2235 and 2245 in sealed enclosures

[Niklas Nord]

Does anybody know anything about using the 2235 or 2245
in sealed enclosures?

I dont have any calculation application to use for this.

I´m planning to buy a TacT, and with this be able to EQ the
lower freq up.

Also, i tend to use corner placed subs.

**The thing i would like to gain here is space, the smaler box
the better, BUT it should not have a BIG impact on sound
quality..

Is sealed box the best if i would like to EQ the driver?

I have the JBL MPA 1100, it will be able to deliver some serius
amount of power also..

WITH room gain, i would be happy with -3db @ 18hz :D

[4313B]

"Does anybody know anything about using the 2235 or 2245
in sealed enclosures?"

Yes

"**The thing i would like to gain here is space, the smaler box
the better, BUT it should not have a BIG impact on sound
quality.."

Wrong forum dood. You need to visit another forum that expresses an interest in finesse. The order of the day here is BIG and LOUD with cracked plaster walls, broken picture windows, dead pets, constant ringing in the ears, live Zappa until you puke, etc. etc.

[Niklas Nord]

OK
thank you :(

[4313B]

I'd be happy to take this offline where we won't be castigated for talking about small boxes and medium to low efficiency systems.

[Mr. Widget]

Originally posted by Giskard
I'd be happy to take this offline where we won't be castigated for talking about small boxes and medium to low efficiency systems.

I find that statement by itself offensive!:flamer:




:D :D :D :D :D

[Guido]

Originally posted by Giskard
I'd be happy to take this offline where we won't be castigated for talking about small boxes and medium to low efficiency systems.

Didn't you once mention to own a pair of BIG and LOUD 4430????

:D

[TimG]

http://www.danbbs.dk/~ko/ubdwnld.htm
The program is called Unibox and runs under MS Excel. You just need to enter the TS specs for the driver in question at the beginning of the spreadsheet and you can compare the response in sealed, ported, passive radiator, or bandpass enclosures.

[4313B]

Originally posted by Mr. Widget
I find that statement by itself offensive!:flamer:




:D :D :D :D :D
Yeah Baby!


Originally posted by Guido
Didn't you once mention to own a pair of BIG and LOUD 4430????

:D
Me??? Mere toys compared to some of the stuff these guys are running! :slink:



:rotfl:

[4313B]

Yeah, I've actually checked that spreadsheet out before but have never actually compared it verbatim to the results given by BB6P, WinISD, LispCAD, etc. so I can't comment on it's "accuracy". Maybe some other forum members who have the various packages can do a compare.

Maybe it would even be of some benefit for us all to pick one driver, synchronize the T/S specs and post our results given a specific volume to work with using our software of choice. I'd be happy to use the ancient "JBL" formulas if others want to employ their various software packages. I think RobH suggested doing this very exercise some time ago, just not with a 2235H or 2245H sealed. Qtc = CD? Bessel? Butterworth? T/S parameters from the 2235H or 2245H product design sheet?

[Earl K]

Hi Giskard

Maybe it would even be of some benefit for us all to pick one driver, synchronize the T/S specs and post our results given a specific volume to work with using our software of choice.

Yes, I'm up for that. I can tune with MacSpeakrZ. What box size?

Something to match the S9500 tuning ( like a Bessel Qtc ) ? How about using the 2245h ? - since Niklas already owns some ( I think ).

regards <> Earl K

[TimG]

I can help too, maybe this weekend. I have Unibox, LspCAD, and I purchased a used version of Soundeasy that I need to install.

[Niklas Nord]

Yes i own both some 2245 and 2235

[4313B]

Sounds good guys. Lets use the T/S parameters from the 2245H Product Design Brief (http://www.jblpro.com/pages/components/2245h.htm) and a Bessel alignment (Qtc = 1/sqrt(3))?

[Niklas Nord]

great!
:)

[TimG]

Using Unibox, with 2245H, in sealed box with Qtc=.577, I computed three different cabinet volumes based on the amount of stuffing used. With no stuffing volume is 219.5L, with the walls covered volume is 199L, and with heavy stuffing volume is 142.7L.
Performance estimated without accounting for compression or room gain with 300watts input.
Freq SPL in dB
100 119
70 118
50 115.4
40 113
30 109.5
20 102.5
16 98.5
Driver may exceed xmax below 32hz with 300 watts assuming a cold voice coil.

JBL 2235 same alignments but with 150 watts input. Volume: no fill 101.5L, walls covered 92L, heavy fill 66L.
Freq SPL in dB
100 114.3
70 113
50 110.6
40 108.2
30 104.8
20 98.3
16 94.3
Driver may exceed xmax below 24.4hz with 150 watts input assuming a cold voice coil.

[Niklas Nord]

Does heavy stuffing mean that it´s packed very tight?
then there must me some kind of mounting so the stuffing
does not touch the cone of the speaker..

[Earl K]

Hi

In MacSpeakerz, with a system Bessel tuning ( .577 Qtc ), the box volume was automatically calculated as 7.743 cu ft.

This jpg. shows input power limited to 135 watts. This is to keep the Xmax from exceeding the speakers limit at 20 hz ( and this gives an output of @ 102 db in freespace with that many watts ) .

Anyhow that's how I interpret the graphics as provided by this tuning software.

regards <> Earl K

[Earl K]

Here's a pdf of the same box/ file with the full 300 watts (Pe) applied .

- The software shows excessive unloading of the woofer below 40 odd hz .

- In a real home application this would be more than fine for my environment and listening habits .

- Based on what I've see here - I'd likely build a 8 cu ft box. I'd also construct it with the option of porting ( with variable length ports ) or sealing it up for the extra VLF extension . This would give something that can be somewhat "tuned" to the realities of the listening environment.

- Alas, 14" woofs is about the max. that my place can accomodate - so this is all academic . :p

regards <> Earl K :)

[TimG]

Your program agrees with Unibox very closely. Your computed cabinet volume is almost identical to what I computed with no stuffing. Our max output at 20Hz is also with .5dB. I found that if I targeted a Qtc of .707 you can drive the woofer with the full 300watts without exceeding xmax, so a slightly smaller cabinet can offer more driver protection but at the cost of some efficiency and slightly worse group delay. Every design involves tradeoffs.

[4313B]

I just ran the 2245H in BB6P and here's what I got:

JBL 2245H
Box Properties
Type: Closed Box
Vb = 5.862 cu.ft
Qtc = 0.577
Fc = 47.35 Hz
F3 = 58.42 Hz
Fill = normal

70 Hz 12 dB/octave low pass filter
110.5 dB @ 51 Hz
107.5 dB @ 28 Hz & 95 Hz
104.5 dB @ 21 Hz & 125 Hz
100.5 dB @ 16 Hz & 171 Hz
Mechanical Limit occurs at 22 Hz with 300 watts input.

This is pretty much the same result as with the old Margolis/Small formulas as printed in the JAES. I don't currently have a 2245H to test but I did use BB6P to design a 2.5 cubic foot sealed test box for a 2242H with a Qtc = .707 and it came out dead on the money.

[Earl K]

So in BB6 , the automatic calculation for box size is almost 2 cu' smaller !?!

That's some difference ! My program and computer must be suffering some form of northern hyperinflation . Good thing I don't have to build these to find out the actual error quotient . That would make me sad. eek:

What gives ?

<> Earl K :D:

[4313B]

When I use WinSpeakerz I get 8.13 cubic feet.
Same with WinISD Beta.

"Good thing I don't have to build these to find out the actual error quotient."

BB6P wants a 3.45 cubic foot volume for a 2245H to end up with a Qtc of 0.707. That size is a bit more manageable as a test box... If one were to build that and measure the error...

*****

"You guys try a bandpass box???"

Well, they can be fun but one is getting away from using the natural room rise for EQ and the second order rolloff of the sealed box. Transient response and group delay will suffer but efficiency goes way up. It's all a compromise.

[GordonW]

BassBox 5.0:

Qtc=.577, NO box fill:

Vb= 7.11 ft^3
Fc= 45.1 Hz
F3= 57.4 Hz

Qtc= .577, NORMAL box fill:

Vb= 6.221 ft^3
Fc= 45.8 Hz
F3= 58.3 Hz

Qtc= .707, NO box fill:

Vb= 4.24 ft^3
Fc= F3 = 56 Hz

One thing I've noticed: If you want the most VERSATILE box, it's useful to size the box for about 5-10 percent OVERSIZE from a Qtc= .577... since if you do that, you will ALMOST ALWAYS wind up with an appropriate box volume, to do an almost textbook standard ported box. All you need to do, is add the port... punch in the driver and box size, and let it calculate the port frequency (in this case, 27 Hz, according to BB5), and there you go... F3 in free space of 35 Hz...

If I can get the old DOS/Win3.1 machine fired up here, I'll run these parameters through the old Warren Merkel PerfectBox program. Nice thing about that, is that you can easily model the second-order high-Q highpass "bass assist" filters such as that in the BX63, easily in that...

Regards,
Gordon.

[Niklas Nord]

So whats the end result then?

sealed vs ported box?
and what sealed candidate would be interesting to
try as an experiment?

how does the Q affect the type of sound?

[TimG]

For versatility, why not build a build a sealed 5 cu ft box if you use the 2235H or an 8 cu ft box for the 2245H. If you feel you need more efficiency and less deep bass extension add ports and you will have the right cabinet volume for a vented box.

A sealed box will give your more extension in the low end with better transient response, and a vented box will give you greater efficiency but will have sharper roll-off below the tuning frequency. You have to decide which trade offs you are most comfortable with.

If you go with the sealed box option, I would recommend going for a Qtc of .707 to .5. A unequilized sealed box that is too small with give you a peaked response with boomier bass, the kind of bass many people with car subwoofers seem to like.

You also have to remember that the room is a huge factor in your system response below 100Hz.

[4313B]

Originally posted by Niklas Nord
So whats the end result then?

sealed vs ported box?
and what sealed candidate would be interesting to
try as an experiment?

how does the Q affect the type of sound?
No one here can tell you what you will prefer. As Tim has pointed out, build the sealed enclosures with the option to port them should sealed not "cut it" in your particular room for your particular tastes. As he also states, you should endeavor to keep the Qts at or below 1/sqrt(2) or .7071.

I personally find sealed VLF systems easier to integrate into the average room. I definitely like the LE14H, 2235H, 2242H, or 2245H vented subs, but the 121H sealed subs toast them all in extended VLF and transient response. My choice would be two sealed 2245H's for home use but the required real estate is simply too much for me personally.

Right now I am playing with sealed 2.5 cubic foot enclosures stuffed with 2242H's (Q = .70) and when crossed over below 50 Hz they are surprising, not quite the extreme low end of the 121's or 2245's but JBL (Joyously Bloody Loud) and able to take the juice. Distortion and power compression are nil. I'll be trying Bessel sealed enclosures with this driver next.

[Niklas Nord]

Hehe, 2,5 cu fett, that is not much, i can live with that.
Then maybe making a box for two 2245 in a sealed chamber,
one for each driver.

maybe something like 2,5 - 4 cu feet then

corner placed, two 2245 per corner hehe

:rolleyes:

maybe i can play around with my old e-155 in a testbox,
maybe blast the darned thing to the space.. and back..

[4313B]

Niklas,

Here's the actual results of the 2242HPL sealed test system -
Note that the enclosure was over volumed to take into account the physical size of the 2242HPL. (Net = 2.2 cu ft, Gross = 2.5 cu ft).

Driver Properties
2242HPL
Fs = 39.94 Hz
Qms = 5.937
Vas = 237.1 liters
Cms = 0.11 mm/N
Mms = 0.144 kg
Rms = 6.094 mohms
Xmax = 9 mm
Xmech = 25 mm
P-Dia = 397 mm
Sd = 0.124 sq.m
P-Vd = 1114 cu.cm
Qes = 0.398
Re = 5.01 ohms
Le = 1.707 mH
Z = 6.012 ohms
BL = 21.33 N/A
Pe = 800 watts
Qts = 0.373
no = 3.658 %
1-W SPL = 97.6 dB
2.83-V SPL = 99.8 dB
-----------------------------------------
Box Properties
Type: Closed Box
Vb = 2.195 cu.ft
Total = 2.513 cu.ft
Qtc = 0.707
QL = 17.94
F3 = 85.22 Hz
Fill = normal

50 Hz 18 dB/octave high pass filter
114.6 dB maximum SPL at 50 Hz
111.6 dB at 36 Hz and 79 Hz
108.6 dB at 29 Hz and 97 Hz
104.6 dB at 23 Hz and 120 Hz

Actual Enclosure Inside Dimensions 23.00 x 18.50 x 10.25 = 2.52 cubic feet
Actual Measured Qtc and Fc with no fill = 0.7678 / 83.5 Hz
Actual Measured Qtc and Fc with 2" thick Owens Corning R-6.7 fiberglass lining all panels except baffle = 0.7026 / 78.8 Hz

[Niklas Nord]

Thats interesting

[4313B]

Yeah... I reckon so.

I'm just goofing around with this transducer :)

[spkrman57]

I had measured some JBL 2235H drivers on my WT2 sometime ago and found it while looking through the saved files.

The cabinets are approx 3 cu ft sealed with test plugs so the ports are a non-factor except for taking up space in the cabinet.

The cabinets were procured from Mike Baker and were built as test cabs for sub 1500's. 4313B should have some knowledge about them.;)

While I did not actually play them in a system(no room at the time), I think the T/S parameters would be useful in this thread!

Revc ---6.8 ohms ---6.4 ohms
fs----- 45.7 hz -----46.1 hz
Qes ----.51 --------.61
Qms ----10.1------- 8.4
Qts ----.48 ---------.57
Zmax --142 ohms---- 94.7 ohms
Le -----1.7 mH ------1.2 mH

I had thought some time ago to try these out as subs for my tube/horn system, but I would rather have my JBL 2240H recones perform that duty as I am not concerned about how low the bass notes go, but rather how dynamic the sound is.

My room is too small for really deep bass, I have to walk to my kitchen to hear those low notes!:blink: So decent response down to approx 38hz is sufficient for me as my musical tastes don't demand much lower bass response.

So if anyone still had any interest in this thread I hope this helps!

BTW I'm researching to see if I can come up with a sealed/ported design that will allow me to use my 2240H from 40hz to 150hz/200hz to match up with a 2202 recone of K120 in a 150hz Edgar tractix wood horn. I'm thinking of something around 4 - 6 cu ft max size! Smaller size would be optimum and I think the room gain may make it possible.:banghead:

Regards, Ron:blah::blah::blah:

[spkrman57]

I'm not sure what differences there are with higher power determining the figures, so just a WAG!

Regards, Ron

[robertbartsch]

....I suppose you are married and your wife does not like big boxes in the house; right?

...join the club!

Anyway, some of the big box issue can be mitigated by building a taller box and having a downward firing driver. I got this idea from an older Kliphorn powered sub that I bought several years ago. Anyway, these boxes look smaller to wives and other big box haters.

I did this with an 18" 2242 with good results. I even have a big 500 watt plate amp installed in the side of the cab that is not visible from the viewing listening area.

...little things like this can make a big difference!

[spkrman57]

And no, I'm not married!

I just have a very small room.

Ron