PT-F95HF Compact Progressive Transition Waveguide

[blackwell]

I waited nearly three years for them to become available, PT-F95HF, the "Compact" version of the 90° x 50° Progressive Transition waveguide, JBL Pro part# 338650-001,....

Why did they opt not to use a CD design on these? I assume it was to keep the depth at a minimum, but is there any other reason?

[blackwell]

Excerpt from pdf link below:

"Compared to JBL’s previous generation of horns, the PT series offers dramatically improved constant-coverage response, and improved frequency response, while keeping distortion low."

http://www.jblpro.com/PD5000/PDF/PT_WaveGuide.pdf

Very interesting. You can see from the plots that it loads the driver less than the 2383, but I guess that's why they call it a waveguide not a horn. The overall responses look really good. Thanks for the link.

[Thom]

Isn't the overall gain of the horn a product of it's directivity? (I did read the literature although possibly not enough times) Also I didn't catch, when you were through, is there still a problem with this horn in combination with the 4435 or was there a problem with your driver?

[Zilch]

Yes. The HF compensation is different for each dispersion pattern among PTs of genrally the same design.

PT-F95HF has a notch in the VHF with 243x drivers. The other PTs I've tried, which is most all of them, don't exhibit that anomaly. Other members are using those combinations successfully, as well.

I haven't pursued it further. They're fine with BMS 4555 or 2452H-SL, as shown in the measurements. Somebody at JBL knows the answer, but I don't have access to them, even if they are willing to disclose it.

They sound fine, actually, but I'm a curve junkie, and just can't rationalize using them that way. Maybe I'll send RobH a pair to verify....

[blackwell]

Isn't the overall gain of the horn a product of it's directivity? (I did read the literature although possibly not enough times) Also I didn't catch, when you were through, is there still a problem with this horn in combination with the 4435 or was there a problem with your driver?

Yes, but what I was refering to is the impedance plot. A horn acts as an impedance matching device and a waveguide is just a patern controlling device. In the plots I saw there is a little ripple in the impedance plot that also shows up in the frequency response. I hope that clears it up.

Cheers.