Building Speakers

bjackman · Post by **bjackman** » Tue Nov 25, 2008 7:53 pm

basically.. Maplin reckon their 15" drivers will go up to 4kHz, and their tweeters will come down to 3 kHz.

is that likely to be true, or do they mean "it ...might... play 3kHz"?

i'm thiknin of building some full-range speakers (nothing fancy or ambitious, low expectations, its just for fun). do you people reckon it would be feasible to have just a 15" driver and a tweeter?

anyone ever built speakers before? did they turn out listenable?

truncated · Post by **truncated** » Tue Nov 25, 2008 8:41 pm

a 15" to handle both mid range/bass hmm

it might work, but then again it might be so insensitive it doesn't work.

are these going to be PA speakers or hifi?

mosfret · Post by **mosfret** » Tue Nov 25, 2008 9:06 pm

yes..... and no......

a 15" driver may well be able to reproduce frequencies up to 4kHz, but its likely to be the -3dB point on said drivers frequency response plot (possibly even -10dB). also the higher the frequency you ask a driver to reproduce, the more directional the output will become...

another thing to consider is forcing a driver to reproduce frequencies it is incapable of reproducing will result in damage... so using drivers at their very limits is never a good idea...

from your original post i'm not sure if you mean using a 15" driver and a piezo tweeter, if this is the case i wouldn't recommend it, i'd be more inclined to use a 12" driver and and 1" compression driver... or if your set on a 15" driver a 2" compression driver might be the way to go...

its late and i've just got back from work so i apologise if this isn't a very good reply... any questions just ask (if i get chance i'll try and find some good links to freq resonse plots and polar plots to show what i mean a bit better)

akira kiteshi · Post by **akira kiteshi** » Tue Nov 25, 2008 9:07 pm

Never use a 15" driver for anything above 250 - 300 hz unless it's dual concentric. The voicecoil is not designed to deal with those frequencies. If you are planning on using a 15, make the cab a 3way with a 10" midrange driver as well, and an app. crossover.....

mosfret · Post by **mosfret** » Wed Nov 26, 2008 11:48 am

Akira Kiteshi wrote:Never use a 15" driver for anything above 250 - 300 hz unless it's dual concentric. The voicecoil is not designed to deal with those frequencies......

wuld you mind expanding on that a little? im not sure i follow you....

akira kiteshi · Post by **akira kiteshi** » Wed Nov 26, 2008 12:52 pm

15's are designed to be used for bass/low mid only. it's something to do with the large diameter of the cone being unable to accurately reproduce frequencies above that (the suspension can not push-pull quickly enough, especially if the driver is a dual spider design as a lot of LF drivers are and also something to do with the thickness of the cone its self) so this in turn effects how the voice coil responds....also larger voice coil, more weight to move back and forward, limited response...

Some 15's however come with a compression driver and flare built in to the middle of them (Dual concentric....... or twin cone.... but they are shit only go up to about 14K and have no additional HF driver) Tannoy use D/C's for some of their studio monitors

I suppose it could be done, but in the 8 years that I worked as a live engineer I never saw it done....

serox · Post by **serox** » Wed Nov 26, 2008 1:11 pm

bjackman wrote:basically.. Maplin reckon their 15" drivers will go up to 4kHz, and their tweeters will come down to 3 kHz.

is that likely to be true, or do they mean "it ...might... play 3kHz"?

i'm thiknin of building some full-range speakers (nothing fancy or ambitious, low expectations, its just for fun). do you people reckon it would be feasible to have just a 15" driver and a tweeter?

anyone ever built speakers before? did they turn out listenable?

I would not believe a word Maplin says about anything tbh.

There are a lot of people on squatjuice.com who own and have built some of the biggest systems in the UK so they might be able to help if you can ignore the trolls.

mosfret · Post by **mosfret** » Wed Nov 26, 2008 2:57 pm

Akira Kiteshi wrote:15's are designed to be used for bass/low mid only. it's something to do with the large diameter of the cone being unable to accurately reproduce frequencies above that (the suspension can not push-pull quickly enough, especially if the driver is a dual spider design as a lot of LF drivers are and also something to do with the thickness of the cone its self) so this in turn effects how the voice coil responds....also larger voice coil, more weight to move back and forward, limited response...

Some 15's however come with a compression driver and flare built in to the middle of them (Dual concentric....... or twin cone.... but they are shit only go up to about 14K and have no additional HF driver) Tannoy use D/C's for some of their studio monitors

I suppose it could be done, but in the 8 years that I worked as a live engineer I never saw it done....

ahhh... i think i see what your saying, allthough its rather a broad generalisation dont you think? horses for courses innit... it depends on the driver in question... both martin and turbosound, for instance, make full range cabinets utilising 15" drivers....

__________ · Post by **__________** » Wed Nov 26, 2008 3:47 pm

nooooo mate that would sound haggard!
15" pumping out 4khz? it might manage it but it'd sound fucking raaank!

save your monies. at least get a 12" or 8" for the mids

edit: if you're going to do it ghetto style, with a 15" for bass and mids, make sure you at least get a crossover

bjackman · Post by **bjackman** » Wed Nov 26, 2008 7:14 pm

Akira Kiteshi wrote:Never use a 15" driver for anything above 250 - 300 hz unless it's dual concentric. The voicecoil is not designed to deal with those frequencies. If you are planning on using a 15, make the cab a 3way with a 10" midrange driver as well, and an app. crossover.....

hmm yeah i think you lot are right, it dawned on me today just how big 15" is, especially when i'm pissing my neighbours off with just 6" at the moment.
(apparently) maplin's 12s have a resonant frequency of 50hz which is really low enough for a full range speaker built by a newbie amatuer.

the original plan was a 3-way 15/10/tweeter flex, but 3 way is just not really cool, too much chance to make mistakes for not enough improvement (and way more expensive too).

not really up on my compressor drivers? would one throw the frequency response way out of balance? these things aren't for any use in clubs or anything, probably no more than 300W each (depending on the cheapest amp i can get)

seriously, thanks alot for this help people, i wasnt really expecting any replies!

ecliptic · Post by **ecliptic** » Wed Nov 26, 2008 8:18 pm

Akira Kiteshi wrote:Never use a 15" driver for anything above 250 - 300 hz unless it's dual concentric. The voicecoil is not designed to deal with those frequencies. If you are planning on using a 15, make the cab a 3way with a 10" midrange driver as well, and an app. crossover.....

Yeh man, you will need a crossover as the 15" Speaker would struggle to reproduce all those frequencies at a loud volume.

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