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Thread: Dual 2202h in a 4 cubic foot box

  1. #1
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    Dual 2202h in a 4 cubic foot box

    Hello, could someone please help tune 2x2202 in a 4 cubic foot enclosure.
    Thank you

  2. #2
    Dang. Amateur speakerdave's Avatar
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    Quote Originally Posted by Sandor the hun View Post
    Hello, could someone please help tune 2x2202 in a 4 cubic foot enclosure.
    Thank you
    With 2 cu ft per you could use it closed, depending on what LF extension you are looking for. Are planning an MTM with a horn?
    "Audio is filled with dangerous amateurs." --- Tim de Paravicini

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    Hello, yes wtw or in this case w horn w, the horn is large butt cheak and the 2426 driver. They will work with a pair of 2245 for each side. A three way system with active cross over and 4 amps. Opinion welcome.

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    Forgot to mention, I would like to X over low as possible to the 2245.

  5. #5
    Dang. Amateur speakerdave's Avatar
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    I'm not sure what "as low as possible" is. Use online box calculators and port duct calculators. Plan on two ducted ports. Rule of thumb each port tunes half the volume, so make calculations for one driver in 2 cu ft with one ducted port. If you can get a result you like, then use two of the same ducted ports in 4 ft.
    Good luck.
    "Audio is filled with dangerous amateurs." --- Tim de Paravicini

  6. #6
    Senior Member ivica's Avatar
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    Quote Originally Posted by Sandor the hun View Post
    Hello, could someone please help tune 2x2202 in a 4 cubic foot enclosure.
    Thank you
    Hi Sandor,

    If talking about JBL 2202A/H , a spec, designed mid-bass driver, I would suggest not to use it under 250Hz. If You need lower frequency, then use JBL 2206H driver. For such usage of 2202H, a small close-box about 25 Lit to 50 Lit would be OK, and it can be used up-to about 1500Hz. Such has been applied by JBL in the 4350/55 monitor solution, so if JBL have not use it under 250Hz, I think, I would not suggest to You either. The mentioned driver has small Xmax (about 3mm).
    It can be put in the 50Lit box, tuned to 80Hz port ( 80mm x 200mm length=43mm), so very sharp Hi-pass filter on about the same frequency has to be used.
    At that time JBL has 2203H and 2204H drivers that ware prepared for lower frequency applications, later 2206H become as a kind of replacement for lower frequency applications but it has several dB less sensitivity, but with active multi-ways system such less sensitivity would not be a problem.

    regards
    ivica

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    Senior Member RMC's Avatar
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    Hi Sandor,

    I don't know why you want this but lowest X-over possible isn't necessarily a great idea with this driver. And the lower the X-over the lower the input power the 2202H will take... A somewhat more acceptable suggestion follows further.

    I've modeled quickly a few tuning/response scenarios in Winspeakerz box design software using 1X 2202H in 2 cu.ft. or 2X 2202H in 4 cu.ft. (same response curve as expected).

    First, the suggested vented box in 2202H driver spec sheet (2 cu. ft. Fb 40 hz) leads to a very dropping LF response shown below 500hz. Moreover, that puts a lot of strain on a low frequency transducer that was made more for low-mid than low bass. Also, X-over in that pretty low region (40 hz or so) sort of "wastes" a good part of the 2245H's usefulness in low bass (you did mentioned "I would like to X over low as possible to the 2245."). That type of "low as possible" doesn't make much sense in my view, nor for the 2202H longevity in such a setup.

    Second, according to my own modelings, by tuning the box higher (i. e. 80 hz) you get improved and reasonably flat response and that 2 cu.ft. box could even be useful on its own or "stand alone" down to about 75 hz (F3), and the driver would survive somewhat longer. With driver Xmax of 3.5 mm don't expect to rattle the neighborhood, though it could still make some loud noise, more so with two units. Above that tuning frequency the response gets bumpy fast (e.g. +3 db @ 115 hz with Fb 100 hz). The 2202H spec sheet boasts a driver frequency response of + or - 3 db from 150 hz to 3 khz and my modeling with Fb 80 hz is also within that same range per Winspeakerz. I tend to think its the best you can do in terms of "as low as possible".

    Winspeakerz suggests a min vent area of 18.4 sq. in. for one driver in 2 cu.ft. (double the area for two drivers, but same vent length). It also suggests use of 2X 4" tubes (25.13 sq. in.) with length of 1.181". So for double drivers in 4 cu.ft. box you would need FOUR such tubes. BTW 3.5" tubes would meet the min area criteria and a bit more, but their lenght would need to be 0.453" (or less than 1/2") and your panel thickness should anyway be more than that...

    In terms of lowest possible "appropriate" crossover point I'd tend to go with 85 hz or so in the context described above.

    Looking at JBL's own response curve this is usually more like a 300 hz - 2khz driver on axis only for a very directional specific application, or 300 hz - 1.2 khz for real life home applications to stay within the + or - 3 db tolerance they mentioned (excluding the 2 db production tolerance).

    As for the highest JBL recommended X-overs for these two drivers they are 800 hz for 2245H and 1,200 hz for 2202H.

    I'm leaving aside for the time being the different sensitivities of the 2245H at 95 db and 2202H at 99 db both for one driver, since you will use active X-over as indicated and one can usually adjust levels with such devices.

    Regarding JBL's recommended box volumes of 2-4 cu.ft. for the 2202H, this seems to me as being somewhat overly optimistic considering T/S (e.g. Qts 0.16) but that's another matter... Regards,

    Richard

    P.S. Don't forget to overvolume the box as each driver takes 0.15 cu.ft of space in the box and the bracing needed takes some too. Vents of the above size/lenght may take a quite marginal amount of volume only if you build the box with 3/4".

  8. #8
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by Sandor the hun View Post
    Hello, yes wtw or in this case w horn w, the horn is large butt cheak and the 2426 driver. They will work with a pair of 2245 for each side. A three way system with active cross over and 4 amps. Opinion welcome.
    Hi Sander,

    Is this for home use or other application?

    In terms of balanced power across the drivers the 2426 on the 2344 butt cheek bi radial may not have sufficient capacity to keep up with the (2X) 2202 and the (2X) 2245 you propose. The 2397 Smith horn with a 2 inch compression driver or one of JBLs PT wave guides and a 1.5 inch compression driver would be more appropriate.

    In terms of layout what have you decided on?

    My initial thought would be to stack both the two 2245s vertically and the two 2202 vertically beside the 2245s with the on top of the 2202's or put the horn between the two 2202s like a Di Appolito design. The two 2202's will give you low power compression and very low distortion in the lower midrange which what that drivers is designed for.

    I agree with Richards comments. You might be better to run the 2245s up to 200-250 hertz with the 2202's sealed. The sealed enclosure with sound better with the 2202. If you were using 2206's then a lower crossover point would be feasible.

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    Thank you for all your help, I will have to give it some thought but I am thinking of sealed and crossed over @200 to 250Hz. How do the 2245s sound crossed over at that frequency?
    Sandor
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    Senior Member ivica's Avatar
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    Quote Originally Posted by Sandor the hun View Post
    Thank you for all your help, I will have to give it some thought but I am thinking of sealed and crossed over @200 to 250Hz. How do the 2245s sound crossed over at that frequency?
    Sandor
    Hi Sandor,

    I have heard it/them in 4350....(2x2235 + 2202 + 2441&2311&2308 + 2405 ) very, very, very nice sound......

    regards
    ivica

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    Thiele Alignment # 1 would be a fit

    You would fix Qt by making it 0.18.
    f3 would be 134 Hz,
    fb would be 100 Hz,
    Vab would be 8.5 ltr.

    Ruediger

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    Thank you all.

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