First speaker design...suggestions? And some pretty CAD pics :)

Hello everyone,
This is my first speaker design, so just experimenting at the moment really.

The tweeter and the mid both have there own compartments in the cabinet, and the mid is a propper dedicated mid, so I don't think this requires a specially designed enclosure, though apparently a 1.5l moulded specially shaped enclosure is available for this driver.

The top bass is sealed and has an optimised volume. The bottom bass driver however I think is intended for installation in sealed applications, however according to WinISD this driver has an extremely low extension (down below 22Hz @ -3dB) if used ported. It seems due to the nature of the driver that this requires a very large enclosure for this to work, perhaps this is why commercial speaker manufacturers don't normally do this? I think it's worth a go for a DIY project though.

Any thoughts or suggestions would be very much appreciated on this as I am a beginner!!!

Thanks everyone,
Steve
 

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low WAF? Yes we were a bit unsure as to what material to make the trumpets from, so we're going to try both. I originally chose ally just because it would match the black granite nicely, for colour and texture, but if it would be detrimental to the sound i suppose it would be a bit rude to use it anyway. The size was a bit of a problem, hehe, we had to have a few redesigns and rethinks to make sure it would go through the door :xeye:
Thanks for the reply!!
Steve
 
Thanks again for all your replies.

Ideally, the tweeter should be at ear level in the normal listening position

so swap the tweeter and the mid over perhaps? neither of these need any cabinet volume as such, so shouldnt be a problem

I would probably relocate the ports to the rear so the port noise is less audible and I think it would look nicer

i agree they would look nicer, but not really that practical as the speakers are 650mm deep, so the closer they can be to the wall the better unfortunately

Thankyou
 
I wouldn't put those trumpet-bell things around the tweeter or midrange as it may have a horn-loading effect at high-frequencies, which you want to avoid - either make a genuine horn or leave it flat. Tweeters tend to be very directional at high frequencies anyway, which would make modelling a horn (in Hornresp or something like that) very inaccurate anyway.

Remember soft-mounting of tweeters and midrange: don't bolt them down with tempered steel and 2-part epoxy!

I only just noticed that it's a 4-way design, not a 3-way design with dual woofers. May I suggest that you rethink some of the sizes of the speakers? I don't know what the exact sizes are from what you said, but it looks like 1" tweeter, 6.5" midrange, 10" woofer, 12" subwoofer. IMO most 6.5" midranges are far too big if they don't have to do frequencies below say 200Hz, and they often struggle with cone resonances above 1kHz. In most cases 12" speakers can do anything 10" speakers can do, except some high frequencies.

How about a 1" tweeter, 5" midrange, 8" midwoofer, and 12" subwoofer? The midrange is then likely to have better sound at the oft' neglected 1kHz to 5kHz range, as for an 8" + 12" combo, boy that'll be some good bass! In an internal sealed enclosure the 8" speaker is the perfect size for handling the "punchy" midbass, while leaving the truly low stuff to the 12" speaker.
 
The sizes are 1", 5.5", 8" and 10". we did originally try a 12", but the enclosure got far too big with a ported layout!! As it is the response simulated goes down below 25Hz at -3dB, and only begins rolling off at around 28-29Hz.

All those trumpets are only 1" radius, would this be enough to make any horn loading effects audible? What would the effect of horn loading be anyway?

Why do tweeters and mids need to be soft mounted? Its not a problem to do at all, but I just cant think why that would be a good thing....surely the only part you would want to be moving is the dome/cone? Wouldnt soft mounting mean that the whole driver could vibrate and colourise the sound somehow?

Were planning on using seas drivers, we simulated peerless as well, but these didn't come out quite so good and theyre a little more expensive. Any thoughts or experiences with these drivers from anyone? I doubt these will be the final version of these speakers anyway, lots of experimenting to be done after weve built them!

Any thoughts on how downward firing ports would sound? The gap between the speaker and the crossover on the bottom is 1", though this could be easily increased by using larger pillars. Hopefully this is clear in the picture. Im just really not keen on rear firing ports as they will take up at least 3foot of space out from the wall. And they look a bit ugly on the front, though the look may grow on me a bit yet.

Thankyou everyone!
 
baggystevo82 said:
The sizes are 1", 5.5", 8" and 10"....
Whoops! My mistake. It's just that the sizes seem a bit skewed in that the midrange has about 15 times as much cone area as the tweeter, whereas the differences between all the other speakers are much smaller.
...All those trumpets are only 1" radius, would this be enough to make any horn loading effects audible? What would the effect of horn loading be anyway?...
I dunno, not much except maybe for some comb-filtering at high frequencies due to diffraction effects.

...Why do tweeters and mids need to be soft mounted? Its not a problem to do at all, but I just cant think why that would be a good thing....surely the only part you would want to be moving is the dome/cone? Wouldnt soft mounting mean that the whole driver could vibrate and colourise the sound somehow?
It's inevitable that the bulk of the speaker moves in the opposite direction to the cone. If it's attached to another mass, then the displacement will decrease but the radiating area will increase. If that mass is something like wood or mdf it doesn't just "vibrate" as such, it resonates at some frequencies more than others. However, a block of granite might just be big and heavy enough that it doesn't matter. Maybe just try it both ways and see.

CM
 
Hello,

That was part of my reasoning for choosing a material so rigid and heavy, and I think it looks nice :) Also I work for my friend as a furniture and cabinet maker in the holidays, and we have a reasonably cheap source of black granite. I think the combination of the rigidity and mass of the granite and aluminium (Ill CNC the trumpets out of solid ally, so they will be quite heavy and rigid too) should be enough to resist any vibrations from the drivers, but thats just a guess, i really dont know so will definitely try both ways. Thanks for the suggestion!

Im just halfway through a little redesign at the moment to make the port(s) downward firing. Ill put some pics up when i'm done as I think ive seen the method on a few subs, but not sure, and not sure how well it will work.

Cheers :),
Steve
 
No, those ally trumpety things will be the interface between the driver and baffle. Ill probably try wood as well, but due to the points made above, I think maybe stick with ally and solid mount the tweeter and mid.
I thought that cutting rebates and counterbores may be a problem, i assume they would have to be ground or something? Quite expensive to get that done i would imagine.
Steve
 
Cool pictures!

Wow. Amazing detail and quality. How much did that CAD program cost you? What is it?

If you produce stuff like this, forget selling insurance and do this for a living. It is good.

How about doing five extra little speakers with only the mids and highs to use for the center channel, plus the other four surround channels and market it as the ultimate home theater setup at an affordable price... matched to your decor!

And I have to agree with 454 Casull. Tweeters, due to the ear's ability to hear directionally more accurately as frequency rises, should be at ear level.

Hey, would having two sets of tweeters, one set at "seated ear level" and one set at "standing ear level" work? If you Xover the tweeters at a high enough frequency, woudln't the sound be suficiently "on axis" that seated people wouldn't get the standing height tweeter sound?

I have seen a Schlieren photograph of ultrasound coming from some medical implement, and it was a tight beam like a headlight for dispersion.

Of course, if the tweeter sound wasn't sufficiently "on axis" then you would get ugly interference when at, uh, "short person standing" height.

:)
 
Designed in SolidWorks, although I could do exactly the same in pro/Engineer. Then did the renderings in 3D Studio MAX

Combined these are probably around £10000 ish, but as it's just for personal use I have no problem downloading them for free off file sharing stuff, plus i'm a student and could never ever fork out that amount.

Im not too keen on the idea of 2 tweeters. I remember one experiment we did at school in physics once in the main hall. We had two speakers, one in each front corner of the hall, emitting quite a high frequency, can't remember what now. but as you walk accross the hall, from 'left' to 'right', you could hear the sound getting louder and quieter as it went in and out of phase, due to the two sources, even though they were driven from the same signal generator.

I just tried my current speakers sat on a table, so they total around 7feet tall. the main change i noticed was a change in balance, and it just sounded a little smoother. also with these new speakers im designing, i imagine the xover frequency between mid and tweeter will be fairly high, as its a fairly small dedicated mid, so i guess a lot of the sound that contributes to how the soundstage 'looks' will be coming from the slightly lower down mid anyway. dont know, i think there may be lots of experimentation ahead!!

cheers,
Steve
 
Instead of granite you could cast a concrete baffle. Then recessing the drivers could be done in the mold instead of having to grind or machine the granite. Concrete can have dye added to it, and I'm sure specs of quartz and stuff like that to give it a very dark granite look. Then, all you'd have to do is polish and seal the concrete. Folks use cast concrete for kitchen counters with nice results.
 
Hmmmm, it's a thought definitely, but I really really like the surface of large grained granite close up. its all kind of 3d and some of the crystals are transparent, quartz or silica, can't remember now. I don't think it's going to be too much of a problem not flush mounting the drives anyway, gives me an excuse to do some machining making the trumets/drive mount plates. Isn't granite harder and more rigid too? Something else to try out though!
Thanks,
Steve