Tests: K-69-A driver on Edgar type wood Tractrix horn

[Rudy81]

There is no doubt that active EQ provides the crazed user with tremendous flexibility. The BM-D 750's arrived today. Sadly, the horns won't get here 'till next week and I will be out of town until the following weekend. So, testing the P. Audio driver/horn combination on my Khorns will have to wait a little longer.

[]

[chrapladm]

Sorry I am just throwing ideas out there but would this horn not be a good option instead of the P.audio?

DDS CFD 2-60X PRO

[Chris A]

DDS CFD 2-60X PRO

That horn approaches the size of the K-402, but they are only showing its polar response down to 630 Hz. What bass bin did you intend to use... (did I miss that?). This horn looks to be viable, but note that its horizontal pattern is 60 degrees, while the K-402's is 90 degrees, I believe. If you put the speakers in the corners of the room, it shouldn't make that great of a difference in your listening experience.

I've not run into this outfit before - they are about 40 minutes away in Waxahachie ('Wocks-a-hat-chee, meaning buffalo creek)--the former home of the Superconducting Super Collider--before its demise (RIP). That was a fun ride--while it lasted...

Chris []

[DrWho]

DDS makes a 90x60 horn similar to the K402...I didn't mention them earlier because of the price. US Speaker sells most of their lineup.

Btw, is there a sharp bend near the throat of the P.Audio horn?

[Chris A]

sharp bend near the throat of the P.Audio horn?

The P.Audio PH-4525 horn's throat isn't like the K-402's throat. It has an apparent (i.e., I haven't measured it) constriction in the horizontal axis before it transitions to the conical section. I'd call it a cylindrical constriction in one axis. This vertical axis is not constricted, and the opening into the horn, looking from the mouth end of the horn, isn't square (az and el dimensions)

However, the FR plots look really good. I wonder what other "features" that this throat constriction might have on other acoustic performance, other than FR?

Chris

[Chris A]

DDS makes a 90x60 horn similar to the K402...I didn't mention them earlier because of the price. US Speaker sells most of their lineup.

Mike,

Are you talking about this horn? The price for such a large horn (apparently made in the US) is pretty low, at least IMHO. Clearly it isn't as inexpensive as the Thailand-based P.Audio PH-4525 horn (~$100US), or the Chinese-based equivalent to the P.Audio 4525 horn (~$50US)

Chris

[chrapladm]

Iam starting to lean towards the Jubilee. I was going to go with a 3 way before consisting of the BMS 4592 for the mid and the Beyma CP25 for the high. I was going to be using a Behringer crossover for the cross duties.

BUT, after asking others on here people have mentioned getting the 402 and just having a 2way. So thats why I was throwing out the idea. Just trying to gather more info. I thought I was sold on the BMS/BEYMA but not 100% now.

[Chris A]

Well, first cut at a smoothed PH-4525 horn with K-69A driver.

Since outside testing is not going well (weather and equipment issues) I thought that I'd post the raw results for the on-axis and the 30 degree horizontal axis results.

The dips at 2.4 and 4.8 KHz could be test related, but further testing indicates a bit of a dip around 2.5 KHz regardless of test conditions.

Chris

[chrapladm]

In case I missed it how did you smooth out the horn?

Oh and is this the BMD750 CD or the K-69a?

[Chris A]

In case I missed it how did you smooth out the horn?

Stand by - I'll let you know as soon as I can recreate the measurement. However, note that I was taking the measurements with the horn pointed straight up, and outside.

Oh and is this the BMD750 CD or the K-69a?

Well, the logo on the driver says Klipsch K-69-A.

Chris

[chrapladm]

Your jpeg info said BDM 750 so I was confused.

[Deang]

The P.Audio BMD750 and the K-69-A is the same driver. IOWs, Klipsch buys the P.Audio drivers and rebrands them.

[chrapladm]

Alrighty something else I didn't know. Makes sense now.

[Rudy81]

I finally got a chance to run some quick plots on the response of the BM-D750 and the PH-4525. My appologies to Al for running off with his thread. However, I would love to see the response on one of Al's new horns.

These were some quick readings with the driver and horn just sitting on top of my Khorns, on axis. The green line is my first run with no EQ, just the horn and driver from 400 to 20kHz. The red line is the horn driver combination with some EQ to raise the rolloff nearing 20kHz. The blue line is my current JBL 2470 on Al's Trachorn. Of course, the limiting factor is the JBL. Impulse Response is 6-12 ms. to prevent room interaction. I am really surprised at how relatively flat the response of this combination is. After the tests, I played a few minutes of music and to my ear there does not seem to be anything 'missing' from the top end. I have high hope for this combiantion as a two way with the upcoming build of JC's DBB.

What do you guys think.

[Rudy81]

This graph is the same as above with the yellow plot added. The yellow plot is my current three way setup. It consists of the Khorn bass bin, Al's Trachorns with the JBL 2470 and an Eminence APT-150. As you can see, it would be a no brainer for me to go to the two way in terms of high frequency capability. The Eminence has always measured much like you see here. I'm not sure if I am messing something up testing the eminence, but the BMD-750 speaks for itself.

BTW, the difference in dB level between the red and green lines was a change in amp volume in order to better match the readings with my old JBL readings. The good thing is it illustrates the EQ vs. no EQ difference better. This was only about thirty minutes of tweaking and that is not nearly enough to set the system up, but it gives me an idea.

My initial impression while I listened to music had it's pluses and minuses. I found the high's to be very good and no problem at all. My only bad 'initial impression' was that the vocals were not as 'smooth' as they are with Al's Trachorns and the phelonic diaphragm JBL's. I don't know if that is due to the Trachorns wood vs. the plastic horn or the driver diaphragms or my being tired after a very long travel day. That is a bit bothersome, but not a deal breaker. On the other hand, I did not do any long term listening. In the next few days I am going to properly mount the P Audio gear and live with it as a two way for a while.....hopefully it will meet my expectations.

[DrWho]

You might want to try zooming in on the vertical axis so that the distance between lines is more like 3dB...you've got a pretty dramatic tilt to the response of that horn, and it's further accentuated where the polars are going to be wider, which means the perceived tonal balance is worse than what you're measuring.

What are the dimensions of the mouth on that horn? I could probably draw a target curve you should aim for with the EQ, and I've no doubt that you'll be able to get that smooth vocal sound back.

Oh the joys of voicing...

[Chris A]

What are the dimensions of the mouth on that horn?

At the transition to the flat flange on the front, the horn dimensions are ~7 7/8" h x 15 3/8" w.

you've got a pretty dramatic tilt to the response of that horn, and it's further accentuated where the polars are going to be wider, which means the perceived tonal balance is worse than what you're measuring.

Rudy, I'm assuming that you are comparing the P.Audio horn/river listening to your JBL/ALK horn plus something for a tweeter? Is this correct?

What I remember with the K69-A is that, once you've got the EQ dialed in, it sort of "comes alive". I'd guess that it may be a bit hot in places on the high end if the vocals sound the way you describe.

Chris

[Rudy81]

You might want to try zooming in on the vertical axis so that the distance between lines is more like 3dB...you've got a pretty dramatic tilt to the response of that horn, and it's further accentuated where the polars are going to be wider, which means the perceived tonal balance is worse than what you're measuring.

What are the dimensions of the mouth on that horn? I could probably draw a target curve you should aim for with the EQ, and I've no doubt that you'll be able to get that smooth vocal sound back.

Oh the joys of voicing...

Dr. Who, Could you explain what you mean by the 'dramatic tilt' in the room? I had the mic about 3 feet from the horn mouth and think I should have set the IR window to 3 ms vs. 6 ms. I would appreciate the target curve.

[Rudy81]

Chris, yes the comparison I showed above is of the crudely arranged P. Audio driver and horn vs. my current 'dialed' in three way Khorn setup with the JBL driver, Al's Trachorn and the APT-150 tweeter.

Overall, the P. Audio driver is superb upon first measurment. Mind you, that horn is not mounted and is just sitting on top of my Khorn right now. The EQ I did was a 10 minute quickie to see what I could adjust in a few keystrokes. Here is what I put in the crossover to give me what you see in the second graph. -9.5 dB at 805Hz Q of 1.6, -6.1 dB at 12kHz Q of 2.8 and +15dB at 20kHz Q of 10.

I certainly didn't expect to stumble upon the ideal solution, but just wanted to see what I could do quickly to help the measurements. As I mentioned above, the driver has no problem with the very high end, so that worry has been put to rest. I hope to have some time today to properly mount the horn in my top hat, then try to dial it in a little better.

[Rudy81]

Chris and Dr. Who, I need to add that I did not mention two other things about my quick music listen last night. These are positives. Imaging was excellent, one of my pet peeves, and soundstange was 'huge' compared to my 1" drivers. Again, just quick first impression. I hope to get serious about this today.....time permitting.