steve@princeton.UUCP (10/07/83)
The Audio Amateur is a good source of information. In addition, the sister publication, Speaker Builder, has some good articles. If you are really hard core, you can did up old copies of the Audio Engineering Society Journal at your favorite technical library. TAA and SB often present projects, but don't really advocate kits. They often evaluate a kit, but the magazine is not geared toward kit building. They do carry advertisements, so feel free to go ahead and buy a kit. My personal feeling is that you get a better price/performance ratio if you do the whole thing yourself. This takes a little bit of carpentry skill but is worth the time spent. In particular, you can make the cabinets as non-resonant as you care to. You are also free to experiment with different kinds of drivers and can get the sound that you want. Crossover design also falls into this category. I'm confused by the stipulation for more than 3 drivers per speaker. What's wrong with a good two-way box. Power handling is no longer a problem, so why parallel drivers? --Steve
david@tekig.UUCP (David Hayes) (03/22/85)
I have a question regarding the physics of reproducing sound, regarding the Bose 901 speakers. The speaker building info I have read speaks of some effort to use speakers in their optimum frequency range, to increase accuracy and reduce coloration. This means you probably do not want to crossover your 15 inch woofer at 1500 Hz, like some JBL's I've known. In the 901s, I can see some advantage in the low end of having 9 smaller drivers for quick tight bass, but getting 5 inch drivers to reproduce high frequencies, even getting the cone to move fast enough, explains why most high frequency drivers are physically smaller. Then, on top of this, 8 of the drivers point rearward to produce that "direct-reflected" full sound. Does this mean if the orchestra all played towards the back of the stage it would sound the same or better?? You may have guessed I do not own 901s, but they will play extremely loud with a small amount of power, and their size is not overbearing in the living room. So how about it, can you equalize a 5 inch driver to give you accurate response at high frequencies? tektronix!tekig!david
sasaki@harvard.ARPA (Marty Sasaki) (03/25/85)
> So how about it, can you equalize a 5 inch driver to give > you accurate response at high frequencies? > > tektronix!tekig!david In Speaker Builder there was a speaker system that used Jordan's 50mm modules that crossed over to a 5 inch woofer at something like 150 hz. Like David, I'm wondering what kind of bass you can get with a 5 inch driver. Does the Bose 901 win because it has so many cones which result in having the equivalent of a larger cone? Along the same lines, Jordan claims that the 50mm modules are flat to above 20kHz. Is this possible? Jordan also claims that by not having a crossover until 150Hz you avoid the problems of phase and amplitude in the range where these things are audible. At 150Hz these problems aren't really problems. Any truth to this? -- ---------------- Marty Sasaki net: sasaki@harvard.{arpa,uucp} Havard University Science Center phone: 617-495-1270 One Oxford Street Cambridge, MA 02138
pmr@drutx.UUCP (Rastocny) (03/27/85)
There's a lot of things to consider when making multiple-driver loudspeakers. Firs,t, ,4when you combine nine 4-1/2" drivers,4 you get an equivalent piston area equal to that of a 10" driver. Please excuse this mess,4 my terminal just died. I'll reply when it's fixed properly. Yours for higher fidelity, Phil Rastocny AT&T-ISL ihnp4!drutx!pmr
klein@ucbcad.UUCP (03/27/85)
Also an important effect is the breakup of the speaker cone. Large cones at high frequencies can no longer be considered pistons. Instead they will have little areas all around the surface that wiggle, each one 180 deg out of phase with its neighbor. Bose's 5 inch drivers may be great (I've heard they are) for say 500Hz to 3kHz or so, but there's going to be some frequency where they no longer look like pistons. Cross over well before you get to that frequency. No equalizer on earth can help this problem. Imagine running your amp output through a comb filter! -- -Mike Klein ...!ucbvax!ucbmerlin:klein (UUCP) klein%ucbmerlin@berkeley (ARPA)
brent@itm.UUCP (Brent) (03/30/85)
X
About 50mm speakers and such... In Thiele-Small speaker design
(woofer-cabinet tuning criteria) The bass response of a speaker is
determined by it's resonant frequency, the Q-factor of that resonant
peak, and the driver's compliance. Period. The diameter of the
driver doesn't enter into the calculations anywhere. What you will
find is that the cone excursion for low bass from a small driver will
be huge. That's how Bose claims to be able to get such bass. Their
drivers have a very long throw: i.e. they have a lot of linear travel
while remaining fairly linear.
On the high end, yes, mid-size speakers may well be linear
out to 20kHz, but the problem there is horizontal dispersion. When
the physical wavelength of the sound is roughly equal to the diameter
of the driver, you start to get "lobing", or "beaming", as the frequency
increases, the sound gets directed into a tighter and tighter beam of
sound (up to a point)
So the bottom line is yes, much of what the man said is true, but
there's more to the story than that.
Happy listening,
--
Brent Laminack (akgua!itm!brent)tommie@psivax.UUCP (08/29/86)
I received this letter today about speaker building and decided to post
it. Please note that *I* would not in a million years suggest using radio
shack drivers for loudspeakers. Also, the given frequency response of Mr.
Hartzog's new speakers is highly suspect.
Minor quibblings aside, I tip my hat to Mr. Hartzog for diving into the
vast unknowns of speaker building and producing something that he seems
very happy with! Here's the article:
Mr. Levin,
My name is Greg Hartzog, and I am the one that put the message
on net.audio several months ago asking everyone to tell me everything
they knew about designing and building audio speakers. Well, after
much research, design, and smashed fingers, I have done it. I have built
my own speakers. tTThey are made with Radio Shack components, including
crossover, and 3/4 inch particle board. They sound quite good, and have
a range of 20 Hz to 22,000 Hz. Please feel free to post this to the net,
and if anyone would like specifics on the speakers, please just send
me a note, and I will happily respond. Thank you for your time.
Greg Hartzog
uucp: ...!{ucbvax,lll-crg}!ucdavis!harpo:u566654244ea
arpa: ucdavis!harpo:u566654244ea@ucbvax.berkeley.edu
ucdavis!harpo:u566654244ea@lll-crg.arpa
csnet: ucbvax!ucdavis!harpo:u566654244ea@tektronix.csnet
bitnet: ihnp4!ucbvax!harpo:u566654244ea@psuvax1.bitnet
decnet: decvax!ucbvax!harpo:u566654244ea@decwrl.decnet
mailnet: ucdavis!harpo:u566654244ea%ucbvax.berkeley.edu@mit-multics.mailnet
--
_______________________________________________________________________
Tom Levin {ttidca|sdcrdcf|logico|scgvaxd|bellcore}!psivax!tommie
"The life of a repo-man is always intense!"