Small Coax vs Waveguides

[Hifisound]

Right now there is a specific unit i have had my eye on, but it would be an almost blind purchase.

Which would be ?

 

[spekr]

COAX-18

Wow, the response measurements at troelsgravesen.dk look terrific! Seas' own data shows some more variance at 0° though.

 

[pos]

The breakups peaks at 6/8/9kHz are from the woofer.
They should have used different colors for the woofer and tweeter curves!

 

[Hifisound]

And for MR18 from SEAS website :

 

[spekr]

The breakups peaks at 6/8/9kHz are from the woofer.
They should have used different colors for the woofer and tweeter curves!

Definitely but it still doesn't look as smooth as the troelsgravesen.dk tweeter measurements. Maybe he measured slightly off-axis and the peaks/dips can only be seen with the mic dead center? Guess this would be a good sign in favor of the driver's performance?

 

[gafhenderson]

Definitely but it still doesn't look as smooth as the troelsgravesen.dk tweeter measurements. Maybe he measured slightly off-axis and the peaks/dips can only be seen with the mic dead center? Guess this would be a good sign in favor of the driver's performance?

Stretch the upper response of the seas measurements to the same size as the individual tweeter response and it smoothes it out. His aren't on a truly log scale.

 

[gedlee]

Those measurements are quite different, which is not just the "scale". They both use exactly the same scales.

 

[gafhenderson]

Those measurements are quite different, which is not just the "scale". They both use exactly the same scales.

Seas is 10hz to 20 kHz, The other is 400 to 40khz?

 

[Hifisound]

These 2 look interesting as well. Experts can comment on these :

http://www.parts-express.com/pedocs/specs/294-1190-faitalpro-8hx200-8-specifications.pdf

http://www.parts-express.com/pedocs/specs/294-1192-faitalpro-6hx150-8-specifications.pdf

 

[gedlee]

Seas is 10hz to 20 kHz, The other is 400 to 40khz?

Then we aren't talking about the same plots. What I see are identical scales, very different responses.

 

[gedlee]

These 2 look interesting as well. Experts can comment on these :

http://www.parts-express.com/pedocs/specs/294-1190-faitalpro-8hx200-8-specifications.pdf

http://www.parts-express.com/pedocs/specs/294-1192-faitalpro-6hx150-8-specifications.pdf

Useless data. The polar map is probably normalized and heavily smoothed.

 

[skodaboy]

Then we aren't talking about the same plots. What I see are identical scales, very different responses.

I think the comparison is with the troelsgravesen.dk measurements of the coax18

http://www.troelsgravesen.dk/COAX-18.htm

 

[weltersys]

Useless data. The polar map is probably normalized and heavily smoothed.

Although the polar map is normalized and smoothed, I don't consider the data useless (as far as it goes) though extending the chart down another 2 octaves would no doubt paint an even less rosy picture.

It is apparent that the Faital 6HX150 has a fairly uniform 90 degree beamwidth from 20kHz to 4 kHz or so, widening to almost 180 degrees at 2kHz, while the 8HX200 goes from only around 50 degrees at 12 kHz and above to over 90 degrees at 5kHz, down to 70 degrees at 3.5kHz, then over 100 degrees at 2kHz.

Just from the charts, easy to see that if uniform pattern control from around 700 Hz up is desired, neither of these two coax really fits that criteria.

Art

 

[Hifisound]

Just from the charts, easy to see that if uniform pattern control from around 700 Hz up is desired, neither of these two coax really fits that criteria.

Art

Oops . I overlooked the fact that the graphs are from 2kHz onwards.
Thanks...

 

[gedlee]

Although the polar map is normalized and smoothed, I don't consider the data useless (as far as it goes)

Art

Hi Art

"Useless" may have been extreme, but "inadequate" is certainly correct. No polar lobes at all - that's not reality.

 

[Hifisound]

This seems to have, relatively, a smooth FR for a coax

H1333-08/06 T18RE/XFCTV2

 

[gedlee]

I think the comparison is with the troelsgravesen.dk measurements of the coax18

COAX-18

I was looking at the two posted above (one was labeled as Troels...). Why are they so different if it is supposed to be the same design?

 

[Hifisound]

A question about vertical directivity : A coax would help achieve similar vertical directivity as horizontal, isn't it ?
Is that desirable or should vertical be lesser than horizontal ?
Though I guess, wider vertical directivity should be beneficial in nearfield...

Dr. Geddes, what would be vertical directivity of NS15/Summas ?

 

[gedlee]

Ideally I would want a narrower vertical than horizontal, but that's virtually impossible with a round woofer - the directivities of the two drivers won't match at the crossover. In the NS15 the vertical and horizontal are the same at about 80 degrees. The vertical has two holes at the crossover point aimed up and down, otherwise the two are the same.