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Registered Member #318
Joined: Tue Mar 14 2006, 07:07AM
Location:
Posts: 6
Im looking to build a subwoofer, and im at the point where its time to order parts. About $700.00 or 112 hours of my life are on the line (plus shipping and cost of wood), I hope some members of .4hv can review my theoretical response plot, parts and give it a thumbs up or down.
Seeing how 10-12" powered subwoofers under 500W can cost as much as a good used car, I thought I might as well buid my own. Im mainly looking for that bassy punch that knocks the wind out of you, such as what my friends two 12" square kicker drivers do in a sealed box.
12.7 Cubic feet for the ported box (green plot). 6th order bandpass is purple, and sealed is yellow. Sealed and especially 6th order arent what I want, so ported it is. Dual 4" vents (I put in single 4" and the program complained to me that its too small).
Driver : Amplifier :
I havent build many subwoofers, and not especially one that costed me more than about $50.00 in total. Speak now or forever hold your peace (any reasonably well thought out comments, questions, or advice is apreciated).
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
1. Don't make your enclosure out of wood. Use 3/4" or 1" thick high density particle board.
2. I'm not familiar with Dayton components? Are they good components? You might want to check into that if you don't already know. Anytime i see amps rated at 1000W for that kind of price always makes me wary.
3. You didn't say if this was for the home or car. If for the car, the amplifer is AC powered, not 12V powered.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
The only thing that looks odd is the purple response plot for the 6th order bandpass. If it really had a response like that, it would sound pretty poor! >_< I guess there must be something wrong with the design.
In a vented box, vents that are too small can cause harmonic distortion and annoying air chuffing sounds. So if in doubt make them big. But bear in mind the bigger you make them, the longer they need to be to keep the same tuning (IIRC.) If you overdo it, you end up with long fat pipes taking up lots of space inside your cabinet.
I don't know how big "big" is, but I do have some examples....
The speaker cabinet I use for bass guitar has two 15" woofers and two 4" ports. (and is a total pain in the *** to carry up four flights of stairs)
The one I had before that had four 10" woofers and a single big port about 8-9".
Some guys I know recently bought a pair of Mackie PA speakers. Each speaker has a 15" woofer with two ports again about 4". They're pretty loud, and you can feel your trouser legs flapping if you stand near the ports. Last I heard they were saving up for the matching Mackie sub which is about the size of a dishwasher. o,O
The subwoofer I used to use with my stereo had a single 10" driver and a single port about 3", and a 100W plate amp. It still kicked out impressive amounts of bass. I don't use it any more since I moved house, my new living room is too small for really low bass, and my regular hi-fi speakers are fine for the bass frequencies that it can hold. (something to think about before you build the giga nuclear subwoofer from hell.)
I used to have a sub for my car with a single cheap brand 10" woofer in a sealed box I made out of MDF. The small sealed box made it roll off below about 55Hz, but cabin gain probably compensates that. It worked great, in fact it was too good for the rest of the crappy stereo system in my car. If I tried to generate proper rice boy levels of bass, it drowned out the other speakers completely.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
A sealed enclosure of less than 4 cu.ft. would give a "Q" of about 0.7 (critical damping) and -3dB at about 40 Hz.
Since there's almost no programme content below 50 Hz and you want 'punchy' bass I'd think a sealed (infinite) enclosure would be best for this driver, Although a vented enclosure would have a lower frequency response I feel the bass is less 'tight'
Registered Member #105
Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408
Also, that driver that you have posted has a relatively low SPL level. For every three decibel increase in the SPL rating, you will notice an about 2x increase in volume for the same power level input. So a 300W amplifier powering a 94db speaker will be twice as loud as the same amp powering a 91db speaker. My bass cabinet is 103dB, and it is *noticebly* louder than plugging my amplifier into normal monitor speakers with the same impedance at the same volume setting.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
EDY19 wrote ...
Also, that driver that you have posted has a relatively low SPL level. For every three decibel increase in the SPL rating, you will notice an about 2x increase in volume for the same power level input. So a 300W amplifier powering a 94db speaker will be twice as loud as the same amp powering a 91db speaker. My bass cabinet is 103dB, and it is *noticebly* louder than plugging my amplifier into normal monitor speakers with the same impedance at the same volume setting.
That is not correct. It generally takes about a 10-fold increase in power to increase the perceived volume by 2x. A 300W amplifier powering a speaker with a sensitivity of 94dB will sound about the same as a 600W amplifier powering a 91dB speaker.
Even so, there will be little perceived different in volume between an amp with some constant power output (say 100W) and then driving a speaker with a sensitivity of 89db and one with a sensitivity of 92dB.
As a general rule of thumb:
1. A 1dB change in volume is not perceptible to humans. 2. A 3dB change in volume is just barely perceptible (threshold)
Registered Member #105
Joined: Thu Feb 09 2006, 08:54PM
Location:
Posts: 408
Oops, sorry, I messed that up- thats what happens when you use your brain
"An efficient speaker helps you maximize your available wattage. Believe it or not, a 3 dB increase in speaker sensitivity produces the same audible increase in volume as doubling your amplifier power!" (from crutchfield.com)
"as the 3dB difference in speaker efficiency is equivalent to a doubling of power."
So it won't be twice as loud, but it will be about equivalent to powering it with double the amplifier power.
Registered Member #318
Joined: Tue Mar 14 2006, 07:07AM
Location:
Posts: 6
Wow, I can see I will make some good progress with this thread. Not even one afternoon goes by, and I get 5 replies with people who know what their talking about. Thanks to all those who replied, I apologize for the lack of information in my first post, but it was around 1-2am. I also apologize for what I am about to present, one of my legendary long-winded quote-a-thons:
EastVoltResearc wrote ... 1. Don't make your enclosure out of wood. Use 3/4" or 1" thick high density particle board.
2. I'm not familiar with Dayton components? Are they good components? You might want to check into that if you don't already know. Anytime i see amps rated at 1000W for that kind of price always makes me wary.
3.You didn't say if this was for the home or car. If for the car, the amplifier is AC powered, not 12V powered.
1.I was planning on using 1†mdf, possibly with some internal bracing (clone the front piece where the woofer mounts to, but make it small enough to fit halfway inside the enclosure. 2.A few audio forums seem to like the Dayton's more than BASH, though its definitely a class G or class-D amplifier, which can be made significantly cheaper and lighter than any others. I will have to look into these Dayton components as much as possible. The amplifier is about half-price of name-brand rack mountable amplifiers, though much of that could be its design. Just remember, subwoofer amps arn't anything like hi-fi amps, they just need to reproduce 10-200hz without too much distortion. Quantity over Quality is the idea with most of the plate amplifiers. 3.This is for home. If It was for a car, I wouldn't have selected a 120vac amplifier.
Steve Conner wrote ... The only thing that looks odd is the purple response plot for the 6th order bandpass. If it really had a response like that, it would sound pretty poor! >_< I guess there must be something wrong with the design.
The 6th and 8th order enclosures are used often in SPL competitions for cars, where one frequency is played for a short time (before the speakers cook or catch amplifiers on fire). I just threw it in there for comparison, I definitely wouldn't be considering anything with such an unusual response for any music... I don't even think it would work well with Miami-bass or rap.
Steve Conner wrote ... In a vented box, vents that are too small can cause harmonic distortion and annoying air chuffing sounds. So if in doubt make them big. But bear in mind the bigger you make them, the longer they need to be to keep the same tuning (IIRC.) If you overdo it, you end up with long fat pipes taking up lots of space inside your cabinet.
My 200W 8†driver I have (JBL), uses a 3†port. The driver doesn't have much for excursion, but much below 60hz, the driver becomes unloaded and really starts to pump air, making more port noise than actual music. 3†gives 7.07 square inches of area, two 4†ports will give 25.12 square inches. The driver is advertised to move up to three liters of air, I believe two 4†vents will be sufficient, though my assumption could lead to a poor build. I had to up the resonant box frequency from the mid 20s to the mid 30s, otherwise I would have needed ports nearly a meter long.
Steve Conner wrote ... I don't know how big "big" is, but I do have some examples....
Well, I have a 5†35w peak Maiden of china driver/amplifier on my floor. At 1/3 volume, I had my floor resonating to some impressively bassy pipe organs, and my cupboards are rattling to Lynyrd Skynyrd. Though, this thing cannot even keep up with this $80.00 5.1 system's 3†woofers. It may be due to the human ears hearing response, or because it just takes a lot of power to make noise at low frequencies. I do know one thing, if the Dayton amplifier isn't a PMPO BS-rated marvel of technological failure, and the driver works as advertised, this subwoofer build should be more than enough to get me evicted from an apartment in a hurry. If I can get my voice to be modulated to the beat of the bass, and have my mouse (once again) walk across my computer desk, I would call this big.
Steve Conner wrote ... The subwoofer I used to use with my stereo had a single 10" driver and a single port about 3", and a 100W plate amp. It still kicked out impressive amounts of bass. I don't use it any more since I moved house, my new living room is too small for really low bass, and my regular hi-fi speakers are fine for the bass frequencies that it can hold. (something to think about before you build the giga nuclear subwoofer from hell.)
You mean, to be sure the rest of the audio setup can compete with the subwoofer? If so, I have that covered already. I don't know what DB levels cause pain, but the kenwood and my midranges/midbass/tweeters are ready. Though, since there are laws on noise levels (not over 90-something If I remember) in the city, Its not really an issue. I have some real speakers in the back of the room, needing to be built into a box (speakers not made in china for $0.20 USD).
Sulaiman wrote ... A sealed enclosure of less than 4 cu.ft. would give a "Q" of about 0.7 (critical damping) and -3dB at about 40 Hz.
Im not sure what “Q†the large ported enclosure I selected, would be... though the lower response seems to be more desirable. The sealed enclosure tapers off fairly early for me. But lets not forget the more important bass area, 50-150hz. I cant say or even speculate on how this driver would sound at 150hz, and WinISD cant tell me.
Sulaiman wrote ... Since there's almost no programme content below 50 Hz and you want 'punchy' bass I'd think a sealed (infinite) enclosure would be best for this driver
No, for the post part of what I listen to, below 50hz wouldn't make noise. Though for some songs/bands, the 50hz region is very active, indicated by heavy red rashes down Spectrum Lab's graph. I'm mainly building this subwoofer and choosing a large driver, because the 50hz and below region is something that's simply amazing at high pressure levels, and very disappointing with a small driver. I also don't want to have this large monster, $700.00 amp/driver combo laying in the corner, because it sounds like Gilbert Gottfried above 100hz.
EDY19 wrote ... Also, that driver that you have posted has a relatively low SPL level. For every three decibel increase in the SPL rating, you will notice an about 2x increase in volume for the same power level input. So a 300W amplifier powering a 94db speaker will be twice as loud as the same amp powering a 91db speaker. My bass cabinet is 103dB, and it is *noticeably* louder than plugging my amplifier into normal monitor speakers with the same impedance at the same volume setting.
120db is 120db. Plain and simple, this $190.00 driver is more than loud enough. I challenge anyone to find a low-frequency bass driver with higher sensitivity, for under $200.00. I have seen many under 90, and a few close to 100 (though they were nearly $1,000 per driver, and wern't low-bass). I've ran several drivers through winisd, drivers from parts express, and many have come short of this one. What I'm trying to find out, from this post, is this : Is the combination of the amplifier and driver I have selected, along with the box which I will soon post, be the cheapest for high volume 20-100hz bass?
Also, as steve mentioned, I will have to look further into this 'Dayton' brand. I've never heard of it before, and it could be too good to be true. Though at $700 for an amplifier and driver, it seems about right. Not cheap by any means, though reasonably priced.
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Subwoofer build, big bass and big money
