Advice for new project

[jimbones]

I have a Fountek NeoX 3.0 lying around and was thinking of building new speaker using it. Candidate woofers are Dayton Rs225P-8 ans Wavecor 223D01/D02. I was thinking of building something like the Alta Audio Alec. I always liked the way the Alta speakers sound. The midrange has to be right so I wasn't sure if the Wavecor would be a better fit? How does it compare? I was thinking of a XO at 3500 since I dont want to fry the tweeter.I figured I'd ask before I go down the wrong road.Thanks

[Paul K.]

Don't believe Alta Audio's claim about "extended transmission lines" in their speakers. They said the very same thing about the Alyssa design which was reviewed twice in Stereophile last year because the first review was performed on a pair of Alyssas that had their ports stuffed with foam, which Alta forgot to remove. Those reviews contained a pretty detailed exploded cabinet drawing, and coupled with their published cabinet dimensions, i was able to reverse-engineer its design reasonably accurately. Yes, there is a transmission line in it but its 1/4-wavelength resonant frequency due to its length, which is the only or primary tuning mechanism in a TL, was ~45-49 Hz, the extent of its tuning ability, so they added a port which further lowered the system tuning frequency to the 30s. In other words, the TL does not literally extend the bass response, the port does (making this a mass-loaded TL). I sent a "letter to the editor" addressing both the reviewers' comments and Alta's comments, pointing out this mis-information and exactly what the design was and was not doing. I thought I might get some feedback or response in a later issue, but my letter was never published and I heard nothing. NOT surprised. I also thought it was quite humorous with Alta saying their XTL designs are tuned with multiple frequencies like a musical instrument, which came off to me like their cabinets vibrate a lot. If you do want to build a proper TL, whether mass-loaded or not, I'd be happy to do some modeling for you to see what might be wrought from whatever woofer you choose.
Paul

I have a Fountek NeoX 3.0 lying around and was thinking of building new speaker using it. Candidate woofers are Dayton Rs225P-8 ans Wavecor 223D01/D02. I was thinking of building something like the Alta Audio Alec. I always liked the way the Alta speakers sound. The midrange has to be right so I wasn't sure if the Wavecor would be a better fit? How does it compare? I was thinking of a XO at 3500 since I dont want to fry the tweeter.I figured I'd ask before I go down the wrong road.Thanks

[jimbones]

Don't believe Alta Audio's claim about "extended transmission lines" in their speakers. They said the very same thing about the Alyssa design which was reviewed twice in Stereophile last year because the first review was performed on a pair of Alyssas that had their ports stuffed with foam, which Alta forgot to remove. Those reviews contained a pretty detailed exploded cabinet drawing, and coupled with their published cabinet dimensions, i was able to reverse-engineer its design reasonably accurately. Yes, there is a transmission line in it but its 1/4-wavelength resonant frequency due to its length, which is the only or primary tuning mechanism in a TL, was ~45-49 Hz, the extent of its tuning ability, so they added a port which further lowered the system tuning frequency to the 30s. In other words, the TL does not literally extend the bass response, the port does (making this a mass-loaded TL). I sent a "letter to the editor" addressing both the reviewers' comments and Alta's comments, pointing out this mis-information and exactly what the design was and was not doing. I thought I might get some feedback or response in a later issue, but my letter was never published and I heard nothing. NOT surprised. I also thought it was quite humorous with Alta saying their XTL designs are tuned with multiple frequencies like a musical instrument, which came off to me like their cabinets vibrate a lot. If you do want to build a proper TL, whether mass-loaded or not, I'd be happy to do some modeling for you to see what might be wrought from whatever woofer you choose.
Paul

Thanks Paul. I'm wondering if I should keep it simple and do a vented cabinet. I have subs so I don't need subterranean bass. The first concern was choosing the right driver to go with the Fountek. I am not stuck on either of the 2 I mention so I am open to other drivers. Your offer to help is appreciated as you have more expertise than I do.

[Paul K.]

I need to correct something I stated in my first reply. I checked my saved copy of my letter to Stereophile and found that I estimated the length of the line in the Alyssa was 48", making its 1/4-wavelength resonant frequency ~70 Hz and, therefore, providing even less tuning of the system. My "expertise" lies with TLs, but I can model a vented box using TL design techniques to optimize locations of midwoofer/woofer and port.

Thanks Paul. I'm wondering if I should keep it simple and do a vented cabinet. I have subs so I don't need subterranean bass. The first concern was choosing the right driver to go with the Fountek. I am not stuck on either of the 2 I mention so I am open to other drivers. Your offer to help is appreciated as you have more expertise than I do.

[jimbones]

Got it. before we even start down that path I am hoping to get consensus from people that these drivers are good candidates

[Kornbread]

Those are both 8" woofers. Are they going to be able to meet the neo?

[donradick]

I made a MTM with the Fountek NeoCD 3.0 and pairs of the Tangband W4-1320 bamboo mid. Love the sound!
Once I got the NeoCD 3.0 dialed in, I really, really liked it.
Hint, crossed it at 3.5Khz, 3rd order electrical.

[Wolf]

It will be very hard to get an 8" woofer to xover at 3.5kHz.
Wolf

[jimbones]

It will be very hard to get an 8" woofer to xover at 3.5kHz.
Wolf

Yes i am concerned about that so then the question is how low can I bring the Neo 3?. Alta audio does it but I dont know what the XO is. Im open to use a smaller driver. I think dayton makes a 7 inch driver of the same type that might be better???

[Kornbread]

Alto mates the neo3 with an 8" driver? Even if the 8" plays to 3k cleanly, am I correct in thinking directivity (is that a word?) will be a major issue? Generally speaking, a smaller woofer will more easily mate with the ribbon as far as freq and directivity is concerned.
Yuk, I spy some nasty bumps in Stereophile's measured impedance plot where they should be audible.

[jimbones]

Alto mates the neo3 with an 8" driver? Even if the 8" plays to 3k cleanly, am I correct in thinking directivity (is that a word?) will be a major issue? Generally speaking, a smaller woofer will more easily mate with the ribbon as far as freq and directivity is concerned.
Yuk, I spy some nasty bumps in Stereophile's measured impedance plot where they should be audible.

Maybe use an RS180P instead? I could also go for something in the scan speak line as that would be new to me.

[Kornbread]

The P looks to be a little smoother from ~1-4k without quite the ringing? from +6k, although, the P does begin a rise at ~4k. Some of the SS can get quite $ expensive. Hmmmmm ... wonder about the sb acoustics sb17cac ceramic woofer? Price wise, it's in the ballpark of the cheaper SS and it might make a great sounding speaker mated to the neo3. Either way you go, I'm wondering how complex the crossover might become.

[donradick]

The P looks to be a little smoother from ~1-4k without quite the ringing? from +6k, although, the P does begin a rise at ~4k. Some of the SS can get quite $ expensive. Hmmmmm ... wonder about the sb acoustics sb17cac ceramic woofer? Price wise, it's in the ballpark of the cheaper SS and it might make a great sounding speaker mated to the neo3. Either way you go, I'm wondering how complex the crossover might become.

Many of the SBs would work well. Meni$&$% has a sale on the SB17NAC and SB15NRX would work great. The tweeter crossover is simple and would just need a little tweaking.

[jhollander]

I used the RS180P to 3.6K and thought it was good.

[jimbones]

Update: After checking, I plan on using a lower XO point, say somewhere between 2750 and 3000 and use a 7 inch driver, thinking that would be a better strategy. So an RS180P or SB17CAC35 and Fountek Neo 3.