FR125S/SDX7 2-way

[Timn8ter]

Love the innovative chamber.

Thanks Cal. I can't provide much in the way of emperical evidence as to why it works so well. It just seemed to make sense, in an intuitive sort of way.
My assumptions are:
1. The pipe reduces reflections back to the rear of the cone.
2. The relatively small area of the pipe provides some air mass support to the cone.
3. The stuffing in the pipe converts much of the higher frequencies to heat so mostly low frequencies are entering the lower chamber.
3. The combination of small area to large area transition, stuffing and length of the "line" is similar to a "restricted terminus quarter wave resonator" though it is a bit short to truly set up a resonance.
Another reason I wanted to use a pipe is that it provides a round surface under the OB'd driver rather than the flat surface of a box. The reflection of the sound wave off a flat surface to the rear of the speaker can be unpleasant to hear.

[planet10]

Originally posted by Timn8ter
[In fact, I would just use 1 SDX7 per side in a TL arrangement. That would be plenty.

I was trying to decide whetehr to do the single or double woofer fonkenWoof 1st... think i'll go ahead with one.

dave

[Timn8ter]

Well Dave, you heard that tower of mine. The bass could get overwhelming. If the bass unit had a separate amp or pre-amp a bipole might be nice. Still, the SDX7 has a lot of output for a small woofer.

[planet10]

Originally posted by Timn8ter
Well Dave, you heard that tower of mine. The bass could get overwhelming. If the bass unit had a separate amp or pre-amp a bipole might be nice. Still, the SDX7 has a lot of output for a small woofer.

Indeed. I told the story of those on 2 consequetive days this WE

Still, with some people buying Apex IIIs with 4 SDX7/side it wouldn't hurt to have an option.

dave

[Timn8ter]

Here's the XO for this design.

FR125S Section

R1 = 5.1 ohm
C1 = 12uF
L1 = 0.8mH
C2 = 10uF
L2 = 0.5mH

SDX7 Section

L3 = 3.5mH
C3 = 45uF
L4 = 3.5mH
C4 = 45uF

[tinitus]

I am surprised to se a 5ohm series resistor on FR125

[Timn8ter]

I had used a 2.2ohm which resulted in a 5db jump at the crossover point, however, an individual could certainly experiment with this value.

[Digeridoo]

Most interesting -- I like the thinking!
What's the baffle width and wing depth you are working with?
How does this relate to the XO freq that you decided upon?
Given the FR125's extension, would a 1st order XO also make any sense here?
I've been thinking about embarking on an FR125 OB project, and this has gotten me thinking for sure!
FYI, here's a photo of a version of the small aperiodic boxes I did for the FR's a while back -- I keep meaning to get around to putting these up as a thread and drafting up a set of enclosure plans, but between a new start-up business and an 18mo old start-up human, those good intentions somehow keep going by the wayside....

[RAW]

Originally posted by Timn8ter
I've been working with the idea of an open-baffle full range mated with a BR woofer and came up with something that seems to work quite well.
This design uses the CSS FR125S on an OB with "wings" and the new CSS SDX7 woofer in a unique curve pipe/expansion chamber enclosure.

Nice design Tim

So you like the SDX7 woofer
Compairing to the OLD Extremis I say no contest.
Cleaner tighter not a bloaty sound.Not that the Extremis was bad just this new woofer I worked with Bob on,takes the size of driver to another level.

As Dave noted Apex III with a quad of the SDX7 per speaker and 8 in a room is good.Well I think so.


So what amp you driving them with Tim?

[DcibeL]

Looks quite nice, except for the low sensitivity (SDX7 advertised as 85dB@1W/1m).

One thing I never really understood about these high excursion mid bass drivers is that while they are capable of producing a lot of bass for their size, they still seem to require a large cabinet in order to do so. If the cabinet size remains large, why not use a larger driver, which will no doubt have higher sensitivity?