Hello
Looking at the possibility to use the Seas W12CY003 as the midrange. Thinking about using a 6,4 litre-ish sealed cabinet for it. However I've seen some other mid range drivers with acoustic vents. Would there been a benefit to use a acoustic vent on the Seas? And would it affect the enclosure size?
Looking at the possibility to use the Seas W12CY003 as the midrange. Thinking about using a 6,4 litre-ish sealed cabinet for it. However I've seen some other mid range drivers with acoustic vents. Would there been a benefit to use a acoustic vent on the Seas? And would it affect the enclosure size?
The size of enclosure is very much similar. BR has a port to add to NET volume and it's a long port so to say. It would make also a nice OB (open B). A BR would be more powerful with 30W for Xmax. Sealed less than 5W for Xmax. They cross nice @100Hz (+/-) neading further adjustments. (Figs. sealed vs. ported)
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Sorry, I am not sure I'm following you. I was thinking about acoustic vents. They're similar to BR obviously. As far as I know, acoustic vents doesn't extent the frequency extension in the low end, because of the port stuffing. The frequency extension isn't important anyway as there will be low bass drives on the speaker as well. Should AVs be sized the same as BRs?
IME, the pioneer's conclusion that the vent can't be too close to the driver is the best way, so 'gap' the driver from the mounting hole and if you need a stronger 'leak' [paper thin often suffices, so have used mechanic's 'feeler' gauges], then do the stuffing 'thing' using open cell foam, carpet felt or similar for an adjustable density 'gasket'.
BR patent: US1869178A - Sound translating device
- Google Patents
GM
BR patent: US1869178A - Sound translating device
- Google Patents
GM
MrGecco, you may be trying to get more information about "Aperiodic Vents", which serve a different purpose than bass reflex vents.
My first thought from your post was you were interested in Vented Mid Range, and brought back memories of the Electro-Voice VMR from the 1970s, a 6" cone with an integral vented enclosure, covering 600 Hz to 4kHz.
My first thought from your post was you were interested in Vented Mid Range, and brought back memories of the Electro-Voice VMR from the 1970s, a 6" cone with an integral vented enclosure, covering 600 Hz to 4kHz.
Aperiodic vents have the action of reducing the Q of a driver's resonant frequency as well as permitting a smaller enclosure.
However, I assume that a midrange driver would not be allowed to operate near its resonant frequency (thanks to the band pass crossover) and that an aperiodic vent would be of no consequence.
However, I assume that a midrange driver would not be allowed to operate near its resonant frequency (thanks to the band pass crossover) and that an aperiodic vent would be of no consequence.
Thanks for all the answears
Aperiodic vents might be what I'm talking about. From what I remember the idea was basically a BR with a stuffed port. I thought a ported enclosure would always have a tuning frequency, and therefore not be considered an aperiodic vent. I suppose the stuffing makes it apreodic?
Regardless, would an aperiodic vent be fitting for midrange frequency usage? As far as I understand they allow smaller enclosure sizes and better transient response but slightly higher f3.
At the end of the day I'm out after a small enclosure with good/best transient response.
Aperiodic vents might be what I'm talking about. From what I remember the idea was basically a BR with a stuffed port. I thought a ported enclosure would always have a tuning frequency, and therefore not be considered an aperiodic vent. I suppose the stuffing makes it apreodic?
Regardless, would an aperiodic vent be fitting for midrange frequency usage? As far as I understand they allow smaller enclosure sizes and better transient response but slightly higher f3.
At the end of the day I'm out after a small enclosure with good/best transient response.
An aperiodic event is beneficial to a woofer since it flattens the bass resonance peak.
By lowering the Q of the peak, it improves the transient response at bass frequencies.
However, as I said above, you would not be operating a mid driver at its resonant frequency.
Here's some information on the aperiodic vent which you may not have seen.
Aperiodic Closed Box Loudspeakers
By lowering the Q of the peak, it improves the transient response at bass frequencies.
However, as I said above, you would not be operating a mid driver at its resonant frequency.
Here's some information on the aperiodic vent which you may not have seen.
Aperiodic Closed Box Loudspeakers
You're welcome!
Depends on what type/how much stuffing one uses.
Right, it's what I've used it for, so headed in the right direction.
GM
I am getting ready to use the Scan Speak "Flow Resistors" (similar to the Dynaudio "VarioVents"). These are not for tuning like a Bass Reflex/vented box; they are mostly used for woofers in a closed box that is too small making the Q too high (ie boomy bass). A closed box rolls off the lows at 2nd order (12 dB/octave); a vented box rolls off the lows at 4th order (24 dB per octave) and an "APERIODIC" vent type closed box rolls off the lows at 3rd order (18 dB per octave). For use on a midrange driver well above resonance; you probably won't gain any advantage because these are primarily used to lower the impedance peak of a woofer. If you are using a LARGE midrange without a X/O on the low end for some reason; then these flow resistors could help.
What do you mean with "midrange driver well above resonance"? Driver Fs or enclosure resonance?
Take for example the SEAS W12CY-003. Free air resonance is given as 60 Hz. Some suggested alignments (Madisound site)
1) sealed box 0.1 ft^3; f3 150 Hz
2) vented box 0.15 ft^3; f3 65 Hz
Are you planning to run this without an X/O on the bottom as a small mid-woofer or are you going to use it as a midrange crossed over at maybe 300 to 500 Hz?
As a midrange with an X/O, the aperiodic vent will have little or no effect. If you did example 1 above with a closed box; it could help. If the sealed box size is smaller than ideal; then the aperiodic vent WOULD help (again assuming no X/O on the low end).
So, it depends on the application. There are numerous papers and discussions on the internet regarding aperiodic vents.
Just now waking up; much needed coffee. If this doesn't help, get back to me; I'll be more alert later!
Seems like an infection of "tunnel vision" here, neglecting various roles for holes and only focussing on tuning.
First of all, nobody would ever intentionally enclose a mid-range driver so as to raise the resonance into the listening band or want to tune it or want to damp it with a vario-vent. So all that talk is off the table.
A hole might relieve a small sealed box from causing the driver into resonance in the band. So that's a possible function of a hole/leak.
More important is the opportunity to benefit from sound coming out of the enclosure to octane-boost the ambiance, room acoustics, and other virtues that open baffles display, and which are so much in taste today.
B.
First of all, nobody would ever intentionally enclose a mid-range driver so as to raise the resonance into the listening band or want to tune it or want to damp it with a vario-vent. So all that talk is off the table.
A hole might relieve a small sealed box from causing the driver into resonance in the band. So that's a possible function of a hole/leak.
More important is the opportunity to benefit from sound coming out of the enclosure to octane-boost the ambiance, room acoustics, and other virtues that open baffles display, and which are so much in taste today.
B.
I have a partially filled (stuffed about 65 %) enclosure for a full range; the "OPEN" back side is blocked but only by high density foam. The enclosure resembles a pipe or tube but is not cylindrical. There is NO baffle front at all; the enclosure dimension in front almost exactly matches the driver dimension. This MIGHT be considered aperiodic but the idea was to not have "ANY" box sound but also not be truly free air. It rolls of very naturally on the low end at around 150 Hz (fs about 75). There may be a small amount of energy entering the room from the rear but as there is a foam back, it is all lower frequencies and the mids and higher ARE fully blocked. I guess you could say this is "tuned"; it really isn't a vented or closed box so not sure what category someone might assign this!??
Anyway, the in-room response is extremely flat from 150 Hz all the way past 5KHz (exactly what my goal was). I hear no obvious peaks or dips; some day I will break down and buy a calibrated microphone and measure it. So, it does NOT act like a "pipe" such as a tuned organ pipe. I run these full range on the bottom with no X/O whatsoever. The cone motion never gets out of control even on deeper bass notes UNLESS, I crank the volume way up beyond normal listening levels. It is a nice compromise between "any" box and "no" box (open baffle)...FWIW...
I think the benefit could be for the flatter impedance curve at resonance. For example if you simulate a first order HP in XSim or similar, with both impedance profiles (stuffed -or vented vs aperiodic), you will probably see a significant change in SPL at resonance.
However, stuffing a normal vent (pipe) does not do so much to impedance peak compared to a 'hole' in the box damped with the right amount of foam etc. Easy to tune the damping looking at the impedance curve. Minimal Q is the goal I would say.
However, stuffing a normal vent (pipe) does not do so much to impedance peak compared to a 'hole' in the box damped with the right amount of foam etc. Easy to tune the damping looking at the impedance curve. Minimal Q is the goal I would say.
I don't have ANY test or measurement equipment, simulation software etc. Could your XSim or other package do an accurate model for what I described above? I can give you the exact dimensions of my "enclosure", the types and amount of stuffing, blocking, etc. and the full TSP's of my driver. I suspect my "non-box" has performance similar to a large, closed box with very low Q with the added effects of aperiodic...just a guess!??
Thanks!
The enclosure has effects around the resonance, thus it might be useful to vent a midrange enclosure when the crossover point is less than two times of the resonance frequency.
Also, it reduces reflections. This could help when the midrange driver has a soft membrane that would otherwise transmit the interior reflections.
In sum, it doesn't matter whether there is a dedicated woofer but what midrange driver is used and how it is used.
You can use a tube like a drain pipe that ends outside the speaker box and stuff it loosely with damping material. Another option is building a funnel or tapering.
Also, it reduces reflections. This could help when the midrange driver has a soft membrane that would otherwise transmit the interior reflections.
In sum, it doesn't matter whether there is a dedicated woofer but what midrange driver is used and how it is used.
You can use a tube like a drain pipe that ends outside the speaker box and stuff it loosely with damping material. Another option is building a funnel or tapering.
DQ10's have no mid enclosure just the felt over the back of the driver. DQ20's have the mid in a stuffed tube with an opening in the end. I was also under the impression that Wilson Audio mid enclosures have openings in the back.
The next set I make will either have the tube all the way through the box open ended with a bit of light stuffing or I'll just put it on top of the bass enclosure ala DQ20. I'm leaning towards the DQ20 type.
The next set I make will either have the tube all the way through the box open ended with a bit of light stuffing or I'll just put it on top of the bass enclosure ala DQ20. I'm leaning towards the DQ20 type.
Without measurements there is not much use to simulate. Then you might just try it and go with what sounds best.
I believe the key is the crossover(XO). As mentioned before, how close the XO frequency is to the resonance, and the topology of the XO. If the mid 'sees' a high impedance from the XO at the mid's resonance, it will resonate more freely. If it 'sees' a short, it will be more damped electrically. If there is little electrical damping(driver sees high impedance at resonance), there will probably be more benefit from 'mechanical' damping like aperiodic.
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Well, OK; I don't have a clue what the software packages can and can't do. In my case; I am actually using a heavy wall plastic storage container that is designed to hold regular/standard size, mass produced, sliced bread. So basically, if you think of the shape of a loaf of "American sliced white bread", this container is that same basic shape and size. I mounted my 4 inch full range driver at one open end and also have the other end open. The mounting diameter of the driver ring is very close in dimension to the container so there is NO front baffle surface. Inside; just behind the driver magnet, I have a space with no fill or any treatments. Then; about 2 inches back; I have poly' fill stuffing (about 65% fill). Then; at the other end; I have a 4 inch thick piece of high density foam. There are 2 "walls" slightly parallel but since this is not a cylinder, square, rectangle, etc.; I detect no standing waves or organ pipe tuning effects AT ALL! To my ears; the in-room response is essentially flat from about 150 Hz to over 5 KHz. So, not a closed box really; probably the closest thing would be Aperiodic??? The fs of the driver is about 75 Hz so this sort of sounds to me like a large closed closed box (infinite baffle) with a very low Q. Perfect for this application. I run it almost full range; no X/O on the bottom end and a single inductor on the high end. This inductor I have on a switch so I can leave it in circuit for a high frequency, 1st order low pass or short across it (bypass) for a more true fullrange. Some streaming audio sounds better with the inductor; FLAC, vinyl, CD and other higher quality sources usually sound better without this low pass.
So, I was curious what people might call this thing? I was also curious if it could be easily modeled and simulated.
I have had these going almost daily for several months now and am extremely happy with the results. One day, maybe soon, I'll spring for a nice calibrated microphone and get some accurate measurements...
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