I was contemplating building a portable speaker system for music and it raised a few questions. If these have been addressed in other threads please let me know.
1- To produce sound we need to move air. For bass, we need to move a lot of air. So larger diameter drivers and higher Xmax will naturally move more air. How is it then that certain cabinet designs can produce higher SPL? For instance I was looking at Bill Fitzmaurice site and how a Titan 48 with a single 15 will produce more SPL than a reflex cabinet with 2x18's. Assuming the twin 18's have similar Xmax, there is a huge cone area advantage and thus more ability to move air...so how does the Titan produce so much SPL? I guess I just have too elementary an idea of how sound is produced.
2- Along the same lines as question #1 and most applicable to the portable project, what design would produce the most bass from a 1-2 cubic foot enclosure? Looking to get down to maybe 35-40hz or so if possible. What general combination would likely work best? Smaller driver in some kind of horn or TL? Larger driver in a simple sealed or ported? I am assuming any given design would require a high Xmax driver.
Thanks
1- To produce sound we need to move air. For bass, we need to move a lot of air. So larger diameter drivers and higher Xmax will naturally move more air. How is it then that certain cabinet designs can produce higher SPL? For instance I was looking at Bill Fitzmaurice site and how a Titan 48 with a single 15 will produce more SPL than a reflex cabinet with 2x18's. Assuming the twin 18's have similar Xmax, there is a huge cone area advantage and thus more ability to move air...so how does the Titan produce so much SPL? I guess I just have too elementary an idea of how sound is produced.
2- Along the same lines as question #1 and most applicable to the portable project, what design would produce the most bass from a 1-2 cubic foot enclosure? Looking to get down to maybe 35-40hz or so if possible. What general combination would likely work best? Smaller driver in some kind of horn or TL? Larger driver in a simple sealed or ported? I am assuming any given design would require a high Xmax driver.
Thanks
1. Undersized horns like titan 48 and for that matter all tapped horns and the majority of back and front loaded horns are multi resonant devices. If you want the resonances to be strong the box needs to be large. In theory a 15 in a multi resonant device COULD beat two 18s in a sealed or ported box but it depends on the details - which 15 compared to which 18s in what style box, how large is the box, how much power fed to each, what filters applied, what are the frequencies of interest, etc?
1b. Bill Fitzmaurice is a marketer more than anything else. He will say whatever he needs to say to make a sale. His designs are mediocre and old, his "facts" are not always factual and he regularly uses trash talk and sockpuppeting instead of science in his debates. Hes also been known to post deliberately misleading measurements to promote his designs. If you want to learn useful information stick to forums like this where people are not motivated by money and figure out who knows their stuff Follow those people.
2. Two cubic feet isn't much space for a multi resonant design so if loud is the main goal you likely want the largest driver you can cram in there with a high tuned port as large and flared as possible with as much power as you can get your hands on. Kicker is pretty famous for designing like this in their recommended designs for their drivers (except they use undersized unflared ports which are excessively lossy). Designing like this can gain you a 10 db bump in response inside your pass band.
2b. While the results will be loud it won't necessarily be high quality sound or even have linear frequency response as spl increases. Learn a bit about the pros and cons of different enclosure types. Bill's claims are vague and misleading. You never get something for nothing. It's got to be really big or really expensive and power hungry if you want to go low loud.
1b. Bill Fitzmaurice is a marketer more than anything else. He will say whatever he needs to say to make a sale. His designs are mediocre and old, his "facts" are not always factual and he regularly uses trash talk and sockpuppeting instead of science in his debates. Hes also been known to post deliberately misleading measurements to promote his designs. If you want to learn useful information stick to forums like this where people are not motivated by money and figure out who knows their stuff Follow those people.
2. Two cubic feet isn't much space for a multi resonant design so if loud is the main goal you likely want the largest driver you can cram in there with a high tuned port as large and flared as possible with as much power as you can get your hands on. Kicker is pretty famous for designing like this in their recommended designs for their drivers (except they use undersized unflared ports which are excessively lossy). Designing like this can gain you a 10 db bump in response inside your pass band.
2b. While the results will be loud it won't necessarily be high quality sound or even have linear frequency response as spl increases. Learn a bit about the pros and cons of different enclosure types. Bill's claims are vague and misleading. You never get something for nothing. It's got to be really big or really expensive and power hungry if you want to go low loud.
Last edited:
So if I follow you correctly, you are basically saying use the largest driver possible and put it in a ported enclosure. I am assuming in general the best drivers to use would be high Xmax, low Fs and low Vas making them more suitable for small enclosures. Yes?
If you only care about being loud that's probably your best path, although as I just said its probably not a high quality approach and you might not like it.
Kicker, the example I mentioned used a high q driver in an undersized box with an undersized high tuned port in a lot of their designs and realized a 10 db hump in response within the passband.
In general ported boxes will give the highest power density per size assuming you can adequately port and power them. You can use design tricks to increase spl like kicker if you want.
Kicker, the example I mentioned used a high q driver in an undersized box with an undersized high tuned port in a lot of their designs and realized a 10 db hump in response within the passband.
In general ported boxes will give the highest power density per size assuming you can adequately port and power them. You can use design tricks to increase spl like kicker if you want.
Last edited:
I actually measured a Titan48 once, it does keep word to its claim of higher sensitivity than 2x18". However that's from 65 Hz and up in my measurement, so below that a 2x18" reflex will quickly dominate in SPL. Also it doesn´t factor in that 2 drivers will likely have half the power compression of a single driver. I did quite like the sound, lot´s of lower kick.
I do agree with just a guy, in 1 - 2 cubic foot there's little to be gained from a ''multi resonant design". A high excursion 10" or 12" driver in a small reflex cabinet will have the easiest mix of SPL and low frequency response.
I do agree with just a guy, in 1 - 2 cubic foot there's little to be gained from a ''multi resonant design". A high excursion 10" or 12" driver in a small reflex cabinet will have the easiest mix of SPL and low frequency response.
'Portable' suggests outdoor.
Not much bass can be made outdoor from a 1-2 cubic feet enclose.
A trick is to not actually reproduce the 40 - 70 Hz range, but only suggest its presence by reproducing its harmonics. This way a woofer that only plays down to 70 Hz is OK and this allows for a higher efficiency. Soundboks 2 is an example of a 2 cubic feet system that utilizes this trick.
Not much bass can be made outdoor from a 1-2 cubic feet enclose.
A trick is to not actually reproduce the 40 - 70 Hz range, but only suggest its presence by reproducing its harmonics. This way a woofer that only plays down to 70 Hz is OK and this allows for a higher efficiency. Soundboks 2 is an example of a 2 cubic feet system that utilizes this trick.
About that psychoacoustic effect, it can be done with simple dsp : SuperBass [Analog Devices Wiki]. I would love to implement one. Even a Ad1701 seems to be able to do it with some efforts if i'm not wrong. On the other side, it can be done acoustically tuning a box with efficiency spike where 2nd/3rd harmonics of the lower missing frequency bandwith efficiency loose occur.
Yes portable would mean that it could be brought outside. Was even considering battery power. Just a project idea.
Sounds like most votes are for as much Sd as you can get and using speakers meant for small ported boxes. Maybe tuned higher than usual... don't go for 30-40hz. Instead tune higher and get more output. Won't be as musical or sound as "good" as other options, but will provide the most bass.
Thanks
Sounds like most votes are for as much Sd as you can get and using speakers meant for small ported boxes. Maybe tuned higher than usual... don't go for 30-40hz. Instead tune higher and get more output. Won't be as musical or sound as "good" as other options, but will provide the most bass.
Thanks
Yea, tune to 50hz and roll it off there.
That will go loud.
Here is a link to the measured response of a titan 48.
Fine, above 100hz.
ProSpeakers Forum - Fitzmaurice Titan 48 - Wayne Parham, October 21, 2007 at 14:31:26
That will go loud.
Here is a link to the measured response of a titan 48.
Fine, above 100hz.
ProSpeakers Forum - Fitzmaurice Titan 48 - Wayne Parham, October 21, 2007 at 14:31:26
Bass horns usually has more radiating area, especially when stacked they become directional = much more bass in front of the stack and at a distance compared to reflex designs having same amount of drivers. And another thing, horns indeed has a lot better efficiency but downside is: they are big and heavy! So no free lunches.
BFM horns are not the best out there btw.. not even close.
How about passive radiator designs? They can be smaller than reflex because no need for reflex ports/tubes requiring more space than pr.
BFM horns are not the best out there btw.. not even close.
How about passive radiator designs? They can be smaller than reflex because no need for reflex ports/tubes requiring more space than pr.
Last edited:
Box itself of any size,
some kind of portable "stage-set" construction will help you reach lower.
Two 4x8' sheets of plywood or one up against a handy wall
will help you project more bass,
at least from 140 hz on up.
Three full sheets of ply (each vertical, side-by-side no gaps)
should make a difference even lower, to 95-100 hz or so, depending.
Scout the site you're taking any portable system to,
a little forethought and planning can give your bass a bigger bump.
Whatever size box, just make a hole in the stage-wall to fit,
at ground level. Make a half-a**ed effort to plug any gaps, that'll help too.
some kind of portable "stage-set" construction will help you reach lower.
Two 4x8' sheets of plywood or one up against a handy wall
will help you project more bass,
at least from 140 hz on up.
Three full sheets of ply (each vertical, side-by-side no gaps)
should make a difference even lower, to 95-100 hz or so, depending.
Scout the site you're taking any portable system to,
a little forethought and planning can give your bass a bigger bump.
Whatever size box, just make a hole in the stage-wall to fit,
at ground level. Make a half-a**ed effort to plug any gaps, that'll help too.
Last edited:
If you're going for 30 -40 Hz, a high excursion 12" is as large as I would go. However, if 50 Hz and up satisfies you, a 15" driver (low Qes, low Vas, medium Xmax) will rule.
I've been through this excercize before.
Best prosound 12" I've found is the Oberton 12NSW600. Has the most xmax of any other driver of it's kind. The rubber surround 12's from B&C and Faital look good too but have shorter voice coils.
For 15" the BMS 15N850 and the highest powered B&C, Faital Pro, Beyma, and Lavoce drivers can all work from 1.75ft^3.
Best peak output would be with two Dayton Audio 12" passive radiators.
Ports will work but they get big quick if you try to keep air speed down. A couple of large radius ports placed strategically would keep chuffing down, balance pressure on the cone, and create a chimney effect for heat exchange. Less maximum peak output but might be better for long-term power compression.
Best prosound 12" I've found is the Oberton 12NSW600. Has the most xmax of any other driver of it's kind. The rubber surround 12's from B&C and Faital look good too but have shorter voice coils.
For 15" the BMS 15N850 and the highest powered B&C, Faital Pro, Beyma, and Lavoce drivers can all work from 1.75ft^3.
Best peak output would be with two Dayton Audio 12" passive radiators.
Ports will work but they get big quick if you try to keep air speed down. A couple of large radius ports placed strategically would keep chuffing down, balance pressure on the cone, and create a chimney effect for heat exchange. Less maximum peak output but might be better for long-term power compression.
You need best compromise between motor force and displacement, and not spending much space on any "loading circuit". If you really want to stretch things far, then I would bet that B&C 15DS115 with passive radiators would be hard to beat.
OK, this is interesting now. I never really looked into stacking before, but apparently placing subs close together quadruples output (6db) instead of just doubling(3db)?
Does this apply to all types of enclosures (sealed, ported, TL, horn, bandpass etc)?
Also, does this apply to frequencies other than bass? I am thinking line arrays and MTM speakers would benefit, yes?
I realize the following is an oversimplification, but see if it makes sense.
Let's assume that we have woofer A with Sd of 100cm^2 and woofer B with Sd of 200cm^2 and they both have the exact same Xmax. Also assume other parameters such as Vas and Fs are the same. So in theory two of woofer A has the same potential to move air as one of woofer B, so in theory should achieve same SPL. Yes?
But...if we stack two of woofer A we now magically double the output.
Comments? Am I thinking about this wrong?
Does this apply to all types of enclosures (sealed, ported, TL, horn, bandpass etc)?
Also, does this apply to frequencies other than bass? I am thinking line arrays and MTM speakers would benefit, yes?
I realize the following is an oversimplification, but see if it makes sense.
Let's assume that we have woofer A with Sd of 100cm^2 and woofer B with Sd of 200cm^2 and they both have the exact same Xmax. Also assume other parameters such as Vas and Fs are the same. So in theory two of woofer A has the same potential to move air as one of woofer B, so in theory should achieve same SPL. Yes?
But...if we stack two of woofer A we now magically double the output.
Comments? Am I thinking about this wrong?
What does your common sense tell you?
Double your cone area nets you 3 db more with same power applied.
Double your power nets you 3 db more with the same cone area.
Double your cone area AND double your power nets you 6 db more.
+ 6db will sound more or less twice as loud.
No magic. EVER.
Double your cone area nets you 3 db more with same power applied.
Double your power nets you 3 db more with the same cone area.
Double your cone area AND double your power nets you 6 db more.
+ 6db will sound more or less twice as loud.
No magic. EVER.
And not that this matters with 2 cu ft subwoofers but stacking does increase frontal area which provides boundary loading but the boundary has to be LARGE to be effective at low frequencies as per previous boundary related posts. This is still not magic or free lunch, just physics at work.
JAG,
Good to see you're back on line!
One "common sense" rule for Nikg736 to also remember, the cabinet volume as well as the cone area must be doubled to net 3 db more SPL with the same power applied.
Nikg736 is running in to the classic output dilemma- the most SPL per cubic foot could be produced by cramming six 12" cones in a one cubic foot box, but the low frequency output of that box would be a fraction of what could be achieved with the same drivers in properly sized ported, tapped horn, or front loaded horn cabinets.
No magic, just size, weight and budget.
Art
Exactly...Price, weight and complexity no object? Sealed...Cram as much cone area, xmax and power handling as possible and attach to whichever amplifiers best approximate a nuclear reactor. Engineer in a air exchange / water cooling system.
Not very practical though.
Small, single driver, vented or passive radiator system tuned relatively high is much more practical and affordable.