1. What is pros. and cons. between sealed and ported in midrange ?
2. In what cases is ported mid desirable than sealed one ?
3. If woofer is ported, is ported mid desirable in terms of group delay ?
2. In what cases is ported mid desirable than sealed one ?
3. If woofer is ported, is ported mid desirable in terms of group delay ?
Hi,
3) makes no sense.
2) hardly ever ( when it is, its complicated).
1) sealed nearly always, and sealed is never wrong.
rgds, sreten.
3) makes no sense.
2) hardly ever ( when it is, its complicated).
1) sealed nearly always, and sealed is never wrong.
rgds, sreten.
pros of sealed:
simplicity
small volume
best transient response
cons of sealed:
may not be able to play as low as you would like (early rolloff)
pros of vented:
potentially lower distortion
potential to crossover lower (may be at odds with first pro)
cons of vented:
more complex, harder to get right.
poorer transient response
Just my take on it, I'm sure there are more factors 🙂
Tony.
simplicity
small volume
best transient response
cons of sealed:
may not be able to play as low as you would like (early rolloff)
pros of vented:
potentially lower distortion
potential to crossover lower (may be at odds with first pro)
cons of vented:
more complex, harder to get right.
poorer transient response
Just my take on it, I'm sure there are more factors 🙂
Tony.
Almost every thing that you expect from midrange is affected negatively by doing it ported. There are just to many drawbacks.
I don't think that it's a smart thing relying on port gain from midrange just so you could xover it lower. I don't think that there is any real advantage besides that.
Aperiodic or cardioid on the other hand is different beast. I would try that because you can control the directivity a bit better at lower frequencies.
I don't think that it's a smart thing relying on port gain from midrange just so you could xover it lower. I don't think that there is any real advantage besides that.
Aperiodic or cardioid on the other hand is different beast. I would try that because you can control the directivity a bit better at lower frequencies.
I'd use hornloaded midrange before ported midrange in PA system anytime. Power handling itself is of no matter to me but rather maximum sensitivity achiveable. When something is playing loud enough, there is no need to push the potentiometer further and molest the loudspeakers.
Going vented for a midrange will reduce distortion in the lows by reducing excursion, and will let you cross lower or use a smaller driver for the same range.
You just have to take the resulting (minimum-phase) HP filter into account when designing your acoustical crossover (likely L-R).
For a given resulting crossover slope the transient response will be exactly the same between a seal and a vented mid : no drawback there.
Of course using a vented mid will force you to have an acoustical crossover of more than 24dB/oct (the natural rolloff of the vented box) as you will want to reduce overexertion under the tuning frequency, so you will likely end up with something like 36dB/oct or 48dB/oct, but that is usually a good choice anyway for a mid driver (close enough to the woofer compared to the crossover wavelength).
So if you can accommodate the port (and avoid port resonances in the intended range) and plan to use 36dB/oct or more acoustical slopes, then going active has only advantages.
You can even use a passive radiator.
You can also shoot for a peaky response right where your driver will need it, with a small box and high tuning, and then use a low Q electrical filter to compensate for it and get your acoustical crossover target with an even more important excursion reduction in the important range.
All this can be simulated using WinISD Pro.
You just have to take the resulting (minimum-phase) HP filter into account when designing your acoustical crossover (likely L-R).
For a given resulting crossover slope the transient response will be exactly the same between a seal and a vented mid : no drawback there.
Of course using a vented mid will force you to have an acoustical crossover of more than 24dB/oct (the natural rolloff of the vented box) as you will want to reduce overexertion under the tuning frequency, so you will likely end up with something like 36dB/oct or 48dB/oct, but that is usually a good choice anyway for a mid driver (close enough to the woofer compared to the crossover wavelength).
So if you can accommodate the port (and avoid port resonances in the intended range) and plan to use 36dB/oct or more acoustical slopes, then going active has only advantages.
You can even use a passive radiator.
You can also shoot for a peaky response right where your driver will need it, with a small box and high tuning, and then use a low Q electrical filter to compensate for it and get your acoustical crossover target with an even more important excursion reduction in the important range.
All this can be simulated using WinISD Pro.
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Of course it can be simulated.
Too small box and there goes advantage of crossing it low (only advantage IMO). Tuning it high makes port resonances right in the critical midrange area.
I'm not saying that midrange in vented box isn't possible, i'm saying that one needs to be very skilled loudspeaker designer to know which, why and where to put ported midrange. For home use there is no reason for ported midrange with abundant of drivers that are available today and can work in closed cabinets without problems and headakes.
Troels always likes ported or aperiodic midrange:
Poor Man'
Transmission line makes sense too. You can use a cheese shaped wedge with damping, open at the back. I do always think some sort of reflex speaker sounds better in the midrange. But perhaps people don't use enough stuffing with closed box to get the best of it. There's an advantage with a huge amount of stuffing that you can damp the speaker chassis easily. 🙂
Poor Man'
Transmission line makes sense too. You can use a cheese shaped wedge with damping, open at the back. I do always think some sort of reflex speaker sounds better in the midrange. But perhaps people don't use enough stuffing with closed box to get the best of it. There's an advantage with a huge amount of stuffing that you can damp the speaker chassis easily. 🙂
Here something I did just yesterday. Fostex FF85WK in a 3" diameter tube, 12" long, stuffed with 24g of polyfill:
Should facilitate a fairly low Xover as far as impedance interaction goes. Simply make the tube long enough to exit the back of the enclosure, but there is a minimum length to respect. You get some bracing as a bonus. 🙂
Thread about this
Should facilitate a fairly low Xover as far as impedance interaction goes. Simply make the tube long enough to exit the back of the enclosure, but there is a minimum length to respect. You get some bracing as a bonus. 🙂
Thread about this
I have never made, or tried to make for that matter, TL loudspeaker before. Besides MJKsheets, is there any other way to do the transmission line loudspeaker calculations that will give satisfactory results ?
I can't seem to make the MJKsheets work. I have free version that was available few years ago but i can't open it properly in MathCAD - there is some software problem that i can't solve.
Other thing is that i've seen and heard few MLTL designs that was done with MJK sheets and did not like the results - i'm not implying that sheets are the problem but that it may be the designers flaw.
I'm guessing that classical TL loudspeaker cabinet could work fine (not just for midrange but for bass as well) but i don't know what would be the right software besides MJKsheets that doesn't rely much on empirical basis.
Naah, if they came to the rave, they deserve it 😎 😀
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Never tried it, but it apears to be good:
http://www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software.html
Hornresp can also simulate different configurations of TL. The ability to model stuffing has also been added.
'Few'? What is the date code of the PORTED worksheet? The freeware hasn't been available in many years and I imagine MJK has had problems with folks illegally publishing/sharing his later licensed software.
Well, we all hear the same, yet not so much, but assuming you find a properly damped vented alignment a good performer, then odds are you’ll prefer a proper MLTL by a wide margin. The trade-off is a larger cab [net Vb].
For sure I did when I learned about these ‘tower’/’column’ BRs after auditioning a late ‘40s Harry Olson designed RCA in the mid ‘60s. Ditto everyone that I’ve designed/built them for over the decades AFAIK.
GM
I love BR loudspeakers when properly done.
This is freeware. The guy who sent it to me told me that he had licenced version but can't give it to me because of respect for the Martin. I told him that i don't want the licenced version for the same reason and settled with free sheets so i can test how do they work. I can send it to you to check and see if it is freeware. If it is not, then i'll erase it from my computer. I think that the ones i've got are not licenced because i was not forced to enter any licence code or anything similar.
I did manage to make it work on my old Win XP but on Win 7 it just don't want to open every part of the sheet. Martin got the same complaints that he discussed on his website but he didn't know what the problem was.
Something with the lowest bass in MLTL that i auditioned was not so precise as i would expect from properly designed cabinet. Everything else worked Ok.
EDIT: Date modified says 2006 for free sheets: http://s9.postimg.org/tdcx13u8v/Untitled.png
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OK, so it is and if MJK doesn't have a solution, then I'm not qualified enough to help. Sorry 🙁 I recently acquired a semi-recent laptop with W7 to use initially for my on-line connection now that XP is officially 'dead', but if it won't 'play nice' with MC, etc., then that's all it will ever be.
So many 'foreign' folks have had troubles that was cured by changing the machine to decimals from commas that I thought it might help, but I imagine that was probably MJK's first solution.
GM
So many 'foreign' folks have had troubles that was cured by changing the machine to decimals from commas that I thought it might help, but I imagine that was probably MJK's first solution.
GM
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