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

[Deang]

Guys, really, I was only trying to spark some conversation. I get the whole polar/power response thing -- I just always thought it interesting that even with the superior bass horn, we still ended up with a 400Hz crossover point. Now, there was another point to the comment, and I see that some have picked up on it (more on that later).

"Actually, the Jubilee has a greater amount of bass energy in where most of the musicpower is: below 500 Hz (between 40 and 120 hz. too) AND it is the optimum xover point matching to the polars of a good 90 degree horn. But one does have the option of going to 800 Hz. if need be in a passive 2-way system with a non-CD horn design."

I think a good rule of thumb is that when you don't have access to all of the information related to a driver or horn, it's best to stay on the conservative side of things. I would split the difference and go 600Hz with a 12dB/octave filter.

"I've asked several bass horn builders / engineers why not cross higher if the bass horn can perform that high. The answer has consistantly been that female vocals or vocals don't sound good when crossed higher than 600hz."

I agree with them, but it doesn't have anything to do with female vocals -- but I guess I can add that to the list.

"The Jub is good to about 1kHz on-axis, but at the expense of some clover-leafing in the polars..."

I've never seen polars for the Jubilee bottom, only the 402 -- have you? I suppose it makes sense to think that if Roy starts crossing a little over 400, then that must be the place that dispersion begins narrowing down. It would be very cool to know how much. Now, on the other side of this is the possibility that it has nothing to do with the bass bin at all, but a decision based solely on how well the mid-horn maintains its pattern control at the lower frequencies. IOWs, the Jubilee bass bin may have good polar response higher than 400, but without plots or Roy's word -- we really just don't know.

"The Khorn does the same thing, but it starts at a lower frequency. I think the Khorn should really be crossed even lower, but then the midrange horn becomes impractical. I think it could be said that crossing the Jub at 800Hz would be like crossing the Khorn at 400Hz."

Those are some interesting statements Mike. I've thought about this stuff a lot, especially the thing about crossing the Klipschorn lower, but you know I've always liked the sound of the Klipschorn bottom, and I ran mine wide open (no coil) --maybe I just don't know what good midbass sounds like -- but it always sounded pretty good to me. Now, on that last statement, I understand your reasoning behind it, but as far as I know, there is not enough available information on either bass bin to make definitive statements like that.

O.K., the 2" drivers, while having more surface area and lower distortion, really aren't that well behaved -- the FR is rough as hell and they fall off fast and early. They need a lot of help from the network (whether active or passive). If we give up a little in power response and raise the crossover point a half octave, then simple filters and other interesting drivers and horns come into view.

[Pete H]

All great points Dean, but don't you have something that you should be working on instead of posting on the forum????????????[*-)][] Just kidding, and LMAO.

[DrWho]

I've never seen polars for the Jubilee bottom, only the 402 -- have you?

Yep []

The K402 is better behaved than the Jub above 400Hz, so I agree that's probably why Roy xovers so low.

O.K., the 2" drivers, while having more surface area and lower distortion, really aren't that well behaved -- the FR is rough as hell and they fall off fast and early. They need a lot of help from the network (whether active or passive). If we give up a little in power response and raise the crossover point a half octave, then simple filters and other interesting drivers and horns come into view.

There's no reason you need to give up power response by going to a smaller diameter driver. I believe distortion would be the bigger concern.

Btw, I think there's a reason PWK went with a 1.5" exit for the home Jubilee....(better HF behavior).

Ok, one more comment...I think a xover with well behaved phase will sound better than one that is "simple" for the sake of less parts...

[Chris A]

Chris, let us know how your testing goes with that horn. It looks like an inexpensive option for some us. Depending on performance, it could provide a great bang for the buck value.

Certainly. It'll be probably 2-3 weeks, based on how long it takes to receive the two horns (...just ordered 'em...) and to get everything set-up/working.

Well, first cut at a smoothed PH-4525 horn with K-69A driver. The three traces are on-axis (zero degrees) in green, 30 degrees horizontally in gold, 45 degrees horizontally in red.

If anyone sees issues (and I'm sure that there are some), please let me know.

Chris

[Chris A]

Same thing, but this time for the PH-3223 horn and K-69A driver. Note that these measurements were done outside, no EQ, pointed vertically with an ECM8000 microphone and REW. Nothing esoteric, but just a first cut on the response of the horns/drivers.

I was thinking about using the PH-3223 horn and K-69A in my Heresy center channel, but use a Dx38 to actively crossover and do EQ. I've got the "dirty plots" for those that are interested.

Chris

[Rudy81]

Chris, thanks for the update. It looks like a good combination reaching down to 450Hz or even 400Hz with a little eq. However, I guess it will not work as a two way. A tweeter is going to be required. I just don't see how you can get the 10-20khz range up to par.

[Chris A]

However, I guess it will not work as a two way. A tweeter is going to be required. I just don't see how you can get the 10-20khz range up to par.

I disagree. Email me and I'll tell you why...

Chris

[Rudy81]

E-mail sent...I'll bite!

[DrWho]

I've got the "dirty plots" for those that are interested.

Do you have my email Chris? If you could send me your MDAT files, I'd love to poke around in REW and play with the gating and all that to get a better look at things.

[Deang]

I've never seen polars for the Jubilee bottom, only the 402 -- have you?

Yep

I do believe I'm a little green with envy.

The K402 is better behaved than the Jub above 400Hz, so I agree that's probably why Roy xovers so low.

Good info, I've always wondered about that -- thanks!

O.K., the 2" drivers, while having more surface area and lower distortion, really aren't that well behaved -- the FR is rough as hell and they fall off fast and early. They need a lot of help from the network (whether active or passive). If we give up a little in power response and raise the crossover point a half octave, then simple filters and other interesting drivers and horns come into view.

There's no reason you need to give up power response by going to a smaller diameter driver. I believe distortion would be the bigger concern.

My personal opinion is that at the levels the great majority listen at in the home, the difference is inconsequential. Now, I didn't say to toss a smooth power response out the window (because it's important), but to give up just a little for the purpose of opening up some other possibilities.

Btw, I think there's a reason PWK went with a 1.5" exit for the home Jubilee....(better HF behavior).

And here is one of them. The 1.5" drivers have a smoother response and go out further before falling off. I mean, are you really going to argue that loading up a filter design with a crap ton of LCRs sounds better? All I'm really saying here is that it would be fun and interesting to hear a comparison of the two different approaches. Less isn't always more -- but sometimes it is.

Ok, one more comment...I think a xover with well behaved phase will sound better than one that is "simple" for the sake of less parts...

Do you really need two dozen elements in a filter to get "well behaved phase"?

[Deang]

All great points Dean, but don't you have something that you should be working on instead of posting on the forum???????????? Just kidding, and LMAO.

Watch it, or I'll make you wait another month.

[Deang]

Chris, thanks for the update. It looks like a good combination reaching down to 450Hz or even 400Hz with a little eq. However, I guess it will not work as a two way. A tweeter is going to be required. I just don't see how you can get the 10-20khz range up to par.

It's not difficult Rudy. With an active set up you just keep adding power to the high frequencies until you get them where they need to be.

[Rudy81]

I may just get this P Audio combination and give it a try. It would be interesting to compare that setup with my current active Khorns with Trachorns, JBL 2470 and the APT 150 tweeters.

[DrWho]

And here is one of them. The 1.5" drivers have a smoother response and go out further before falling off. I mean, are you really going to argue that loading up a filter design with a crap ton of LCRs sounds better? All I'm really saying here is that it would be fun and interesting to hear a comparison of the two different approaches. Less isn't always more -- but sometimes it is.

Ok, one more comment...I think a xover with well behaved phase will sound better than one that is "simple" for the sake of less parts...

Do you really need two dozen elements in a filter to get "well behaved phase"?

I thought you were referring to first order filters with your "simple" comments...

I'm not a big fan of L's and C's between my amp and speakers which is why I like the active route. []

Btw, you can keep the same power response by going to a 1.5" driver...so you end up trading a bit of distortion down low for some smoother highs. I also wanted to add that the craziness up high isn't just limited to 2" compression drivers. All sorts of speaker topologies exhibit the same types of behavious to varying degrees.

[Deang]

I'm not a big fan of L's and C's between my amp and speakers which is why I like the active route.

Ouch. Good one.

[Rudy81]

Based on Chris' results, I just ordered the PH-4525 horns and the BM-D750. We will see if I can get it to work as a two way system with good sound. I will be comparing that driver/horn combo against my ALK Trachorsn/JBL2470 mid and Eminence APT150 tweeter.

Can't wait for the stuff to arrive.

[Chris A]

No pressure, right? [8-)]

Chris []

[Rudy81]

No pressure, right?

Chris

No pressure at all my friend. I really want to try a driver/horn combination that can take me to a two way system. My new goal is to build JC's infamous DBB bass bin and cross it over at near 600Hz. Then, hopefully use the BM-D750 and PH-4525 to go the rest of the way. I will cut out the DBB at near 45Hz and send the lowest frequencies to the RSW-15. Dr. Who, yourself and the rest of the gang created an active filter monster. I now have the ability to try various combinations on the fly. For now however, I will be using the Khorn bass bin for the LF.

It will be most interesting to compare both the measurements and the subjective listening between the above combination vs. the three way I have now.

Whatever I don't keep, I should be able to sell and not lose too much.

[homemadeheresy]

So from what I have read here... the need for EQ is determined by the horn type ? A 402 or 510 you need to EQ any driver, some more, some less. The 2" Tractrix with the proper driver, like a EV DH1A would not need EQ

I think you may have answered your own question, most likely not the horn but the driver.....

[ClaudeJ1]

I will cut out the DBB at near 45Hz and send the lowest frequencies to the RSW-15. Dr. Who, yourself and the rest of the gang created an active filter monster. I now have the ability to try various combinations on the fly. For now however, I will be using the Khorn bass bin for the LF.

You can tame the peaks in the Khorns and give it a Linkwitz-Riley slope at the Xover point, which does a good job, as you probably know. This effectively extends both ends of the spectrum. Digital PEQ rocks.