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Thread: Box tuning question

  1. #1
    Senior Member davidpou's Avatar
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    Box tuning question

    Hi,
    I am still exploring box tuning with some 2214H.
    The first box of 52 liters has been built with the JBL TS parameters, and calculated with a french software. The Vb has been decided by the soft, which prescribe aswell a port length of an astoninshing 51 cm long (for 8.5 cm in diameter). In fact the Fb with this port in this volume gave a measured Fb at 20 Hz ! below Fs!, and only with a 36 cm long port I could measure the predicted Fb at 29.5 Hz…..
    So I started to doubt the french soft, and thanks to precious advice and with the help of this soft http://www.mh-audio.nl/reflexboxcalculator.asp I decide to buit a new box in the 70-75 liters range. I also thought that may be there was some issues with the woofer being 30 years old. So I measured its TS parameters. Over 8 caculated parameters, only 3 were at +/- 20 %, the others were in the 10 % range as compared to stock values from JBL. These are: Q(ms), Le and M(ms). I refoamed one of the woofer with mister Rick Cobb foam, but the tree parameters stayed almost unchanged.
    Anyhow my new boxes calculated with the new soft were done with the mesured TS parameters. Here is a picture of the results. In fact in order to obtain a 33 Hz Fb, I had to divide the port length by 2 !
    Here is my question : the second pic shows in red the 75 liters box with a 10 cm port length (diameter: 9.5cm) and the green curve is the 52 liters box with a 25 cm port length (diameter 8.5 cm). The response curve are almost the same and I could make the almost identical by a little port length tuning….
    What is the advantage of a bigger box ? (apart from inserting other drivers in the same box ?) ? how can one say that this woofer is “happier” in this volume rather than another ?

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    Last edited by davidpou; 06-05-2017 at 12:26 AM. Reason: presentation orthographe

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    David,

    If you are happy with the bass performance available from the smaller box > then use it .

    The 2214H in the smaller box should ( theoretically ) offer better transient response up in the speakers upper range .



    PS; When ports & tuning ducts get put near a flat ( internal ) surface ( wall ), then that surface tends to get added into the length of the duct .

    That might be an explanation as to why the predicted duct lengths have been inaccurate .

    I don't know of any software that actually takes this effect into account .

  3. #3
    Senior Member davidpou's Avatar
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    thanks Earl !
    I am happy with the small box ? I don't know! It s been a while since I haven't listen to the 4425, it seems the 52 liters boxes are giving a slightly deeper bass.... not worth the trouble if you ask me !
    The aim of these tests is to get enough knowledge in box design to built some for the 2216Nd1....IN ORDER NOT TO PAY 15 GRAND for the 4367.... I know that once the boxes are there, there is still the filter/equalization but I am (was) working on this also....

    And cherry on the cake, the 2426H I have ordered in january (yes january!) are nowhere to be found ! there seems to be a problem with the production,... I canceled my order to the french retailer and now speaker exchange says the same; idem for parts express that do not even dare to mention a date of delivery anymore ....
    so ....I am confused... and some more...

    I might aswell work harder and buy the damn speakers !


  4. #4
    Senior Member RMC's Avatar
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    Hi David,
    If my memory is correct, the box picture from your previous 2214 Thread on similar issues, did show ducted ports at the bottom of the cabinet near side walls ? This would tend to confirm what Earl said.

    Did other parameters (other than the three) changed after re-foaming with Cobb ? Same software used for both boxes? Same parameters AND box loss assumption (QL) ? You're possibly tuned a bit too low, as for the 51L box, though the red curve (75L box) shows a slightly lower F3. Try tuning a bit higher than 33 hz, like 35hz or more since output is a bit higher at 100hz than at 50-55hz (that difference at same frequencies is even a little more on the green line, which tends to lead to a more mid-bassy sound). In other words, try to get the 50hz or so level more in a straight line with the 100hz level. See what happens to F3, Fb, ripple if any. Your box size seems to be approaching the practical limits of the 2214H, specially if tuned to low.

    As I mentioned to you before in private e-mails, softwares for the "common man" like us (not Pros) usually seek max flat response by default, even if the response curve may look weird in some cases. It is your job to vary the box parameters (Vb and Fb) in the software until such time you reach a logical and acceptable result for you. Since this is a JBL driver/box related issue, I'm tempted to quote what "Mr. JBL" says about alignments: "What we are aligning is, of course, the driver and the enclosure both with their own resonance frequencies in a coupled system." (Assuming the enclosure is in a half-space boundary condition). "There is a continuous range of alignments possible with any driver and enclosure, but Thiele and Small have labeled certain of the possible alignments ..." John M. Eargle, Loudspeaker Handbook, Chapman & Hall, 1997, p. 58.

    So experiment with the software (within reason), as well as with other software to double check, like Win ISD Pro Alpha, to find what's suitable for you. I said logical/reason because too much (Vb or Fb) or not enough creates problems. I don't worry much about a 0.5 db positive ripple, though I prefer to avoid negative ripple. Look at the response curve you get and see what it means in terms of Vb and Fb/Vent size. Acceptable or not? Then make some changes if required. JBL used 54L net and Fb 34HZ in the 4425, about 90L (net?) in L-100T and I used about 70L net and Fb around 37-38hz for my boxes. That gives you some starting points.

    What is the advantage of a bigger box? In principle, lower F3, subject to box tuning chosen. But there is a point where it may just be too big for the driver. You can't stretch that indefinitely. Drivers with relatively low Qts (such as 2214H) tend to be best fit, "happier" as you say, in relatively smaller boxes. It can be "happy" in many different boxes, within a certain range (examples above), but extremes must be avoided because over stretching it either way leads to poor performance.

    Richard

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    Senior Member davidpou's Avatar
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    Hi Richard,

    "If my memory is correct, the box picture from your previous 2214 Thread on similar issues, did show ducted ports at the bottom of the cabinet near side walls ? This would tend to confirm what Earl said. "


    Here is a pic of both boxes: I strat to think that I should have put only one vent on the small box (52 L) and two on the big one (75 L)…..
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    Did other parameters (other than the three) changed after re-foaming with Cobb ? Same software used for both boxes? Same parameters AND box loss assumption (QL) ?
    Here is a synthesis of the measurements (same soft same woofer same spot)
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    "In other words, try to get the 50hz or so level more in a straight line with the 100hz level. See what happens to F3, Fb, ripple if any. Your box size seems to be approaching the practical limits of the 2214H, specially if tuned to low.
    And
    JBL used 54L net and Fb 34HZ in the 4425, about 90L (net?) in L-100T and I used about 70L net and Fb around 37-38hz for my boxes. That gives you some starting points.
    Well this is what I get (always same woofer) in the 4425: indeed tuned at 33 -34 Hz!"
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    This is what I get in the 75 L box with a 15 cm port (9.5 cm in dia)
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    And same as compared to the 4425:
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  6. #6
    Senior Member davidpou's Avatar
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    sorry it s the following of the previous post as i coudn't upload anymore...: please read post 5 first...
    I coudn't get the 52 L box to have the 50 Hz and 100 Hz match yet as the smaller vent i measured was of 25 cm long ,
    but from what I read on the measurements: the shorter the vent the higher the vent response goes so with 20 cm or so I should get both frequencies "aligned"....but with a poorer response than the 4425 's (isn't it ?)
    so here is what I get in the 52 L box with both ports at 25 cm (if I follow you I shall go to 20 cm or so ?)
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    And this is the comparison with the 4425: tend to think that if I go down to 20 cm this 52 l box will do worse than the 4425….
    Attached Images Attached Images  

  7. #7
    Senior Member RMC's Avatar
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    Hi David

    Issue # 1 Take a break and read my latest Thread next to yours: "Online calculator precision...". It MAY be that in order to get your right foot out of a "problem" (51L box), you have put your left foot into another "problem" (75L box)... Not critical though, depending on what you are trying to achieve.

    Issue # 2 The 1.3L you put in the calculator for Vdr (volume of internal driver and parts) is way too low. You will not reach the model used predicted performance (even supposing it was exact, which may not be the case) if the real box net internal volume calculation is more than 5% wrong (5% of 75L = 3.75L).

    For a previous Thread I wrote "JBL conversion constants and useful data" I did check in tech sheets the volume displaced by each of four other JBL 12" drivers before stating it is 4 L (your 3.75L error margin is already gone), and to satisfy my curiosity I also checked one E-V driver (DL 12 X) which had a 5.3 L vol. disp. In addition to this, you must also calculate space taken by proper bracing and vent, which gets you even further from 1.3 L. The more stuff in the box, the more a determined Vb goes down... You would be lucky to get a 70L NET volume, probably less in fact.

    Issue # 3 The numerous curves you posted today, which I was still digesting and figuring out what they really implied, may now be purely academic at this point...

    If I were you I'd put things on pause (avoiding further "damage") to assess the situation, like re-modelling the box/driver with better (more exact) software with realistic data for space takers. Sorry for the bad news...

    Richard

  8. #8
    Senior Member davidpou's Avatar
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    “Issue # 1 Take a break” : Yes, I will take a break....!
    I did read your post
    Yes I had the sad feeling that I wen't from one wrong Vb to another.... allthough respecting the caculator rather seriously...

    « Issue # 2 The 1.3L”: Regarding the small 1.3 L entered into the calculator it is indeed a mistake it should have been 2.3 liters, I must have entered my addition wrong, but it is wrong of only 1 liter as I have 0.8 liter for the driver (calculated by the french soft, i kept the result) and 1.5 liters of cleats only, as it was a test box....(I run the measurements with the vent outside the box, so no need for estimated volume of the final vent dimensions) so It s too big by one liter....so less than 5 %....unless I am missing something else ?

    “For a previous Thread I wrote "JBL conversion constants and useful data" I did check in tech sheets the volume displaced by each of four other JBL 12" drivers before stating it is 4 L (your 3.75L error margin is already gone), and to satisfy my curiosity I also checked one E-V driver (DL 12 X) which had a 5.3 L vol. disp.”
    This I do not understand….sorry…can you re explain in “play school” terms, please ?

    “The more stuff in the box, the more a determined Vb goes down... You would be lucky to get a 70L NET volume, probably less in fact. “
    This, I am not quite sure to understand: the stuff that goes in the box (vent, drivers, braces) are added to the net Vb caculated, no?


    “Issue # 3 The numerous curves you posted today, which I was still digesting and figuring out what they really implied, may now be purely academic at this point...”
    Well these were trying to show my attempt to match SPL levels of 50 Hz and 100 Hz as advised, but maybe be you meant just the driver FRC not the driver and the vent… Cause if it is the driver alone then, after measuring 5, 10, 15, and 20 cm long vent, none made this happen! (The calculator indicated 18 cm), so ….For the 52 liter box it was bound to show that this box performs worse than the 4425, no matter what….

    “If I were you I'd put things on pause (avoiding further "damage") to assess the situation, like re-modelling the box/driver with better (more exact) software with realistic data for space takers.”
    Yes a last desperate attempt would be to test WinSdpro that I have dowloaded against my actual measurements: no matter how wrong accoustically these bowes are the soft should predict the not optimal responses I obtained….(no sawing !)

    “Sorry for the bad news...”
    Thanks, but son’t be sorry, I d rather built up wrong boxes and learn something than make a 6 000 $ of carpenter copy of a JBL design not knowing even how to measure my drivers…

  9. #9
    Senior Member davidpou's Avatar
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    My actual Vb is 72.5 liters.... sorry... I rounded up a bit the heigth advised ..., in fact I got 73.5 liters but i have to substract 1 liter (not substracted in my 1.3 L that are actually 2.3 l), so I have in fact 72.5 liters...not 75.

    Actually Win SDpro and mh-audio.nl lead to very similar results.

    Indeed i obtained on WinSD a nice predicted curve with a vent of 11 cm long nicely tuned at 39.5 Hz.... exactly what you suggest me to reach...
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    But with a 10 cm long vent (the closest I have) my actual tuning freq is ....32.5 Hz !
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  10. #10
    Senior Member davidpou's Avatar
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    I think my wrong TS parameters are responsible for the difference between calculators and reality... Here is a simulation with as much as stock TS as I could fit in and as much as my measured TS to compare the FRC int he same volume: I try to match FRC and see what is the Fb.... 10 Hz difference !
    Why do I say "as much as stock parameters", it is because in WinSD pro indeed one have to enter parameters in an order... I respected the order but then some automatically completed parameters are not close (veryclose) to say stock parameters (cause they are supposed to be coherent); if I force the system to stick to stock parameters it won't take it and refuse to save the driver in database because it sees incohencies...So i let the soft complkete where it wants to and enter "as much stock or my parameters as i can" see below the differences in response, Fb, and vent length....! so assuming my driver being in accordance with stock TS is wrong, sensitivity to certain TS precision is such that it deeply impacts the result....this must explain a good deal of the discrepancies, doesn't it ?
    Name:  FRCs COMPARISON OF TS IMPACT IN SAME BOX.jpg
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    you can see my measured TS in the previous post... so my drivers are ill....and indeed according to stock parameters the correct Fb is around 37 Hz , but mine has to be tuned at 27 Hz !!!!! with a vent that has to have a radius for not fitting in the box !!!

  11. #11
    Senior Member RMC's Avatar
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    Hi David,

    Issue # 1 Your "75 L" box isn't that bad in terms of real volume, not what you were expecting but not critical as I said, it can still be usable.

    Issue # 2 Here you ARE missing everything... The "wrong by 1 liter only" doesn't make sense at all. Any solid stuff inside the box will "steal" away some volume from your box, except soft fiberglass wool for example.

    The MANUFACTURER of your JBL driver, which has/had one of the most advanced and extensive speaker lab on the planet, with some of the most talented people in the business, HAS DETERMINED that the space taken in the box by a 12" driver is 4 liters (NOT 0.8 liters). I've tried myself one Web calculator for determining space taken by driver (called volume displaced by driver) and the result was too low compared to JBL specs. The calculator gave me 1.99 liters for the 2214H, compared to JBL's usual 4 L for 12" drivers (a 50% error).

    " as it was a test box" If you make your tests with a wrong box net volume the results will not be as expected, you may be thinking all is fine but it's NOT the case. Remember the old saying "garbage in, garbage out". If you input wrong (too optimistic) data in the software, the resulting box will be wrong too...
    The 1.5 L assumption on bracing for a box this size with this driver is a dream, a Cinderella story if I may say. Proper bracing here would, from the top of my head, be more like in the 7.5 -10 liter range !

    The estimated, or better yet calculated, volume of the ducted port MUST be included in the volume calculation, even if tested from outside the box, since one day it WILL take its place INSIDE the box.

    So, if for example you want a NET volume of 75.6 L. like that used in the MH software, then you have to build a box of: 75.6 L + 4 L for driver space taken + 7.5-10 L for bracing space taken + 0.3 L (a rough guess, not real number) for vent space taken = inside box GROSS volume required of 87.4 - 89.9 L depending on bracing size. Now, since your box is already made (volume determined), then you have to make the same calculation but the other way around, starting with the box inside gross volume of 76.91 L (taken from the MH Audio calculator in your first post) and SUBTRACT the inside box volume taken by each of those solid items, in order to reach your actual or real NET box volume of 65.11 L - 62.61 L depending on bracing size. Yes, it will in fact be that low, since the stuff that goes in the box is NOT added to net volume but rather subtracted from gross volume in order to reach the net volume. This changes again the curves you have produced with the Win ISD software... By analogy, If you put 13 L worth of bricks (solid items) in a box of 25 L capacity, the amount of air left in the box is 12 L, that net volume of air is the working ground of a loudspeaker driver, because the other 13 L of air is gone having been displaced by the bricks' volume...

    All of this is assuming you don't have excessive box losses (softwares usually assume QL 7 - I think Win ISD Pro in the "advanced" section has a default assumption of QL 10, check it out and if so change it for QL 7 and this will change again your response curves in the low end), but your actual could be a QL 5 or worst 3 more lossy box if you were not meticulous with the caulking gun all around the inside joints of the box (Including around vent tube when fixed in place) and with your choice of driver gasket (on the picture it looks like an "El cheapo"gasket made of 4 parts, do better with a single part all around, thicker, wider foam or rubber one), otherwise you're begging for more trouble. Lower QL numbers actually require an even larger net internal volume, to compensate for losses, in order to reach predicted performance, and right now you don't have any volume left to spare or share with losses. You have just enough for your driver.

    Issue # 3 Your attempt to try to match 50hz or so level with 100hz level seems correct (maybe a hair's size too high, like 39hz instead of 39.5hz) , that's good news, you picked it up pretty fast ! The bad news, as indicated above, is that since your net volume calculations are wrong, you'll have to re-do the curves with a more acceptable net volume in the 62.6 to 65 liters range... This will probably change ducted port lenght required so maybe you don't have to find another one...

    BTW we are not measuring the drivers here (you have DATS for this task) but rather the driver in a box combo, trying to optimize that odd couple...

    That results from MH audio and Win ISD Pro are similar is normal. Both are originally based on the Thiele/Small model, except one is from a Keele re-work to simplify (approximate) and the other is the real thing.

    There are two ways or sequences (taken from Win ISD web site?) I know to enter the driver parameters, I printed that page for my use to free my memory... But as you go entering numbers Win ISD Pro calculates other parameter values since the formulas for these are integrated in the program. If I remember correctly, you can change the values but the program may not like it...

    Your driver does appear to be "ill" particularly on the Mms parameter. Could it be due to rotten sticky foam or dirt in the voice coil gap creating more difficult cone movement, therefore making it appear (in DATS) like a more massive cone to move ? (Since the measured Vas parameter related to suspension compliance did not vary much, its difficult to blame a much too stiff surround for example). Could it be related to previous owner's re-foam job and /or your own re-foam job ? For example, was the dust cap cut to use shims and re-glued carefully or less so or another bigger or different dust cap used to cover the "mess" to make it look good ? Was the back of cone cleaned correctly before glueing new foams ? Was the foam glued on the front of the cone instead of the back (easier job) to avoid cleaning the old glue on the back ? Many questions could be asked about re-foam jobs... What could have changed the mass so much compared to factory specs ?

    Richard

  12. #12
    Senior Member davidpou's Avatar
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    Hi Richard,

    I can t beleive the bastard who did the french soft got the driver 's volume so wrong ! I have to blame myself for taking it for granted.... for the cleats I used very few of them but surely a proper bracing takes much more volume. As for the volume of the vent why adding it if in a test box it was meant to stay outside (I would have done a better box with the exact volume of the final vent).
    Indeed with a wrong volume and two ill drivers this story couldn't end happily.

    Provided that with my ill M(m)s driver has to be tuned around 29 Hz to align 50Hz and 100 Hz, one question would be: do i put these drivers in danger if the big box (I am cautious about volume now...) is tuned to that frequency (in a say 70ish liters box) ?

    I have learnt a lot by doing all these mistakes and working with damaged drivers, and this is thank's to you.

    May be , if you have time and will, you could edit a simple guide to box building with tips and tricks, so other greenies like I could benefit from it and waste less money, and obtain good results more easily .....in addition to articles for experienced builders.

    I think that the small boxes will make acceptable sub boxes for the country house (backing up the 4312A), and the big box, the garbidge.
    So if you know an affordable 12 inches subwoofer that would be happy in so less than 50 liters don t hesitate....

    Most of all, a really sincere and big thank you.

    David

  13. #13
    Senior Member RMC's Avatar
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    Hi David,

    Re "play school" explanation of net box volume calculation I should have given you first the "classic" explanation for that, though the bricks in a box example was not bad. Here it is, it works also with liquid in a bottle. Think of an empty 1 L bottle which can be seen not only as a container but also as an enclosure similar to a vented box. Think of the water as driver, bracing and vent.

    Empty means It has 1 L of air in it right now. If you put 0.5 liter of water in it, you don't have 1 L of air anymore in the bottle but rather only 0.5 L since the other 0.5 liter of air has been displaced by the liquid. The volume of the bottle is fixed or already determined as being 1 L, you can't increase it. So this is why to know the net volume of air in this bottle (after water added) you have to SUBTRACT the space taken by the water.

    Now, if what you wanted to have left in the bottle, after 0.5 L of water was put in it, is 1 L of air then you should have chosen a 1.5 L bottle from the beginning and you would have it. Starting from nothing, then in your mind you would have ADDED the numbers: 0.5 L of water that must be in the bottle + 1 L of air that I want or need = 1.5 L bottle required. The speaker box you would have to build is related to the 1.5 L here, but the net volume number you use in the software for design purposes is the net air volume of 1 L .

    Why adding vent volume in test box ? If the test box and the final box are not identical then you may be measuring two different stories... Since in the real or final box the vent will be inside it and take some space, that has to be accounted for also in the test box net internal volume, like in the final box...

    With regards to box tuning. I don't know why but you seem to have only a 29 hz or so box tuning in mind for small and larger box... Maybe to re-use the same vent in a future project ? Be advised that a different net box volume, or other driver in a box, may require a quite different vent size from the one you have now. It's not sure if you can "recycle" that vent in your next boxes. Keep them in stock just in case...

    Since your 51 L box is somewhat small, the low end response would possibly peak a little, if it was not for the lower tuning used in this case to flatten response. And, yes your "caution about the sound level now" does make a lot of sense with Fb 29 hz to avoid driver damage at high sound level.

    To know if a 29 hz Fb makes sense in a 70 L box with the 2214H you have to model it in speaker software... At first sight (compared to my 2214H 70ish L boxes), it appears too low, may create more dip in response and may expose the drivers to higher risk of reaching cone travel limit sooner at high levels.

    Aligning the 50 hz or so level with the 100+ hz level in the 75 L box you had, is not a must have to be followed to the letter. Its a worthy idea or tip for balancing (trying to match or so) driver output levels at different frequencies to minimize hearing predominant mid-bassy sound.

    Sorry, I have no time, nor will, to write a guide for beginners as it would be too time consuming. There are already many books on that, such as David B. Weems, Designing, building and testing your own speaker system, McGraw-Hill, 4th ed. 1997, which I have among many others. 26 $ Cad. Now a 5th or 6th edition?

    There's many driver manufacturers in Europe. For less expensive names you may want to look at SB Acoustics, Tymphany (who took over the Vifa and Peerless brands I'm familiar with) for Hi-Fi type, and Fane acoustics (UK) for more Pro sound reinforcement type, some affordable Sovereing Pro models. Many other known brands like RCF, B & C, 18 sound and Faital Pro but more expensive... Most likely find one with rubber surround = no more re-foam to do. Maybe a low Qts of about .21 - .23 range to be happier in the small box of 50ish L and low Fs in the 20-30hz. The 2214H T/S factory parameters are a good starting point. Before purchase do some trial runs in software re suitability.

    Richard

  14. #14
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    Try a sealed box and listen, I mean really listen to the bass, more tuneful and not resonant. It's really easy, just block off the ports with a piece of wood, use a gasket. I went to a sealed 8 cu ft cabinet for my 2235s and love the sound. I'll never go to a vented cabinet again, all 1 note bass. Seal your driver to the cabinet too with a gasket, I use felt just like old Wharfedales. Wharfedales W60s sound great too but the are very British, reserved and polite where JBLs are very Californian, loud and in your face which I prefer for ROCK AND ROLL. Cheers Bloys

  15. #15
    Senior Member RMC's Avatar
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    It appears to me that your idea of switching to a sealed box to cure the issues is sort of a false good idea...

    Before going to a sealed or vented box, one should consider a driver's Efficiency Bandwidth Product (EBP) as determined by well-known Loudspeaker Engineer R.H. Small (EBP = Fs/Qes, values taken from driver's T/S parameters). According to Dickason, the EBP number is a good rule-of-thumb regarding a driver's suitability for sealed or vented box use. Driver EBP number around 100 indicates a vented box is more appropriate, and an EBP number around 50 or less indicates a sealed box would be more appropriate to load the driver (See: Vance Dickason, The Loudspeaker Design Cookbook, 5 th Edition, 1995, P. 16 and 43).

    Driver Qts parameter number ( < 0.40) is also a yellow flag in this regard in favour of a vented box.

    The 2214H has an EBP of 92 and a Qts of 0.24. The 2235H has an EBP of 71.4 and a Qts of 0.25. Seems pretty clear to me the right box choice = vented box in both cases as the best way to go.

    Moreover, JBL Engineers only used these two drivers in vented boxes, as far as I know, and that should tell or mean something worthwhile.

    Your sealed box design suggestion will certainly produce sound, which may even sound acceptable to you or others, as the case may be, however it will NOT be anywhere near an optimized design by just blocking the vent and not re-modeling it in sealed box speaker design software.

    Just to satisfy my own curiosity, I did model quickly the 2235H in an 8 cu. ft. sealed box with Winspeakerz software to see what happens. Closed box resonance freq. 35 hz. The results are disapointing in the bass range: - 1.5 db @ 100 hz, - 3 db @ 65 hz, - 6 db @ 40 hz, and about - 8 db @ 30 hz. This looks like pretty weak bass performance for a 2235H in an 8 cu. ft. box. Unless one uses two (wall/floor) or even three (corner)boundary speaker placement justice isn't done to that woofer in such a closed box...

    Never going back to a vented box?? Well, you're missing some important things like more efficiency and/or deeper bass. Plus, vented box vent air moving does give some real bass distortion reduction which the sealed box does not provide...

    I do agree that in a pinch a sealed box is better than nothing or a lousy vented box, but again one should model that driver in speaker design software for a sealed box to get an idea of what you're really getting, not just cover the port and go...

    Richard

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