XT25 and XT19 below 3khz???

[Jim85IROC]

I've got a pair of Vifa XT19 tweeters that I'd like to use with a pair of Silver Flute W14 woofers. Over and over I hear people say that the XT tweeters don't perform well below 3khz, but because of their nice low resonant frequency, it seems like they'd be a good candidate for low frequency use. I know that Jon Marsh is using the XT25 with sucess in his Hivi MTM with the cauer filter. So... if it works well at such a low crossover using an LR-8, how should it work at say 2khz or 2200hz with an LR-4?

For that matter, how about the DX19 and DX25? Can they work well down to 2k with an LR4? I'm interrested in also pairing these with the Silver Flutes in an automotive application.

Thanks.

[Jim Holtz]

Hi Jim,

I've sent Dennis Murphy a pair of DX19's to play with. It'll be interesting to see what he comes up with. I want to see if these are a poor mans Hiquphon. He just got home from a trip to the Southwest so he'll have some results in a week or so if I know Dennis.

Jim

I've got a pair of Vifa XT19 tweeters that I'd like to use with a pair of Silver Flute W14 woofers. Over and over I hear people say that the XT tweeters don't perform well below 3khz, but because of their nice low resonant frequency, it seems like they'd be a good candidate for low frequency use. I know that Jon Marsh is using the XT25 with sucess in his Hivi MTM with the cauer filter. So... if it works well at such a low crossover using an LR-8, how should it work at say 2khz or 2200hz with an LR-4?

For that matter, how about the DX19 and DX25? Can they work well down to 2k with an LR4? I'm interrested in also pairing these with the Silver Flutes in an automotive application.

Thanks.

[JonMarsh]

The XT25 and XT19 have less radiating area then conventional tweeters of equivalent VC diameter, due to the fixed phase plug in the center. The Xt19 is 3/4 nominal, and it just doesn't have the Sd to go lower than about 3-3.5 kHz with reasonable distortion in the mid 90's SPL.

You can try this combo, as low as you want, and if your playback levels aren't too high, it might work OK for you. A 27TDFC would be a lot more robust in a simple small 2 way, though, and even work fairly well at that freuqency with a 3rd order crossover.

Just my 0.02.

[Jim85IROC]

Thanks for the info guys. I guess I'll toss these on a shelf until I can get around to doing a 3-way, and look for something else to pair up with the Silver Flutes.

[Jim85IROC]

Just me thinking out loud again. How much smaller is the SD on these tweeters? My XT19s are as wide (or wider) than the dome of a typical 1" tweeter, and the XT25s I've seen are at least 1.25" across if not larger. It seems that even with the phase plug, these tweeters have a fairly large radiating area.

More outloud thinking: What about the DX25 and DX19? These have similarly low resonant frequencies, and seem to have more surface area than the XT tweeters. Anybody have experience with them?

[JonMarsh]

Jim,

Why don't you measure the output and distortion performance. I think that will settle any questions you have.

I would compare the DX25 and DX19 to other offerings in that price range or lower, like the Seas 27TDFC. Google is your friend.

~Jon

[dlr]

DX line Sd

Jim,

Why don't you measure the output and distortion performance. I think that will settle any questions you have.

I would compare the DX25 and DX19 to other offerings in that price range or lower, like the Seas 27TDFC. Google is your friend.

~Jon

I think it was John Krutke who pointed out that the Sd of a DX25 is actually greater than that of a typical 1" dome. IIRC Mark K's distortion tests showed the DX line to be better down low than some other 1" drivers, which would be consistent with a greater Sd. The question may be that since both the inner and outer regions of the rings are flexing and not fully displacing, what is the effective Sd even if the measured Sd is greater?

The DX19 seems to be acceptable, but to me the DX25 is not, due to FR problems on-axis. I've heard that newer DX25s are performing better.

IMO the poor man's Hiquphon is the XT line. I had been using the OW1 for quite some time in a 3-way 4th Order at 4500. I put in the XT19. The XO due to slight differences in rolloff and possibly AC ended up at 4K. I lived with that for quite a while as well. I found it to be identical to the OW1 for practical purposes at this Fc and slope.

I would summarize it as saying that the delineation is what the Fc needs to be. The OW line will go lower than the XT, but outside of that I see them as equivalent. I would recommend the XT simply due to cost if the XO is going to be 3-3.5K+

At some point I'm going to have what I think will be an interesting page that shows how to take a DX25 and get a surprisingly nearly flat FR to 20K. It will only be worth it if one currently has a DX25 that is not up to the task, as my original ones were not due to horrible FR response.

dlr

[Jim85IROC]

Jon,
Hopefully soon I'll have my testing rig set up and I'll get to play. In the meantime I've been spending a lot of time at Mark K's site and taking it all in.

The reason that I'm trying so hard to make the DX tweeters fit is that physically they fit my needs well. My plan is to do an automotive kick-panel install, and enclosure volume for the woofer is at a premium. The majority of tweeters that can cross at my 2khz target have large rear chambers and large magnet assemblies. The DX and XT tweeters seem to have somewhat more compact motor assemblies and a faceplate that can be trimmed down. Car audio tweeters are out of the question because they're all overpriced and can't play a note under 3khz.

Anyhow, thanks for the info.

[JonMarsh]

Well, I can see how for car audio the rear volume of the tweeter would be a big deal. The XT series is convenient in that regard. Other tweeters with good performance and mechanically compatible faceplates will probably be much, much deeper.

Getting an accurate idea of the Sd of the Xt series is somewhat impractical- as my friend Charles Hansen, formerly of Avalon, currently chief designer of Ayre Acoustics said, it's an odd thing to make a tweeter where the hold radiating element is the suround... no conventional diaphram, per se. So there's no substitute for direct measurements.

I've seen Davids work with the XT and DX tweeters- you should check that out.

With conventional crossoers, I'd recommend high crossover frequencies, too, for the XT series.

Regards,

Jon

[AJINFLA]

XT19 below 3k

Hi Jim,

I've seen this question on 3 different forums now and felt compelled to reply.
If you would like to HEAR what a XT19 sounds like XO'd at 1.8k LR4, find a Pro-audio store nearby that sells Blue Sky speakers. Their Sat 5 model uses this configuration. I've heard them myself (before final decision to use the XT19 in my own design), and heard no hint of distortion, even at high volume, in the lower mids. The link below is for that model. Read the reviews.

http://www.abluesky.com/p_s_gb/p3s2s1.html

Cheers, AJ

[AJINFLA]

Btw

BTW, the venerable Vifa D25AG35-06 is still available at both Madisound and PE for about $30 ea. and is about the same depth as the XT19, although a bit wider in dia.,but can definately be crossed low and has even stronger off axis performance. Might be just the ticket for a car environment. :T

http://www.partsexpress.com/pdf/264-512.pdf

AJ

[Mark K]

Hi Jim,

I've seen this question on 3 different forums now and felt compelled to reply.
If you would like to HEAR what a XT19 sounds like XO'd at 1.8k LR4, find a Pro-audio store nearby that sells Blue Sky speakers. Their Sat 5 model uses this configuration. I've heard them myself (before final decision to use the XT19 in my own design), and heard no hint of distortion, even at high volume, in the lower mids. The link below is for that model. Read the reviews.

http://www.abluesky.com/p_s_gb/p3s2s1.html

Cheers, AJ

Well, I think you have to be careful and take a look at exactly how the xt series is distorting (see my site). The xt series is actually a overall very low distortion motor, even down low. But it has an achilles heel. It has highish second order products when crossed lower than 2.5-3k. But higher orders are still very low even well below this.

So, an xt19 or 25 crossed at 2k or below won't have the "typical" distortion pattern, but will have some coloration from second order products. It doesn't really sound like distortion, and is not really offensive, but it's not quite accurate. And all in all, it may be better than a tweeter with more higher order products.

[AJINFLA]

Hi Mark,
I agree with everything you said (I've had you test page in my favorites list for a while now) - just trying to give Jim a preview of what he could have - using the XT19. Measurements are indispensible of course, but it seldom possible to hear/measure without spending! Again, just trying to show Jim a "real life" application of what he is imagining. Won't be exactly the same, but could be used as a guide. Other than annoying some sales people, should be painless - and free! :B

Cheers, AJ