now HERE is a TB driver that I like!

[charlielaub]

Check out this unit:
<A HREF="http://www.tb-speaker.com/detail/1208_03/50-1426sa.htm">http://www.tb-speaker.com/detail/1208_03/50-1426sa.htm</A>

Why so special??? I always keep my eyes open for tweeters that can cross low, say at 1kHz. I have to keep looking because there are virtually only 1 or 2 that I can think of (one is made by scan-speak I think) that can "really" be used this low. This is because excursion starts to be an issue, even if the passband extends down that low. Just getting the Xmax spec for a tweeter is pretty difficult!

So what we have here is actually a small mid dome (even though it is listed as a tweeter at TB's web site) but it does have extension in the passband up to at least 8-9k and then smoothly rolling off above that. The ear really is not all that sensitive to smooth deviations in the FR starting around 10kHz. Personally, I think that my hearing extends only to about 14k-15k anyway and this region is one that can easily be lifted with the oft-maligned "treble" control on your preamp should you find the sound too "dull". I have a tweeter that has a similar droop in the FR starting around 6kHz (-6dB, see "Human Pro 002" under tweeter measurements at Mark K's new web site, <A HREF="http://www.audioheuristics.org">http://www.audioheuristics.org</A>) and I can honestly say that this is not such a big deal. On the low end, the Sd and Xmax are sufficient for operation well below 1kHz. There is a good combination of thermal power handling and efficiency to boot.

Anyway, I'm envisioning a nice 2-way with an 8" or 10" woofer (e.g. Dayton RS-270) and this dome up top, crossed over as low as 800Hz. I would probably use active x-overs since the impedance peak is so broad (my thing anyway). This driver has nice sensitivity and could be lead to some interesting systems.

-Charlie

[Pete Schumacher ®]

> Check out this unit:
>
> <A HREF="http://www.tb-speaker.com/detail/1208_03/50-1426sa.htm">http://www.tb-speaker.com/detail/1208_03/50-1426sa.htm</A>
> Why so special??? I always keep my eyes
> open for tweeters that can cross low, say at
> 1kHz. I have to keep looking because there
> are virtually only 1 or 2 that I can think
> of (one is made by scan-speak I think) that
> can "really" be used this low.
> This is because excursion starts to be an
> issue, even if the passband extends down
> that low. Just getting the Xmax spec for a
> tweeter is pretty difficult!

> So what we have here is actually a small mid
> dome (even though it is listed as a tweeter
> at TB's web site) but it does have extension
> in the passband up to at least 8-9k and then
> smoothly rolling off above that. The ear
> really is not all that sensitive to smooth
> deviations in the FR starting around 10kHz.
> Personally, I think that my hearing extends
> only to about 14k-15k anyway and this region
> is one that can easily be lifted with the
> oft-maligned "treble" control on
> your preamp should you find the sound too
> "dull". I have a tweeter that has
> a similar droop in the FR starting around
> 6kHz (-6dB, see "Human Pro 002"
> under tweeter measurements at Mark K's new
> web site, <A HREF="http://www.audioheuristics.org">http://www.audioheuristics.org</A> )
> and I can honestly say that this is not such
> a big deal. On the low end, the Sd and Xmax
> are sufficient for operation well below
> 1kHz. There is a good combination of thermal
> power handling and efficiency to boot.

> Anyway, I'm envisioning a nice 2-way with an
> 8" or 10" woofer (e.g. Dayton
> RS-270) and this dome up top, crossed over
> as low as 800Hz. I would probably use active
> x-overs since the impedance peak is so broad
> (my thing anyway). This driver has nice
> sensitivity and could be lead to some
> interesting systems.

> -Charlie

Smooth response to 10KHz with a resonance peak at 13KHz that is easily dealt with. Not only that, there's no doubt about the distortion performance as low as 600Hz.

[charlielaub]

I guess I could make a notch filter for the peak and the RS52 does have better response out almost to 20k! I wonder what the Xmax is for the RS52. I actually have a pair of these in a 3-way speaker and I could try this out tonight! Thanks for the suggestion.

I think that I will keep my eyes open for other small dome mids that would also work in this application.

> Smooth response to 10KHz with a resonance
> peak at 13KHz that is easily dealt with. Not
> only that, there's no doubt about the
> distortion performance as low as 600Hz.

[Jim Holtz]

> I guess I could make a notch filter for the
> peak and the RS52 does have better response
> out almost to 20k! I wonder what the Xmax is
> for the RS52. I actually have a pair of
> these in a 3-way speaker and I could try
> this out tonight! Thanks for the suggestion.

> I think that I will keep my eyes open for
> other small dome mids that would also work
> in this application.

Hi Charlie,

Xmax per Darren is .75mm. In comparision, the Morel MDM-55 is 1.0mm.

HTH

Jim

[charlielaub]

Hmmm, I am at work and can only waste so much time on the fun stuff... but I plan to put the RS52 parameters in to Unibox to do a quick check of the displacement-limited low end output versus frequency. I would guess you could get at least 105dB when crossed over as low as 750Hz while staying within Xmax. That's loud enough for me!

Another concern is distortion at the low end. Although the CSD as shown on Zaph's web site (http://www.zaphaudio.com/smalltest/) gets worse as you drop below 1k, I have no CSD data for the TB dome and I would guess that the TB could only be worse. I noticed that, on the description of the TB dome mid posted on their web site, they do state "low 2nd and 3rd order distortion", FWIW.

I think that either of these could work well. If you do not want the hassle of the notch filter, go for the TB dome; I still think that it could work out nicely. If you can easily pull off the notch filter, the RS52 might be a slightly better performer overall.

-Charlie

[Deward Hastings]

of 2" dome "tweeters" are that they start beaming an octave lower than 1" and they get weird over 10 kHz because of dome size/wavelength issues. In applications where that's not an issue (or where you don't need response over 10 kHz) the RS52 makes a great "tweeter", and the TB may also.

All that's needed for the RS52's ringing is a .1mH and a 1.5uF . . . not exactly a big deal. It makes a great little speaker with a RS150 in the PE 1/4 ft box . . . very clean and "natural" sounding (needs a sub, of course, crossed over at 80 Hz).

[Pete Schumacher ®]

> Hi Charlie,

> Xmax per Darren is .75mm. In comparision,
> the Morel MDM-55 is 1.0mm.

That comes at the expense of smoothness of response and more than double the cost. The RS52 also has a slightly wider bandwidth for use as a "tweeter." A second order filter at 600Hz and you'll be able to run full RMS levels without fear of Xmax issues.

Of course, that takes nothing away from the MDM-55 as an elite performer as a mid.

[ctbowman]

If your interested in a pair of human tweeters, I have a pair of cores you could have for shipping cost. I believe thier worth $15 a piece towards the cost of a new pair of tweeters.

[Wolf]

For some reason it moved voluntarily.
Later,
Wolf