RS100 vs. RS125

[Max_Andrews]

So I finally have some time and a teeny bit of extra cash on hand, so naturally I'm going to go right ahead and blow it all on speaker projects

I need to finish up my three-way towers and that means building new boxes as I have done some design changes and my first boxes, although built like tanks and sanded smooth over many days, will no longer be of any use

So before I cut into another sheet of expensive Russian Birch, I want to verify my selection for the midrange. Currently it is the RS125, a driver that I have used many times and that already sounds great in this design. However, the RS100 came out since the original design, so I'm wondering if this is perhaps a better choice. For one thing, the FS spike isn't as high in amplitude so will be easier to control the high-pass filter section in the crossover. I'll also be able to get the tweeter and mid a bit closer which should slightly improve off-axis response (although it doesn't seem to be an issue with the RS125). Lastly, the 3rd order HD and breakup in the 2-3khz region is a lot lower in the RS100, and this would make the mid/tweeter filter sections behave a bit better, as the RS125 is a bit ragged. Lower sensitivity is actually a plus, as I'm padding the RS125 down with 2 ohms as it is, so the rs100 would allow me to skip those resistors - and i'm always down for reducing the parts count in the crossover. And finally the RS100 is a bit cheaper, which is not a huge deal but still it's nice to save a few bucks when you can.

So there are obviously a lot of benefits to using the RS100, but since the RS125 already sounds good I'm having terrible nightmares about ruining a good thing. So convince me otherwise!

Crossover points are 350hz/2200hz

[ocool_15]

I only have the RS125S-8 but both look to be good performers. From what your requirements are I'm kind of leaning towards the RS100.

What slopes are you going to use. Is this going to be a passive crossover?

[Max_Andrews]

Yep passive, above is the simulation. Woofer slope is about 18dB/octave and the tweeter is a bit steeper, about 21dB/octave.

[brianpowers27]

I asked myself this question a while back. I came to the conclusions that if you don't need the extra sensitivity, lower xo point and sensitivity the RS100 is the clear winner.

P.S. How does that model look on various degrees of vertical and horizontal off access?

[Max_Andrews]

Yeah, I think I'll go ahead and use the RS100 - it also allows me to place it up a bit higher, thereby making the woofers looks lower which is aesthetically pleasing.

In terms of off, axis, I didn't model it but I can share my listening impressions from the earlier build. These have a transmission line terminated midrange like Curt's mini statements, so it's in a tunnel that goes through the enclosure and ends in an opening in the rear. This is to reduce front-to-back standing waves and to improve midrange detail like you can often get with an OB design, but the cancellation here happened low in frequency - about 350hz and below - because there is a lot of distance between the front of the driver and rear as the waves must traverse around the entire enclosure. I was curious on how this would affect the off-axis response, and luckily it turned out to work very well! The result is that the horizontal off-axis response, at least to my ears, is excellent, and I was able to walk all the way around the speaker and not hear that much of a midrange dip - as as soon as you start to get behind the speaker the rear wave picks up where the front wave left off and so you get pretty close to 360 degree midrange response with a bit of a dip directly to either side, although even the dip is not that audible. I need to buy a new mic and I will measure this to find out the result.

Vertical off axis seems the same as a standard 3-way speaker, but in my first build I had put the tweeter about 4" too low, which is one reason for my slight enclosure redesign. So with the tweeter at the correct height, the vertical response is normal and the horizontal is excellent.