Tweeter types...

[Ten 99]

Jon and Thomas, this question is mostly directed at you guys. But I would enjoy any input from anyone who has good knowledge to share on the subject.

I'm curious as to what typical sound qualities are prevelant from different types of tweeters. I am fairly familiar with the differences between metal dome tweeters and soft dome tweeters. I'm very curious about ribbon tweeters, and any other types out there. I know that this is a very generic question. I realize certainly, that the sound difference in just "soft dome" tweeters as a category can be widely varied.

I'm looking for some input as to what the general categorical sound differences are, and the pros and cons of each.

I'm sort of curious as to why Jon and Thomas chose to use soft dome tweeters in the MKIV speakers, as opposed to a ribbon like the Ravens, or another type. I know that specifically there is a very good reason for this decision, but I'm trying to get some general knowledge from the thinking side of why. (Cost? X-Over capabilities? Dispersion? Sound Quality? Personal Tastes? Power capabilities? etc).

Thanks for any inputs. I'm learning as I go, and I'm the type of person that likes to draw upon the experiences of those who are very respected in their wisdom on such things.

Chris

[ThomasW]

Actually we're not fans of soft domes. The MKI-MKIII versions of the M8a all used metal domes. The XT25 was chosen because it was a moderately priced, good sounding tweeter, that could handle a lower XO point than the metal domes used in the previous versions. Remember that the whole concept behind the M8a project was to create an affordable speaker

Our dome tweeter of choice is the SS9800, most people faint at it's $200 cost.

The primary reason we prefer metal domes is that they create an 'air' or 'presence' that soft domes can't reproduce. Now most people design with soft domes. One fundamental reason for that is that they are much more forgiving of suboptimal XO design. Metal domes can so revealing that they can cause ear bleed if not used with sophisticated crossovers.

RE:leaf/ribbon/planar tweeters. We love them, but only when used in tall line arrays. My mains have 16 Technics EAS400H leaf tweeters/side. I've used this array continuously since 1987, the original cost was $50/tweeter. Describe the sound, nope can't, it's like trying to describe the sound of a Magnepan or Apogee vs any dynamic driver system. Just hearing one is enough to seduce most people.

The fundamental issue with a single leaf/ribbon is that the vertical dispersion is too limited. Finally we've yet to find a good 'inexpensive' leaf/ribbon. As a result today line arrays of them end up costing thousands of $$$$.

In the last 6 mo or so we've seen a couple of 'reasonably' priced ribbon tweeters appear. But 'reasonable' in 2004 means $90 ea. Bulk pricing is probably available if people are willing to go for a couple of dozen pieces.




theAudioWorx
Klone-Audio

[JonMarsh]

Thomas covered the bases pretty well.

I prefer hard dome tweeters because most remain pistonic within the audible range, unlike many soft domes that flex. But another key issue and difficult one for the M8 derived projects was even working with the elliptic crossover, we needed a somewhat exceptional tweeter to handle an 8th order effective crossover at 1.25 to 1.5 kHz. This low crossover point rules out some otherwise good tweeters, like the Hiqaphons.

The XT25, the SS9800, and the modified Hales Transendence tweeter are all favorites of mine because of their approximately 600 Hz Fs, 4 ohm impedance, and near interchangeability- the XT and 9800 basically have the same faceplate and compatible hole size requirements; the Hales is somewhat bigger. Note that my preferred configuration for the old MB Quart tweeter as well as the 9800's is with the acoustic disperser REMOVED. This device, ostensibly used to enhance off axis dispersion and on axis response, is a type of Hemoltz resonator, and can lend a more etched quality to the highs which I don't like.

The M8 Mk1 used an MB Quart titanium dome tweeter. The MkII used an Accuton C23-6, which was not as flat as it's published specs would lead one to believe; the MkIII used a Focal TC120, but really didn't work well unless crossed over at 1.5 kHz, a little high for the M8a, but fine for the W22.

The MkIV uses the Vifa XT 25 because it worked well, was smooth and fairly flat down to below 1 kHz, and the price was in line for a bookshelf speaker project for AudioXpress, which these speaker was created for, in a sense.

My M8ta is an "ultimate" M8 expression, and uses the the elaborate cabinet and the Hales tweeter. It would work OK with the SS9800, but I got a number of sets of the Hales at a good price.

The Arvo Part dipole is being done with the SS9800 not because the Hales isn't good enough, and not because I don't have enough Hales tweeters to build several sets (I do) but because the other folks that are already interested or committed to this design can't get Hales tweeters for themselves. So, it wouldn't be very nice of me. ;^) Though actually the SS9800 would essentially drop in, and wouldn't be "off" by much more than 1 dB at any point with the same crossover.

There are good and bad examples of any technology implementation- for example, the Seas Millenium is a great tweeter, but is a very carefully executed example of soft dome- it ain't cheap.

If you talk $30 tweeters, this is where things get a lot harder finding good performance; I would prefer the LPG titanium over most soft domes in this price range. YMMV- I have really clean electronics; with mid-fi gear, a less resolving soft dome might be a better match; the LPG would pass on too much of the problems from the electronics or source components- as would the Millenium!

Ribbons are a real love/hate thing- love the transient response and airiness, hate the dispersion and limited low end extension. I'm looking at a possible line array of Fountek JP3 above 4-5 kHz to work with my RD50's. Needless to say, Raven's or Arum cantus would be a little pricey in that application. But a single 3-5" ribbon has too many compromises IMO compared to a top flight dome. Just read Stereophile's April review of the Ariel 20T for an understanding of some of the problems. If you're willing to put your head in a vise for listening, it's OK. Not just OK, great. But of you want to stand up, or more around, Fuggetaboudit.

~Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[Ten 99]

Jon, and Thomas,

Thank you both for the detailed responses. That's the kind of information that helps me absorb this thing. I'm not at all inventive or talented enough (nor do I have the electronics background and understanding) to actually "design" speaker systems like you do. But I am (barely) smart enough to follow along with what you guys and others do, as long as there's some basic explanations about certain things. I've never fancied myself as someone who can invent anything. But I'm definitely good at replicating, and I've always been one who likes to know 'how it works' and why.

I'm very greatful for you taking your time to impart your wisdom with me, and other curious folks as well. You two gents are good souls. I think that truely most of the folks I've stumbled across online seem to be, but some people really excel at such.

Chris

[JonMarsh]

Thanks for the kind words, Chris. I think we're all in this for the love of music, and sharing that experience with others- that's what makes it fun and worthwhile.

Best regards,

Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[Hank]

I second what Chris wrote. Thomas and Jon have answered several questions for me over the last couple of years and I appreciate their kind, patient, gentlemanly attitude. They are the epitome of internet forum unselfish knowledge sharing. I hope they don't read this - we could have two cases of swelled heads here. :^x

BTW, after hearing the Seas Millenium tweeter in a Joseph Audio speaker at the 2003 CES, I decided that a soft dome tweeter can sound as good as any hard dome (but, as noted, they aren't cheap).

Chris, are you planning to build some new speakers?

[David Meek]

Seass

Is that the Texan pronunciation of Seas? See-ayuss? :B

[Ten 99]

Hank,

Yep. I'm considering it. I had a good time building my parents L&R speakers. I'm gonna do a center for them next. Some surrounds after that.

I'm looking to build something that can replace the speakers that I have now. Don't get me wrong, I really like the speakers I have now (Onix Rockets), but I know that I could have a better sounding set of speakers. I'm seriously considering building some of the designs that Jon and Thomas have created. I'm just not sure yet what. God knows I've got other priorities, but at the same time, it is fun and very rewarding.

[Ten 99]

Hi-Vi R1L

Over on another site, someone posted about this new tweeter:

http://swanspeaker.com/product/htm/view.asp?id=226#

I gather that they're claiming (by virtue of design) that this ribbon will do equally well at both horizontal and vertical dispersion. I'm curious to hear what you guru's might think about this? Curious looking tweet. Could it be the first of a new type of tweet that could actually go a long way towards solving this?

There are greater minds here than mine. I'd love to hear their gut feelings, and if anyone here plans to experiment with one or two of these?

[JonMarsh]

I saw this last week when Thomas and I were nosing around the Swanspeaker site, and Thomas pointed it out.

Might be interesting, but I have two concerns.

First, most of the other HiVi/Swan planar ribbon tweeters (they're not true ribbons, but plastic film with depositied and etched condcutors with magnets behind the diaphragm only)) have rather poor linear distortion characteristics; to put it charitably, their motor characteristics s*ck next to something like the VC motors in the Seas Millenium tweeters or the ScanSpeak SD1 motor used in tweeters like the SS9800. What this means is that IM distortion is pretty huge; any kind of multi-tone plot looks like a forest in the output, instead of a couple of trees standing next to each other. I don't like the sound at all. A lot of planar midrange/tweeter drivers suffer from this problem. IMD is IMD.

Second, the frequency range is a bit limited. Looks like the Fs is around 3.5 kHz; that's quite a bit higher than "inexpensive" ribbons like the Fountek. If you cross over no lower than 2X the Fx with a steep crossover, that means you wouldn't use these below 6 or 7 kHz. What are you going to do with that? Cross to a wideband dome mid? Now, there are certain relationships I try to follow for driver spacing and crossover frequency; this is part of what's necessary to get good integration and a good listening window. The center to center distance should be less than about 13578/Fxover. So, for example, with a driver crossover at 1250 Hz (the M8 system), the driver spacing center to center should be no more than about 11 inches, for example. This insures a good vertical window and good power response integration in the crossover region. This is a point in which many speakers I see and hear go wrong, IMO.

Now, what if we try for a 6 kHz crossover? For the same level of integration and vertical window, the driver center to center spacing should be 2-1/4". Oops, that's going to be a little tough to achieve, isn't it?

This is a problem with many speaker designs, IMO. Let's take a typical 6-1/2" two way, with a 3 kHz crossover. The center to center spacing should be no more than 5". This is possible if the tweeter is one of those little neodynium jobbies about 2" in diameter, but one problem with this is that the plane of the acoustic origin is quite slanted relative to the front baffle with this close spacing. This implies the need for a slanted front if you take this approach; otherwise the power response lobe will not be angled perpendicular to the front panel.

You see, there are more than one reason why the two way speakr I designed a few years ago uses tweeters capable of a low crossover frequency, and woofers selected for pistonic operation up to that crossover point. :W

Not many of the tweeters were very interesting to me. This one didn't look too bad.

Wide Range Dome






I thought the new MY series 8" woofer was more intersting than their tweeters...



Very smooth, well damped behavior for a metal cone driver; supposedly using some new technology from Germany. Deutscheland uber alles!


And of course, there's the perennial vaporware favorite of mine, the M12...






The closest thing I've seen to this is the TC Sounds TC2+, which has twice the Xmax, but much lower sensitivity. But you can get those; I've got a couple in my living room in the Arvo MKIII test mule.

Regards,

Jon

[Ten 99]

Wow...

Thank you for that detailed response. This is definitely a sacred learning ground.

I've been following the Arvo updates. I wish there was a way for me to get your bosses to give you some time off so you could do more work. It's entertainment for us.

I sure do enjoy reading about your successes. Also gives me the ability to hopefully replicate something in the future.