Bass Extension
I plugged the T/S numbers for 4 319s1's into WinISD last night, and in a vented box, they have a theoretical -3db of about 57hz. In a sealed enclosure they came in around 120hz.
I assumed that the Spires are vented, but I don't know for sure. Also, I don't know how the additional driver affects these numbers.
I plugged the T/S numbers for 4 319s1's into WinISD last night, and in a vented box, they have a theoretical -3db of about 57hz. In a sealed enclosure they came in around 120hz.
I assumed that the Spires are vented, but I don't know for sure. Also, I don't know how the additional driver affects these numbers.
Ok
Tuned to a F3 of 83hz they can go lower but power handling goes down as you must remeber these are only 4 3" drivers.
Tuning higher is recommended for higher power handling.
As well the center is tuned around 90hz I have 2 designs i just passed to Bob at CSS.
Single vented cabinet rear vented if room allows.
If not a ported cabinet front twin ports.
Sealed they just roll off way to high to match to a sub.
Al
Tuned to a F3 of 83hz they can go lower but power handling goes down as you must remeber these are only 4 3" drivers.
Tuning higher is recommended for higher power handling.
As well the center is tuned around 90hz I have 2 designs i just passed to Bob at CSS.
Single vented cabinet rear vented if room allows.
If not a ported cabinet front twin ports.
Sealed they just roll off way to high to match to a sub.
Al
RAW said:
if the 871 is being used as a tweeter (albeit rolled of at 1000Hz why not use a smaller driver that can improve dispersion?
I stll have not found a colclusive answer to my fulllrange quest.
i was wondering how the reduction in high frequency polar infterference caused by using multiple 3" drivers in a line fullrange compares to the reduction in high frequency due to beaming of a single larger (read as 6" or 8" Fostex) fullrange driver. any ideas?
Timn8ter said:
Tim, I just happened to surf on your web site and found this
An externally hosted image should be here but it was not working when we last tested it.
Holy smoke dude !!! This is definitely one hot Isa.
I could definitely live with a couple of these in the house.I bet you'll need testers for these babies. You better count me in.
Do you plan on marketing these beauties ? If so, fully built, as a kit or just the plans ? Man, I can't wait to read the reviews. Washington is quite a drive from Trois-Rivières. I guess I'll have to miss the NWWA DIY Audio Meet this coming week.
In the mean time, would you mind sharing some of the technical stuff with us folks from far away ?
Nice work man !
You must frequent my site often, I just put that picture up. I was trying to sneak it in as I'm waiting judgment by my peers at the Meet. I've been toying with the idea of making a CAD drawing but I've been very busy getting ready for the Meet. It's looking like we'll have close to 70 people showing up.
In brief, it's essentially two cabinets. The upper cabinet houses the 6 W3-871s and is sealed. The volume causes a natural roll-off of the the drivers beginning around 200Hz. The lower portion houses two W5-740S woofers in a vented ML-TQWT tuned to 50Hz, bipole, parallel wired, push-push. The upper end of the woofers is rolled off with a simple .5 way XO consisting of an air core inductor and a resistor. It has a rather large soundstage and when I play them I tilt them back using adjustable toe spikes just enough so the center of the array is at ear-level. I like them but let's find out what others think.
Thanks for the compliments.
In brief, it's essentially two cabinets. The upper cabinet houses the 6 W3-871s and is sealed. The volume causes a natural roll-off of the the drivers beginning around 200Hz. The lower portion houses two W5-740S woofers in a vented ML-TQWT tuned to 50Hz, bipole, parallel wired, push-push. The upper end of the woofers is rolled off with a simple .5 way XO consisting of an air core inductor and a resistor. It has a rather large soundstage and when I play them I tilt them back using adjustable toe spikes just enough so the center of the array is at ear-level. I like them but let's find out what others think.
Thanks for the compliments.
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Timn8ter said:
this is very nice. i am considering a desgn tha tis similar i have just 3 questions....
1. to prevent the taper why no tuse 4 or 6 smaller woofers instead of 2 bigger woofers?
2. did you consider a open baffle for the 6 x 871s array? If so why did you decide against it?
3. with 6 x 871s operating up to 20khz u should be getting interference and cancelation effects after about 4500Hz? right?
1. Just trying to be different I guess.
2. This started out with an OB prototype of 4 drivers and ended up being 6. I did like the open and very detailed sound of the OB until I tried to play them loud. The W3-871S don't like being in open air unless rolled off very high and that didn't fit with my goals. I suppose if you went with a full length array along with row of small woofers they might handle it ok. A higher Q driver like the Fostex FK-85 would work better. As I kept experimenting with baffles I eventually ended up with the closed taper. I was also trying to create the illusion of the cab looking smaller than it really is.
3. It sounds pretty good to me. As long as it's angled back a bit the little oddities are minimal. The link below includes pics of a couple of the prototypes.
Isa
p.s. I WILL build an OB some day!
2. This started out with an OB prototype of 4 drivers and ended up being 6. I did like the open and very detailed sound of the OB until I tried to play them loud. The W3-871S don't like being in open air unless rolled off very high and that didn't fit with my goals. I suppose if you went with a full length array along with row of small woofers they might handle it ok. A higher Q driver like the Fostex FK-85 would work better. As I kept experimenting with baffles I eventually ended up with the closed taper. I was also trying to create the illusion of the cab looking smaller than it really is.
3. It sounds pretty good to me. As long as it's angled back a bit the little oddities are minimal. The link below includes pics of a couple of the prototypes.
Isa
p.s. I WILL build an OB some day!
You should try changing the woofers to these more robust bass drivers:
TB W5-876SA 5" Shielded "Subwoofer"
5mm Xmax
Fs 50Hz
Response: 50-2,000 Hz
At Parts Express
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-826
An externally hosted image should be here but it was not working when we last tested it.
TB W5-876SA 5" Shielded "Subwoofer"
5mm Xmax
Fs 50Hz
Response: 50-2,000 Hz
At Parts Express
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-826
I don't know if they are a direct "drop-in" replacement (probably not) but they have a much thicker paper cone and a heavy-looking poly dust cap. I don't know about the stamped frame but I guess in that sort of driver it doesn't really matter. Oh, and it's also shielded, making it a great driver for your towers. While they might not be Martin Logans, your towers do follow some very similar design characteristics with the bipole bass section and dipole upper frequency section. These should make a great home theater speaker for a middling budget.
ADDENDUM:
Oops, apparently the top is sealed. You might consider making it a dipole upper section. Also, perhaps you might consider a way of mounting the woofers so that the one on the rear is wired out of phase and has the magnet facing out, for distortion-canceling push-pull operation. You could make it a different model.
ADDENDUM:
Oops, apparently the top is sealed. You might consider making it a dipole upper section. Also, perhaps you might consider a way of mounting the woofers so that the one on the rear is wired out of phase and has the magnet facing out, for distortion-canceling push-pull operation. You could make it a different model.
Ok, here's a drawing I made. The gray lines show where grilles are supposed to go. Be careful to use a fairly steep crossover on the bass section or else there may be a midbass suckout due to cancellation from the rear wave of the 3" drivers and the rear 5" woofer. It will have a power handling of 100w RMS and 200w max. Inside the bass section, I show how a ML-TL can be made to fit. You can definitely adjust the dimensions of the bass box. Also, in that unused air space is the crossover circuitry.
Edit: How about the Isa II Signature?
Edit: How about the Isa II Signature?
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That's just a little humorous to me because "isa" means "one". So you'd be saying "one, two".
If I had more forethought I would have snapped a picture of the plans for this one (they were posted on the wall
) It's OB on the upper drivers and vented for the woofers. They sounded awesome!Attachments
Timn8ter said:
an option is to XO the 871 about 250Hz that would be almost 1 octave higher than the current XO right?
Timn8ter said:If I had more forethought I would have snapped a picture of the plans for this one (they were posted on the wall
which drivers are these? what was the XO for the OB upper drivers.
I didn't post a picture of it but there was one more prototype that was the sealed upper box. I tried many XO points and styles, series, parallel, AR series and I liked the sound of the natual roll off in the sealed box and the control it exercises over the drivers.
The picture is the Foxtex room at T.H.E. Show in Las Vegas. Like I said, I didn't get the plans and found out later it's not a published Fostex design.
The picture is the Foxtex room at T.H.E. Show in Las Vegas. Like I said, I didn't get the plans and found out later it's not a published Fostex design.
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