In the large rooms that sound reinforcement systems are used, it would be extremely difficult to pressurize the space below something like 40 Hz. The LAB Horn Subwoofer only accomplishes its 32 Hz by causing a slab of air to move 3" in either direction. It would require a huge amount of displacement. Instead, sound reinforcement engineers focus on getting the most response from the least amount of power, and this has the advantage of requiring sound guys to spend less money on amplification. It is an OK tradeoff because live music doesn't have that much sub-bass content anyway.
BAM said:
It should be pointed out that the lowest note on a normally tuned bass guitar-the instrument which often provides the "bottom" on most popular music-is 42 Hz.
Also, when it comes to moving air, 6 dB=1/2 octave. So all other things being equal, you can design a box that delivers down to 30 Hz with 91 dB@1W/1M sensitivity or one that delivers 42 Hz with 97 db@1W/1M sensitivity.
Put another way, it takes the same amount of air moved to produce 30 Hz at 91 dB as it does to produce 42 Hz at 97 dB.
Most 3 Ft³ DJ cabinets with 15 inchers have an F3 around 60 Hz, so by experience that seems to be low enough for popular music, and allows the designer to turn his attention toward sensitivity.
Talking to some cyber friends who are DJ's, it often occurred to me how fine a thing it would be to design a 3 Ft³ cabinet with a 15 incher that had an F3 of 42 Hz and a sensitivity of 97 dB@1W/1M. To my knowledge, there is no such beast presently, (if someone knows of one, please post).
The 15 incher with the closest Thiele-Small numbers that I know of that might get close is the McKenzie C15 400lr. I don't even know if that is sold in North America.
kelticwizard said:
That was then but this is now.
What I mean is these days the 5/6 string bass guitar (at one time rare) has become quite common place if not the norm. Lowest note for them is normally a B approximately 31.5 Hz! This is why I recommend port tuning no higher than 36 Hz for PA /Home music subs or bass guitar cabs, because of the increasing risk of over excursion damage do to port unloading. I've known a few 5/6 string bass players to rip the drivers right out of the spider using a cabinet tuned to high (41 to 50 Hz range). Most older cabs are tuned to high (following the old 4 string bass standard) & I'm surprised how many newer ones are still. I had one guy bring his 2x15" spkrs into the shop that were ripped totally out of the spiders. He was playing a 5 string bass through a sub octave box that adds a note an octave below what's played!!!
Cal Weldon said:I don't mean what they are used for, I mean why is there a 15" driver that is down 3dB already at 45 Hz. What is the advantage in building this over a driver that completes the bass spectrum.
Thanks
Cal
There is a Huge difference from playing music in your
home, and, providing sound reinforcement in a venue.
1. Turntable Rumble And The Launching Of Cones
Turntables, and, vibrations don't mix. Especially when you
have 10 - 10,000 party goers jumping to the beat. You
will have a greater chance of destroying your woofers
if you don't use some kind of cutoff frequency to prevent
uncontrolable excursion.
2. Sub Frequencies That Are Just Not There.
Rock, Dance, and, Hip Hop generally don't have any low
frequencies under 50Hz. The rare few, are so low (In
SPL) it can easily be rolled of without being noticable.
3. Home Speakers -vs- Pro Audio Speakers Requirements
Pro Audio Speakers are designed to not rely
on room gain to get the necessary bass under High
SPL usage. When the object is to achieve lower bass,
you generally add more subs. Thus making the cabinets
couple, and, having the Lower Bass increase. So, you
can achieve 20Hz by merely adding more subs, instead
of fighting with one box to cover the lower notes accurately.
For the home Audiophile, room gain is welcomed. For
the Soundguy, it is the biggest obstacle we need to
overcome.
4. Screaming Fans, And The Need For Volume
Keep in mind that efficency is the key, when you are
required to cover a large area. PA speakers are designed
to play loud to overide the screaming fans when they
hear their favorite song. This is why home speakers,
and, car speakers cannot be used for PA Requirements.
They are just not loud enough. PA Subs are designed
to perform with only one boundary........ The Floor.
Home Subs are designed to use with more boundaries.
(Floor, Corners, Wall)
The frequency response needs to stay within the Flat
range, and, rolloff to the desired f3. Using an Equalizer
or Room Gain to make up the declining rollof like home
subs........... Not Possible
Just thought I'd throw in a note here, so to speak. I'm a bass player, usually 4-string, but I do own a 6. While it's true that if a 6-string bass is tuned low, i.e. to a B (the tuning on 5 and 6-string basses cannot be taken for granted, some tune for a higher pitch), you'll get a low pitch out of the instrument. But...the actual--and I mean real-world--response of most bass rigs is pathetic by hifi standards. As an example, the specs frequently quote low end response as being down 10 dB. "Usable?" I don't think so! That simply won't do for home use, and I question its validity for bass rigs and PAs.
Setting aside questions of efficiency, reliability, and so forth, most people (bassists and synth keyboardists included) wouldn't know true low end if it bit them on the ***. They, like the boom-boom car stereo guys, think that if it vibrates their chest, it's deep. Nope. Just loud midbass. We're talking 60-80Hz.
Also, like many foolish stereo users, musicians sometimes have really destructive ideas about how to match a head (the amp) to a cabinet. Yes, it's quite possible to rip a cone loose from the basket. But that's not necessarily saying that it was playing a deep note at the time--just a loud one.
Playing through an effects box that synthesizes sub-harmonics can be thought of as an IQ test. Anyone who blew their drivers failed the test. If you're going to pull stunts like that, plan your rig accordingly. Spend lots of money. Lots. And still you should live in fear.
To answer Cal's original question in the vernacular, you can't have loud and low at the same time without spending a really, really huge amount of money. Given that choice, most people would choose loud over low every day of the week, cuz money don't grow on trees.
Grey
P.S.: Wanna scare the hell out of a bass player? Get him to play through his stereo at low volume. Ninety-nine out of a hundred bassists will have a heart attack--they never knew that much low end was available from their instrument; their bass rig just couldn't cut it.
I take no responsibility for what happens if they start trying to crank up their stereo once they've had that revelation.
Dynamics are a whole 'nother thread. Most 300-500W bass rigs have enough capacitance in their power supplies for a 30W home stereo. If that much. 'Nuff said.
Setting aside questions of efficiency, reliability, and so forth, most people (bassists and synth keyboardists included) wouldn't know true low end if it bit them on the ***. They, like the boom-boom car stereo guys, think that if it vibrates their chest, it's deep. Nope. Just loud midbass. We're talking 60-80Hz.
Also, like many foolish stereo users, musicians sometimes have really destructive ideas about how to match a head (the amp) to a cabinet. Yes, it's quite possible to rip a cone loose from the basket. But that's not necessarily saying that it was playing a deep note at the time--just a loud one.
Playing through an effects box that synthesizes sub-harmonics can be thought of as an IQ test. Anyone who blew their drivers failed the test. If you're going to pull stunts like that, plan your rig accordingly. Spend lots of money. Lots. And still you should live in fear.
To answer Cal's original question in the vernacular, you can't have loud and low at the same time without spending a really, really huge amount of money. Given that choice, most people would choose loud over low every day of the week, cuz money don't grow on trees.
Grey
P.S.: Wanna scare the hell out of a bass player? Get him to play through his stereo at low volume. Ninety-nine out of a hundred bassists will have a heart attack--they never knew that much low end was available from their instrument; their bass rig just couldn't cut it.
I take no responsibility for what happens if they start trying to crank up their stereo once they've had that revelation.
Dynamics are a whole 'nother thread. Most 300-500W bass rigs have enough capacitance in their power supplies for a 30W home stereo. If that much. 'Nuff said.
Hi guys first post here (nice site btw! hope the server issues get sorted!)
kelticwizard you asked for some 15"ers with a low Fs and high sensitivity
here's some at Precision Audio Products
they'll all do the job some better than others
i use the PD 154's in a dozen short folded horns i've got - kick *** punch around the kick drum
the PD 1550's are 99dB with an Fs of 31Hz - that do ya?
dunno if you can get them in the states but Eminence have just bought the company so there is every possibility
laters
dave
kelticwizard you asked for some 15"ers with a low Fs and high sensitivity
here's some at Precision Audio Products
they'll all do the job some better than others
i use the PD 154's in a dozen short folded horns i've got - kick *** punch around the kick drum
the PD 1550's are 99dB with an Fs of 31Hz - that do ya?
dunno if you can get them in the states but Eminence have just bought the company so there is every possibility
laters
dave
Low Fs looks good in simulations, but does not equate to flat response in the real world, witness the Shiva/Titanic/et. al. Fs for these drivers is typically in the teens to twenties, depending on driver and version, yet not one of them can reproduce anything like flat bass without eq. You'll invariably find that a driver of that nature will, like most bass and PA drivers, give a lot of output in the 60-100Hz range, then begin a long, slow rolloff, leading to response in the 20-30 Hz range being 10-20 dB less. Cabinet design choices do not cure the problem. The best you can do is put the driver in an undersized cabinet, thus raising the Q, which will flatten the response down to 40Hz or so, yet with a dip-bump before rolloff. Surprise! We're back where we started. Getting response anywhere near flat down into the 30 Hz and below range is not easily--or cheaply--done.
Trust me. Been there. Done that. Got a drawer full of T-shirts to show for it. Still there, for that matter. Good tweeters and midranges aren't hard to come by. It's 150Hz and below where you hit the hard rocks and start running into serious problems.
Grey
Trust me. Been there. Done that. Got a drawer full of T-shirts to show for it. Still there, for that matter. Good tweeters and midranges aren't hard to come by. It's 150Hz and below where you hit the hard rocks and start running into serious problems.
Grey
Fellow bass-player GROLLINS wrote:
Unfortunately thats also what guitar-players, drummers, soundmen etc prefer our instruments to sound like !
One of my next experiments will be two ELF subs (using RCF L18P300 drivers).
And yes, I prefer the sound of an uncompressed bass over the mainstream bass-sound even if it doesn't get as "loud" using an 1 kW amp as some 200 Watt instrument amps go.
Regards
Charles
Unfortunately thats also what guitar-players, drummers, soundmen etc prefer our instruments to sound like !
One of my next experiments will be two ELF subs (using RCF L18P300 drivers).
And yes, I prefer the sound of an uncompressed bass over the mainstream bass-sound even if it doesn't get as "loud" using an 1 kW amp as some 200 Watt instrument amps go.
Regards
Charles
Subliminal Crowd Control..........
"Unfortunately thats also what guitar-players, drummers, soundmen etc prefer our instruments to sound like !"
.......But not all soundmen.
The sound I do on Friday nights has all the LOW bass you could ever want, but not that sternum rattling emphasis.
Shirts, trousers, soles of the shoes rattle, but none of that peaking around 60-80 Hz that Grey mentioned.
Moving 20, 25 or 30 Hz graphic faders by 1 dB or less is clearly aparrent.
Fine tuning eq's can deliberately add slight emphasis to any particur area of the body from the chest all the way down to the shoes, and getting audience buzzing around the groin area gets the whole room bopping everytime.
Eric.
"Unfortunately thats also what guitar-players, drummers, soundmen etc prefer our instruments to sound like !"
.......But not all soundmen.
The sound I do on Friday nights has all the LOW bass you could ever want, but not that sternum rattling emphasis.
Shirts, trousers, soles of the shoes rattle, but none of that peaking around 60-80 Hz that Grey mentioned.
Moving 20, 25 or 30 Hz graphic faders by 1 dB or less is clearly aparrent.
Fine tuning eq's can deliberately add slight emphasis to any particur area of the body from the chest all the way down to the shoes, and getting audience buzzing around the groin area gets the whole room bopping everytime.
Eric.
Yeah, Some Sound Engineers Have Cloth Ears...........
No insult taken.
Eric.
A Dire Straits show I saw 20 years ago had serious low bass too.
And a AC/DC show that I worked too - that rig was all Meyersound and one of the best sounding systems that I have heard - lows, mids and highs were all great.
No insult taken.
Eric.
A Dire Straits show I saw 20 years ago had serious low bass too.
And a AC/DC show that I worked too - that rig was all Meyersound and one of the best sounding systems that I have heard - lows, mids and highs were all great.
Synergy:
Thanks for the tip on the Precision Devices-I had heard of them but never checked them out.
Just saw one model-the PD152. Once you get past a little discrepancy in their stats-resonsnce frequency is listed as 45 Hz in one place and 40 Hz in another, it looks pretty good Thiele-Small wise.
The response gets kind of ragged over 800 Hz, or so, but this is meant for bass guitar anyway. BK electronic sells them for the equivalent of $160, once you eliminate the VAT.
Put into an 3 ft³, (85 liter) box, it should yield an F3 of 45 Hz-significantly closer to my goal of 42 Hz than other drivers come.
The hitch is the Qts of 0.269. Too low to give a smooth response. That is the problem with the McKenzie as well.
There is a possible solution. This is the Augmented Passive Radiator enclosure invented by Thomas Clarke in the 1970's. Been meaning to build one for some time, haven't gotten around to it. He write two articles, complete with index, equations, etc for the Journal Of The Audio Engineering Society in the seventies.
Here are some posts on the Augmented Passive Radiator System:http://www.diyaudio.com/forums/showthread.php?postid=82564#post82564
Although the illustration would seem to show diffuculty in using this for a bass cabinet, I believe it can be constructed. The Large external PR would be on the back of the enclosure.
This is supposed to match most any speaker to any size box with a 3 dB advantage. The 3 dB advantage can take the form of ¼ octave lower F3 or the same F3 as a ported box of similar size but with a 12 dB instead of a 24 dB rolloff.
Stephen D:
Thanks for the update on the bass situation. Still, considering that most 3 Ft³ cabs have an F3 of 60 Hz, (albeit with a lower Fb), I still think that a cab with an F3 of 42 Hz or so is a step in the right direction. 30 Hz F3 in a cab of 97 dB@1W/1M would appear to be out of reach with an unequalized 3 Ft³ cab, at least for now.
Grey:
Are you saying the simulations are not correct-yes, I know the room throws everything off anyway-or that there is more to this than looking up the free air resonance of the driver, sticking it in any size box and expecting response down to the Fs?
All I am asking is that if we simulate a speaker/box combo and it shows the F3 at a certain frequency, do we have a fighting chance of it actually going down and acheiving that F3 in a real world situation, understanding the enormous variations room-to-room?
Thanks for the tip on the Precision Devices-I had heard of them but never checked them out.
Just saw one model-the PD152. Once you get past a little discrepancy in their stats-resonsnce frequency is listed as 45 Hz in one place and 40 Hz in another, it looks pretty good Thiele-Small wise.
The response gets kind of ragged over 800 Hz, or so, but this is meant for bass guitar anyway. BK electronic sells them for the equivalent of $160, once you eliminate the VAT.
Put into an 3 ft³, (85 liter) box, it should yield an F3 of 45 Hz-significantly closer to my goal of 42 Hz than other drivers come.
The hitch is the Qts of 0.269. Too low to give a smooth response. That is the problem with the McKenzie as well.
There is a possible solution. This is the Augmented Passive Radiator enclosure invented by Thomas Clarke in the 1970's. Been meaning to build one for some time, haven't gotten around to it. He write two articles, complete with index, equations, etc for the Journal Of The Audio Engineering Society in the seventies.
Here are some posts on the Augmented Passive Radiator System:http://www.diyaudio.com/forums/showthread.php?postid=82564#post82564
Although the illustration would seem to show diffuculty in using this for a bass cabinet, I believe it can be constructed. The Large external PR would be on the back of the enclosure.
This is supposed to match most any speaker to any size box with a 3 dB advantage. The 3 dB advantage can take the form of ¼ octave lower F3 or the same F3 as a ported box of similar size but with a 12 dB instead of a 24 dB rolloff.
Stephen D:
Thanks for the update on the bass situation. Still, considering that most 3 Ft³ cabs have an F3 of 60 Hz, (albeit with a lower Fb), I still think that a cab with an F3 of 42 Hz or so is a step in the right direction. 30 Hz F3 in a cab of 97 dB@1W/1M would appear to be out of reach with an unequalized 3 Ft³ cab, at least for now.
Grey:
Are you saying the simulations are not correct-yes, I know the room throws everything off anyway-or that there is more to this than looking up the free air resonance of the driver, sticking it in any size box and expecting response down to the Fs?
All I am asking is that if we simulate a speaker/box combo and it shows the F3 at a certain frequency, do we have a fighting chance of it actually going down and acheiving that F3 in a real world situation, understanding the enormous variations room-to-room?
Attachments
>Low Fs looks good in simulations, but does not equate to flat response in the real world, witness the Shiva/Titanic/et. al. Fs for these drivers is typically in the teens to twenties, depending on driver and version, yet not one of them can reproduce anything like flat bass without eq.
====
True, but it has absolutely nothing to do with their low Fs, only their high inductance. Cancel it out and they will perform as predicted.
GM
====
True, but it has absolutely nothing to do with their low Fs, only their high inductance. Cancel it out and they will perform as predicted.
GM
"Yes, it's quite possible to rip a cone loose from the basket. But that's not necessarily saying that it was playing a deep note at the time--just a loud one."
True, but most often it is the result of notes that are far enough below the port tuning where the port & spkr are out of phase & the spkr moves wildly from the unloading with little to no effective SPL output. I've seen it to many times to count. Even just last week a kid brought his Bass combo amp to me thinking there was something wrong with his amp because it made this loud clicking
sound every time he played the bottom few notes on his low B string (5 string bass). Well. he was just hearing the speaker slapping against the back plate. He wasn't playing loud. It was just a cheap combo bass rig with a 15" in a ported cab with a
port tuning to high (About 50 Hz I'd guestimate).
Agreed.
I didn't mean to imply that the goal should be to achieve an F3 down to that lowest B on a 5/6 string bass. Just think it needs to be taken into consideration when choosing ported spkr/cab alignments & at least shoot for alignments that allow low enough port tuning to offer some protection against over excursion from sub port tuning frequencies. I try to keep port tuning less than a half octave above the lowest rational frequency expected.
I think F3 of 42 Hz is an amiable goal as long as the Fb is well enough below that (as I said at most around 36 Hz). The ported subs I'm currently building for my bands small club gigging PA have an Fb of 36 Hz & a calculated F3 of 39.4 Hz. I think it's a fair enough compromise.
PS. That PR looks interesting.
True, but most often it is the result of notes that are far enough below the port tuning where the port & spkr are out of phase & the spkr moves wildly from the unloading with little to no effective SPL output. I've seen it to many times to count. Even just last week a kid brought his Bass combo amp to me thinking there was something wrong with his amp because it made this loud clicking
sound every time he played the bottom few notes on his low B string (5 string bass). Well. he was just hearing the speaker slapping against the back plate. He wasn't playing loud. It was just a cheap combo bass rig with a 15" in a ported cab with a
port tuning to high (About 50 Hz I'd guestimate).
kelticwizard said:
Agreed.
I didn't mean to imply that the goal should be to achieve an F3 down to that lowest B on a 5/6 string bass. Just think it needs to be taken into consideration when choosing ported spkr/cab alignments & at least shoot for alignments that allow low enough port tuning to offer some protection against over excursion from sub port tuning frequencies. I try to keep port tuning less than a half octave above the lowest rational frequency expected.
I think F3 of 42 Hz is an amiable goal as long as the Fb is well enough below that (as I said at most around 36 Hz). The ported subs I'm currently building for my bands small club gigging PA have an Fb of 36 Hz & a calculated F3 of 39.4 Hz. I think it's a fair enough compromise.
PS. That PR looks interesting.
Wizard,
Sad, but true. The Thiele-Small parameters are way, way too simplistic to give a good estimate of real response once the driver is bolted into the cabinet. Then the room complicates things even further. But the T-S calculations barely get you out of the starting gate.
Any more, I build a test chamber of the same volume and configuration as the final cabinet I intended to build when I started, then test the response. It's enough to drive a man to drink. I don't blame the T-S model, per se, it's just that it doesn't cover enough factors.
This is why speaker companies have test equipment. If it were as simple as a few equations in an Excel speadsheet, no one would buy commercial product. Yes, yes, I know...not everyone owns a table saw, etc. but out in the real world T-S is only half, if that, of what you need to get flat response.
Beg, borrow, or steal some test equipment.
Then be prepared to cry real tears.
Eric,
Yeah, I vote for the groin effect.
Grey
Sad, but true. The Thiele-Small parameters are way, way too simplistic to give a good estimate of real response once the driver is bolted into the cabinet. Then the room complicates things even further. But the T-S calculations barely get you out of the starting gate.
Any more, I build a test chamber of the same volume and configuration as the final cabinet I intended to build when I started, then test the response. It's enough to drive a man to drink. I don't blame the T-S model, per se, it's just that it doesn't cover enough factors.
This is why speaker companies have test equipment. If it were as simple as a few equations in an Excel speadsheet, no one would buy commercial product. Yes, yes, I know...not everyone owns a table saw, etc. but out in the real world T-S is only half, if that, of what you need to get flat response.
Beg, borrow, or steal some test equipment.
Then be prepared to cry real tears.
Eric,
Yeah, I vote for the groin effect.
Grey
I assume that you are using 15 or 18 inch drivers for you P.A. subs. So your 36 Hz tuning is O.K. to me. But I don't think a 36 Hz tuning would be good for a 4x10" bass-box since you won't have enough excursion control between 40 and 60 Hz. In this case a tuning over 40 Hz and the use of a highpass filter would give better results IMO.
Regards
Charles
phase_accurate said:
Enough port air support for excursion limiting of the more used 40 - 60 Hz range was also a concern to me & is why I also chose 36 Hz as the lowest freq I was willing to tune to for this project. I'm actually using a pair of 300 watt 12" Pioneer car subs for one cab since I had them & they are a little higher efficiency than typical of comparable 12" car subs with a pair hitting about 94dB 1w/1m & they have 8.4 mm linear Xmax so they should do OK for this small club venue application though not really a candidate for pro sound reinforcement like being discussed here. We have some
JBL 4530 scoop cabs & some 18" ported cabs for our outside
& large venue gigs but needed something smaller for some of the smoky little bars we do. I still have to come up with one more small to medium size cab for this small venue rig. One candidate
is a 4x10" using the Dayton Quatro 10's. They have an 8 mm Xmax & model pretty well with a 36 Hz tuning in roughly 3.5 cub ft.
For this small venue application I can get by with medium efficiency long excursion drivers but moving to high efficiency drivers for large venue applications it becomes difficult as you
suggest to utilize that lower port tuning as the excursion on
the smaller high efficiency drivers is generally to low except for
the most expensive drivers.
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