Which RS180/RS28F MTM crossover- The Modula, Natalie P, or RJB Audio MTM 2.5 way?

[linguistisch]

Looking for opinions on which crossover network I should run in my MTM design. I've got my design nearly completely with several rounds of help from you guys here and from the PE board, now it's a matter of which crossover parts to purchase before I start putting it all together.

Here're my goals in general (even though they don't necessarily involve the crossover):
-Open, spacial sound. No listening position per say, they won't require a pinpoint focal alignment or pinpoint stage as I'll be walking around or in front of my computer for design work.
-Building a left and right for stereo music only, no HT ever, I have another setup entirely for that.
-Will have a built in subwoofer crossed over at 80hz, they will not need to be on extended bass duty.
-Cabinet will be sealed for a tighter midbass, not ported.
-Each MTM will have its own 100w channel from a H/K capable of 4ohms.
-Crossover cost is not my first concern, although obviously I would love to save money.

Thoughts?

[JonMarsh]

As the designer of two of those, (Modula and NatalieP), my vote goes for the NatalieP; very short on time this weekend, but the long and short of it is that it manages the crossover transition with less issues in power response and amplitude response and uses a clever technique (series LR3 crossover) to compensate for the inherent time offset of drivers mounted this way, and stabilize the inherent phase transition with minor variations in the driver. Oh, the other thing- very subjective- it sounds better.

Some time in the next three weeks while I'm on travel I may be able to elucidate, but one point- a "built up" version of the NatalieP in a larger enclosure for extended LF with some of the better tweeters has even won open class competition in a DIY meet, though it's hardly what you'd call an open class design, budget wise. I think it's one of the two best two ways I've ever designed, the other being the Modula MT XE.

Even on TechTalk you will find guys advising one to stay away from the older PE MTM design - I don't remember the details at this point (years ago when it came out), but my reconstruction and analysis of the crossover led me to "not worry about it as a competitor". YMMV, I don't like the idea of talking down someone elses work, but that one was an easy target, if I remember correctly.

[craigk]

Jon,

is there a link to the imp. Nat. P ? i would be interested in seeing the prints. thanks craig

[fbov]

... a "built up" version of the NatalieP in a larger enclosure for extended LF with some of the better tweeters has even won open class competition in a DIY meet, though it's hardly what you'd call an open class design, budget wise. ...

Well mine didn't come in first, but I was up against the Dayton Storms.

I knew an MTM didn't stand a chance in a sighted test, but I didn't expect others at DaytonDIY (now Midwest Audio Fest) to privately say mine sounded noticably better. To my ears it was a distortion issue; the Dayton Classic drivers were good in their day, but didn't sound nearly as clean. Of course, in 65L, tuned to 30Hz, there was no lack of bass relative to the 15" 4-way, and the RS28A is a sweet tweeter... all with Dayton poly caps and Jantzen air core inductors.

BTW, I have built Roman's 2.5-way XO, but as part of a learning process that never gave it a fair chance. I will note that it was 50% more expensive, even with an steel core inductor for the 5mH.

Have fun,
Frank

[Lamski]

Frank, so what was it you had in that competition? Do you have a write up on it? I assume it is a "built up Nat P.?

[fbov]

It was a standard NatP in 65L tuned to ~30Hz. They ahve a build thread, but it's got a lot of "evolution in thought" up front... and it's not my title!

http://www.htguide.com/forum/showthread.php?30536-My-5-1-design-project

HAve fun,
Frank

[wkhanna]

I also made a set of the 65L NatP many years ago.
I still use them for my main system as they have kept up with all the many upgrades I have made to the other components over time.

I have also heard many other speakers over the time I have had them, both in other systems, & more importantly, in my own system. The NatP Never fails to impress both me & anyone who has ever heard them.

I will be happy to answer any other questions might have as best I can.

[eyekode]

I have not personally heard this design but the crossover is elegant: http://techtalk.parts-express.com/sh...180-MTM-Design