14G-Dutch^ said:
You still can Jon. An unvented enclosure is far more forgiving, size change wise, than a vented one, but they all have an "optimum" size. According to the WinISD program, the optimum size for a closed cabinet is .348 cu ft. That's half the size that is mentioned above. It's just that the low end they will give you is higher. If you are using a subwoofer, that is not a problem.
With the smaller size, and totally enclosed, the lowest frequency will be right at 105 cps at minimum 3db. With the larger enclosure the frequency will still be almost the same. The curve will change, but the minus 3db point will be pretty close. My advice is to use the smaller cabinet size.
This TB driver is a perfect example of the "jack of all trades" driver, but "Master of none". It is right in the middle and will work well with vented or closed, but none of them are perfect, size-wise. Usually drivers, like this, give up size advantage to attain this.
With the vented enclosure, the "optimum" size is .642 cu ft, but the .75 cu ft size Jay uses is still acceptable. My only complaint is the port size of the cabinet, which calls for a 4" x 12.4" vent. Twelve inches is totally unacceptable(it would have to be curved), so the size must be cut down to 3", making the same tuning frequency possible with a 6.47" length. That will get you the same box tuning frequency. So, 3" X 6.5" is going to be fine here.
Soooooo, go with the .348 cubic foot cabinet(don't forget to make it slightly larger to account for bracing, drivers, etc) and forget about the porting. Then use it with your subwoofer and you are 'good to go'. If you don't have a subwoofer already, make plans to do so. 😉
My real shortcoming in this entire thing is the crossover techniques. I need a good progrem to work with and learn all about crossovers before I can talk with any authority there. Maybe I just need to finally invest the money in Soundeasy and go that route, since it is supposed to be a wonderful program.
I finally located my older Bass Box program and just installed it yesterday. For box modeling it is great, but never took the time to use the X-Over program, which I have been told is not all that good. Anyway, I probably need an upgrade if I am going to run with the horses here. 😉
3" is plenty large for a vent on this TB driver! Even 2" prob. wouldn't be noisey enough to hear over the music. It's not uncommon to see 3" vents even on subwoofers. Better to have a little chuffing than an audible resonance in the tube.
For myself, I will most likely use these drivers sealed with a seperate enclosure under (also serving as a speaker stand) with a couple 6" TB subwoofers (vented), or, possibly some type of 8" driver(s)...
edit: the bottom enclosure would prob. be tuned to somewhere around 30 - 40hz, going up to 80 - 100hz - so, while I'll use "subwoofer" drivers, I wouldn't quite call the finished box a subwoofer? I might even make that box sealed too, possibly, to better crossover to a "real", larger sub sitting in the corner.
For myself, I will most likely use these drivers sealed with a seperate enclosure under (also serving as a speaker stand) with a couple 6" TB subwoofers (vented), or, possibly some type of 8" driver(s)...
edit: the bottom enclosure would prob. be tuned to somewhere around 30 - 40hz, going up to 80 - 100hz - so, while I'll use "subwoofer" drivers, I wouldn't quite call the finished box a subwoofer? I might even make that box sealed too, possibly, to better crossover to a "real", larger sub sitting in the corner.
Were it me, I would go with a seperate subwoofer that can be placed anywhere. Much more flexible and can be used with other projects you want to add. Saves money too. 😀
John L said:
Well... After extensive listening tests, we found that having a front firing low range speaker located at least near, if not under, the front L+R speakers made a significant, noticeable improvement.
Ideally, the low range driver will extend high enough to alleviate the null caused by "floor bounce" cancellation. (Unless the small speakers are not placed more than a few inches above the floor). I'm not sure about if the speakers were wall mounted up high...
So, I got the measured specs of this driver from Zaphs post on another server that was recommended. When I plug them into WinIsd it actually recommends a small enclosure for closed, and vented is about what you recommended. If I am willing to lose some low end extension a somewhat smaller box looks good too. What I am ot sure of is if I am putting the numbers in right, or if this recommendation by the program is misleading. I will try to post an image of what my results were.
Jon
Jon
Ok, after looking at the spec I put in the WinIsb program I noticed that I mistakenly left the Xmax in Meters, so i have a 5 1/4 inch driver with a 3 meter xmax!
Sweet! bassheads have found their new champion!
I thought maybe this screwed things up, but after putting the figures in correctly, I think, nothing changed much.....Vented now shows 23L but 43.5 tuning, and closed is now 11L.
If I mis-entered anything else, please do tell.
Jon
Sweet! bassheads have found their new champion! I thought maybe this screwed things up, but after putting the figures in correctly, I think, nothing changed much.....Vented now shows 23L but 43.5 tuning, and closed is now 11L.
If I mis-entered anything else, please do tell.
Jon
John L and 14G,
I don't know how your WinISD sims gave those numbers. But according to my Unibox sim, using Zaph's new 704D T/S measurements, a sealed box volume that gives Qtc=.707 to a pair of 704D's is about 19 liters (0.7 cu ft). This is obtained by assuming no leakage, heavy damping, and 0.3 ohm series resistance (from inductor DCR in xover).
According to the Unibox calculation, a vented design with two drivers requires a large box volume. Software suggests 57 liters, and at the minimum a 28 liter (1 cu ft) box is needed to have reasonably smooth bass response without a peaky midbass. Two woofers in a 28 liter box with 45 Hz tuning give an F3 of 44 Hz with a .7 dB response peak around 100 Hz.
I don't know how your WinISD sims gave those numbers. But according to my Unibox sim, using Zaph's new 704D T/S measurements, a sealed box volume that gives Qtc=.707 to a pair of 704D's is about 19 liters (0.7 cu ft). This is obtained by assuming no leakage, heavy damping, and 0.3 ohm series resistance (from inductor DCR in xover).
According to the Unibox calculation, a vented design with two drivers requires a large box volume. Software suggests 57 liters, and at the minimum a 28 liter (1 cu ft) box is needed to have reasonably smooth bass response without a peaky midbass. Two woofers in a 28 liter box with 45 Hz tuning give an F3 of 44 Hz with a .7 dB response peak around 100 Hz.
14G-Dutch^ said:
Are these for a single driver, aren't they?
If so, your numbers are similar to mine.
Yeah, that is a little strange. On the closed box, it is supposed to be at a Q of .703 and an optimum box size of .348 using two drivers.
On the vented side, it shows the optimum at .642 cubic feet, tuned at 56 hz. I'm not sure which set of numbers I used. Perhaps I probably should use the ones dlneubec actually measured and posted over at the HTforum.
Either way, the smaller or larger cabinet sizes should still work well, especially for the closed box. I don't see much change in the curve there.
On the vented side, it shows the optimum at .642 cubic feet, tuned at 56 hz. I'm not sure which set of numbers I used. Perhaps I probably should use the ones dlneubec actually measured and posted over at the HTforum.
Either way, the smaller or larger cabinet sizes should still work well, especially for the closed box. I don't see much change in the curve there.
John L said:
You used the values on the manufacturer's spec sheet?
You should use Dan's or Zaph's new measurements posted at HTG.
There's a substantial difference.
Well, I put in Dan's specs and also entered John K's specs and with each model, the calculator came out with 49 cubic feet and some change. I double checked things and can't see where I went wrong. I don't know what is happening here.
I ran WinISD. Its default suggestions are .78 cu ft for closed and 1.61 cu ft for vented. Close to what Unibox suggested. See the attached image.
I used Zaph's new measurement. All values are very close to Dan's except Le. But Le doesn't affect bass response modeling. In WinISD, I found that only Qts, Vas, and Fs affect the modeling result. I think Unibox provides more sophiscated modeling.
14G,
Mine matches your result except (it seems that) you used a single driver rather than two.
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I used Zaph's new measurement. All values are very close to Dan's except Le. But Le doesn't affect bass response modeling. In WinISD, I found that only Qts, Vas, and Fs affect the modeling result. I think Unibox provides more sophiscated modeling.
14G,
Mine matches your result except (it seems that) you used a single driver rather than two.
----------------------------
Attachments
This makes no sense to me. I put in pretty much the same specs as you Jay, and come up with totally different volumes. You can look at my post to see this. I set it up for 1 driver, so there should be no difference. I will run it again.
Jon
Jon
I checked it again, what you see in my gif on the lower leftin my previous post is what I put in to model the drivers.
BTW, Jay you have your Xmax on meters like I did, doesn't make much difference though.
Jon
BTW, Jay you have your Xmax on meters like I did, doesn't make much difference though.
Jon
Jon,
You obtained essentially the same result as I did. Only difference is the number of drivers. Similar responses were given by the Unibox, too.
Xmax is nothing to do with bass response.
I played with other box volumes. It turns out that two of these drivers can be used in as small a box as 10 liters to obtain a good, sealed 12 dB rolloff with a negligible midbass peak. For vented, as John said earlier, a 20 liter cabinet can be used with a mild midbass peak. But I prefer a result with 28 liters or larger.
The conclusion is, it is optimal to use this driver in a sealed design, but a vented design is also doable. Ideally, I'd do an MTM or a TMM in a 15 to 20 liter sealed cabinet for use with a subwoofer.
You obtained essentially the same result as I did. Only difference is the number of drivers. Similar responses were given by the Unibox, too.
Xmax is nothing to do with bass response.
I played with other box volumes. It turns out that two of these drivers can be used in as small a box as 10 liters to obtain a good, sealed 12 dB rolloff with a negligible midbass peak. For vented, as John said earlier, a 20 liter cabinet can be used with a mild midbass peak. But I prefer a result with 28 liters or larger.
The conclusion is, it is optimal to use this driver in a sealed design, but a vented design is also doable. Ideally, I'd do an MTM or a TMM in a 15 to 20 liter sealed cabinet for use with a subwoofer.
Jay,
Are you modeling this with 2 drivers in one box? Is that what you have been trying to tell me? If so, that is why we have been on different pages. I am planning on an mtm, but with the drivers in separate volumes. I realize Xmax has nothing to do with it, as I stated before. 😉
Jon
Are you modeling this with 2 drivers in one box? Is that what you have been trying to tell me? If so, that is why we have been on different pages. I am planning on an mtm, but with the drivers in separate volumes. I realize Xmax has nothing to do with it, as I stated before. 😉
Jon
Ok, I am now wondering what I was even thinking, I don't need separate volumes. Probably the cause for all the confusion, sorry, and thanks for your help.
Jon
Jon
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