hi
i already have 2x 12" and 2x tweeter setup that i run on AGM batteries. in sweden, when people graduate, they celebrate on a truck bed like this:
i have already used my setup on this event once but i want some more umpf. i run my setup on a 1000w car amp and with batteries.
is it a stupid idea to built a 15/18" subwoofer and run it on batteries? i am thinking a horn design, like a tham15 or something to keep it as efficient as possible.
good thing with batteries is i dont need an generator making sounds. although i have a 2.2kw diesel generator and i have an RCA output from my car stereo that i could use. maybe that is a better option? although it would require a somewhat expensive PA amplifier
anyways, what would be the ideal subwoofer for an outdoor environment like this? sound quality is not my priority
i already have 2x 12" and 2x tweeter setup that i run on AGM batteries. in sweden, when people graduate, they celebrate on a truck bed like this:
i have already used my setup on this event once but i want some more umpf. i run my setup on a 1000w car amp and with batteries.
is it a stupid idea to built a 15/18" subwoofer and run it on batteries? i am thinking a horn design, like a tham15 or something to keep it as efficient as possible.
good thing with batteries is i dont need an generator making sounds. although i have a 2.2kw diesel generator and i have an RCA output from my car stereo that i could use. maybe that is a better option? although it would require a somewhat expensive PA amplifier
anyways, what would be the ideal subwoofer for an outdoor environment like this? sound quality is not my priority
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Lots of crazier setups than that have been run on car batteries.
It may run fine using the same amp as the other drivers, depending on the impedances.
Give it a try.
https://www.svsound.com/blogs/subwoofer-setup-and-tuning/strengths-and-pitfalls-of-big-subwoofer-drivers#:~:text=Low frequency extension and sound,than a smaller subwoofer driver.
It may run fine using the same amp as the other drivers, depending on the impedances.
Give it a try.
https://www.svsound.com/blogs/subwoofer-setup-and-tuning/strengths-and-pitfalls-of-big-subwoofer-drivers#:~:text=Low frequency extension and sound,than a smaller subwoofer driver.
i am already using all my channels so i will need another car amp. would 1000-2000w be enough for bass? i think i could be getting away with that without having to use generator. i have 240ah agm bank now, but can increase if needed
i am using it for this purpose:
the ones in this video are on the more extreme side...
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Double the sound pressure would be 6, not 3 dB.
THAM 15 is a good standard allround design, with good efficiency for the size. I should know, because I performed the measurements Anders Martinsson has on his website
-> https://www.martinsson.cc/blog/index.php?entry=THAM15-measured-and-compared
THAM 15 is a good standard allround design, with good efficiency for the size. I should know, because I performed the measurements Anders Martinsson has on his website
-> https://www.martinsson.cc/blog/index.php?entry=THAM15-measured-and-comparedoyh cool!
what i mean is, doubling the wattage means +3db, so having +3db from just adding another speaker should mean twice the efficiency
i think i need 2 of those to match my 12" tops which are monacor sp-12a/302pa https://www.eluxson.se/produktkategorier/430-sp-12a-302pa.html and spaudio tw-35s tweeters https://www.thesoundking.com/en/tweeters-bandeja/1739-tweeter-sp-audio-sp-tw35s.html this tweeter is very loud
what 15" element would you go for? i dont want to ruin my bank account completely lol
what i mean is, doubling the wattage means +3db, so having +3db from just adding another speaker should mean twice the efficiency
i think i need 2 of those to match my 12" tops which are monacor sp-12a/302pa https://www.eluxson.se/produktkategorier/430-sp-12a-302pa.html and spaudio tw-35s tweeters https://www.thesoundking.com/en/tweeters-bandeja/1739-tweeter-sp-audio-sp-tw35s.html this tweeter is very loud
what 15" element would you go for? i dont want to ruin my bank account completely lol
It may be counter-intuitive, but this is wrong.
It is mostly true that a single sub with greater Sd will be more efficient and will couple to the air better at low frequencies.
But in the case of multiple subs, each needs to be driven with the same amount of current to each produce identical SPL, so for each sub you add you are increasing the amplifier power requirement. No efficiency gain at all. zero. zilch. Doesn't matter how you wire them, each sub still needs to draw XXX power to produce YYY SPL.
nah rotary feels way too complicated.
i am thinking either a tham or cubo type of box. question is, do you think B&C 15PS76 is enough or do i need something more extreme? https://en.toutlehautparleur.com/speaker-b-c-speakers-15ps76-8-ohm-15-inch.html
two of those or would it be better with one 18ps100? that would be cheaper https://en.toutlehautparleur.com/speaker-b-c-speakers-18ps100-4-ohm-18-inch.html
there is also a 18lb100 and honestly i am not expert enough to say what is better for a horn design like this
i am thinking either a tham or cubo type of box. question is, do you think B&C 15PS76 is enough or do i need something more extreme? https://en.toutlehautparleur.com/speaker-b-c-speakers-15ps76-8-ohm-15-inch.html
two of those or would it be better with one 18ps100? that would be cheaper https://en.toutlehautparleur.com/speaker-b-c-speakers-18ps100-4-ohm-18-inch.html
there is also a 18lb100 and honestly i am not expert enough to say what is better for a horn design like this
Sorry Charlie,
Doubling cabinets (and driver Sd) gains +3dB sensitivity/efficiency.
Doubling power is a +3dB gain, together a +6dB gain, (assuming the power/voltage source does not current limit).
No one would consider lugging double the amount of cabinets and power for a measly +3dB gain
Here is an example of one Danely Sound Labs BC218 front loaded horn cabinet compared to two cabinets, each driven with the same voltage:
Obvious +6dB low frequency gain, plus a little more in the configuration that increases its frontal boundary.
Anyway, Stoneeh, myself, thousands of others have measured the same, and most simulations agree with the measurements.
Here's a thread that documents some more about the effect of multiple cabinet combined response for those wishing for a "deeper dive":
https://www.diyaudio.com/community/threads/multiple-cabinet-combined-response.204472/
Cheers,
Art
Nothing is going to beat the efficiency of horn loaded, within the realm of one or two drivers.
If you have the vehicle space for the box, that is bound to give the loudest, longest sub output for whatever battery capacity is available.
I've run main's and subs on battery/inverter power...out the back of a minivan. Sub was a double 18" reflex......it got a big deep cycle marine battery and 2300W inverter. Each 12" and horn main got a more normal car battery and 800w inverter. All would last for about 2.5 - 3hrs at party volume.
And just so nobody can claim the former measurement is horn stacking gain, here's a measurement of bassreflex speakers, showing the same thing. Infinity SM125, measured in GPM. Yellow and gray one box each, green both running in parallel.
+3 dB total amp power for +6 dB gain; meaning +3 dB comes from the doubling of membrane area. Note that at some point in the HF, the gain is lost, because at those frequencies the wave length gets so small that a mic being even slightly off center causes phasing / cancellation. So the prerequisite for the +3 dB gain is perfect addition of waves between boxes - which will always be a given though with subwoofers in stacks at low frequencies (very large wavelengths).
Any good simulation indeed shows the same. Even such a basic one as WinISD. Here's identical BR boxes, running at total 1w (2,83V for the single box, 2V for the two boxes in parallel). Green shows single, red shows both. Yet again, a 3 dB gain:
+3 dB total amp power for +6 dB gain; meaning +3 dB comes from the doubling of membrane area. Note that at some point in the HF, the gain is lost, because at those frequencies the wave length gets so small that a mic being even slightly off center causes phasing / cancellation. So the prerequisite for the +3 dB gain is perfect addition of waves between boxes - which will always be a given though with subwoofers in stacks at low frequencies (very large wavelengths).
Any good simulation indeed shows the same. Even such a basic one as WinISD. Here's identical BR boxes, running at total 1w (2,83V for the single box, 2V for the two boxes in parallel). Green shows single, red shows both. Yet again, a 3 dB gain:
i have done some arguing with myself. these are the setups i am considering for now
2x B&C 15TBX100. rated 1000rms, 2*260 EUR at a local dealer: https://en.toutlehautparleur.com/speaker-b-c-speakers-15tbx100-4-ohm-15-inch.html
1x B&C 18TBX100. rated 1200rms. 1*240 EUR: https://www.sonovente.com/en-gb/b-and-c-18-tbx-100-4-p62579.html
2x B&C 15PS76, rated 550wrms(?) but higher sensitivity than 15TBX100. 2*215 EUR: https://en.toutlehautparleur.com/speaker-b-c-speakers-15ps76-8-ohm-15-inch.html
2x B&C 15PS100 2*240 EUR 700wrms: https://en.toutlehautparleur.com/speaker-b-c-speakers-15ps100-8-ohm-15-inch.html
any inputs??
i think these are my best options, maybe i should go for B&CA 15PS76 because of the price tag. i believe tham15 was originally designed for 15TBX100, but martinsson has also used 15PS76 for the MK2 version on his blog.
it also seems that the sensistivity difference between tham18 and tham15 is not huge, compare curves here: https://www.martinsson.cc/blog/index.php?entry=high-end-low-end---diy-notes and: https://www.martinsson.cc/blog/index.php?entry=THAM18-details
2x B&C 15TBX100. rated 1000rms, 2*260 EUR at a local dealer: https://en.toutlehautparleur.com/speaker-b-c-speakers-15tbx100-4-ohm-15-inch.html
1x B&C 18TBX100. rated 1200rms. 1*240 EUR: https://www.sonovente.com/en-gb/b-and-c-18-tbx-100-4-p62579.html
2x B&C 15PS76, rated 550wrms(?) but higher sensitivity than 15TBX100. 2*215 EUR: https://en.toutlehautparleur.com/speaker-b-c-speakers-15ps76-8-ohm-15-inch.html
2x B&C 15PS100 2*240 EUR 700wrms: https://en.toutlehautparleur.com/speaker-b-c-speakers-15ps100-8-ohm-15-inch.html
any inputs??
i think these are my best options, maybe i should go for B&CA 15PS76 because of the price tag. i believe tham15 was originally designed for 15TBX100, but martinsson has also used 15PS76 for the MK2 version on his blog.
it also seems that the sensistivity difference between tham18 and tham15 is not huge, compare curves here: https://www.martinsson.cc/blog/index.php?entry=high-end-low-end---diy-notes and: https://www.martinsson.cc/blog/index.php?entry=THAM18-details
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Art, none of that has anything to do with "efficiency", which is what the OP asked about.
You seem to be confusing voltage sensitivity (SPL at some Voltage, e.g. 2.83V) with efficiency (SPL per Watt of input power).
Hi Charlie,
Efficiency does go up too, not just sensitivity.
Here's one 8 ohm driver, 2.83V, so 1 watt.
Here's 4 of the same driver in a 2P 2S config, for the same nominal 8 ohm impedance, so again 2.83V and 1watt.
And as expected (without showing the graphs), the 4 drivers vs one, show close to +6dB sensitivity gain for the same 1 watt of power.
Efficiency does go up too, not just sensitivity.
Here's one 8 ohm driver, 2.83V, so 1 watt.
Here's 4 of the same driver in a 2P 2S config, for the same nominal 8 ohm impedance, so again 2.83V and 1watt.
And as expected (without showing the graphs), the 4 drivers vs one, show close to +6dB sensitivity gain for the same 1 watt of power.
@mark100 Well I can't argue with THAT! OK, I think this has to do with how I am/was envisioning the problem at hand:
In the system you have just described, each driver is 8 Ohms (nominal) impedance. Let's call that 1W for 2.83V input regardless of frequency for simplicity and this produces 90dB@1m. The voltage sensitivity is 90dB AND the efficiency is 90dB, but more specifically 90dB@2.83V for the former and 90dB@1W for the latter.
Now consider the 2P2S arrangement. The nominal impedance of this arrangement is again 8 Ohms. When you drive it with 2.83V it will produce and SPL of 96dB. Because the impedance is 8 Ohms, is will also draw 1W of power when driven with 2.83V but that power is being equally distributed four ways, so each driver is getting 1/4W.
In the way I perceived the question, the efficiency of each driver in its enclosure is not increased, you are just using more of them. But from a "system" perspective the overall electrical energy conversion to acoustic energy has indeed increased, which IS an increase in efficiency.
I took the question in the OP to be "how to build a more efficient single speaker" and not how to wire up many of them. But I guess the answer to "use more" is perfectly valid, it's just not how I was envisioning the problem. In fact and TBH I never realized that an NP-NS arrangement of N^2 drivers will result in better efficiency overall without requiring more input power, although of course at the expense of an increase in the total volume (and weight) of the system by N^2.
In the system you have just described, each driver is 8 Ohms (nominal) impedance. Let's call that 1W for 2.83V input regardless of frequency for simplicity and this produces 90dB@1m. The voltage sensitivity is 90dB AND the efficiency is 90dB, but more specifically 90dB@2.83V for the former and 90dB@1W for the latter.
Now consider the 2P2S arrangement. The nominal impedance of this arrangement is again 8 Ohms. When you drive it with 2.83V it will produce and SPL of 96dB. Because the impedance is 8 Ohms, is will also draw 1W of power when driven with 2.83V but that power is being equally distributed four ways, so each driver is getting 1/4W.
In the way I perceived the question, the efficiency of each driver in its enclosure is not increased, you are just using more of them. But from a "system" perspective the overall electrical energy conversion to acoustic energy has indeed increased, which IS an increase in efficiency.
I took the question in the OP to be "how to build a more efficient single speaker" and not how to wire up many of them. But I guess the answer to "use more" is perfectly valid, it's just not how I was envisioning the problem. In fact and TBH I never realized that an NP-NS arrangement of N^2 drivers will result in better efficiency overall without requiring more input power, although of course at the expense of an increase in the total volume (and weight) of the system by N^2.
The common misconception is "the bigger system requires more power", when the opposite is true.
And tapped horns can cut the amount of power required for a given SPL compared to bass reflex by around -6dB, with a system volume and weight increase of only +1 to 3dB.
Exactly Charlie.
I love it when communication issues and starting perspectives get cleared, and well intentioned clear thinking folks get to get down to a common understanding of the facts once we're all on the same page.
You might like this.....TDanley designed a DIY FLH sub about 30 years ago for the prosound community that was crazy efficient, called the Labhorn.
Big boxes for sure, 45x45x22.5 inches, designed for efficient truck packing.
A bank of 4 of them, wired 2P 2S, gave 118dB 2.83V !!! I'd call them 6 ohm nominal drivers.
Here's some old posts of mine https://forums.prosoundweb.com/index.php/topic,161015.0.html
I've enjoyed many fine exchanges with Art over the years, as you might see some in that old thread...
.I've learned that telling him about how subs work, is akin to telling Noah how to build the ark Lol. Experience rocks.
Well... If it is "bang per buck" we are chasing, and there is a car amplifier available.
Is it a stereo or a mono amplifier?
Is it safe to assume it can handle a 2 Ohm load?
4 x the box Speaker 12-280/8-A would be less than half the budget and roughly equivalent to 2 x 18", 2 x 2 driver boxes all in parallel nets you a total impedance of 2 Ohms, the sim is 4/pi so relatively realistic max level, HP filter recommended.
To save additional funds build them using 18mm OSB.
Is it a stereo or a mono amplifier?
Is it safe to assume it can handle a 2 Ohm load?
4 x the box Speaker 12-280/8-A would be less than half the budget and roughly equivalent to 2 x 18", 2 x 2 driver boxes all in parallel nets you a total impedance of 2 Ohms, the sim is 4/pi so relatively realistic max level, HP filter recommended.
To save additional funds build them using 18mm OSB.