Active Crossovers

[ben.]

If the sound from the woofer were to join with the sound from the horn and behave as one, they would exhibit the same characteristics and properties. We both know that's not true. The woofer's sound will obey the inverse square law, decreasing by 6dB per doubling of distance. The horn's output will not, instead losing 3dB of intensity per doubling of distance. This is a bit of a simplification but I'm running out of ways to explain...

In your classic pro sound line array, you've got a lot of direct radiators....if the sound from each driver decays 6dB per doubling of distance, then why does the output only drop 3dB per doubling like a plane wave? Are the engineers wrong for calling that "combined wave" (or whatever you want to call it) a "plane wave"?

You cannot join or meld sound waves.

Then Danley's synergy horn concept is impossible.

All you can do is get them to arrive at a chosen point together.

The implication is that there is a problem anywhere but that point....I don't agree with that conclusion. It 'can' certainly introduce problems off-axis, but in a competantly designed system it shouldn't be an issue.

Ok, Mike. I see that you disagree but you don't answer my questions leading you to prove your points. I've countered each of your statements with logical, fact based replies and will continue to do so as long as I have patience.

"Classic" line arrays using direct radiators are inferior to horn loaded designs since that behavior is strictly linked to array length. Off axis response is a mess as well. Horn loaded designs are better. Horn loaded designs utilizing Synergy technology are even better. google around and you might start to see where I am coming from. Hop a plane to Buffalo and I'll prove it to you and buy you dinner afterwards.

Regarding the joining of sound waves, I don't relly know why you are not getting the point. The Synergy horn concept does not join sound waves. It arranges them so they act like a single acoustic source. The output of the various drivers arrive at the same time because they are originating from the same horn, not because they have been adhered to each other in some way. You simply don't understand this and I don't know why. It's simple. Do the string thing. Just do it. If the sound waves were "melded" they would stay together as you moved off axis. They don't. They are discrete acoustic events and act that way.

I'm not implying that there is a problem other than the point where arrival times are aligned, I've said it over and over. Do the darn string experiment. It's simple.

[ben.]

Is there any way to get it perfect without acoustically aligning the sources? No.

I understand what you mean by this (especially since you referenced Danley earlier), but I would suggest that what you call perfect alignment isn't necessarily better. It depends on the specifics of each situation. I'm not trying to knock Danley at all, but the marketing propaganda would have one believe there was no other way...

Well, it is marketing. I can't disagree about that. But I do disagree that there is a better way out there.

Please describe to me a specific situation where digital correction of acoustically seperate sources works better in any way than the Synergy Horn solution. If I can't refute it, I'll send it to Tom. He's a lot smarter than we are.

I could have worded that better....I was trying to say that other approaches can be just as good, not necessarily better.

For what it's worth, the idea behind the Synergy horn seems to me to be a lot better than how it actually shows up in practice...and I hate to be one to say that when I know I couldn't do any better. Nevertheless, take a look at the CLF data posted on the website.

Another thing about horns is that the acoustic centers shift with frequency and the angle at which you're measuring from the speaker. It's just another form of time arrival offsets present in the off-axis...I don't think Danley's horns are immune to this behavior.

What about the CLF data? Stop talking about what things seem like to you and say something. Tell me about those other approaches. I'm putting effort into proving these points - stop dancing and pony up.

What you say about acoustic centers shifting with frequency doesn't make any sense and betrays a complete lack of understanding of the Synergy design. Please explain how I'm wrong here.

[Rudy81]

So have you purchased an active xover yet?

No, not yet. I am trying to do this on the inexpensive side on a trial basis. If I commit to run active permanently, it would only be if I can clearly hear a difference between passive and active. In my search for information, I have run into comments from both camps. Those that swear by active and those that swear that you can't tell a difference. So, I have had a few offers from our members to lend me their DX38 on a trial basis. I am currently looking at picking up a 5 channel amp I can use for my effects and center speakers. That would free up my current 5 channel Parasound HALO amp, which has XLR inputs, for use with the DX38 or any other pro gear crossover.

Ideally, I would run the pc based program to control the crossover. Hopefully that will allow me to make changes on slope and time delay on the fly while sound is playing. If I can do that, it will be very easy to tell if it makes a difference or not. Sounds simple enough anyway.

What I don't want to do is buy a lot of gear that I later decide doesn't do much for me and end up storing more crap.

[Coytee]

As far as what you're hearing, what I've been trying to do is help you understand what it is you're hearing and why, so when you give advice it's rooted in reality and not conjecture so as not to confuse matters further. I know you're trying to help and it's really cool that you are so generous with others to expose them to new gear and help them improve their systems, but some of the conclusions you come to are not logical.

One of the things I'm trying to make clear is that the coherent bubble of sound you're hearing has more to do with the fact that you're hearing the bulk of the sound from one source, not the fact that you are time aligned around 400Hz. Try changing your delay settings a few milliseconds - see if it makes it all fall apart or if it still pretty much hangs together. Then you're actully learning things. You've got everything you need to stop guessing

I do always try to couch my coments with an I think or suggest... just to give me enough wiggle room so that when I'm wrong I can deflect all the blame onto DocWho! []

I'll try the delay thing you said...actually... I think I already stumbled onto that once and didn't realize it. (and note here that I didn't hear a whole lot of change!)

If this is accurate that the biggest change in sound quality I'm hearing is being derived more from the change to a 2-way setup from the Khorn 3-way setup then I feel even more for Khorn owners. I actually thought they could align their 3 drivers and obtain more of the 'one voice' that I hear. Given your suggestion that it's the 2-way that's more responsible that infers they will never be able to achieve this more singular voice (than they might already be able to achieve).

If I try the delay experiment that you suggest above, might I presume it to be better to start in mono so I don't have other influences?

This might be interesting! Have someone at the controls and have them dial in some delay until I can hear any noticable difference while standing 30' away!

What source would you listen to? Drum hits, vocals, instrumentals, would it really matter?

[Coytee]

Ben, I would ask in a general sense (since I don't know your background but it seems to be very technical in this area.... are you an engineer of some form?)

From a technical perspective, I can see how you don't meld, merge or hot glue two sounds into one. Ok. I would infer that same logic to continue to say that virtually everything we hear is an illusion of some form or another? (relative to the actual recorded event) In other words, the stereo image in front of us isn't real, yet...we still hear it and since we hear it as this phantom image in front of us, we discuss it as an event, not the illusion it really is.

Since we're reproducing an image that is not real, since the sound (using this example I give with my Khorn 30' away) "sounded" like "one voice" I think in the real world it's ok to call it that. Perhaps it isn't and I sure don't want to be one who is misleading anyone on anything.

I'm dogging off now, I've got some signal delay to go play with!

[8]

[Coytee]

I just did a little 10 minute experiment. Perhaps others (Ben?) can chime in if I did it in a reasonable way or screwed it up.

I went downstairs, hit play on what ever was currently in player (Toto live). Killed my right channel, hit the mono button on the Peach. Even as I sat there, I merely dialed the delay on the woofer way out there. I figured let's start long & work short.

I put it the delay mode into meters so I could get away faster. Had it up to something like 500 meters lol. Talk about sounding kind of funny.

I dialed it down, back up, back down.... I'd say that Ben is absolutely right. The biggest single change that makes these thing "one voice" is simply going to a 2-way. I had the delay set on 9 meters. I could still hear a difference as I sat right in front. I went to my location 30' away and gave a listen. The scale of the "one voice" was still there but it had some echo in it. Even though it had some echo, it still sounded more similar 30' away as it did 10' away which is something I never said about the Khorns.

Thanks for giving me a mild enough kick in the pants (and the suggestion) to try something like this. If I did it totally bass ackwards, tell me how to do it better and I will.

[Coytee]

By the way, Ben... did you know there's a pair of Jubilees in Buffalo?

[Rudy81]

Coytee: So, based on your experiment and ben's comments, can I conclude that electronically aligning the 3-way drivers is really not going to do much? At least not the level of change you would see if I went two way? Is that correct? The more we discuss this, the more I realize that time aligning and increasing the slope in a Khorn is not nearly as productive as using a two way system. It may not be worth the effort to go to all the trouble of actively crossing a Khorn.

I think I now see why PWK may have been so interested in going two way vs. three way in his last major design.

Next time I'm in Knoxville, I'm inviting myself to your home so you can let me have a listen. []

[ben.]

Ben, I would ask in a general sense (since I don't know your background but it seems to be very technical in this area.... are you an engineer of some form?)

From a technical perspective, I can see how you don't meld, merge or hot glue two sounds into one. Ok. I would infer that same logic to continue to say that virtually everything we hear is an illusion of some form or another? (relative to the actual recorded event) In other words, the stereo image in front of us isn't real, yet...we still hear it and since we hear it as this phantom image in front of us, we discuss it as an event, not the illusion it really is.

Since we're reproducing an image that is not real, since the sound (using this example I give with my Khorn 30' away) "sounded" like "one voice" I think in the real world it's ok to call it that. Perhaps it isn't and I sure don't want to be one who is misleading anyone on anything.

I'm dogging off now, I've got some signal delay to go play with!

I work for a PA manufacturer (not Danley). My main responsibilities are US sales and support for our line array division. If you're more interested in more detail, PM me as I don't want to be seen as promoting our products (not I think anyone here is gonna drop 50K on a line array anytime soon).

I don't know about the stereo imaging thing - that gets into perceptual matters that I think I "get" but can't speak to with any real knowledge.

[ben.]

I just did a little 10 minute experiment. Perhaps others (Ben?) can chime in if I did it in a reasonable way or screwed it up.

I went downstairs, hit play on what ever was currently in player (Toto live). Killed my right channel, hit the mono button on the Peach. Even as I sat there, I merely dialed the delay on the woofer way out there. I figured let's start long & work short.

I put it the delay mode into meters so I could get away faster. Had it up to something like 500 meters lol. Talk about sounding kind of funny.

I dialed it down, back up, back down.... I'd say that Ben is absolutely right. The biggest single change that makes these thing "one voice" is simply going to a 2-way. I had the delay set on 9 meters. I could still hear a difference as I sat right in front. I went to my location 30' away and gave a listen. The scale of the "one voice" was still there but it had some echo in it. Even though it had some echo, it still sounded more similar 30' away as it did 10' away which is something I never said about the Khorns.

Thanks for giving me a mild enough kick in the pants (and the suggestion) to try something like this. If I did it totally bass ackwards, tell me how to do it better and I will.

Cool. I'm glad you tried it. I think what you did is perfectly fine. You now have an idea what time alignment actually does and sounds like. I think your conclusion makes sense, too. The best results are possible when digital correction is not required (which is from about 400Hz on up in the Jub).

And no, I didn't know there were Jubs in the Buff. Anyone I might know from the old days? pm if more appropriate. - thanks.

[Rudy81]

ben: In your opinion, then, is it a waste of time (and money) to try to time correct Khorns?

[ben.]

ben: In your opinion, then, is it a waste of time (and money) to try to time correct Khorns?

I'm not sure. My experience with Khorns is with '76 models using original AA and Dean-built Jensen PIO type A networks.

If you buy the gear right and can sell it for about what you have into it, money isn't an issue outside of short-term cash flow. Time? The value of time is up to you. I think it would surely be illuminating. If I were to do it, I would set up the crossover with no delay and mostly listen that way for a few days (occasionally adding the delays to time align for the ideal listening position), then reverse that - listening primarily with the delays in place, occasionally removing them. Then you know what you've got in your room and can make a reasonable judgement based on your perceptions and priorities.

My hunch is that it would make a slight but noticable improvement to electronically time align the Khorn, compared to the same crossover with no time align. I also have a hunch that I would prefer it with my type A networks, though.

[ClaudeJ1]

My hunch is that it would make a slight but noticable improvement to electronically time align the Khorn, compared to the same crossover with no time align. I also have a hunch that I would prefer it with my type A networks, though.

Just as important would be to smooth out the inhereent center hump of any horn with PEQ, effectively boosting the high and low ends of the band. I did that with my 'cheap LaScala" (Peavey FH-1 bass bins with K-33 woofers) and the darn things went to 30 Hz in a small room.

I have not tried this with my Khorn clones that have the Crites woofers (old square Magnet K-33 equivalents).

BTW, I only use type A networks in my setup, which means only one capacitor per driver (not the MWMs obviously). I don't even bother with autoformers or L-pads or resistors because all the relative efficiencies are matched with my choice of drivers and horns. Audyssey EQ doesn't have to do very much, especially in the bass section (surprisingly) since the system is pretty flat to begin with.

[Coytee]

can I conclude that electronically aligning the 3-way drivers is really not going to do much?

I'm really not a technical one to ask. Especially now that Ben has turned my brain to mush. I would speculate that going from a passive to fully aligned active would yeild some results, even if only in a technical sense. Given what I went through yesterday, I now see where going to a 2-way is a larger step forward than I had previously thought.

Next time I'm in Knoxville, I'm inviting myself to your home so you can let me have a listen.

I've not turned anyone away yet. Although it would have some poetic humor if I made you the first person refused, we all know I wouldn't do that. [A] Anytime you happen to find yourself hanging out in the Knoxville area, you are more than welcome to let me know and/or come by. I'll even buy lunch. This way I won't feel so bad when I abuse your hearing. [6]

[Coytee]

I work for a PA manufacturer (not Danley). My main responsibilities are US sales and support for our line array division

I didn't (and don't) mean to put you on the spot. I was merely curious as a technical background was coming through as I read what you have to say. I was presuming you were an engineer, like DocWho (meaning, I was presuming you were an EE verses some other kind of engineer).

[Rudy81]

I've not turned anyone away yet. Although it would have some poetic humor if I made you the first person refused, we all know I wouldn't do that. Anytime you happen to find yourself hanging out in the Knoxville area, you are more than welcome to let me know and/or come by. I'll even buy lunch. This way I won't feel so bad when I abuse your hearing.

I can tell you one thing, you wouldn't buy lunch. Thank you for the open invitation. If I ever end up in Knoxville, I will certainly let yo uknow. BTW, that is a beautiful area.

[Rudy81]

[Just as important would be to smooth out the inhereent center hump of any horn with PEQ, effectively boosting the high and low ends of the band. I did that with my 'cheap LaScala" (Peavey FH-1 bass bins with K-33 woofers) and the darn things went to 30 Hz in a small room.

I have not tried this with my Khorn clones that have the Crites woofers (old square Magnet K-33 equivalents).

I had been totally unaware of the 'hump' in the Khorn until I started measuring frequency response in my room. My system shows a hump right around the 200-300 Hz band. I found, totally by accident, that it is what gives the Khorn a bit of a 'tubby' sound. I can easily turn that on and off now and the difference is clearly obvious. I started using Audyssey to tame minor room influences, and that hump was cleaned up by Audyssey. Now that I am used to a flat response, or close to it, listening to the Khorns without Audyssey is an annoying experience. Just goes to show that we are all influenced by what we are 'used' to hearing. This all occurred after I spent quite a bit of time on acoustic room treatments. I heavily treated the room for bass standing waves, but could never get rid of, or flatten out, that hump. Fortunately, Audyssey can do it. That little event sold me on electronic manipulation of the source signal. Up until then, I detested any sort of electronic manipulation that was not absolutely necessary.

[Rudy81]

Ooops, double post.

[ben.]

I work for a PA manufacturer (not Danley). My main responsibilities are US sales and support for our line array division

I didn't (and don't) mean to put you on the spot. I was merely curious as a technical background was coming through as I read what you have to say. I was presuming you were an engineer, like DocWho (meaning, I was presuming you were an EE verses some other kind of engineer).

Not at all. Just trying to be respectful of the forum. Thanks, though!

[Rudy81]

Coytee: I just did some critical listening with "The Ultimate Demonstration Disk" to try and discern the issues you have talked about, in particular the lack of coherence at close distances with the Khorn. Either I don't know what I'm listening for, or it is not evident in my room. That got me to wondering where you had your Khorns. Is your room acoustically treated? Is it very live, lots of glass, things like that?

I started to wonder if up close you are hearing room reflections that are creating the illusion of lack of coherence. It seems to me that a relly reflective room would seem poor up close, but as you move far out, the detrimental sound effects would not be as evident. I have a relatively flat room with heavy bass treatment in all corners. Early reflection treatments, and rear wall diffusors. My room measurements helped me select the treatments and I finally have a relatively flat response. Audyssey takes it one step further and takes out the Khorn hump.

I now beleive that the biggest advantage for me with an active crossover will be the ability to steepen the crossovers. Isolating the drivers may provide a larger improvement than 'time alignment'.

I will certainly keep after this 'experiment', if nothing else to satisfy my curiousity and to learn something new.