechanical problem. And yes AR1W did have 30 hz THD of 5% measured. Around 1956 the NY Audio League (predecessor of AES) took four AR1Ws and 150 watt Western Electric amplifiers to Riverside Church in upper Manhattan and played an LvR demo against an Aolean Skinner pipe organ. Evidently it was rather remarkable. AR's design for that woofer culminated in Teledyne AR9 (there was a later AR9 that was entirely different) where two were installed in a 4 cubic foot box with a system F3 of 28 hz. I can testify that it can be room shaking and window shattering. It's not an issue of how loud it can play but of how low it can go without distortion. A horn with equal performance would have to be enormous, entirely impractical for almost anyone.
Apperently you are not familiar with tapped horn designs. A well designed tapped horn can achieve similar bass extention as a bass reflex design about 1/2 it's size while achieving SPLs roughly 15-20db higher and far better impulse and transient response as well as much higher sensitivity. There are a lot of threads discussing tapped horn designs on this forum. I have one in my living room right now that is about 24 cubic feet (I know, not practical for most people but I designed it around the driver I had and didn't care about size) that is capable of about 135db down to about 22hz the entire house shakes and rattles long before the sub does, and I only have an 85 Watt amp on it.
Threads where Qm among others is on topic.http://www.diyaudio.com/forums/multi-way/83982-enclosure-high-q-driver-3.html#post976183
http://www.diyaudio.com/forums/subw...e-braking-one-coil-shorted-3.html#post1120919
b 🙂
" I have one in my living room right now that is about 24 cubic feet (I know, not practical for most people but I designed it around the driver I had and didn't care about size) that is capable of about 135db down to about 22hz the entire house shakes and rattles long before the sub does"
I have no idea what the purpose of such a device in a home would be. BTW, do you have two of them for stereo? 24 cubic feet, sound's like an armoire for a European castle. The volume of the enclosure is of course related to how deep the bass goes, not how loud it can play. BTW did you test it all the way to 135 db? Did you wear ear protection if you did? Does your homeowner's insurance company know what you're up to? 🙂
Correction it models up to 135db but of course my house would probably have crumbled if I had actually played it that loud(old mobile home). Oh yeah and I don't have insurance, don't know of any companies that would insure a trailer with a wood stove. Actually with a horn a larger mouth will almost always give you more volume but then you have to make it longer too. I guess I didn't make it clear this is by no means an optimum design I have designed many tapped horns well under 4 cubic feet with extension down near 20hz, this one just happened to be this large because that was what the driver required, besides it make for great bragging rights at local bars. Actually I do have two for stereo but the second is not nearly as large and doesn't go quite as low.
Ive never built one of his designs, and id like to build and own a small-ish, very powerful (SQ) sub for any outdoor event/party i may attend in the next 20 years. just in case 🙂
anyone have any experience / understanding / knowledge of his designs?
ive done some searching and found some photos and videos.
id be happy to drop about $150 into a driver/drivers.new or used. and i am good with tools and wood.
up to about 100lbs, dry tight loud as possible bass up to but nO bigger then 30x30x48- ish
1 box, not 2.
looks to me like a lot of his designs will do it.
do i build one of his or do you know of a better design to reach my goal?
Tuba 30
anyone have any experience / understanding / knowledge of his designs?
ive done some searching and found some photos and videos.
id be happy to drop about $150 into a driver/drivers.new or used. and i am good with tools and wood.
up to about 100lbs, dry tight loud as possible bass up to but nO bigger then 30x30x48- ish
1 box, not 2.
looks to me like a lot of his designs will do it.
do i build one of his or do you know of a better design to reach my goal?
Tuba 30
As long as you are happy with 13db drop from 100hz to 40hz -- go for it. Yes, I've built many of those cabinets -- been there, done that, have the scars to prove it.
ProSpeakers Forum - Fitzmaurice Titan 48 - Wayne Parham, October 21, 2007 at 14:31:26
Check out the 800watt input vs 100 watt input.... and then compare it to the published charts in BFM land.
To be perfectly fair, you need a minimum of four BFM boxes of about any kind, or a pair v-plated and corner loaded. However, you stated you want single box performance.
Best box he has is the T18. Build it double driver (series) with the mcm 55-2421, 24" wide and build a quad of them. If you want to use single box indoors, corner load, add a 10-12mh iron core inductor and cross at 80hz. That'll get you roughly flat to 40-120hz. and you can pull 126db @1m
Davy has a six of AT's with HL10c's... that's pretty impressive as well.
ProSpeakers Forum - Fitzmaurice Titan 48 - Wayne Parham, October 21, 2007 at 14:31:26
Check out the 800watt input vs 100 watt input.... and then compare it to the published charts in BFM land.
To be perfectly fair, you need a minimum of four BFM boxes of about any kind, or a pair v-plated and corner loaded. However, you stated you want single box performance.
Best box he has is the T18. Build it double driver (series) with the mcm 55-2421, 24" wide and build a quad of them. If you want to use single box indoors, corner load, add a 10-12mh iron core inductor and cross at 80hz. That'll get you roughly flat to 40-120hz. and you can pull 126db @1m
Davy has a six of AT's with HL10c's... that's pretty impressive as well.
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i want to build 1 big subwoofer.
of all the single box subwoofers you have ever heard,
which has the best sq and loudest and gets lowest,
outdoors
of all the single box subwoofers you have ever heard,
which has the best sq and loudest and gets lowest,
outdoors
stadiumhorn is lowest, ss15 is loudest (single box DIY) that I personally know and have measured. The furysub is also a great box. (my brother has a quad of them)
Xoc1's design may be the middle ground between those two designs and may be the ticket. We'll know after it's built and tested.
If you want a rock-n-roll box, that's the ss15.
Don't knock the little T18, build a quad as a single cabinet if you feel you have to. Inch for inch it's the best BFM box built.
Xoc1's design may be the middle ground between those two designs and may be the ticket. We'll know after it's built and tested.
If you want a rock-n-roll box, that's the ss15.
Don't knock the little T18, build a quad as a single cabinet if you feel you have to. Inch for inch it's the best BFM box built.
i definitely use my subs as subs, 60 hz and lower only (down to a clean AND STRONG 30 hz would be AWESOME !!)
what's a BFM box?
what's a BFM box?
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