Tweeters for 1st order crossover

[martinbls]

Hi all!

I would like to replace my current tweeter (older Vifa D27TG) with another tweeter. The concept of the speaker calls for a tweeter that works well with just a single cap in series and a fairly high crossover frequency of around 3,5 to 4,5kHz (that would approximately lead to a single 3,3uF cap for a 8 Ohm tweeter and a 4,7uF cap for a 6 Ohm tweeter).

It has to be a tweeter with a 104mm faceplate, a quite flat frequency response and a flat impedance curve. Oh, and a not so high sensitivity would be great to omit any resistors in series. Something around 88-90dB would be nice.
I searched the net and I'm particularly interested in these tweeters:

Seas 27TDFC
Morel CAT-308
Peerless/ScanSpeak 810921 (D2608/913000)
Vifa HT 270 VF/6 (same as ScanSpeak D2606/922000)

Although I read that the Peerless 810921 isn't that happy with just a cap and needs a few more parts to get it to sound right.

Regarding the other three I just can't decide which one to buy!
(Budget is tight so it's not a great idea to buy all of them.)

Any experiences with 1st orders on these tweeters would be appreciated!

Martin

[DrDyna]

I ran XT25's like that for a long time, but in the end I ended up with something a little more complex.

[martinbls]

Originally Posted by DrDyna

I ran XT25's like that for a long time, but in the end I ended up with something a little more complex.

That's exactly the problem. I already tried the XT25's, like their sound but they have a impedance rise at the resonance frequency that has to be flattened with a parallel notch and they just won't respond to a single cap! They simply have too much energy at lower frequencies. One has to use at least 2nd order to get them to work properly...

[infinia]

I've used the Morels with a single series 8uF cap w/o problems at > 100 W. Recommended for 1st order designs b/c Dynaudio technology.

[Zero D]

Morels are nice I havn't heard that one though.

I do prefer 1st order, with the right drivers

[martinbls]

Originally Posted by infinia

I've used the Morels with a single series 8uF cap w/o problems at > 100 W. Recommended for 1st order designs b/c Dynaudio technology.

A single 8uF cap you say? Well, in this case I think I won't get any problems with a 3,3uF cap at all!

I heard about the high power handling capabilities of the Morel drivers, but how do they sound with a 1st order x-over pushed hard? Do they stay smooth, effortless and well controlled?

(I know, I'm asking pretty much here...)

Btw, it seems the CAT-308 is a replacement for the MDT30 (or MDT30S). Which one did you try?

[DrDyna]

Originally Posted by martinbls

A single 8uF cap you say? Well, in this case I think I won't get any problems with a 3,3uF cap at all!

I heard about the high power handling capabilities of the Morel drivers, but how do they sound with a 1st order x-over pushed hard? Do they stay smooth, effortless and well controlled?

(I know, I'm asking pretty much here...)

Btw, it seems the CAT-308 is a replacement for the MDT30 (or MDT30S). Which one did you try?

Eek, up to 100w with an 8uF cap! Those must be some beefcake tweeters. I'd expect welded voice coils if I pulled that trick. I'd guess that with a 4.7 or 3.3 they should be able to give you any volume you'd ask for, unless you're trying to fill an auditorium / chapel.

[infinia]

Martin, I bought a case lot of the MDT-28S pretty much the same replaceable dome/VC assembly as the 30's. on that I expect CAT-308 to be just as good if not better. I crossed very low to mate with a 8" woofer. IMO sounds/acts very similar to Dynaudio D-28 AF, which I also use, if you've ever heard those. They sound smooth and clean pushed hard but I'm not a fussy guy.

[infinia]

Originally Posted by DrDyna

Eek, up to 100w with an 8uF cap! Those must be some beefcake tweeters. I'd expect welded voice coils if I pulled that trick. I'd guess that with a 4.7 or 3.3 they should be able to give you any volume you'd ask for, unless you're trying to fill an auditorium / chapel.

Actually used a 200W amp with a 8 ohm 3 dB pad. have not burn't any out yet. While watching the amp clipping lights, I detected some thermal compression up there. I wouldn't recommend long term with highly compressed music, MP3s and such ie not pro-sound

[martinbls]

Originally Posted by infinia

Martin, I bought a case lot of the MDT-28S pretty much the same replaceable dome/VC assembly as the 30's. on that I expect CAT-308 to be just as good if not better. I crossed very low to mate with a 8" woofer. IMO sounds/acts very similar to Dynaudio D-28 AF, which I also use, if you've ever heard those. They sound smooth and clean pushed hard but I'm not a fussy guy.

I want to mate them with a 8" woofer, too, but one with a very extended frequency range up to 4kHz with a single 0,82 or 0,68mH coil in series. Another reason is, I just like the sound of a midrange covered by a large woofer. But no pro audio here, just for the living room. And yes, I know the Dynaudio D28 AF. Unfortunately these are no longer available for the diy'er.