PDA

View Full Version : which 10" drivers



Akira
06-15-2005, 10:17 AM
i am building dual 10" compression subs. the design is simple: separate 10" reflex enclosures aimed at each other, housed in the same box, firing through a narrow slot. this is a trick used in sound reinforcement systems designed to give more kick and impact verses smooth low end response.
this sub need only reproduce 30Hz to 60Hz.
what drivers should i use, new (prefered) or vintage.
i don't want to go any larger that a 10" driver for three reasons-- size, diaphram motion speed and tightness. (no over hang common in 18" drivers)
Akira

speakerdave
06-15-2005, 10:54 AM
Interesting idea. I would suggest you consider going to 12". Study the information on the woofer in the LSR32/LSR6332, the 252G. This woofer is available new for something around $250, as I recall. Also available in a 2-ohm version, the 252F, which JBL uses in a sub for the LSR series.

David

whgeiger
06-15-2005, 11:58 AM
…your design strategy, as it is based on false premises:

A,

Remarks {...} follow your text.

Regards,

WHG


)snip( this sub need only reproduce 30Hz to 60Hz.
{A one-note boomer! Why? It must also perform well for at least one octave into the crossover overlap region(s).}


what drivers should i use, new (preferred) or vintage.
{Those with large [Vd]=[Xmax]*[Sd] and low [Qts] <= 0.3 (this is not typical vintage performance). Whatever driver you choose to use, enclosure acoustics will need to be tweaked to match its TSP’s.}


i don't want to go any larger that a 10" driver for three reasons-- size, diaphragm motion speed and tightness. (no over hang common in 18" drivers)

{“size” (Presume in regards to enclosure footprint required) - It is possible to have a larger driver in an enclosure of a footprint smaller than that of the one you are considering. For an example of this, see products from Velodyne }
http://www.velodyne.com/velodyne/products/specs/DigitalDrive.html (http://www.velodyne.com/velodyne/products/specs/DigitalDrive.html)

{“diaphragm motion speed” - Presume slower is what you are after; but, for equal output, a smaller [Sd] diaphragm must move further in the same time frame (same frequency) than that of one with a larger [Sd]. So the larger [Sd] driver moves slower over a smaller distance, but weighs more. So?}

{“tightness” - has everything to do with [Qts] and little to do with [Sd] other than the associated increased mass of the larger diaphragm. Here the mass increase is typically compensated for by use of a larger (stronger) motor. Also, mass roll-off and the upper limit of the driver’s piston range are non-issues at the frequencies of interest even when they are extended several octaves into the crossover overlap region.}

JuniorJBL
06-15-2005, 12:09 PM
simi 5th order. Tune (port) the center chamber then it is a fifth order. Tune the 2 outside chambers (as well as the 3rd) and you will have a 7th order. I think JBL made a control series sub in the early 90's with this design, but I think they were 6" drivers. Also this is a Bose approach. Used alot in car audio designs.

IMO they are not quite as responsive as a sealed or 4th order box:)

They do make some lowend tho....

Zilch
06-15-2005, 12:26 PM
http://www.jblpro.com/mpro/PDF/MP255S.pdf

http://www.jblproservice.com/pdf/MPro%20Series/MP255S.pdf

More like triple-chamber bandpass, actually:

http://audioheritage.org/vbulletin/showthread.php?t=3922

Try 123A-1, maybe. They cheap.... :D

johnaec
06-15-2005, 12:34 PM
This too: http://www.jblproservice.com/pdf/Sound%20Factor/SF22SP.pdf

John

JuniorJBL
06-15-2005, 12:48 PM
The Control SB-5
http://www.jblpro.com/pub/obsolete/Control_sb-5.pdf

Mr. Widget
06-15-2005, 12:51 PM
Isn't that the triple chamber bandpass design that Bose has the patents on and forced JBL to stop making them?

Widget

JuniorJBL
06-15-2005, 12:54 PM
Isn't that the triple chamber bandpass design that Bose has the patents on and forced JBL to stop making them?

Widget

I was not aware that that had happend.

They (bose) had one for a car and we called it the Bose Hose:D
It had 2 hoses comming out of it to go into the cab of the car.

Zilch
06-15-2005, 12:56 PM
See the thread I referenced above in post #5. The Bose patent has long since expired, and JBL is "dabbling" in multi-chamber bandpass subs again.

Gordon discloses a cool design using 123A-1's there.

See also 4682 (12" 2206), 4685 (15" 2225), and 4688 (18" 2240) "push-push" TCB designs:

http://www.jblpro.com/pub/obsolete/4682.pdf

http://www.jblpro.com/pub/obsolete/4685.pdf

http://www.jblpro.com/pub/obsolete/4688.pdf



And "slot" array alignment of PD125 at bottom here:

http://www.jblpro.com/pages/pd_series/pdf/PD125.pdf

There's more info on subwoof arrays on the JBL pro site in various application manuals. Use "Search" there to find it.


Nobody's come up with the subject Tech Note, though, Volume 1, #19.

C'mon, guys, I KNOW somebody's got it out there.... :D

speakerdave
06-15-2005, 01:43 PM
Could somebody sketch the inside of one of these things for me?

thanks,

David

Zilch
06-15-2005, 02:24 PM
Huh?Inside of SB-5 is shown in the link provided by JuniorJBL above. That's a dual isobaric (push-pull) triple-chamber configuration. The two outer chambers are tuned to the high-pass frequency, and the common center chamber to the low-pass frequency. The frequencies can be determed from the impedance curves.

The layout of the push-push 468X series is unknown here, thus far. Subwoof was gonna sketch one up for us.

[With pics and dimensions, please.... :) ]

JuniorJBL
06-15-2005, 02:48 PM
You da Man:applaud:

Zilch
06-15-2005, 02:54 PM
You da Man:applaud:Subs is just plain FUN stuff. :D

Control SB-5 knocks me out when I put the cover on.

I can just imagine what one built with REAL drivers would sound like.... :p

JuniorJBL
06-15-2005, 03:01 PM
We used to build lots of boxes. The best one(s) was in an Ford e350 extended van
with 14 12's in 2.5cu ft boxes with 4 Hifonics Collosus (1000w per ch@4ohms) It did 171db.:blink: It felt like your chest was gona cave in and your head was gona explode. It used to pop the windshield out if you did not leave the doors open:applaud:

I was a bit younger then:D

P.S. I should say no one was in the van when we did the reading:bouncy:
C weighted

Zilch
06-15-2005, 03:11 PM
Heh.

Gordon's box will get you 110 dB, exceeding THX specs, with justa 200 W amp.

That'd be more age-appropriate, now.... :p

speakerdave
06-15-2005, 03:14 PM
I think I'm getting it.

What are the special requirements of drivers being used that way?

Thanks,

David

Zilch
06-15-2005, 03:45 PM
What are the special requirements of drivers being used that way?Dunno. Whgeiger suggested high Vd, low Qts. JBL made 'em work without using extended bass drivers; 2226H is not a subwoof, for example. 123A-1 is not low Qts, and Gordon's design uses them.

We'll have to make an empirical determination, maybe. How 'bout we start with 2242H? :p

Titanium Dome
06-15-2005, 04:40 PM
We used to build lots of boxes. The best one(s) was in an Ford e350 extended van
with 14 12's in 2.5cu ft boxes with 4 Hifonics Collosus (1000w per ch@4ohms) It did 171db.:blink: It felt like your chest was gona cave in and your head was gona explode. It used to pop the windshield out if you did not leave the doors open:applaud:

I was a bit younger then:D

P.S. I should say no one was in the van when we did the reading:bouncy:
C weighted


If you want to get to the edge in bass, you've got to talk to the car guys and gals. They're in the true petri dish of bass evolution. :yes:

whgeiger
06-15-2005, 05:42 PM
Whgeiger suggested high Vd, low Qts. JBL made 'em work without using extended bass drivers; 2226H is not a subwoof, for example. 123A-1 is not low Qts, and Gordon's design uses that.

We'll have to make an empirical determination, maybe. How 'bout we start with 2242H? :p

Z-Man,

Everyone gets the [Q] they deserve. ;-)

For ‘rings-allot’ alignments, high order and high [Q] is the prescription that ‘works’.

But of course, the accompanying overshoot may be characterized as ‘punch’ and the ‘ringing’ as increased output, but when such behavior is characterized as ‘tight’, it is shear disillusionment that prevails.

The only thing I do not like about an Infiniti FX45 is the Bose audio system that comes with it!

Regards,

WHG

JuniorJBL
06-15-2005, 06:17 PM
Heh.

Gordon's box will get you 110 dB, exceeding THX specs, with justa 200 W amp.

That'd be more age-appropriate, now.... :p

I still have 4 sub1500's and 2 2242's in the same room/system:applaud: so if need be 134db is possible with very moderate power input:nutz:

As you said it's Fun:thmbsup:

We are in this hobby to have fun right:blink:

Shane:)

pelly3s
06-15-2005, 06:29 PM
I personally would go with a LAB horn and call it a day. what the hell why not build two of them lol.... the drivers are dirt cheap just a matter of building the box. hell i got a lab12 frame for free and paid $14 for a recone kit from MWA.

Earl K
06-15-2005, 07:12 PM
you've got to talk to the car guys and gals.


They're in the true petri dish of bass evolution.

Okay, well, & with that intro from TiDome ; ;)

- Here's a good engine block to build a custom Hi Performance HiFi woofer from . :p / it'll just need a more appropriate piston/coil combo for the mentioned type of work .

- A crafty & creative reconer/rebuilder should be able to work with this motor . ( I think the W10GTi motor would be beyond most to manipulate into a useful custom driver ).



:blink:

hector.murray
06-15-2005, 07:58 PM
The amount of info spat up in this thread is amazing.
I'm DLing all this stuff that I'll need a week to comprehend!
Looking @ gordons 123a box gives me my winter project. I think it will go nicely with the 4 4313 clones in the works now.

JuniorJBL
06-15-2005, 10:11 PM
The one thing you can do is try new things.
Think you have a new design.... Then build it and see if it works!
If not try again.
I built a box for 2 4" full-range drivers once and it sounded very good.
The other thing is remember a two way will sound amoung the best because you will have less of everything phase,group delay :blah: problems.
Just give it a try, if it looks cool it might sound cool as well.:applaud:

Mr. Widget
06-15-2005, 10:22 PM
Everyone gets the [Q] they deserve. ;-)

For ‘rings-allot’ alignments, high order and high [Q] is the prescription that ‘works’.

But of course, the accompanying overshoot may be characterized as ‘punch’ and the ‘ringing’ as increased output, but when such behavior is characterized as ‘tight’, it is shear disillusionment that prevails.


:applaud: :rotfl: :applaud:

Widget

GordonW
06-15-2005, 10:36 PM
Basically, in a nutshell: Slot loading is in essence, "air-mass-loading" the driver and/or enclosure. It's placing an "inertia mass" in front of the speaker. Whether it be a slot, or a full-blown vent or port, it's the same principle.

So, yes, it would be a sort of bandpass enclosure, as noted above, if there were any appreciable chamber volume in front of the woofer, in the slot. Depending on the "tuning", it would be anything from a "one-note boom" in the midbass, to a VERY LOW frequency "rumble generator", or many other variations between. It's just the region that you tune it to... the region 30-60 Hz would more be percieved as "rumble"... the "hit" or "impact" range is more like 60-150 Hz, in rough terms...

If it's a very TINY slot, then it would probably just act to add mass to the effective moving mass of the woofer cone... which would lower resonance, raise Q, and add low-bass output at the EXPENSE of high-end response. This would tend to make a "rumbly" sound, as opposed to "high-impact" bass. This principle is used in many "true subwoofers" such as the Vandersteen 2WQ and such... which are known for their tremendous low-end reach, but not really as being a "rock-and-roll-punch" device. Great for 100-Hz-and-down (and preferably, probably 60Hz-and-down), but not really a good midbass producer...

Regards,
Gordon.

GordonW
06-15-2005, 10:41 PM
Dunno. Whgeiger suggested high Vd, low Qts. JBL made 'em work without using extended bass drivers; 2226H is not a subwoof, for example. 123A-1 is not low Qts, and Gordon's design uses them.

We'll have to make an empirical determination, maybe. How 'bout we start with 2242H? :p

There's definitely more than one way to skin this cat.

The 123A, while not being particularly low Qts (.49 or so), IS a relatively high-displacement driver for its era, at the very least. With an electrical X-max of 8mm, four of these in an enclosure can get with the program, in a BIG way. Especially with the bandpass enclosure "excursion-controlling" the drivers... usually, the port frequency is RIGHT IN the main "boom" range for HT stuff (ie, around 40 Hz), so you get MONDO output between 30 and 60, without over-extending the drivers...

But, the nice thing about bandpass boxes, is that there are MANY different tuning options... the chamber volumes, the RATIOS between front and rear chamber volume, the port frequencies (both front and rear). Between these, these boxes can be "optimized" for MANY different driver parameter sets... anything from low-Q to relatively-high-Q drivers can be "dialed in" successfully...

Regards,
Gordon.

Zilch
06-15-2005, 11:13 PM
Cool Gordon!

Sounds like Hector's gonna put 123A's to the test in your platform.

[We'll want LOTSA pics. ;) ]

And me, I'm still learning LE14's, all varieties.

Gonna try isobaric and simple push-push.

Soon's I wrap up the "Quick and Dirties" here. :p

[Pickin' up the second Citation 7.4 from TiDome on Saturday....]

hector.murray
06-16-2005, 06:44 AM
Sure, I'll send lotsa pics, but this will be in the Jan. Feb time frame. This will be the sub for my HT. Lots of interesting things happening here with the 4313s, too much to post in this thread. I'll start another in a few days.
On vacation for the moment.
I'll post more later.

subwoof
06-16-2005, 07:07 AM
I have one 4688 sitting in storage taking up space and know of 2 more available nearby. ALL are NOS but have minor moving around scratches. they were purchased from JBL at the *first* sale in 1997.

I have a pair of K151 ( alnico mag ) with new 2240H kits installed and would be willing to sell it loaded. I have a mini-van and can travel a few hours to meet. PM with email address if interested - NO tire kickers please.

Nogo on the tech note ( yet ) my library stops at 15 then goes to 22 in the vol. 1 series. I *know* I saw it somewhere....

I can do plans but other projects prohibit the time. The box is not that complex.

I would LOVE to find the dual 15 version of this to make dwgs from..... anybody know of one???

:cheers:

sub

Akira
06-16-2005, 08:49 AM
did not expect the wealth of info:blink: ...seems like my project is quite feasible, but maybe not in the volume enclosure size i want. may just have to go with a single high powered 10" in a reflex design. i'm still sticking with 10's, i have (4) 2241's vented gap in dual 18" cabs (sold to facilitate this project)...sound great but, they are huge...this is a home application.
Akira
just for the record, sound is a multifacted thing...you can't know everything. my forte is mixing...been a pro sound engineer for 20 years (semi retired...or maybe i'm deaf!) though speaker design is merely a side interest i have built many systems using simple bass reflex designs using JBL drivers as my "B" system. i thought they were better and certainly more durable than the "turbosound" designer system i had, which set me back $4,000. x 16 boxes...but, contract riders are the rule or you don't work.
now i'm down to a pair of 4412's and the original century 100's which started this obsession 32 years ago...thus the sub.
my past inventory:
(2) L100
(2) 4412
(2) 4425
(4) 4663 3way (2205/2470/2x2405)
(8) dual 18's (2241)
(8) dual 12's/2" (E120/2241/2245)
(4) dual 15's (E140's)
(4) single 12's/1" (E120/2420)
(11) 4602 stage monitors
(1) dual 15"/2" drum fill (E145/2441)
...maybe i should have bought a house instead

JuniorJBL
06-16-2005, 09:02 AM
You could find some sub1500's and put them in a 2.2 cu ft sealed box and :rockon2: (rock) out!:applaud:

Titanium Dome
06-16-2005, 02:00 PM
...maybe i should have bought a house instead

Or maybe a warehouse. :p Someday you'll need that room.

Zilch
06-16-2005, 02:52 PM
I would LOVE to find the dual 15 version of this to make dwgs from..... anybody know of one???Yeah, that's a more "practical" size:

4682 = 23.5 x 39.25 x 20.75 (Think "B460")

4685 = 29.5 x 49 x 20 (Think "dual B380")

4688 = 29.5 x 59.2 x 29.5 (Think "refrigerator")

[I now notice that tuning frequencies are actually given on the data sheets. :D ]

O.K., who's got access to ANY of these they can make drawings from, please?

Zilch
06-16-2005, 03:50 PM
http://audioheritage.org/vbulletin/showthread.php?p=60075#post60075

I take issue with a couple of assertions there:

1) That "Push-push" arrangement "reduces mechanical stresses and minimizes third harmonic distortion through cancellation of nonlinearities." Isobaric "Push-pull" arrangement (4 drivers) would do that, which this ain't, or alternative mounting of 2 drivers could, as well.

2) "High performance in a compact size." Yeah, well, compare to 4645C.

[I am not deterred, tho.... :p ]

JuniorJBL
06-16-2005, 05:34 PM
rulz!!:yes: