Which Driver to use for 100hz-500hz?

KCCT82

Member
2007-12-21 5:47 pm
Hi,

I want to build a 4-way system that would do quite well from 20-20k, with 90+ sensitivity (size is not a big problem).

I'm using for each side (2) JBL 2242H for 20hz-100hz, then from 500hz-20K I'll be using the BMS 4592ND coaxial CD.

Considering the importance of the frequency range, I'm having trouble deciding on which driver to use for 100hz to 500 hz. The JBL 2206H in a sealed box or JBL 2020H sealed?

I have no experience with TAD, anyone have suggestions on whether the TAD 1102 is worth the price? Thanks

Keith

PS- i'll be using (2) behringer dcx2496 for all the x-over points 48db/oct
 
I don't have any experience with the particular drivers you describe. But I know the JBL professional line to be good quality and well designed. The only risk would be that JBL expects a certain cabinet configuration to make the drivers give their best but I also have faith in Theile-Small.

My only comment would be on the choice to put a XO point at 500Hz - right, smack in the middle of human voice fundamentals. That XO point will have such sensitive perceptual adjustment and I know I'd drive myself crazy trying to tune such a node. I really believe you need one driver for 350Hz to 1KHz as a bare minimum, then that critical band is under a known mechanical control.

Is it too late to reconsider your drivers?
 

KCCT82

Member
2007-12-21 5:47 pm
Do you suggest crossing the 2242's at 350hz? then something like JBL 2012H for 350hz-1000hz, then the compression drivers?

actually the BMS coaxial CD works pretty well down to 350 provided you have a large enough horn to go with it.

Perhaps the JBL 2020H or 2206H for 100hz-350hz only?

and no, it's not too late to change drivers, i only have the BMS's right now, thanks

Regards,
Keith
 

MaVo

Member
2006-01-07 12:40 pm
i bet you will allways get into a "critical" band while crossing over, depending on whom you ask. example: lowest voice fundamental may be below 100hz and highest overtones into the thousands. and who says only voice is critical?

i would rather say, make the transition as smooth as possible, regardless of crossover point. i think gedlee has done a very nice try on this with his summa, which is explained in other threads here in more detail than i could do.

my second thought is, why cant the bass driver handle up to 350 or 500 or even 1000hz, so that you get a 3 way instead of 4way? pro drivers are made to handle those frequencies, i think.
 
both the 2020 and the 2206 are excellent woofers but I can't recommend a 12" driver to be very good at 1KHz. You can see the off-axis response is getting a bit gnarley on the JBL datasheets.

I prefer a 3-4" midrange for good omnidirectionality but these might be hard to find for the power levels you're looking for.

I only advise caution in this band because the human hearing is very critical of human voice as we know this sound so deeply, especially female voice. My personal preference is for a single, very high quality driver to cover the 350-1KHz band which covers most voice fundamentals. (Barry White excepted;) )
 

vasyachkin

Disabled Account
2007-12-31 1:16 am
lowest octave

two things

1 - you dont need 48db/oct crossover points everywhere even though they come free on the behringer. as compared to 24db/oct you will have more phase shift which is not the end of the world but if you dont need it then why ? you should experiment with both 24db/oct and 48db/oct settings to see what sounds IMHO.

2 - the range of 20hz to 100hz will be better covered by a TC Sounds (Audiopulse) unit than JBL imho. JBLs are designed to cover 40hz+ strictly in vented enclosures. TC Sounds are typically designed to work in either vented or sealed boxes and (depending on the model) to go down to as low as 16hz.

i have some 15" jbl speakers and a 18" TC Sounds LMS subwoofer ... forget it. in the lowest octave there is no contest. i respect JBL as a company but the standard practice in pro audio is to filter the bottom octave out, not reproduce it.
 
I'd horn load two of the 2242's -they are as good as it gets below 100 when horn loaded, and use the second pair as mid bass up to 500. A usable to 300 cycle horn with a compression driver will require a 200 HZ or lower flare and will have too much coloration and beam. A smaller 300 Hz flare horn used to 500 will sound better. If size isn't an issue horn load a good pair of 12's for midbass, use a 60 Hz flair straight hypex horn like used in the Edgar Titan 2 - Another excellent way to get killer bass in the right room is use multiple 10's and 12's (mid QTS but still efficient drivers) on an open baffle. Think big and thin
 

vasyachkin

Disabled Account
2007-12-31 1:16 am
horn load 18" JBLs ? :eek:

well it wouldn't really make them go lower ... just make them 10 times louder.

of course you can then use DSP processing to turn that extra SPL into extra low end reach but if you dont need the SPL itself then i think the price/performance ratio of that system would be off (when considering the cost of plywood and the very space it would occupy)

if you must have better efficiency than TC Sounds woofer then maybe 18" Aurasound with a pair of 15" TC Sounds passive radiators hanging off of it.

Aura has twice the linear displacement of JBL ... i mean if we must get silly might as well

just giving you ideas ...
 
vasyachkin said:
horn load 18" JBLs ? :eek:

well it wouldn't really make them go lower ... just make them 10 times louder.

of course you can then use DSP processing to turn that extra SPL into extra low end reach but if you dont need the SPL itself then i think the price/performance ratio of that system would be off (when considering the cost of plywood and the very space it would occupy)

if you must have better efficiency than TC Sounds woofer then maybe 18" Aurasound with a pair of 15" TC Sounds passive radiators hanging off of it.

Aura has twice the linear displacement of JBL ... i mean if we must get silly might as well

just giving you ideas ...


Of course it will go lower in a horn. Plus it will have lower distortion, plus higher output. Those 'stroker' 18's require massive power, plus the more the cone moves (paddling air) the less efficient they are at moving air at low distortion. I image six or eight strokers might be OK but that will take up more space then a single 1/8 space 20 Hz horn.

DSP processing? Why bother? What DSP system is at full resolution with a variable input? I listen at different volume levels and sine waves aren't much fun.
 

vasyachkin

Disabled Account
2007-12-31 1:16 am
Magnetar said:



Of course it will go lower in a horn. Plus it will have lower distortion, plus higher output. Those 'stroker' 18's require massive power, plus the more the cone moves (paddling air) the less efficient they are at moving air at low distortion. I image six or eight strokers might be OK but that will take up more space then a single 1/8 space 20 Hz horn.

DSP processing? Why bother? What DSP system is at full resolution with a variable input? I listen at different volume levels and sine waves aren't much fun.

well, like i said, it depends on the size of the room.

for my room a single "stroker" sub (18" TC Sounds LMS 5400) driven by a 2400W rms QSC audio amp (channels bridged, voice coils in parallel) seems enough. so far nobody complained that it was lacking. but my room is only 12 x 20 feet.

in a slightly larger room i would simply use two of the same subs in a "stereo" setup. but then if the room was bigger still i would not have enough power at 120V to drive them so horns would be the way to go.

by the way what do you think of horn loading a sub like this:

http://www.audiopulse.com/products/subwoofer-drivers/lms-ultra

this is basically identical to mine, except mine is red ... was sort of a prototype stage. i think such a driver would actually work well in a horn because efficiency is the only thing it lacks and a horn would restore it.

?
 
vasyachkin said:


well, like i said, it depends on the size of the room.

for my room a single "stroker" sub (18" TC Sounds LMS 5400) driven by a 2400W rms QSC audio amp (channels bridged, voice coils in parallel) seems enough. so far nobody complained that it was lacking. but my room is only 12 x 20 feet.

in a slightly larger room i would simply use two of the same subs in a "stereo" setup. but then if the room was bigger still i would not have enough power at 120V to drive them so horns would be the way to go.

by the way what do you think of horn loading a sub like this:

http://www.audiopulse.com/products/subwoofer-drivers/lms-ultra

this is basically identical to mine, except mine is red ... was sort of a prototype stage. i think such a driver would actually work well in a horn because efficiency is the only thing it lacks and a horn would restore it.

?


The Danley Labs Tapped Horn can use such a driver and is both fairly easy to build and compact. In this linked paper Tom Danley shows the decrease in excursion, lowered distortion and increased output of his design. Pretty neat how he uses both the front and backwave delayed to sum as one. Your horn would be larger of course because you seek the ultimate bottom extension.

The simplest way to increase output of your sub is stick it in a strong walled corner - is that where it's placed? Also large (24-36 inch diameter) tube traps can help the standing waves (you have plenty)
 

KCCT82

Member
2007-12-21 5:47 pm
Thanks everyone for helping me out

vasyachkin- i think the LMS is good, real good, really really good!! Being 80lbs it has to be good :D thanks for showing me that speaker, i think i'm gonna get it. You're right about the 2242 going down to 40hz, i simply didn't know there was something like the LMS so goodbye to JBL.

Magnetar- thanks for showing me Danley's site, it looks promising but believe or not this is my first attempt at building speakers so horn loading is probably out of my league.

Convergence- I called my dad and asked about his BMS coaxial CD, he agreed with you that they're not so good at the low end. Over the past 30 years he played with numerous systems which included some "good" CDs like jbl 375, altec A5/6's horn (i don't know the model, but whatever came with those systems) so i'll probably say goodbye to BMS too...

At first I really wanted to use horn to as low a fq. as possible, but after doing some research, a 300hz CD IS gonna be a pain, and nothing besides BMS goes that low (well, Goto... i'll have to sell my already non existing house, and Jbl 2490 if I lived in a theatre). So now, after reading Drew Daniels' system on the lansingheritage forum I think I'll use the 10" JBL 2012 for 300-1.2khz.

Revised system for each stereo side:

(1) LMS 18" vented for 20hz-50hz or so
(2) TAD 15" sealed for 50-300hz
(1) JBL 2012 10" sealed for 300hz-1200hz
(1) TAD 2002 CD for 1.2k-27k (they claim 27k but 20k is good enough for me, I used to bang on drums so I can't hear above 14k anyway)

These is one thing that is bothering me though. The dual 15" TAD probably isn't made for sealed enclosures so they'll be a waste, does anyone have good suggestions for 15" in a sealed enclosure pumping 50 or so-300hz? I'm pretty sure something better is out there for my application, thanks guys.

Keith
 

vasyachkin

Disabled Account
2007-12-31 1:16 am
KCCT82 said:
i simply didn't know there was something like the LMS so goodbye to JBL.

here is a picture of mine (friend included for scale is 5'8")

TC Sounds change the appearance of the cone from time to time, mine is plain aluminum

by the way more likely than not the vent will not be able to handle the amount of air that it will need to move, this is why i went sealed. since i built my sub TC Sounds now offers passive radiators to match it:

http://www.audiopulse.com/products/passive-radiators/vmp

which would be a better option than going vented imho.

[IMGDEAD]http://www.box.net/shared/static/qhsy2cbr6f.jpg[/IMGDEAD]
 
KCCT82 said:
Thanks everyone for helping me out

vasyachkin- i think the LMS is good, real good, really really good!! Being 80lbs it has to be good :D thanks for showing me that speaker, i think i'm gonna get it. You're right about the 2242 going down to 40hz, i simply didn't know there was something like the LMS so goodbye to JBL.

Keith

Please let me know how much you want for those four JBLs'.

Thanks
 

KCCT82

Member
2007-12-21 5:47 pm
by the way more likely than not the vent will not be able to handle the amount of air that it will need to move, this is why i went sealed. since i built my sub TC Sounds now offers passive radiators to match it:

right, i tried putting it in WINISD and the vent part was showing something I couldn't understand, figured it probably meant wouldn't work vented. It seems that I'll need 2 passives for an 18", The LMS is really expensive, do you know how much the passives are?? I'd like to use it vented if it's at all possible, thanks


Please let me know how much you want for those four JBLs'.

I haven't paid for them yet, backed out on my order quick enough, sorry
 

vasyachkin

Disabled Account
2007-12-31 1:16 am
i believe the passives used to run about $150 a piece

the LMS used to run for about $900 but i paid $1200 for mine because i pre-ordered it before production began. after they filled out the pre-orders they lowered the price to around $900. the lesson i learned that way is never to pre-order stuff.

i believe the price is about right for both the LMS and the passives though. if you consider that the driver has twice the motor force (BL^2/Re), twice the excursion and probably 10 times the linearity of JBL then i feel it is well worth even the preorder price.

the passives obviously don't cost much to make, but they are a unique product. nobody else makes passives that big or ones that allow you to add so much mass to them. so with the passives TC is in position to charge so much simply because they dont really have any competition there.

ye if you begin to model this sub with vents the software tells you that you need vents like 10 feet long. this is because of how strong the motor is. to counteract this motor the passive radiators have to be fitted with very high mass and VMP are really the only ones that can handle it.

TC Sounds used to offer a complete system (finished subwoofer) consisting of a 15" LMS driver, a pair of 15" VMPs and an (external) 3200W Crown amplifier. the radiators were tuned to 16hz.

i went on the TC forum and asked there what should be the arrangement of VMPs for the 18" LMS and one of their staff replied that i should use either 2 x 18" VMPs or 3 x 18" VMPs. however when modeling that it looked like using 18" VMPs i would need to push them just slightly outside of their ratings (in terms of adding too much mass) ... so i also considered using 3 x 15" PRs instead as well as multiple 12" ones but in the end just went sealed ... partly because the PRs were in the "coming soon" stage and partly because i did not want to spend money on them.

on the other hand the sealed box turned out to be way too tight. so if you can manage to do something with PRs that would be better. as it is, i am using DSP equalizer to restore the bass that this driver overdamps. too much damping is not really a problem, it just means you will need an amp with a lot of voltage swing and an EQ to boost the bass. some people would use Linkwitz Transform, but i prefer to use DSP instead because it can also perform room equalization.

by the way my friend (the one in pic) prefers how this sealed sub sounds without the EQ, he likes his bass tight and lean. i like bass heavy rather than lean so i electronically boost it around 30hz.
 

MaVo

Member
2006-01-07 12:40 pm
vasyachkin said:


by the way what do you think of horn loading a sub like this:

http://www.audiopulse.com/products/subwoofer-drivers/lms-ultra

?


i simulated a tapped horn with the axis 12inch driver in hornresp. about 314 liters of enclosure will get you -3db points of 13hz and 45hz with 130db displacement limited maximum spl. pretty crazy thing, it would be 8meters long... quite a folding problem :)