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P. Audio PH-4525 horn and BM-D750 (aka. K69)


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I moved our previous discussion concerning using the P. Audio horn and K69 or BM-D750 to this thread in order to minimize confusion. I am ready to begin really testing and attempting to 'voice' the P. Audio horn/driver combination with my Khorn bass bin as a two way active setup. I hope to be able to work this as a two way in anticipation of my DBB build to also work as a two way system.

The picture is of the horn and driver temporarily installed. Not very pretty, but good enough for testing without encountering weird anomalies by not having the horn mouted. This is looking like a "FrankenHorn" for sure.

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Close up shows you just how large this horn is. It just barely fits under the top hat. Please, no derogatory comments on my wood work, this was just a quick frame to stabilize the horn for testing.....at least I painted it.[:)]

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After installing the horns somewhat properly, I have had time to run some measurements with the horn/driver installed in my top hat. Mic was placed 6 feet from the front of the Khorn at 38" off the floor with mic pointed at speaker. IR window set at 6-12 ms. First, the raw bass bin and P. Audio horn/driver readings. No EQ, no Audyssey. For all these tests I disabled Audyssey since it was set for my previous set up.

post-10337-13819583498272_thumb.jpg

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Actually, I was thinking about how convenient it is that the PH-4525 horn with BM-D750 driver fits so nicely inside Khorn, CW and La Scala cabinets...

Chris

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Finally, a full range plot with the applied EQ settings shown below. I had to play a little with the crossover point and phase in order to get it as you see it here. For a long time I kept seeing the crossover point as a problem where the PAudio driver was cancelling out the woofer, causing a huge drop in dB. I finally settled on the following parameters.

- Woofer crossed at 510 Hz. L-R 48 filter.
- P. Audio driver crossed at 467 Hz. L-R 48 filter
- Normal polarity for both drivers, no phase adjustment.
-EQ settings:
- -7dB at 161 Hz. Q-1
- +7.2 dB at 401 Hz. Q 3.2
- +3 dB at 5.42kHz Q 1.6
- -7dB at 11kHz Q 2.5
- +10dB at 20kHz Q 6.3
- +4 dB at 15.1 kHz Q 1.6

With Audyssey off, the system sounds very good overall. I'm sure I could tweak it a little more, but no use in spending more time on this since I plan on changing the bass bin in the not too distant future. I do need to run the Audyssey calibration program again since it is now boosting the heck out of the high's. I guess my old plots were correct and the tweeters were being boosted by Audyssey. That is one thing I don't like about Audyssey is that I can't see what it is doing to the system.

BTW, my previous complaint concnerning vocals not sounding as good as my Trachorn/JBL combination has been fixed somehow. Vocals are crystal clear, imaging is excellent. I certainly need much more time to make a final determination, but this is a good combination. I think it will be much better when I have a bass bin I can cross a little higher.

I welcome comments and constructive criticism. Anyone see any major issues. Looks like the FrankenHorn will be a keeper until I get the DBB bins done.

Now, back to listening!

post-10337-13819583499572_thumb.jpg

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Actually, I was thinking about how convenient it is that the PH-4525 horn with BM-D750 driver fits so nicely inside Khorn, CW and La Scala cabinets...

Chris

I think anyone with a K69 lying around should give this a try. I still need lots of time with the new setup, but the potential is there for most Heritage systems.

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Hey Rudy,


According to the dimensions that Chris mentioned in
the other thread, your horn is gonna lose vertical pattern control near
1.7kHz and then lose horizontal pattern control near 900Hz.


Looking
at the closeup picture of your horn, that crazy shape in the throat is
going to introduce some beaming above certain frequencies, and it'll
also be different in the horizontal and vertical. Looking at your raw
frequency response, I would wager that they're happening at around
6.5kHz and 8.5kHz.


So if you drew a flat line through the HF passband, then you
would want everything below 1.7kHz to be slightly below that line and
then below 900Hz you want to be down just a bit more. And then above
6.5kHz and moreso after 8.5kHz you'll want to be above the line. I
can't give you exact numbers because it'll depend on the acoustics in
your room, but basically what you're trying to do is strike a
compromise between the tonal balance of the direct sound combined with
the tonal balance of the indirect sound.


Looking at your EQ'd
plots, it seems like you're tilted a bit in the other direction. Your
gate for the HF section seems a bit long (there's comb-filtering
showing up in the measurement), but if you threw in a shelf filter
around 4kHz (either to boost the highs or cut the lows), then I think
you might end up real close with the other filters you've already got
engaged.


Of course I'm recommending that sitting in a chair
across the country where I have no clue what it is you're hearing. One
thing I always do when voicing the system is I try to pick filters
where it's easy to manipulate the response in areas where there is
obviously stuff happening...and then I'll listen to a huge slew of
source material that I know really well and then tweak the filters by
ear. One thing you'll probably discover is that although you start with
a "flat curve", usually whatever you end up with will also be flat
too...it'll just be a different flat curve.


Btw, I personally find that it's easier to start with the shelf
filters, because then it makes it easier to match the Q in all the
parametric EQ's.



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Getting late, but I had to finish setting this up so I can get my media room back working. I ran Audyssey two times to make sure I had good readings. All done and sounding really good. These drivers have plenty of high frequency capability. This Audyssey setting reduced what it had boosted with the last setup. I am very satisfied, for the time being with the current EQ setup. The difference between Audyssey on and off is minimal. The less the difference the more I know I am close to a flat response in my room.

I do know I have one minor issue to resolve, but it is not worth the time right now. I did not change the driver delay settings in the Behringer. The difference is a ms. or two I'm sure since the driver is further forward than the JBL/Trachorn combination. I figure it is not worth the effort until I get the DBB bins in here.

Anyone want to buy a set of Trachorns and JBL drivers?

This active crossover ROCKS.

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Hey Rudy,

According to the dimensions that Chris mentioned in the other thread, your horn is gonna lose vertical pattern control near 1.7kHz and then lose horizontal pattern control near 900Hz.

Looking at the closeup picture of your horn, that crazy shape in the throat is going to introduce some beaming above certain frequencies, and it'll also be different in the horizontal and vertical. Looking at your raw frequency response, I would wager that they're happening at around 6.5kHz and 8.5kHz.

So if you drew a flat line through the HF passband, then you would want everything below 1.7kHz to be slightly below that line and then below 900Hz you want to be down just a bit more. And then above 6.5kHz and moreso after 8.5kHz you'll want to be above the line. I can't give you exact numbers because it'll depend on the acoustics in your room, but basically what you're trying to do is strike a compromise between the tonal balance of the direct sound combined with the tonal balance of the indirect sound.

Looking at your EQ'd plots, it seems like you're tilted a bit in the other direction. Your gate for the HF section seems a bit long (there's comb-filtering showing up in the measurement), but if you threw in a shelf filter around 4kHz (either to boost the highs or cut the lows), then I think you might end up real close with the other filters you've already got engaged.

Of course I'm recommending that sitting in a chair across the country where I have no clue what it is you're hearing. One thing I always do when voicing the system is I try to pick filters where it's easy to manipulate the response in areas where there is obviously stuff happening...and then I'll listen to a huge slew of source material that I know really well and then tweak the filters by ear. One thing you'll probably discover is that although you start with a "flat curve", usually whatever you end up with will also be flat too...it'll just be a different flat curve.

Btw, I personally find that it's easier to start with the shelf filters, because then it makes it easier to match the Q in all the parametric EQ's.

Dr. Who. as always, thank you for your assistance. I will look at your suggestions when I have some time to kill. I will say that after about 3 hours of listening tonight it sounds very good. As I mentioned in another post, the difference between having Audyssey controlling the system and turning Audyssey off is not much at all. That gives me comfort that I'm close to a good listening curve.

After obtaining these settings it sounds pretty darn good. I do plan to tweak some more, but today was the first day to set this stuff up.

I know what you mean about the throat, it is rather funny shaped. That driver is very capable and I just need to get the most of the setup. I think with the DBB bass bin it should get me to where I want to be.

Thanks again.
Rudy

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This active crossover ROCKS

[Y][:D]

Hey Rudy you might already do this but when I do listening test for any audible problems such as clarity, tonal balance, etc.... of the system I like to use an RTA to see approximately what frequencies are being reproduced when I identify a passage in the music were the problem is experienced. It's a great way to teach oneself what frequency bands corelate to what is being perceived and also a real learning experience to be able to accurately corelate and dial in the very best correction with the DSP.

mike tn

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Actually, I was thinking about how convenient it is that the PH-4525 horn with BM-D750 driver fits so nicely inside Khorn, CW and La Scala cabinets...

Chris

I think anyone with a K69 lying around should give this a try. I still need lots of time with the new setup, but the potential is there for most Heritage systems.

Rudy. I don't get why, especially with Active EQ to tame the bass horn anomalies, you want to downgrade your bass to DBBs (like Michael Jacksonvmoonwalking). If a cone moves, it produces distortion, and since the bass has the greatest cone motion, that is the FIRST place where you want a horn todecrease distortion, and get the maximum transients and definition..............sez Roy Delgado.

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Rudy. I don't get why, especially with Active EQ to tame the bass horn anomalies, you want to downgrade your bass to DBBs (like Michael Jacksonvmoonwalking). If a cone moves, it produces distortion, and since the bass has the greatest cone motion, that is the FIRST place where you want a horn todecrease distortion, and get the maximum transients and definition..............sez Roy Delgado.

Claude. As you can clearly tell I am no expert. This idea developed over time as follows. I always wanted to go back the kind of bass that kicks you in the chest vs. the kind that envelops the room. Since changing over to Khorns from my belle and at one time La Scala's, I have missed that direct bass. So, that started me on the journey to find a better mouse trap. I also, at one time, owned cornwall's and really like the bass they produce.

After spending much time reading about the Jub, Jamboree and DBB builds I decided a fun project would be to go that route. I have spent quite a bit of time trying to decide which way to go. I have settled on the DBB's for simplicity of build and hoping that I can again experience that powerful 'in your face' bass.

I understand that horns reduce the distortion, but frankly am not totally clear on any pitfalls of going the DBB route vs. say a Jamboree. I am now rather comitted to going with 15" drivers since I have 4 Eminence Kappalite 3015LF's sitting upstairs.

I would appreciate any explanations and a better picture of the pitfalls. How much better would a horn be vs. direct radiator? There must be some tradeoffs, I know there is no free lunch.

BTW, another influence was my audition of the big Palladiums. Those have some very powerful, in the chest beatin', bass.

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After spending much time reading about the Jub, Jamboree and DBB builds I decided a fun project would be to go that route. I have spent quite a bit of time trying to decide which way to go. I have settled on the DBB's for simplicity of build and hoping that I can again experience that powerful 'in your face' bass.

I understand that horns reduce the distortion, but frankly am not totally clear on any pitfalls of going the DBB route vs. say a Jamboree. I am now rather comitted to going with 15" drivers since I have 4 Eminence Kappalite 3015LF's sitting upstairs.

If you look at the cuves from a Cornwall, you have a peak at about 90 hz. that give the "fat low end." If you want "chest beating bass, then I recommend you build 4 MWMs bins (pretty simple construction) or just EQ up your Khrons, since you have the Behringer. I had 4 MWMs but found out I only need 2, so I sold all 4 matched set with aluminum trim to Fyrpwr and got 2 plain wood clones instead. Chest provided by visitors, the rest is provided by 4 15" drivers in any type of good Klipsch designed cabinets. Good luck.

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Claude. I can always boom myself out of the room if I want with two big subwoofers and boosting the Khorns. But, that is not quite what I am looking for. The Khorns have more of an eveloping, all around you, bass that is difficult to describe. I find that I miss the more direct firing, chest pressure, type of bass.

Decisions, decisions.

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Claude. I can always boom myself out of the room if I want with two big subwoofers and boosting the Khorns. But, that is not quite what I am looking for. The Khorns have more of an eveloping, all around you, bass that is difficult to describe. I find that I miss the more direct firing, chest pressure, type of bass.

Decisions, decisions.

FWIW Rudy, I know exactly what you are describing with the Khorn versus La Scala - eveloping versus punchy. I'm suprised you didn't go with Jubilees. To my ears (and chest), they have the punch the Khorns lack along with the depth of the Khorn.

Greg

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FWIW Rudy, I know exactly what you are describing with the Khorn versus La Scala - eveloping versus punchy. I'm suprised you didn't go with Jubilees. To my ears (and chest), they have the punch the Khorns lack along with the depth of the Khorn.

Greg

Well, I haven't started yet. I might just build the DBB's to get my feet wet on builds and build the Jub clone or Jamboree when I get some experience. OTOH, I could just start with the Jamboree.

My brain hurts again.

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Rudy, there are a number of us out there that can relate to what you are hearing and your preferences. First of all, congrats on the sound that you are achieving from the PH 4525 and BM D750 combo, but frankly I anticipated that you might have some success based on my experience with the similar Goldwood horn (but with a different driver).

As for your potential movement to direct radiators, I would only say trust your gut and your ears. After all, as you know, the only one you need to make happy is you........After owning Belles and Cornwalls (after a succession of various cone woofers), I also missed some "punch" after moving to Khorns. It took me a couple of years attempting to tweak the Khorns and/or trying other remedies/supplements before I quenched my thirst. I ended up with somewhat of a non-traditional solution by keeping the Khorn bass bins up front in the corner (as subs), and moving to JBL-fed VOTTs for my "punch" up front. I also added Forte direct radiators to beef up the punch in the rear (with my Belles).

So, I can understand your current thoughts regarding the DBB as being a simple build to get the sound that you are looking for (as opposed to, e.g , a more complicated build such as the Jubilee bass bins). Or, like you said, the Jamborees may also be an option.

Carl.

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