The D7608 is my favorite mid dome, so I'm always happy to see when others choose to use it in their design.
How steep are you wanting to cross the mid? I wouldn't go lower than 800 hz 2nd order if you want some level out of it, meaning you need the correct back chamber volume and dampening to get the Qtc down under 1.0 for best power handling and lowest THD. This is THE key fiactor in getting the best out of it and means a 1 - 1.5 ltr volume stuffed with fiberglass (good) or sheeps wool (best) will work best. The correct dampening can considerably affect THD for the good.
I like to use a midbass in between the D7608 and a larger than 8" LF driver for best results at higher SPLs. The limited xmax is the weakness of this mid, so if you want it to play considerably louder than low 100s dB, crossing 3rd order at 700+ or 2nd order at 900+ is necessary. Most larger LF drivers aren't speedy enough to gel seamlessly with this dome and the big jump in radiating pattern this creates is also undesirable for the sake of good power response, making the use of a midbass driver (resulting in 4 way design) more beneficial overall.
If you're skilled enough to design and fabricate a WG large enough, the mid dome will have usable response to almost 300 hz, making a 500 - 550 hz xover 3rd order possible with good power handling. A 6 - 8" midbass is the best fit with WG loading while a 5 - 6" works best without a WG on the D7608.
I'm currently working on a writeup of the D7608, touching on all of the above mentioned things. The main reason is to show this mid is a worthy and capable driver even by today's standards, hopefully encouraging others to consider using this mid. It would be sad to see it die off and fall by the wayside along with the many other amazing Scanspeak drivers that already disappeared.
I hoped that D7608 can be crossed a bit lower than Dayton RS52, but now I see that it is about 100Hz lower in some projects. I was wondering if there are 12" woofers good enaugh for that kind of cross. Beyma 12br70 can be crossed over 1kHz but they are opinion that bas is low but not too quick.
Maybe I should go for 10" woofer for D7608 or RS52...
The issue with a higher xover on the woofer is a jump in directivity between it and the smaller mid. There is a sudden widening in radiating pattern once the mid takes over from the point of the woofer beaming. That puts alot of uneven FR off axis into the room and makes that overall balance in sound dictate the character of how the speaker sounds. Thats why i advocate a midbass in between the drivers among other reasons.
The problem discussed above will worsen with an even smaller mid dome, plus the RS52 doesn't have the ability to play louder and lower because of its size / surface area. It can be used in a lower SPL system crossed on the lower side and the only benefit of doing so is a slightly higher xover to the tweeter. It won't however work better at a given HP xover than the D7608 due to the driver surface area itself. There are larger LF drivers that will play up into the high 100s hz range, but they wont do anything better for overall performance based on off axis behavior dictating in room FR and SQ. Using 2 smaller LF drivers ie 2 x 8" in a .5 configuration (one of the LF drivers playing up higher to the mid dome xover and the other only up to 200 hz or so) will give the benefits of a larger LF driver while giving better continuity to the mid dome. Those 2 x 8" LF drivers almost equal one 12" driver.
The problem discussed above will worsen with an even smaller mid dome, plus the RS52 doesn't have the ability to play louder and lower because of its size / surface area. It can be used in a lower SPL system crossed on the lower side and the only benefit of doing so is a slightly higher xover to the tweeter. It won't however work better at a given HP xover than the D7608 due to the driver surface area itself. There are larger LF drivers that will play up into the high 100s hz range, but they wont do anything better for overall performance based on off axis behavior dictating in room FR and SQ. Using 2 smaller LF drivers ie 2 x 8" in a .5 configuration (one of the LF drivers playing up higher to the mid dome xover and the other only up to 200 hz or so) will give the benefits of a larger LF driver while giving better continuity to the mid dome. Those 2 x 8" LF drivers almost equal one 12" driver.
WWMT arrangement with smaller LF drivers would work best with the D7608 or other smaller mid dome.
The new Hivi dome isn't as great as it looks on the outside. It has considerably higher odd order HD than the D7608 based on various research I've done when I first got excited about a new larger mid dome coming on the market. The biggest problem with the Hivi mid is the shape of the dome. The D7608 is much more shallow in profile, which is a considerable benefit to off axis performance alone. The motor is very well designed if you look at the distortion performance alone on the hificompass website. You get a lot of mid for $100.
The new Hivi dome isn't as great as it looks on the outside. It has considerably higher odd order HD than the D7608 based on various research I've done when I first got excited about a new larger mid dome coming on the market. The biggest problem with the Hivi mid is the shape of the dome. The D7608 is much more shallow in profile, which is a considerable benefit to off axis performance alone. The motor is very well designed if you look at the distortion performance alone on the hificompass website. You get a lot of mid for $100.
Any good and not expensive 8-9" woofer recomendation for crossing with dome mid in 0,5 configuration?
I'd consider SBNRXS45-8. They play low and handle a decent amount of power. Nice sounding paper cone.
Also, look at the Dayton RS225-8. Not cheap for a Chinese driver, but decent alu cone design.
Scanspeak 22W8534 plays low and smooth. Price is low for what you get. Fiberglass cone is nice quality. Probably my second choice behind the Seas below.
Seas CA22RNX is a great sounding woofer with a coated paper cone. Very snappy sounding driver that would go well with the D7608. Efficiency is really good and allows for enough meat in the curve for BSC to mate with the 92 dB mid band SPL
Also, look at the Dayton RS225-8. Not cheap for a Chinese driver, but decent alu cone design.
Scanspeak 22W8534 plays low and smooth. Price is low for what you get. Fiberglass cone is nice quality. Probably my second choice behind the Seas below.
Seas CA22RNX is a great sounding woofer with a coated paper cone. Very snappy sounding driver that would go well with the D7608. Efficiency is really good and allows for enough meat in the curve for BSC to mate with the 92 dB mid band SPL
Those aren't bad, but won't handle alot of power. Definitely a budget driver. VC is pretty small for an 8" driver.
If you wan't use 10" woofer with dome midrange. You need driver that goes very nicely over 1khz.
Something like:
Seas ca26rfx
Visaton w250s
Monacor sph-250ke
Something like:
Seas ca26rfx
Visaton w250s
Monacor sph-250ke
Visaton w250s looking good, and not so expensive. Is 4 Ohm version the same efficienty like 8 Ohm? 4 Ohm has low mms=32g so it should be "quick".
What about Dayton DSA270-8, DS270-8?
What about Dayton DSA270-8, DS270-8?
Lavoce seems little known, but they look like a nice option in the lower cost pro driver segment. I got the WSF122.02 12” woofers. Wood for the boxes is taking time to dry, so I haven't properly auditioned them yet, but the build quality looks good. Magnet pole pieces nicely centred and profiled for good saturation. Good glue lines, nothing unexpected. The cloth surround is stiff compared to the usual rubber surround and obviously isn't designed for high xmax, but I chose it for extended mid-range, so we shall see.
In germany they have made even 2 way with w250s, so 3way should work fine.
Is it a stupid idea to use 2x Visaton w250s 8 Ohm and connect them In parallel? Lower woofer filter additionally with a coil. Like 3,5 way? Midrange and high efficiency about 90dB, single woofer 90dB too. Can it help with baffle step correction? Baffle will be about 12-13" (300-330mm, maybe some more) wide.
A 3.5 way as you suggested is certainly viable. Have a look at Tony Gee's approach in this 2.5 way "I use the second woofer to compensate the so-called baffle-step. So the bass is only as deep as with a normal two-way but efficiency is much better."
Lower woofer is vented and rolled off 1st order to upper woofer which is closed. He uses a series crossover but the principle can be adapted.
I don't know how the D7608 will do on an open baffle. @profiguy ?
Lower woofer is vented and rolled off 1st order to upper woofer which is closed. He uses a series crossover but the principle can be adapted.
I don't know how the D7608 will do on an open baffle. @profiguy ?
"I don't know how the D7608 will do on an open baffle"
It won't do 🙂 It needs 1dm3 enclosure.
I bought Visaton G 50 FFL (D7608 is more difficult to apply and can go down about 150Hz or so lower cross point)
It won't do 🙂 It needs 1dm3 enclosure.
I bought Visaton G 50 FFL (D7608 is more difficult to apply and can go down about 150Hz or so lower cross point)
The D7608 absolutely needs a chamber, regardless of enclosure topology. Without it, the lower mids won't be there and it will sound way to lean without any power handling capability in that range.
Again, you want to keep the woofer diameter on the smaller side to blend well with the mids dispersion angle at xover. The directivity jump will otherwise hurt off angle linearity. An 8" LF driver is the largest Id go with.