[drtweak]

I'm just curious because I'm having a little tweeter trouble right now. We think it's a bad cap but I won't know for sure until I get a new one from Brian to try.

My thinking is that maybe something like a ScanSpeak Illuminator model of suitable efficiency and power handling may work well. The main difference (as I see it) is that a dome would disperse the highs better vertically.

Has anyone tried high-quality dome tweeters, and if so, how did it compare to the standard FST tweeters ?

[Pez]

Well ou wouldn't be able to just drop it in. It would take some serious crossover reworking.

[drtweak]

Well if the specs are relatively the same, and I believe they are regarding efficiency rating  (91.5db @ 2.83 volts) and bandwidth, then I don't see why it wouldn't drop in and work fine. The mounting flange on the Illuminator is a few mm less than the FST but it would probably work. The power rating on the Illuminators is higher than that of the FST. The impedance is less at 4 ohms but my amps will drive low impedances with no problem.  And I think it's just a simple first order single cap crossover to the tweeter.

Perhaps this is a question for Brian. My concern is more about lobing effects from the different radiation patterns of the midrange ribbons vs the point-source dome. Still, I don't know that this would be much of an issue either.

But really, I was wanting to hear from anyone who actually tried this. Still I thank you for your reply.

[drtweak]

Maybe adding a coil for a 12dB/octave rolloff would work better to integrate the dome tweeter with the planar midranges. That way the area of overlap would be less and where the drivers actually overlap they would be out of phase reducing the brightness in that area slightly...?

[DFaulds]

What he said.  The elctrical and acoustical properties will most likely be quite different than the original tweeter.  It would obviously play, but performance would be compromised.

It's fun to experiment with things like this, but the RM40's appear to be WAY too nice a speaker to start second guessing the designer.  There is more to matching drivers than efficiency and basic FR.  Unless you have the time, patience, money for test equipment, and desire to learn like many of the posters on the PE tech talk board, it's best to leave these types of things to the experts, and there are few people with more experience and success than Brian.

Well ou wouldn't be able to just drop it in. It would take some serious crossover reworking.

[drtweak]

I thought that some of the group members might have already experimented with this but perhaps I was wrong.

My feeling is that the RM40 is a fantastic speaker and nearly state-of-the-art. Surely its bass and midrange are top drawer and would be difficult to improve upon. That being said, I think the upper treble could be improved and if it could be improved to near state of the art then the RM40 would be difficult for any speaker to surpass (no matter the cost).

It would also be nice if the tweeter was not the limiting factor in the RM40's dynamic capability.

[Pez]

The tweeter is most definately NOT the limiting factor in the RM40. If you're going to change anything get rid of the passive crossover and go full active. Having heard the Illuminator up close and personal on several speakers I can only say it is the best silk dome tweeter hands down, but in no way outclasses the FST tweeter. I personally think the only tweeter that is commercially available that best the FST is some of the upper end RAAL tweeters.

Any way Dr Tweak, I think you're barking up the wrong tree here. any nominal improvement you might gain by screwing around with different tweeters is far out weighed by A. the fact that the 40s already have a superlative tweeter and B. the fact that you are using a passive crossover. You want state of the art? Think outside of the box.

[drtweak]

Really Pez,

Is that what you have--a tri-amplified set of RM40's? If so, which amps and electronic crossover are you using?

I am actually thinking of going that way in the future. I have the Lyngdorf DPA-1 digital preamp which has a provision for bi-amping with its own internal adjustable electronic crossover. So who knows, I may sell the passive RM40's and go for a fully active setup.

That said, the midrange/tweeter section would still have the internal passive cap crossover, although the lower roll off between the woofers and midranges could be removed. I think Brian sets them up this way on request.

On the other hand, do you know if it's easy to bypass the internal passive crossover and connect the amps directly to the driver sections if you have the model with the passive crossover? If so, I may stay with the pair I have and do it that way.

Please understand, I'm not trying to upset anyone here. I'm just trying to gather some useful information because I believe the RM40s have a lot of potential that may not be fully realized.

Frank A

[Pez]

The RM40s, as with any speaker, would require you to desolder all connections from the crossover and wire them directly to the speaker terminals. As is the case with most speakers removing the crossover for the woofers is a great place to start as the coils and cap values are the largest of the entire circuit.

<--- My setup is listed in my 'Systems' under my avatar to the left. The quick and easy is I have a SET amp I made hooked up to the tweeter, another one I made to the midrange and a QSC pro amp to the woofers. All connected to a DCX that serves as crossover and allows me to notch out room modes and speaker anamolies. This combination is very very good and despite the 8 watt amps it has the drive to go incredibly loud and sound absolutely amazing.

[drtweak]

Pez, I must admit you've put together a really cool and I'm sure a great-sounding system there.

I think I will repair my speaker when I get the TRT tweeter cap and see what I get. It actually sounds quite impressive even with the FST out on the one side.

Once I live with that for a bit I may sell the passive pair and get Brian to make me a pair for active bi-amping. I have the Lyngdorf preamp going into a Wyred 4 Sound STI-500 presently and the sound is very impressive. And I do have a very good sounding Tri-path amp that could power the mid-top if I biamp. For that matter I have a QuickSilver GLA tube amp that could power the tweeters if I tri-amp. Hmmm, this is getting interesting.

Frank :)

[Pez]

Dr, thanks for the compliment on my system! I love the way it sounds and am constantly tweaking this and that. Just last week I rewired my speaker with some really great copper/silver cables and it made a pretty sizable difference. Of course building my own amps was one of the greatest and most experiences I have ever had in this hobby. It would have been fun if I made the amps and they worked well enough to be in my system, but what blew me away was they were better than anything I have ever had in my setup!

Any way, you don't need Brian to build you a new pair, you just need to rework the pair you have! I think that there are topics somewhere to help you with this.  Of course now I can't find them. At any rate I am a major advocate for active speakers. I think it is probably the most important change to any speaker you can make, yet people are more apt to focus on cables and isolation devices... Hey I'm all for that stuff, but if you have $2000 to put into tweaks such as that or converting to active the most benefit is absolutely derived from active. 

[John Casler]

The tweeter is most definately NOT the limiting factor in the RM40. If you're going to change anything get rid of the passive crossover and go full active. Having heard the Illuminator up close and personal on several speakers I can only say it is the best silk dome tweeter hands down, but in no way outclasses the FST tweeter. I personally think the only tweeter that is commercially available that best the FST is some of the upper end RAAL tweeters.

Any way Dr Tweak, I think you're barking up the wrong tree here. any nominal improvement you might gain by screwing around with different tweeters is far out weighed by A. the fact that the 40s already have a superlative tweeter and B. the fact that you are using a passive crossover. You want state of the art? Think outside of the box.

As often is the "truth", PEZ is the dispenser of same.

I think the tweeter is well integrated with the RM40 design and Brian employs Ribbon Tweeters to match the charachteristics of the NeoPanels.

Thinking (and moving) outside the box can and does offer an improvement and that is why the SERIES II speakers have OXO and D-OXO standard.

Do be aware that "triamping" means using "extreme" caution with the tweeter since it can be blown easily when amped direct, but having the D-OXO "BEFORE" the amps makes for some very interesting flexibility and adjustability, and one of the reasons I campaigned so hard to get it as an option a few years ago.

With the amp after the XO, you can use relatively low power tube amps on the tweeter and or Neopanels.

And also be aware that such flexibility adds a bit of complexity, so it can be a journey.

To Triamp you would need to add an additional pair of binding posts, and wire DIRECT to all three binding posts from the drivers.