Hi all,
New project I call DAD (dual acoustic dipole), OB (20 cm width) with two FR Monacor SPH60X, wired in parallel and out of phase..
Only notch filter cause this driver have a hump near 1400 hz..
Just build one cause one driver is missing today.
Anyone build ths kind of speaker ?
Thank's, Phil.
New project I call DAD (dual acoustic dipole), OB (20 cm width) with two FR Monacor SPH60X, wired in parallel and out of phase..
Only notch filter cause this driver have a hump near 1400 hz..
Just build one cause one driver is missing today.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Anyone build ths kind of speaker ?
Thank's, Phil.
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Interesting design. I have seen something similar with a dipole woofer or sub but not for the full range tops. You have a dipole with two drivers but the back side radiation now hits the opposite baffle wall which appears to be about 10cm away? This will cause sidelobe emissions at 90 deg rather than a null at 90 deg like a true dipole. Furthermore there will be a reflection from the back wall at 10 cm causing some interference in the 1khz to 3khz range (probably the source of the two dips near 900 Hz and 3.4 kHz) that will cause dips and peaks and coloration. Your frequency response plots are actually pretty good and I assume you will be using a subwoofer to handle frequencies below 200 Hz?
What is the polar response like? Probably pretty good bit could be better if you simply made frame about same width as driver and not have the offset as it is not providing any bass boost given that one edge is almost nonexistent and will dominate the low freq open baffle cutoff. Maybe add felt or foam to line inside walls of front and back baffle to reduce reflections back through cone?
What is the polar response like? Probably pretty good bit could be better if you simply made frame about same width as driver and not have the offset as it is not providing any bass boost given that one edge is almost nonexistent and will dominate the low freq open baffle cutoff. Maybe add felt or foam to line inside walls of front and back baffle to reduce reflections back through cone?
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It is a 'symmetrical' dipole. 
I built a prototype similar to this a few years ago but offset the drivers vertically so the "baffle" thickness would be much less. I also closed-in the edges with half chunks of PVC piping. It looked a lot like the Grimm LS-1 actually.
Some further off-axis measurements would be neat to see.
Cheers,
Dave.
I built a prototype similar to this a few years ago but offset the drivers vertically so the "baffle" thickness would be much less. I also closed-in the edges with half chunks of PVC piping. It looked a lot like the Grimm LS-1 actually.
Some further off-axis measurements would be neat to see.
Cheers,
Dave.
Hi all,
I said "true dipole" just cause rear and front wave are the same..
But I do not know what the exact name of this speaker.
Xrk, yes the inside depth is 11 cm, and I add later a subwoofer, near 150/200 hz.
Adding stuffing (mutton wool) like in a TL or MLTL change a little the response curve and it was better at listening. I build yesterday another speaker.
I try panels at side of enclosure like Dave said, it's don't work in my case.. But a vertically offset driver is a good idea, thank's.
After two hours of listening, I think that sounding was very pleasant, room are like "full of music"..
Next step, try in bipole and add Lpad to "balance" level from front to rear and reverse..
Off axis mesurements for tomorrow..
Do you knaw if it's possible with Arta to "draw" a polar response ?
Phil.
I said "true dipole" just cause rear and front wave are the same..
But I do not know what the exact name of this speaker.
Xrk, yes the inside depth is 11 cm, and I add later a subwoofer, near 150/200 hz.
Adding stuffing (mutton wool) like in a TL or MLTL change a little the response curve and it was better at listening. I build yesterday another speaker.
An externally hosted image should be here but it was not working when we last tested it.
I try panels at side of enclosure like Dave said, it's don't work in my case.. But a vertically offset driver is a good idea, thank's.
After two hours of listening, I think that sounding was very pleasant, room are like "full of music"..
Next step, try in bipole and add Lpad to "balance" level from front to rear and reverse..
Off axis mesurements for tomorrow..
Do you knaw if it's possible with Arta to "draw" a polar response ?
Phil.
It looks like the mutton wool improved the smoothness by reducing the reflection from the insides of the rear baffle. Looking forward to off axis measurements. Just plotting the different angles as full response on same plot is sufficient rather than making a polar plot. Those are pain to make manually.
Hi,
New mesurements with Lpad, (distance from rear wall 60 cm), in a small room at listening point..
Thank's for your comments..
Phil.
New mesurements with Lpad, (distance from rear wall 60 cm), in a small room at listening point..
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Thank's for your comments..
Phil.
Hi Xrk,
Thank's, indeed sound stage is just amazing..
I built several OB or MLTL Bipole, I never heard this sound.
Yes, lambwool is permanently and add a tweak at the rear frame of driver. I think this is case of dips and holes, and the chamfer at rear too..
Another point, it don't need a tweeter, I use this driver in monopole and always I add a tweeter. At this time I think build a serious enclosure with birch plywood and select a good FR, FF125WK, FE126eN or W5 1611.. The top was a Fostex with basquets of TB Speaker !
Soon I try with adding dipole sub, maybe U frame with Alpha 15A or my special driver, with polystyrene cone (non pistonic mode).. Do not laugh it works !
Phil.
Thank's, indeed sound stage is just amazing..
I built several OB or MLTL Bipole, I never heard this sound.
Yes, lambwool is permanently and add a tweak at the rear frame of driver. I think this is case of dips and holes, and the chamfer at rear too..
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Another point, it don't need a tweeter, I use this driver in monopole and always I add a tweeter. At this time I think build a serious enclosure with birch plywood and select a good FR, FF125WK, FE126eN or W5 1611.. The top was a Fostex with basquets of TB Speaker !
Soon I try with adding dipole sub, maybe U frame with Alpha 15A or my special driver, with polystyrene cone (non pistonic mode).. Do not laugh it works !
Phil.
Some news mesurements, off-axis..
Phil.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Phil.
You might want to give the Vifa TC9FD a try - it might be a simple subsitution as the cutout is about the same I think - at 3.0 inches. The Vifa is inherently very smooth response and has great polar off axis performance too. If you can live with 85dB sensitivity it is one of the best full range drivers in the 3.5 in range. The drives you mention are good too but more expensive and I am not sure they are quite as smooth. The FE126eN has a big rising response that will probably need BSC otherwise it will shout at you. Is that a bicycle inner tube you wrapped around the magnet or is that closed cell pipe insulation foam tube?
Nice work - time to make it look good I guess. Did yo make your own polystyrene foam cone driver? Do you have a thread on that?
I won't laugh as I know that a simple exciter voice coil glued to a panel of foam core sounds very nice as a simple open baffle.
Nice work - time to make it look good I guess. Did yo make your own polystyrene foam cone driver? Do you have a thread on that?
I won't laugh as I know that a simple exciter voice coil glued to a panel of foam core sounds very nice as a simple open baffle.
Yes it's foam pipe insulation..
For the drivers, I'am looking for 5 inches, paper cone, low Mms, and "inverted roll" (sorry I not sure of this name in english)..
So maybe the FE126eN. I have one pair in OB, and you are right a BSC is required.. But nice sounding and smooth too.
About polystyrene foam cone driver, I build a diy prototype, size is 50 cm x 70 cm (Mms 115 gr, Qts 2.12), motor is like a diy body shaker but glued to the panel. It can down near 15/20 hz.
I can not say more for now, I have to rebuild two speakers with better "driver".
In fact this is act like a drum, a big like japanse drums :
Kodo - "O-Daiko" - HD (japanese drummers - Taiko - tambours géants Japon) - YouTube
Have a look near 30 secondes for example..
Phil.
For the drivers, I'am looking for 5 inches, paper cone, low Mms, and "inverted roll" (sorry I not sure of this name in english)..
So maybe the FE126eN. I have one pair in OB, and you are right a BSC is required.. But nice sounding and smooth too.
About polystyrene foam cone driver, I build a diy prototype, size is 50 cm x 70 cm (Mms 115 gr, Qts 2.12), motor is like a diy body shaker but glued to the panel. It can down near 15/20 hz.
I can not say more for now, I have to rebuild two speakers with better "driver".
In fact this is act like a drum, a big like japanse drums :
Kodo - "O-Daiko" - HD (japanese drummers - Taiko - tambours géants Japon) - YouTube
Have a look near 30 secondes for example..
Phil.
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