Ignite said:
</lurk>
I've had 4 of the w3-881s sitting around for a couple of months now. I'm using two in a simple PVC tube transmission line (tuned to 100hz). They are my day to day computer speakers running off of ... a pair of Wave 8s. It is a *great* pairing (and cheap!).
Impressions? They don't go low (obviously), but they sound great. The highs are a bit lacking, but they work magic with voices. My musical selection varies greatly, ranging from Tool to Lee Hazelwood to Tony Bennett. The t-line configuration with these drivers are much better suited for non-rock. And there is no comparison if you put them up against other computer speaker systems, Klipsch Pro Media included, except for the lack of bass.
When the w3-881ss first arrived I tossed two of them in an open baffle configuration for break in, but after 20-30 hours of listening I was a bit disappointed. Now with spring time rapidly approaching, I've been kicking around a few ideas for using a whole mess o' these w3s.
One project that has been through a few design iterations is a line array. At this point I'm thinking 16 w3s per side (seeing an 8 ohm load) in either an open baffle, or sealing each driver in an inverted horn. Open baffle is the easiest, so I'm rapidly moving towards that option. That will be coupled with a 10" sub (looking at the Ultimate Platinum or Cupric from Parts Express) in a transmission line, ala El Pipe-o, for each side.
(I should have posted this as a seperate thread...)
So I have a few questions re: what to watch out for. I'm familiar with the comb filtering effects associated with line arrays, but that's acceptable for right now. Am I going to be looking at any serious problems with an open baffle line array? And regarding the inverted horn idea, does anyone know of any resources that explain the theory and perhaps some formulas? :Googling: for inverted horns mostly turns up nOrh and B&W references.
planet10 said:
Your graph seems to prefer much larger baffles when compared to this :
An externally hosted image should be here but it was not working when we last tested it.
planet10 said:
Mine definately don't go very low for bass in the current setup. I put them in my other room wedged between 2 larger floor standing speakers, and closer to the wall, and there was more bass.
I just threw these together to get an idea how the drivers sound, and how loud I can reasonably turn it up. I had the wood already cut. I don't think I will keep these drivers in the current setup, once I start building boxes.
--
Brian
What about the 6dB/octave slant with open baffles?
This thread is _really_ interesting. I got myself a pair of
JX92S drivers, and have built a 6L vented box as per
the Jordan Website, just to see what these animals sound
like. Detailing is excellent, bass is weak (expected) and
the sound tends to become quite confused and "loud"
sounding at high volumes (do they need a sharp bass
rolloff?)
I was wondering how my Jordans would sound on an
open baffle, but Linkwitz' site (my reference site for
open baffle concepts) clearly says that such a baffle will
give you a slope of 6dB/octave high pass, i.e. it'll weaken
bass and mids w.r.t. highs. I have built a rough-hewn OB
sheet with three drivers some time back, and my ears tell
me Linkwitz was spot on... the highs were terribly loud
and glaring and the speaker didn't have any balance. Even
with the inexpensive drivers and crossover that I had used
on that sheet, there's no reason to expect such poor
balance, unless it was this 6dB/octave upslope.
So how come none of you are experiencing any of this
problem with your open baffles? Or are you correcting
for this in your crossovers?
Yours confusedly,
Tarun
BTW, this is my _first_ post to diyaudio. Hello everyone.
This thread is _really_ interesting. I got myself a pair of
JX92S drivers, and have built a 6L vented box as per
the Jordan Website, just to see what these animals sound
like. Detailing is excellent, bass is weak (expected) and
the sound tends to become quite confused and "loud"
sounding at high volumes (do they need a sharp bass
rolloff?)
I was wondering how my Jordans would sound on an
open baffle, but Linkwitz' site (my reference site for
open baffle concepts) clearly says that such a baffle will
give you a slope of 6dB/octave high pass, i.e. it'll weaken
bass and mids w.r.t. highs. I have built a rough-hewn OB
sheet with three drivers some time back, and my ears tell
me Linkwitz was spot on... the highs were terribly loud
and glaring and the speaker didn't have any balance. Even
with the inexpensive drivers and crossover that I had used
on that sheet, there's no reason to expect such poor
balance, unless it was this 6dB/octave upslope.
So how come none of you are experiencing any of this
problem with your open baffles? Or are you correcting
for this in your crossovers?
Yours confusedly,
Tarun
BTW, this is my _first_ post to diyaudio. Hello everyone.
Re: What about the 6dB/octave slant with open baffles?
A better way to describe it is that below the frequency where the baffle becomes too small to keep the back from canceling the front you get a 6 dB/octave rolloff. Above that it should be relatively flat. An example can be seen in the graph of Olson's i posted earlier in the thread and the cutoff can be approximated using the chart i posted a little later.
dave
tcpip said:
A better way to describe it is that below the frequency where the baffle becomes too small to keep the back from canceling the front you get a 6 dB/octave rolloff. Above that it should be relatively flat. An example can be seen in the graph of Olson's i posted earlier in the thread and the cutoff can be approximated using the chart i posted a little later.
dave
Re: the 6dB/octave rolloff
Dear Planet10,
Thanks for clarification, and I remember seeing the flat
latter portion in Linkwitz' graph. But in that portion, he
talks of the comb filtering notches when the back and front
sound waves exactly cancel each other out at certain
frequencies. Won't those mess up the response? Or will
your earlier suggestion of off-centre driver mounting take
care of that adequately?
Talking of off-centre mounting and comb filtering, it's
interesting that Linkwitz himself didn't try to use this to
advantage in his speaker system... his drivers are all
exactly equidistant from both sides. I never could figure
that one out.
And how big is big for the baffle by the way? In your graph,
which linear dimension is measured in the inch-axis?
Thanks and regards,
Tarun
Dear Planet10,
Thanks for clarification, and I remember seeing the flat
latter portion in Linkwitz' graph. But in that portion, he
talks of the comb filtering notches when the back and front
sound waves exactly cancel each other out at certain
frequencies. Won't those mess up the response? Or will
your earlier suggestion of off-centre driver mounting take
care of that adequately?
Talking of off-centre mounting and comb filtering, it's
interesting that Linkwitz himself didn't try to use this to
advantage in his speaker system... his drivers are all
exactly equidistant from both sides. I never could figure
that one out.
And how big is big for the baffle by the way? In your graph,
which linear dimension is measured in the inch-axis?
Thanks and regards,
Tarun
Hi all,
JoeBob, your project is very interesting, please, can you zipped all the drawings (crossover, wood, etc) and send to this thread?
I are very interesting, and I supposed that some others also.
Your design can be used for a active system, with a simple amp with balanced inputs, as be seen in the thread about gainclone.
Anticipated thanks.
Happy days,
Raúl Couto
JoeBob, your project is very interesting, please, can you zipped all the drawings (crossover, wood, etc) and send to this thread?
I are very interesting, and I supposed that some others also.
Your design can be used for a active system, with a simple amp with balanced inputs, as be seen in the thread about gainclone.
Anticipated thanks.
Happy days,
Raúl Couto
Re: Re: Re: the 6dB/octave rolloff
Dave,
Thanks for the clarification. But in that case, how do
people do dipole bass drivers with just a flat baffle? Won't
all "normal" baffle sizes be too small? Does this mean
that for normal sized woofers, you'll have to go either
with boxes or Linkwitz or Lynn Olson's style of dipole
arrangement? I guess so, right?
And if someone is brave enough to try open baffle for
the woofer, he'll have to neutralise the 6dB rolloff in a
crossover, either before or after his power amp, and then
use a real long-excursion driver. Am I correct in this?
Just checking. I have these little JX92S boxes that I'd
mentioned, and I'm now trying to figure out what to do
about bass extension. Needless to say, the simplicity of
open baffle for a woofer unit is tempting, but from my
limited understanding, an open baffle woofer will have
all these extra complications.
BTW, what do you feel about dipole versus ordinary
box for woofers (crossover freq 200Hz or less)? By
ordinary box, I'm talking sealed or vented box. And by
dipole, I mean open baffle, or Linkwitz style, or two
drivers on opposite surfaces of a (sealed?) box, as in
Lynn Olson's design. Should I bother with dipole woofer
at all? For mids, I can imagine that dipole may give me
much more clarity/delicacy over the average boxed
design.
Thanks for all the responses, Dave, Joebob, others.
Tarun
Dave,
Thanks for the clarification. But in that case, how do
people do dipole bass drivers with just a flat baffle? Won't
all "normal" baffle sizes be too small? Does this mean
that for normal sized woofers, you'll have to go either
with boxes or Linkwitz or Lynn Olson's style of dipole
arrangement? I guess so, right?
And if someone is brave enough to try open baffle for
the woofer, he'll have to neutralise the 6dB rolloff in a
crossover, either before or after his power amp, and then
use a real long-excursion driver. Am I correct in this?
Just checking. I have these little JX92S boxes that I'd
mentioned, and I'm now trying to figure out what to do
about bass extension. Needless to say, the simplicity of
open baffle for a woofer unit is tempting, but from my
limited understanding, an open baffle woofer will have
all these extra complications.
BTW, what do you feel about dipole versus ordinary
box for woofers (crossover freq 200Hz or less)? By
ordinary box, I'm talking sealed or vented box. And by
dipole, I mean open baffle, or Linkwitz style, or two
drivers on opposite surfaces of a (sealed?) box, as in
Lynn Olson's design. Should I bother with dipole woofer
at all? For mids, I can imagine that dipole may give me
much more clarity/delicacy over the average boxed
design.
Thanks for all the responses, Dave, Joebob, others.
Tarun
tcpip, I'd say try an open baffle. Because the bass is really exceptional compared to a ported enclosure (never heard a high quality sealed box before). I get usuable bass from around 45Hz up to between 100Hz and 200Hz (where the driver is crossed over). And in another thread Peter said that his 15" focal goes down to 25Hz (I do believe he said not eq'd) in a relatively small folded baffle (the dimentions wouldn't lead you to believe that it would go down to 25Hz). So it's worth a try to see how your jordan will sound, just slap it into a huge baffle to get an idea and then work from there. Try using this excel spreadsheet to get an idea of how your driver will preform, I found it pretty usefull ( http://melhuish.org/audio/Xlbaffle.xls ).
Variac, the frequencies that the graphs show (which ever is the correct one) would probably be the -3dB points (just a guess, but it makes sense) and the driver will drop 6dB an octave after that (although I'm not sure how the driver will act below resonance).
Variac, the frequencies that the graphs show (which ever is the correct one) would probably be the -3dB points (just a guess, but it makes sense) and the driver will drop 6dB an octave after that (although I'm not sure how the driver will act below resonance).
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