SEAS Thor Speaker / NCMS Rhythm 9500 Unlimited

Tweekerman, my tweeters are a very common model from Vifa. I feel it is probably the best bargain in tweeters, very underrated and underappreciated. At just $25, it takes one to spend $100 to best it. However, I really should have upgraded it to the ScanSpeak Revelator, which is a direct replacement(in my speakers), long ago.

As, I am putting together a second system right now, and that system already sounds terrific, the tweeter upgrade is on the back burner.

I feel the Revelator offers improved smoothness and refinement, in comparison to the Vifa. I also have another pair of speakers with a Hiquphon tweeter. That is a really terrific driver, offering every last bit of detail, with no harshness or brightness. My kind of tweeter. I have read the pair goes for $275, but I have never priced them, so I am unsure if that is correct. Whatever the cost, it certainly deserves to be more well known than it is.

By the way, I am so enamored with the Vifa tweeter, I bought another pair(not so wise, should have just used the ones I have when I upgrade) for my next speaker building project. Just a little two way monitor. Will feature 1" thick solid maple outer walls, possibly with a layer of viscoelastic inside of that, and finally a layer of 3/4" MDF. This one will use a series crossover. But, it will be simple nonetheless. The other driver is a 6 1/2" mid - woofer, also from Vifa. If I need more bass later, I can assemble a pair of subwoofers, which can also serve as stands if I want. The subs would use the same 8" wide maple, with the drivers on the sides. Probably go with Peerless or Vifa 10" woofers. Sometimes, I kind of like having subs in the corners(not always the "approved" means, but I don't care), and monitors out in the room.

I don't have any experience with active crossovers, but have always kind of wondered...

In my opinion, less is definitely more. I am a big proponent of a first order network, be it parallel or series in configuration. Series crossovers offer something special in the way of cohesiveness in the sound. I also like running mids flat out, without any crossover components in their circuit at all. Now, one can't get any "less" than that. Only the tweeter really needs anything, a cap, just to keep it from getting fried.

Yes i've heard very good about the Hiquphon's. Dave Ellis uses them in his kit Ellis 1801's with a Seas W17. Another experienced builder says the OW1's are his best pick. This Danish DIYer has a Skaaning + ATC + Scan-Speak, very nice speaker! the Hiq's are like $160/pr, they have 2 models OW1 OW2. Some folks like the Scan-Speak's others the Seas tweets. Why do you use budget speakers? But i have to say the Peerless 10 and 12 sub's is the best bang. Very nice looking units. Some folks dissagree that you cannot tell what it sounds like from the looks. Tell us if i'm right on about your Peerless 10's. But i'm going with no sub. I'm satisified with the 30 hz's of the W22. But i've got plans for the new W26's that will go to 20 hz! And the good thing about the Seas is their clean upper bass. This Danish guy says the Seas will do at least 90% of the Skaanings at way less than half the price! I need to order that intro book on xover networks.

Bryhifi,
If you are still debating between the two, here are my thoughts.
I have built both - the NCMS system based on scan-speak drivers a few years ago, and the Seas based Thor last year.
The Rhythm is a well behaved system. Good bass extension, lots of mid-bass, strong detail.
The Thor system is more open/ airy / more detailed with less bass extension, but more "accurate" bass (quicker transients comes to mind) in my opinion.
I believe the reasons for this difference stems from two basic differences between the two systems. First, The Thor is a TL, and the Rhythm is a vented design. The vented design type has more overshoot, and less control of the driver around the resonance frequency. The TL behaves like a closed box around resonance, with better cone control (more damped behavior). Second, the midbass drivers themselves exhibit different behavior. See Siegfried Linkwitz's website (www.linkwitzlabs.com) for his testing and analysis of the underlying driver's stored energy characteristics.
The tweeters used are both excellent. I continue to use both in my "personal" designs.
For the record, both are excellent kits. Both are (IMO) likely the best examples of the use of the drivers in question. I have kept the Thors, and disassembled the Rhythms - I am going to build a Transmission line for them and see how they compare to the Thors one-on-one.
Any questions... please ask. Any different opinions... please comment.
Regards,
Keith Van Vleck

Keith , Very nice post! Is it true the Thor MTM is best with ss amp? What db changes take place in the 2 W17's? Alot less sensitivity correct? Thus ss amps can supply bigger ohm load?

Just returned from Jamaica then Hilton Head,,,,,3 weeks without access to the net!

I still have not made up my mind yet on which one, but the itch is getting intense! I've got to do something soon!!!!

Trelja, I think we need to get in touch again. As always your points carry much validity and your interest in speakers sparks my old time passion for them. If you remember, we live rather close to each other. (Discussed Community Audio) Your preference for Vifa is a solid one. I used them to a great degree back in the late 80's to early 90's for custom built jobs and they always won the price/performance contest.

Keith, thanks for the direct comparison between the 2 kits! That is exactly the kind of thing I was looking for. Question??? Since you built your Thors last year which cabinet plan did you end up using? There was discussion of the original plans at SEAS website being preliminary blue prints and ended up not being what J.D. finished with.

Tweekerman, Thank you for all your input on this topic too. I love your enthusiasm for the hobby! Keep me posted if you hear anything else at M.A.D. please. I've got a ton of catching up to do after being away for 3 weeks and know I will miss something.

Best Regards,