Advice for new project

[Kornbread]

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

How steep?

[Kornbread]

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.

Don't get stuck on the sb17cac, sb has some good $/performance drivers. Just though that might be a good woofer to mate with a ribbon. IIRC, Wolf or pwryde used the cac in a project and it got good reviews.

[jhollander]

How steep?

8th order 1/48

[Kornbread]

8th order 1/48

Steep.

[jimbones]

8th order 1/48

Lol OK Lol. Steeeeeeepppppp

[hex168]

A two-way with the Fountek and an 8" or 7" will be problematic in terms of directivity. For near-field use it should be OK since less of the sound at the listening position will be from reflections. The issue with directivity is that the reflected sound will have very uneven frequency response and will influence the overall tonality.

Here is a well-executed three-way with a ribbon. Take a look at the horizontal polars:
https://www.erinsaudiocorner.com/lou...lharmonic_bmr/

Here is a ribbon two-way with a small enough woofer for smooth directivity (ignore the frequency response issues caused by port or cabinet resonances). Again, look at the horizontal beamwidth:
https://www.audiosciencereview.com/f...-review.17181/

Since I can't find measurements for an 8" two-way with a ribbon, here's an 8" / 1" dome two-way that displays the problem I anticipate. See the horizontal contour plot, and the way it narrows as the woofer starts to beam and flares out when the tweeter comes in:
https://www.audiosciencereview.com/f...-review.11108/

Advice? Listen near-field, or add a midrange.

[fpitas]

Have to agree with hex168. A ribbon with a 7" or 8" woofer is an awkward design. Maybe use a much smaller woofer and add a subwoofer?

[jimbones]

Have to agree with hex168. A ribbon with a 7" or 8" woofer is an awkward design. Maybe use a much smaller woofer and add a subwoofer?

I would agree with that however how does Alta Audio do it? Their speakers sound very good...
I agree that the theory does not support a large midbass and ribbon. ok so does that mean I go 3 way 8 inch, 3 inch and ribbon? or 8 inch larger soft dome tweeter and XO high for the ribbon?

[Paul K.]

My RS duets build used an RS225-8 with an RS28F-4 dome tweeter. The crossover was designed by Mark Krawiec since the duets were based on one of his designs. In order to minimize "nasties" from the RS225's metal cone as well as allow the tweeter to play low, Mark used a notched, Cauer-Elliptic quasi-8th-order crossover at 1400 Hz (the crossover is complex but it sure did the job). It would be interesting to hear from Alta on how they managed it and get some details about their crossover design.
Paul

I would agree with that however how does Alta Audio do it? Their speakers sound very good...
I agree that the theory does not support a large midbass and ribbon. ok so does that mean I go 3 way 8 inch, 3 inch and ribbon? or 8 inch larger soft dome tweeter and XO high for the ribbon?

[jimbones]

A two-way with the Fountek and an 8" or 7" will be problematic in terms of directivity. For near-field use it should be OK since less of the sound at the listening position will be from reflections. The issue with directivity is that the reflected sound will have very uneven frequency response and will influence the overall tonality.

Here is a well-executed three-way with a ribbon. Take a look at the horizontal polars:
https://www.erinsaudiocorner.com/lou...lharmonic_bmr/

Here is a ribbon two-way with a small enough woofer for smooth directivity (ignore the frequency response issues caused by port or cabinet resonances). Again, look at the horizontal beamwidth:
https://www.audiosciencereview.com/f...-review.17181/

Since I can't find measurements for an 8" two-way with a ribbon, here's an 8" / 1" dome two-way that displays the problem I anticipate. See the horizontal contour plot, and the way it narrows as the woofer starts to beam and flares out when the tweeter comes in:
https://www.audiosciencereview.com/f...-review.11108/

Advice? Listen near-field, or add a midrange.

Thank you Hex!!