Just be sure it doesn’t interfere with the movement or the cones.
'Dis gettin fun now.
I got to thinking about what to do with all that back-of-the-speaker sound. The problem with it is of course that it is out of phase with the front-of-the-speaker sound. Now if we could just invert the phase somehow, then we could just let it out and use it.
I present, a simple mechanical sound wave phase inverter:
When the speaker membrane moves back, the air behind the speaker gets pressurized.
That makes the membrane move to the right, which in turn moves the hinge down.
When the hinge moves down, it sucks in air from the aperture, just like the speaker does, meaning that the sound coming out of the aperture and the sound coming out of the speaker would be in phase.
The stiff board might just be a stiff piece of paper, and the hinges might just be made of tape. Not sure how to make a good membrane though. Maybe steal one from a speaker with a burnt-out coil?
Not sure how well this would work, but it’s an idea at least. 
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That’s a bit too many added moving parts. At that point you’re better off going to a tuned port enclosure.
Entirely possible, but aren’t tuned ports too big to fit in a saber?
from what i have work out in the past, yes, in my opinion.
i calculated it for a 28mm speaker for 200 Hz and had the calcs come back saying it needed a 1 inch port 1m long! 
so based on this your summery would be correct.
a sealed and tuned chamber would be a good bet, takes up much less room and has a more gradual roll off at the lower frequencies as opposed to a ported chamber where the port is tuned to a specific frequency before the roll off.
i have also been playing with the “infinite baffle” concept.
this uses a speaker chamber so large the air inside simulates a ported chamber / open air but you get more pronounced lows than a traditional sealed chamber.
@A_Rogue_Child would a passive radiator do something similar?
i’m still experimenting with this concept and also waiting for bits to turn up before i can compare oval to round “PR’s”
Most chassis are already a passive radiator in a way. It’s just with a bunch of material, a battery, board, wiring, switches and a pcb in the way. I’m gonna say stick with the draft above, use the sealer material in between the speaker faces and see what you can get away with as far as the existing space. Change up the amount of free space in the chamber to play with tuning and you can even try pieces of cotton ball glued to the end of the chamber in there too. I’d have to chat w a friend who’s a pro at this for added input. I was just throwing darts as far as the tuned port. It would have to be micro 3d printed and is probably a pipe-dream because how the hell are you gonna accurately tune something that small.
Pretty sure you have the math but just in case, it’s easily searchable.
Calculating passive radiator
Passive radiator calculator – enclosure design
- Volume of the box : Vb = Vas / α = 95 / 2.78 = 34.17 L.
- Tuning frequency : fB = H * fs = 1.51 * 21 = 32 Hz.
- –3 db point : f3 = (f3/fs) * fs = 1.59 * 21 = 34 Hz.
- PR displacement : Vpr = (Vpr/Vd) * Vd = 2.35 * 0.00044 = 0.001034 m3
Some interesting speakers have been posted, but no speaker comparisons have been done. I live around 20min from Dayton Audio, so I thought I would pick up the CE30P-4 1-1/4" Mini Speaker and compare it to the Saberbay 28MM X-BASS 4OHM/3W speaker I have in my hilt currently. I don’t know how the Saberbay speaker compares to other 28mm bass 3watt speakers, but I assume they are similar.
CE30P-4 1-1/4" Mini Speaker $5.50
Dimensions: 1.25"x.57", 31.75mmx14.478mm
Frequency response: 280HZ-14KHZ
Sensitivity: 81dB
28MM X-Bass 4OHM/3W $6.50
Sensitivity: 83dB
Frequency response: 230HZ-20KHZ
Dimensions: 1.1"x.433", 28mmx11mm
I will start by saying that my saber (Punk/CCS Sabers Dark Disciple) cannot take a 32mm speaker, it barely fits a 28mm. The sound quality test were done by putting the speaker against the saber tube and putting the pommel over it. I have done this test before with my X-Bass and the sound is similar to when the speaker is properly mounted inside the saber (at least with the X-Bass).
Hooking up the CE30P it was immediately obvious that it had a much richer/fuller sound than the X-Bass. There are tones that I was unable to hear on the X-Bass that I can easily hear on the CE30P. As expected the Dayton Audio Speaker is overall not quite as loud as the X-Bass, but the sound clarity more than makes up for that in my opinion. The differences in frequency response make themselves obvious pretty quickly as the CE30P starts to make crackly noises on the low end at volume levels around 800; good reason to use frequency filter.
Overall I would really like to use this speaker in my saber. I found that it is possible to fit the CE30P into my saber if I trim down the edges with a dremel and put it in horizontally rather than vertically, but I dont have time to do the re-design on my chassis to make it work as a long term solution right now.
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Topic bump. Thanks to @profezzorn for an inadvertent reminder to do a high and low pass to clean up some (static-clicky thing I guess you’d call it?) sound issues I happened to notice this past week.
Run the filters people. This among the main tips in this topic are needed before you go chasing your tail trying to fix stuff.
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1" port 1m long? So…the speaker should be in the blade? 
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Well said, Driftrotor. I would really like to see some YouTube experiments done on the various positionings of the speaker and sound holes and with varying resonance chamber scenarios. A 3d printed modular chassis with spacers and interchangeable resonance chambers could be useful. I can try some spacer trial-and-error experiments myself as I have a 3d printer and am already currently constructing a new chassis for a new saber (Vader saber by Korbanth). I’ll construct it so I can plug in various spacers.
Sound flowing upwards with many port holes from which sound can emanate is a very interesting concept. I have a relative who is a sound engineer at Ford and next time I see him I am going to run this by him and I’ll try to get back here to load up his thoughts.
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Or just a tube with a plunger backplate that you can adjust by sliding in out behind the speaker. It could have a rotating part on the back that opens holes if you turn it. Like a baby powder lid, but larger holes to emulate wirepasseges/chassis design ports.
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Excellent idea! Glad you mentioned it before I printed my chassis. I’ll see if I can pull it off in Tinkercad. I’m still kind of new at 3D designing so making moving parts with tight tolerances might be difficult, but I’ll try to see if I can implement that into the design I am currently working on. The design I’m working on at the moment has a removable speaker housing so I could swap out various sizes/port hole sizes and shapes. I am also trying to figure out how to add another speaker to a speaker that would be placed on top of a crystal chamber. If anyone has tried this already or any other upper-speaker designs I’d love to hear about it.
i did do the plunger idea when working with @mcarcher, and he also did some testing with this setup too.
it was a good way of finding the best for each speaker we tested and we compared results.
we found that if the space was too shallow that the sound would be tinny with little drive at the lower frequencies.
we also found that if the chamber were too deep it would muffle the high’s and the low’s would become muddy.
we found that each speaker make / model had their own setup requirements as we expected because of the speaker specifications / differences.
my only advice would be that if you intend to build your own chassis and want good sound to do this type of experiment and find what you like the best.
i personally liked the 24mm speaker with a 15-24mm chamber behind the speaker as for me it gave the best all round performance.
unfortunately as this was such a long time ago i no linger have the notes i took when playing around with this.
would be intersting to see what you will find and what you think works well for you @Steve_Gutierrez .
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also to note, we found that vented chambers did not perform as expected.
the low end would roll off sharply and produce little to no depth in that end.
it did on the other hand enforce the high’s but made the overall sound not appealing at all.
maybe you will find the same but for me personally, i preferred the sealed chamber.
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Thanks for the response Drift Rotor. I just printed my chassis off (resin print) with a sealed chamber that’s at the high end of your recommendation with a depth of around 25mm. The speaker is a 28mm bass type with a rather thick housing tho so the available open air space in the chamber is probably around 15mm.
Due to the shape of the sound grill on the bottom of my Korbanth Vader hilt I had to elevate the speaker away from the end cap to prevent it from bottoming out and sealing itself closed. The sound vents are these small little slits on the outer edge of the cap and I’m concerned about sound transmission with this, I might even go rogue and drill some holes in the end cap depending on the end sound result.
So to deal with that I built a small spacer with slanted grill slots so as to prevent the speaker from closing itself off by touching the end cap. I’m curious to find out how it will affect the sound. Ill reprint it with a more shallow chamber if it sounds too muddy. I’m most concerned about the little slits though and if my spacer is going to mess up the air vibrations trying to get out of the tiny slits. I’ll let you know in a few days how it comes out! Well, probably more like a week or so… thanks for the advice!
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If sound ends up being altered too much by the pommel i would suggest 3d pringing some with different sound holes in to find the best for your set up.
At least this way if it doesnt work out you wont be ruening you expensive hilt.
By any chance has you looked at the pdf that both @mcarcher and i made? It has a few tips and tricks that may be of use to you.
When you say 1" from the pommel, do you mean 1 inch from the beggining of the pommel or 1 inch from where the pommel vents begin?
from the opening, wherever you consider that to be.
I find it depends on the speaker you have and the hilt / sound holes.
Also the space behind the speaker is quite important to the end sound.
I also found that having the space behind the speaker being sealed gave much better defined base from the speaker.
If you can play around with space in front and behind the speaker to choose what you think is the best for you.
Sound perception is very personal and what i like might not be what you think sounds good.
In my sabre with a 28mm off brand bass speaker i have it set up with 24mm sealed chamber behind the speaker and 12mm before the sound holes.
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100%. A perfect example is my recent Qui-Gon hilt that has the deep movie accurate groves down the handle, basically has no actual mass behind the speaker pod for sound to vibrate up the hilt. This hilt is by far my worst sounding hilt in my collection. Sounds thin, raspy, tin-can and all treble. And that even with swapping out the speaker to a good one too!
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