Pros / cons of using a pair of RS125's vs an RS52 as a midrange driver?

[fjhuerta]

Hi all!

I'm on the planning stages of a new (for the moment) MTMWW speaker, which has been constantly changing in its design (see, Jon? You aren't the only one with 3 projects running at any given time! )

For the moment, I've settled on a pair of RS125's as mids, an RS28, and a pair of RS225 woofers. Which is what I have now.

I've been intrigued about the recent PE sales thread and Zaph's RS52 tests. I'm aiming for about 88 ~ 89 dB's sensitivity with full baffle step. A pair of RS125's will barely get me there. A single RS52 has sensitivity to spare.

Then again, I'd assume a pair of 4" woofers, properly crossed over to the woofers may have an extra bit of dynamics.

But... the RS52 will be simpler, the cabinet can be smaller, and off-axis dispersion will be better. Plus, the crossover points can be shallower (since I'd have to cut the 125's quite quickly in order to avoid cone break-up).

As it is, I *think* a wise decision may be to start all over again with a TMWW design, and keep the RS125's for another project. But I don't know if I'm overlooking something... I don't see many RS52 projects here, although there are a couple using the RS150 as a midrange driver.

[Jed]

For the moment, I've settled on a pair of RS125's as mids, an RS28, and a pair of RS225 woofers. Which is what I have now.

This quote says it all. You made good choices with the driver selection. I'd cross around at 300HZ and 1.6-2K LR4 to the RS28. No cons here except a lot of design decisions that still need to be worked out. I'd do something like the Wilson X1s in concept, only much smaller obviously.

[fjhuerta]

Thanks a lot for your input, Jed.

I suppose I was (unconsciously?) influenced by those Wilsons. The moment I saw the pic I just thought it was a great idea.

Besides, I suppose it'd be so much work I would have a project that could last 6 months or more. Not that I'm that patient, but I've never tried building a 3 way crossover...

[Jed]

The speaker above I built for a friend, since he helped me a lot on projects with my house. They turned out pretty nice, but I bet they would be better if we used RS drivers like you will be using.

There is definitely something nice about having dual midranges. Perhaps it is the lower distortion, and when crossed low enough, lobbing is a non-issue.

With Dual RS225 in a ported enclosure you are looking at 100-120L though. That's a big speaker so you might want to go sealed and add a sub @ 50HZ or so. This all depends on your size requirements, however; and how the lower bass bin integrates visually with the top MTM section. Since the MTM section won't be too large, a massive 120L box below it might be visually obtrusive. One RS225 ported might be enough as well.

I've never used the RS225 in a sealed enclosure, so I can't comment on the subjective bass qualities. I've heard them in 50L (1 RS225) and 60L ported, and I'd say I preferred the slightly larger volume.