Experience with PT Wave Guides

[Robh3606]

Just wondering if any of you have any experience with them??? I just Ebayed a pair of 2431's and am looking for a suitable horn. I was thinking of swapping out my 2344's with the 100x100 model and was curious how they are in a home setting. Do they image well??? and so on.

Thanks Rob

[johnaec]

Zilch has a lot of experience with them. Check out his Index to the Q&D threads: http://audioheritage.org/vbulletin/s...ead.php?t=9901

John

[Guido]

Hi Rob!

Please follow my "4435 cabinets arrived" thread in the DIY forum.
I'll test a PT Waveguide / 2435 driver combo in an 4435 "environment" soon.

From the first testing the crossover mod seems not too difficult.
Well, my experience tells me that listening tests will be another story

[Robh3606]

Zilch has a lot of experience with them. Check out his Index to the Q&D threads: http://audioheritage.org/vbulletin/s...ead.php?t=9901

Thanks I have been going through the thread. I am looking for real time side by side comparisons with a 2344. I didn't see that in the mix unless I missed it. I am about half way through. The 2344 set-up sounds very good in my room and will be hard to beat. I am concerned if these will be another step forward or not.

Rob

[frank23]

Thanks I have been going through the thread. I am looking for real time side by side comparisons with a 2344. I didn't see that in the mix unless I missed it. I am about half way through. The 2344 set-up sounds very good in my room and will be hard to beat. I am concerned if these will be another step forward or not.

Rob

Hi Rob,

I'm trying the same. I now run a 2420/2344 combination and have acquired a pair of 2435 drivers. I have been waiting for my PT 100x100 waveguides to be delivered to me for over 3 months now though...

Frank

ps. I am now playing blue by joni mitchell through my 2420/2344's and the 2435's will have a hard time beating this!

[Zilch]

The best assessment I can offer is that they (PT vs. 2344) are different.

Purchase either PT-H1010 or PT-F1010 (my preference) to mate with your 2431's and build up the HF section of AM6212/00 modified as per Q&D for the compensation. You can "shape" the curve by varying the values in the final LCR notch filter there.

Let them roll off a bit above 16 kHz. If I "push" the UHF extension very hard, the breakup colors the entire upper midrange.

Also purchase the JBL throat adapters. These allow you to use 2426H's exposed snoot to mount to PT waveguides, which combination also works with the AM HF filter. You can directly compare the two driver families that way.

Note that the total compensation "boost" employed with PT waveguides is less (2 - 4 dB) than 443x filters apply with 2344(A) horns. You may find that even 2426H sounds better on the PT's.

The "HF" tagged on to the PT part numbers indicates they are high frequency waveguides; using them at 800 Hz is dubious, but they seem to handle 1 kHz fine.

Another forum member (Stevem) is using 2450SL, as I recall, on PT's, with apparent success. I don't know how low he's playing them.

Finally, I found the 2352 horn to be the best of all those tried, and also developed a preference for the 50° x 90° dispersion pattern over the course. The PT-H version of that pattern, having a long throat, requires delay of the LF driver for optimum time alignment, however. When last checked, the PT-F95 was still not in production, but the $9.90 1" thread-on version is well worth trying with 2426H in comparison....

Edit: Frank mentions 2435. According to the published curves, they have better HF extension than 2431 before breakup. They don't "push" gracefully, either, tho. It's them playing on the 2352's here....

[Earl K]

Hi Rob

Take a look at Mr. Widgets' CLIO studies of the "PT" waveguides mated to various 234x drivers.
IMO, they tell most of the story about these particular waveguides.

Notably :
- the PT-H, 100° x 100°, looks to have a loading limit of around 1500 hz .

FWIW :
- the 2344 spec. sheet mentions a 800 hz load limit for that horn bell .
- AC Impedance Studies using a 2344/2425 combo, bears this figure out .

Of Interest ( at least to me ) :
- The newer Array stuff seemingly uses the midhorn right down to the horns' load limit.
- This post strongly suggests the implementation of this loading practice .
- A quote from G.T. on the crossover point for his prototypes.

Conclusion :
- If you like how the 2344 performs in your listening space & if you already own the original 2 piece 2344 , I'd work with someone ( like Widget ) to make up a new 1.5" throat entry carved out of wood ( Widget has already published nearly all the pertinant info in various places ). Then, I'd lower the horns' crossover point to it's load limit and build a new crossover for it .

[Robh3606]

Thanks for the responses. I tried ordering from JBL Pro and of course they are out of stock on the 100x100's Sooooooooooo I will have to wait and see.

Rob

[Zilch]

Alas, I've sold all of my spares.

[I can send you some funky-ass 1.5" P-Audio PH-316's to try with 2431H in the meantime, tho.... ]

[Robh3606]

Hello Zilch

Thanks for the offer I want to see how long the wait is before I borough them. They are supposed to get back to me via email.

Rob

[frank23]

Hello Zilch

Thanks for the offer I want to see how long the wait is before I borough them. They are supposed to get back to me via email.

Rob

ok, that might be the same reaon then that my importer also does not get his 100x100 order delivered

frank

[Robh3606]

Hello Frank

I will let you know what happens with them.

Rob

[stevem]

Another forum member (Stevem) is using 2450SL, as I recall, on PT's, with apparent success. I don't know how low he's playing them.

I cross over at 1 KHz, using 48 db/octave slopes. They sound real nice with the 2450SL, and have no trouble going flat out to 20 KHz (with some EQ or course).

[Zilch]

OTOH; properly designed , true Constant Directivety horns ( which I suspect Bruno is not contemplating using down to 500hz ) offer a sort of builtin BrickWall Brake-effect for the loading of the lower frequencies. Ie; they seem to offer true loading right down to high side of the lowest, most significant impedance peak . At least that's my interpretation of all the various horn/driver impedance plots I've studied....

Notably :
- the PT-H, 100° x 100°, looks to have a loading limit of around 1500 hz .

WT2 impedance curve for 2431H on PT-H1010 waveguide.

First peak is at 560 Hz.

It's loaded down to ~750 Hz, then, no?

EDIT: Added the FR curves. First one says "PT-F," but it's PT-H. Bottom one is similar PT-F, which seems to play a little lower, and flatter from 2 kHz - 6 kHz....

[Earl K]

Hi Zilch,

- The red lines in the picture below show where my words are drawn from .
- The operative words from JBL are : "on a true full-bandwidth constant directivety horn design ".

The 2380 and the 2344 are obviously not "true full-bandwidth" and one can see the ambulations in their Z responses, as well as the attendant Frequency Response drops. I've identified the loading limits that I would use based on available info ( mostly the FR curves ) .

The impedance ambulations that you've shown has some aberrations that make it obviously deviate from a " true full-bandwidth constant directivety horn design " ( ie; there is no single loading peak at resonance). In a case like that one must trust a full bandwidth study of the driver/horn combo and choose the appropriate load-limit based on a 3 db down point . ( I find the 2380s' response interesting in that it shows a significant weakening in what the bell can support below where I drew the red line ) .

It's ( PT-H ) loaded down to ~750 Hz, then, no?

No . Reading an impedance plot from a horn like that , requires a different set of criteria ( since it's obviously not a "true full-bandwidth constant directivety horn design " ) . I don't know what causes that little promenance that's attached to the side of the most significant Z peak / but I would ignore it's relevance in this study .


Cheers