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/diy/ - Do-It-Yourself

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Anonymous 05/26/14(Mon)17:51 UTC+1 No.643618 Report

Sup /diy/nosaurs?
I'm planning to make this speaker from Zaph audio (flat FR on axis, downward sloped offaxis FR, low distortion down to 100Hz so it needs a sub, flat downsloping power response because only 1 driver) but I'm struggling with a way to 3dprint this. I can't work with a router to save my life and making the plans open so anyone can make these would be pretty cool so that's why I want to machine/print it.

But how to model the parts? Would sketchup suffice? Those interlocking wood things that you often see on lasercut things would be nice, but how do I make these?

There's a fablab in my city that I'm planning to use:

Anonymous 05/26/14(Mon)17:59 UTC+1 No.643621 Report

this is the frequency response of the b3s (on axis, 15 degrees, 30 degrees), no idea what's happening around 10Khz..
Anonymous 05/26/14(Mon)19:58 UTC+1 No.643685 Report

what you see at 10khz is cone breakup. music wise there is little to nothing up that high so it tends to go unnocticed.

im not completely familiar with 3d printing, and have only operated a cnc from drawings/files already saved, so can't help you there. however, this setup won't really provide solid output from 250hz or so and down with any kind of volume. if you look at your follow up picture the decline really starts from 1khz and down. what you'll end up with is a "they sound great for their size" situation. you don't need a subwoofer, but rather a woofer in general. they make a great set of desktop sized computer speakers though.

best of luck on your project though.
Anonymous 05/26/14(Mon)20:03 UTC+1 No.643689 Report

>cone breakup
is that causing the offaxis swings? you'd expect a downward trend, but there's no trend at all really
>250hz down
according to Zaph it looks good until 100hz, where my sub can take over
>best of lucks
thanks :)
Anonymous 05/26/14(Mon)20:35 UTC+1 No.643702 Report

>is that causing off axis swings
yes. likely due to cancellations happening on the cone. you can see almost identical trends occurring at different frequencies on just about every driver available.
the guy who does noaudiophile just did a a review going over the stuff in laymen's terms which i thought was a good read, though there are more extensive writings on the subject.

>according to zaph...
in a 10'x10' room and in the extreme near field, sure, you can get the 100hz out of it. but in a regular sized living room space, sitting back on the couch or something, it simply wont be there. watching tv or a movie you'll notice the male vocals being on the "thin" side in some cases. zaph tries to combat this (like almost EVERY designer these days) with 1/2 a truck load of baffle step compensation, just quickly looking at the schematic, about 3dB worth. Overnight sensations are the same thing and just about every other minion, small cube, full range driver all suffer from the same issues. I'm not saying it's bad, it just is.

>thanks :)
you're welcome
Anonymous 05/26/14(Mon)20:42 UTC+1 No.643706 Report

>ith 1/2 a truck load of baffle step compensation, just quickly looking at the schematic, about 3dB worth. O
fugg, I still need to understand bsc before I attempt this. Read a dozen posts about it and did a ton of modelling but still don't understand what's happening with the whole 2pi space thing
Anonymous 05/26/14(Mon)20:54 UTC+1 No.643718 Report

well zaph puts in boundary effects filters etc because he knows what he's doing. there's all sorts of stuff out there to get really deep into it, but basically, a BSC filter picks a frequency, and attenuates all frequency above that. the reason they are used is because of the wrap around effect of sound waves on thinner baffles. they are essentially a circuit that turns the bass up by turning everything else down.
on the 6" - 8" baffles, this attenuation usually happens at 400-500hz, woofer size etc all plays in but for a rule of thumb sort of thing that's about it.

so in the case of this design, by using the amount of baffle step he is (we'll go with the +3db) he is essentially doubling the volume of the midbass to bass region by halving the volume of everything else.

boundary effects shit, to me, is so far above and beyond for 98% of listeners it's not funny and i think the only people that should mess with it are people pigeon holed into odd room configurations.
Anonymous 05/26/14(Mon)21:15 UTC+1 No.643729 Report

>forgot pi spaces
really just used for calculating gain effects and more prominently used for subwoofers and lower frequency stuff.
Anonymous 05/26/14(Mon)21:45 UTC+1 No.643741 Report

yeah but what does that have to do with baffle size?
I want to understand it, not just know how to work around it, I ordered the loudspeaker cookbook, maybe it's explained in detail there
Anonymous 05/26/14(Mon)22:22 UTC+1 No.643759 Report

doubtful that it's covered in loudspeaker design cookbook. they may have updated it though.

>what does it have to do with baffle size?
the physical size of the sound waves. as they are pushed out from the speaker (sound waves) they use the baffle as a spring board. lower octave notes (mid bass and bass region) have long wavelengths. This means on narrow baffles the sound wave wraps around the enclosure and ends up in the back or off to the sides. Larger 3 way systems don't tend to have this issue too much because of the increased width of the baffle. (14" - 18" usually) on a narrower baffle, something like 8", frequencies upwards of 500hz never get a chance to spring off the baffle because they end up wrapping the edge. This gave way to faceted faces, huge round overs and all sorts to try to reduce the phase issues associated with that wrapping. a study of physical acoustics vs psycho acoustics (things such as lobing)
brings you back to baffle step compensation. the bass "lost" by the wrapping around of sound waves can be brought back by simply making everything else quieter. a physical acoustics problem with an electrical engineering solution for a psycho acoustic result.

boundary effect filters are doing the same thing but in regards to the specific environment, i.e. that speaker is in a corner and this one isn't. by being in a corner that speakers lower end will be more amplified, so with some mathematical wizardry we can figure out a circuit that can help nullify those gains so the pair sound the same but are placed differently. (there's much more to it than that, but again, i find it impractical for most people.) Jeff Bagby and FRD Consortium amongst others have made all sorts of stuff to calculate the specifics of all this.

studying the physical acoustics, sound waves etc will lead you all sorts of fun places like horn theory, transmission lines and inevitably into the psycho acoustics that guys like linkwitz and d'appolitto played with.
Anonymous 05/26/14(Mon)22:32 UTC+1 No.643765 Report

> frequencies upwards of 500hz never get a chance to spring off the baffle because they end up wrapping the edge. This
this is a metaphor that doesn't really help with understanding, how is it a springboard? It's like saying
> did you know that you shouldn't replace your motor oil too often because your engine gets lazy and starts using more oil?
Anonymous 05/26/14(Mon)22:45 UTC+1 No.643770 Report

a baffle is an acoustic spring board. if the baffle is too narrow for that wave to reach it's 1/4 wavelength the physical wave will wrap around the edge, and the sound will develop on the side. notes from about 80hz on down are considered omni directional, meaning your ears don't differentiate the source. notes above that and our ears/brain can determine where they originated from, which if it's from the side, creates an issue.
Anonymous 05/26/14(Mon)22:46 UTC+1 No.643771 Report

Take it over to audiokarma.org they have a DIY section also the speaker section. Ken Kantor is over there often, he may even advice you.
Anonymous 05/26/14(Mon)22:47 UTC+1 No.643772 Report

>forgot my picture
circa 1968
Anonymous 05/26/14(Mon)22:56 UTC+1 No.643774 Report

yeah but in an average room you're listening mostly to the sound power, especially bass gets reflected really effectively so if it just wraps around the corner then that doesn't seem like an issue, it'll get reflected back to the listener. So from what I've read you should only use BSC when you put speakers outdoors.
will do
Anonymous 05/26/14(Mon)23:02 UTC+1 No.643777 Report

small spaces unnecessary imo
larger rooms getting over 16' dimensions, it should absolutely be considered, or just use your bass knob.
for speakers outside you can just use larger baffles, since, you know, it's outdoors and there's actual space.

or say fuck it all and go full on dipole

diyaudio or parts express
Anonymous 05/26/14(Mon)23:10 UTC+1 No.643781 Report

Easier for OP to get a pair of KLH Model Fives and recap them. Still DIY...
Anonymous 05/26/14(Mon)23:28 UTC+1 No.643792 Report

b-but then I won't have an excuse to use a 3d printer
Anonymous 05/27/14(Tue)00:06 UTC+1 No.643809 Report

OK call the KLH's plan B.
Anonymous 05/29/14(Thu)21:10 UTC+1 No.645141 Report

OK, I signed up for the €60 CNC router class, maybe I'll have finished this project before it falls off the catalog :^)
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