ok, so I know its been some time since I posted anything to this section but I’ve been working hard and wasting lots of printer filament 
as discussed earlier that proper testing equipment would show the true gains from this experiment I’ve been trying but i can rest assured that all I have managed to do is make it sound worse 
I think I printed 4 sets of differing ported chambers and 3 closed type (1 had a resonance chamber included)
all of the ported designs printed resulted in sound degradation and almost total loss of low end frequencies and, well sounded awful 
all of the closed chambers performed rather well.
the standard chamber was, well standard…
the second I reduced the volume of air behind the speaker and got marginal low end gains, not huge but noticeable to the ear when played back to back.
the best to my ear was the last… I was merely mucking about by this point as I’ve done a roll and a half of filament printing these speaker chambers and seem to have stumbled upon something…
it was based on one of the ported designs and I simply removed the port holes to create a chamber that resonates the low end frequencies. (at least that was the aim)
it seems to work well.
i think this speaker is not suited to ported chambers and will I have 1 in mind that might work better.
the speaker i used was 40mm 5W full range speaker.
not great quality but i am working on a budget.
let me know what you think?
always welcome the feed back with this stuff as I’m mainly just playing and by no means am I a sound engineer.
pic is of the resonance chamber goof experiment.
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A youtube video which demos how the different chambers sound would be fantastic. 
that would be a good idea, but im not very good at that stuff and most have now gone to be recycled 
so sorry for that.
i might if i get time design on that uses a bass radiator and see how that works but i think it might take up a lot of space.
interestingly though the closed chamber with the resonance chamber did cause quite a lot feed back to the board causing clashes to be triggered and i had to change my G to 3.2 before it stopped.
An interesting design and concept!
One thing i wish saber smiths would start to consider in hilt designs is the use of sound resonance, and how sounds travels/disperses not only from the front side of the speaker…but also behind it and into the saber hilt in general. Ive noticed in my hilts that when i cover up my activation buttons (power/aux) with the palm of my hand, i do notice a change in sound overall from the saber. Showing that even sound travels inversely behind the speaker and up into the upper end of the hilt as well. Some saber designs should take into consideration and actually take advantage of this and make tiny sound holes/ports in the upper areas of the hilt to allow that inverse sound to come out.
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The problem is that nobody has great understand of what works and what doesn’t work. I’ve looked around, and speaker design is either based on very rudimentary calculations or on proprietary algorithms, and none of them really specify what happens in spaces small enough for a lightsaber. A fair amount of trial-and-error has been done, but I don’t know that anybody has been able to take that knowledge and cook it down into a solid guide that explains what works and what not to do.
Personally I don’t think resonance is really a thing in a lightsaber. They are too small to really do anything with resonance. The differences we usually attribute to resonance are down to three things I think:
- sound cancellation (sound from rear of the speaker joins up with sound from the front of the speaker and cancels it out)
- air restrictions. I’m not sure how this works, but I’ve noticed that sometimes speakers sounds louder when the sound comes out through a pommel. I think this is because the smaller holes are causing air to move in ways it wouldn’t if the speaker was unrestricted. Similar things can happen when air behind the speaker escapes out through holes in the hilt.
- air springs, if the space behind the speaker is enclosed, the air compresses and pushes back on the membrane. The amount of air in the air spring changes the dynamic of the membrane. If the space is big enough, you could get reverb going on, but in a saber, the standing waves would be in the 5-10kHz range which would just be unhelpful. For frequencies below the standing wave, the air spring acts as a dampener, which is probably not what we want.
I suspect that the first one is the most important. If that is the case, then the goal of a hilt designed for good sound would be to direct the sound from the pommel to go mostly in one direction and the sound coming out from the back of the speaker to not go in that direction, as that would cause cancellation.
There’s plenty of it happening in the portable Bluetooth speaker market though. Cones might not be as small as what we use, but I’d imagine they have a handle on making the most of the small spaces
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i totally agree, we do need more research into this area, but having now said that every saber is different.
I’ve done quite a bit of research into what makes speakers sound good and like Prof said we don’t have the luxury of space to achieve the sweet spot so to speak.
the other variable is speaker choice and the capabilities of each.
in my experimentation with my speaker i have worked out that an enclosed speaker gives more resonance down the hilt resulting in feedback to the board and triggers the “clash” prematurely, but the sound is better.
a more open design gives less bass response depending on the restrictions and volume of air behind the speaker. but gives less resonant feedback through the hilt.
porting and resonance chambers are calculated to be a specific length and width to enhance a certain Hz target before the 3db drop and if done properly dose work.
the harder part is to keep it in phase with the sound from the speaker.
if it is not in phase then i cancels the bass produced by the speaker and just sound like you hit a low end cut.
i think when i did my ported designs i hit just this problem.
they were defiantly loader than the enclosed chambers but they lacked any bass so would have been useless and totally defeated what they were meant to do
the other reason is that we point the speaker out the bottom so sound is projected in that direction adding to what appears to be a quieter experience for us as this is generally pointing away from out head.
one way to combat this my be to turn the speaker round and have sound holes all the way round the hilt to more evenly distribute the sound.
no idea if this would work but in principle this could be way forward?
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so I’ve been doing more research into making better sound from our set ups either with good speakers / drivers, bass reflex porting and passive radiators…
i thought of trying to work on a passive radiator system to try it out and see if this would work in real life when i stumbled upon a really interesting document by Harry F Olson on speaker cabinets.
http://cyrille.pinton.free.fr/electroac/lectures_utiles/son/Olson.pdf
page 40 and onwards is about were it gets to the good stuff.
it explains cabinet arrangement and shape and different sizes and while it is generally meant for larger speakers than what we use, it might be worth trying to apply his findings.
it would seem that the very thing we have been mounting our speaker in is the worst to create good sound.
apparently a cylindrical baffle / cabinet creates a lot of reflected pleasure waves that interfere with the speaker causing peaks and troughs throughout the frequency bands.
a very interesting read… but would this mean that out hilts will now be rectangular?
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I’m no audiophile but there’s no reason why the pommel could not be a square.
Or at least the inside of the pommel could be square…but leave the outside shell circular so it looks normal.
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To further the theories and study papers I’ve been looking over I have managed to come to some simple rules and results that may allow us to at least make to best of what we have.
Granted I have a slight advantage in that I’m building a saber from the ground up so I can design my set up to optimise this.
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speaker specification
there are a lot of speakers available for our installs but good ones come with (or found online) specification sheets detailing the characteristics of the speaker. (this is quite important for the later steps)
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frequency you wish to achieve.
This could be lower than what the speaker is capable of and uses the cabinet resonance to enhance the speaker output.
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available space in the hilt
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speaker cabinet requirements
after entering the speaker specs (online calculator) you end up with a capacity the cabinet must contain in order to reach the optimal performance for your speaker.
these basic steps will allow you to get the most from your set up.
However, there are a few more things we can do to get close to the optimal set up…
eg, my 40mm driver cabinet ideally would require 380cm3 air volume. this means my cabinet would have to be 40mm dia x 305mm long 
so the trick is to divide in even orders - so 2, 4, 6, 8 etc
this trick enables us to keep the harmonics (reflected pressure waves) in sink with the speaker, thus minimising the effects working against the speaker and the sound we hear.
using this trick I divided by 6 to give me a 40 x 50 mm cabinet. much better 
the other trick is to pack a dense fibre material (stuffing is a good one) behind the speaker to slowdown and disrupt the pressure waves in the cabinet.
this reduces the effects acting against the speaker.
with this i 3d printed it and it seemed to give a relatively full sound and was certainly better than my other attempts
my next adventure will be exploring the bass radiator design as I’ve been working on this to hopefully 
to truely get a full range speaker set up.
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I saw something on page 161 of the PDF posted above that might be interesting: A drone cone.
In a saber, a drone cone could be added behind the regular speaker to delay the phase of the sound and possibly reduce cancellation. Not sure if it would work, but it seems interesting to experiment with.
yes, this is (now) commonly referred to as a bass radiator.
the pdf is very old, being published in 1959 but strangely almost nothing has changed with reference to this.
modern ones (or the good ones at least) have weights that you can add or remove to change the frequency response to your requirements.
waiting on a bit of cash and I will be purchasing these items to see how it all works out plus they seem to be a matched set so should work well
https://www.daytonaudio.com/product/1612/dma45-4-1-1-2-dual-magnet-aluminum-cone-full-range-driver-4-ohm
https://www.daytonaudio.com/product/1624/dma45-pr-1-1-2-dma-series-passive-radiator
either way the driver unit interests me and should give a noticeable quality increase as I think in one of your videos you showcased a high quality driver with a voice coil of 10W and you noted that the bass was much tighter and did not sound strained when played at louder volumes.
This PDF is still the best reference material I’ve seen on the subject.
It should be enough to make some educated guesses, and possibly even write some software to simulate sound enclosure behaviors. I just a need a few clones of myself, or a few more hours per day…
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Didnt see them, they look quite good.
The cabinet requirements should be quite small.
I may have to get some of these too.
Nice find.
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just a quick pic of my speaker cabinet on my V1 concept.
I’ve added the circular peak and trough design (as this should absorb the sound waves) to reduce the feedback vibrations to the rest of the hilt and then packed the space behind the speaker with stuffing, this should also reduce the reflected pressure waves going back to the speaker and interfering with the sound.
I’m quite pleased with the result as i got no false clashes triggered with this set up and the sound was better with noticeable bass.
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anyone seen these?
they look quite good and offer a good low end response for such a small speaker
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If one is simply trying to block sound waves from traveling behind the speaker, couldn’t one simply use foam encasing behind it? Kinda of like what mix engineers use in their ‘treated rooms’ in a sound room, to absorb reflections and trap bass. Certainly one could just get some thin pieces of foam and stuff it behind the speaker and this would still allow wires to run through it not disturbing the inner guts of the saber build.
it certainly wouldn’t block the sound completely behind it, but it could at least slow down sound waves and muffle it.
