rs driver project confusion

[knifeinthesink]

Hi guys,

I've been looking at this forum for a few months now and I'm really amazed at the quality of the projects and the amount of effort some people here put in on other peoples projects. It’s great to encounter such a welcoming and accommodating environment to learn more about this stuff.

Anyway, I've been putting a lot of thought into my next speaker project using RS drivers. I've read through most of the projects here, and there are a few I'm seriously considering, but there are some questions that are nagging at me. I'm hoping that someone here can help me sort some of this out.

A few two ways had caught my interest, namely the NatalieP, the Modula MT, and Marks 8" 2 way, but then I read the loudspeaker distortion primer on Marks site (a real revelation, and a pleasure to read. Thanks for putting it up Mark) and this got me thinking more. I want to try and clear up some things in my head.

Firstly, the RS180 seems to be the most popular driver by far in spite of the peaks close to its midrange and the requirement that the tweeter be crossed low. I assume that one of the reasons to use this driver, apart from its excellent distortion measurements, is that it provides decent bass response. Assuming, though, that there is a woofer filling in at, say, 500hz, would it be possible to achieve a better mid range using one of the smaller drivers, such as the RS125 or RS150, or is the RS180 the best driver to fill the midrange regardless.

Secondly, as far as bass response is concerned, the information on Marks site regarding harmonic distortion in the bass range made me wonder if a dedicated woofer taking care of the lower frequencies would provide more accurate bass. With the modula mt, natalieP, or marks 2 way, are you hearing 2nd or 3rd order harmonics in the low bass or can you get undistorted bass from these. I've seen the RS three way, and its existence suggests that the bass can be improved by adding a woofer section, although in my case its probably too much for my space as well as too expensive. Is the purpose of adding the woofer section here just to add extension or does it result in lower bass distortion.

Hopefull getting answers to these questions will get my head abit more clear about where to go from here. I'd appreciate any input that any of you have to offer.

Cheers,

David

[Paul H]

Hi guys,
...
Is the purpose of adding the woofer section here just to add extension or does it result in lower bass distortion. ...

David

Yes ...

No matter what your approach, knowledge or skill level, speaker design is about trade-offs. Going from a 2-way to a 3-way design by adding a woofer section will normally provide more bass extension and lower distortion in the lower registers.

The major trade-offs are increased cost, and complexity of the crossover design. A multi-way speaker puts a much larger premium on the designer's skills and tools available to produce a clear clean sound, as the crossover components have more interaction and anomalies than in a simpler two-way.

I'm going to stop there as I'm using too many big words without finishing my first coffee ...

Paul

[Paul H]

... and after your first post, welcome to htguide :T

Paul

[Brian Bunge]

My reasoning for going with the big RS 3-way towers was lower distortion in the bass to midbass range along with higher output capabilities. I was afraid that dual 7's, say in a Modula MTM tower style design, wouldn't be able to properly reproduce midbass and integrate well with a sub in a large, open floor plan style room. It's quite possible that it would have been capable, but I figured I might as well expect the worst and aim higher!

[ThomasW]

The midbass from the RD180 is very clean. I had my first chance to hear them in the Modula MT last week and was quite surprised to hear so much bass from a single unit. I think anyone would be happy with a mini-tower MTM version and a sub.

If you're wanting even more output build the MTM as a bookshelf and place it on top of an actively XO'ed bass bin containing a 12" or pair of 10"s.

[cjd]

Having both RS180's doing midbass and RS150's doing midbass here, I can say they're very similar.

The RS180's take a little more care in crossing I believe, and the RS150's may be a bit less picky in this regard, but ultimately taking the same care is going to result in the best sound anyhow.

Any time you do a separate bass-bin, I would go RS180 because it will handle standing on its own a little better.

But, the bass out of my RS150 MTM in the right setup can be surprisingly full still.

Um.

Yeah. They're all really good drivers, you know?

C

[knifeinthesink]

thanks for the input guys.

That clears up the bass question. Three way it is.

Right after I posted my questions I saw the three way thread with the rs28,150, and 225s with XOs by Dennis Murphy and Curt C. Just had a look at the thread and it looks like its the kind of thing Im looking for.

What an all-star thread that is!

I Love this forum.

[Jim Holtz]

The crossovers in the RS W-T/M-W thread are for a center channel. Dennis is currently working on a crossover for the same drivers in mains to match. He's also creating a crossover with the Seas H1212 tweeter instead of the RS28 so there will be a couple choices. Dennis should have them done soon, I think.

Jim

thanks for the input guys.

That clears up the bass question. Three way it is.

Right after I posted my questions I saw the three way thread with the rs28,150, and 225s with XOs by Dennis Murphy and Curt C. Just had a look at the thread and it looks like its the kind of thing Im looking for.

What an all-star thread that is!

I Love this forum.

[cjd]

with XOs by Dennis Murphy and Curt C

Jon and I both contributed crossover schematics to that thread as well.

And yeah, we're still waiting on measurements for a vertical tower.

C

[Jim Holtz]

Chris,

Actually, You, Curt, Jon and Dennis all have crossovers posted for the center design, but I read knifeinthesink's message as an inquiry about 3-way mains. Dennis is the only other person besides you to have come up with a 3-way design for the main channels, as far as I know anyway.

Jim

Jon and I both contributed crossover schematics to that thread as well.

And yeah, we're still waiting on measurements for a vertical tower.

C

[cjd]

Ahh... were data files posted for the mains? I think that may be the missing link.

I'm ready to take a swipe at it, but of course no worries otherwise.

C

[kgveteran]

I had to give up on my twoway mains and center because even xover at 100hz the midwoofer was attempting to produce 100hz and the midrange suffered.

This all took place if the SPL got to 85db or more.I rarely went up as high as 90db (nominal).

I'm sure the RS center will give me a real clean 90db with more in the tank for peaks.

I'd really like to make two more just like the center.With the xover lowered to 80hz these will still have an easy time in the 85db catagory

[cjd]

Yeah, you're not going to have any trouble hitting 90dB with those!

Or higher, I suspect.

C

[dawaro]

The files for the WWMT towers have not been posted yet. Dennis is still working on his design. Once he finishes up I will post everything.

[Landroval]

Right after I posted my questions I saw the three way thread with the rs28,150, and 225s with XOs by Dennis Murphy and Curt C. Just had a look at the thread and it looks like its the kind of thing Im looking for.

Here's RJB's version for 28/125/225:

http://www.rjbaudio.com/Daedalus/daedalus.html

[jhd]

Any estimate on when Dennis's design will be finished and posted?

I know, I know, I should be patient...

[cjd]

Hmm. I'll try to remember to snag the files and load them into my laptop to spend some quality train-ride time on this. Of course, it won't be listened to and tweaked like Dennis's will be, and I am a tad unsure about a couple of the notes included with the measurements, but...

Just imagine you're the one designing your own speaker, and there it sits, cabinet done, components there, and you're still tweaking, tweaking...

C

[dawaro]

Chris I thought I sent the files to you via e-mail. If not let me know and I will forward them again.

[cjd]

Have the files. Just not on my laptop. I only skimmed the notes that went with them. Should be all set.

C