Network slopes and listening distance

[pauln]

I read an opinion / observation that 1st order 6dB slope networks like the BEC A's sound best when you get a little further back so the sounds of the drivers can better integrate. Intuitively, I would first guess that this would be more the case for higher order networks and especially extreme slopes. Any ideas about this?

I'm wondering because I moved the La Scalas into the big room placed in the corners on the long wall - 17W x 12D x 10H; so that is a little more than 2000 cu ft. Just listened to some Bach organ fugues (Glenn Gould playing) at medium volume. I was struck by the low end. I'm sure you all know how an organ in a church sounds - not that loud, but the presence and resonance of the lower pipes are physically felt. Same thing listening to the live orchestra tune up before a performance (one of my favorite 'songs' by the way). You hear the violin and then a few instruments for a second, horns playing scales, strings playing other scales, then they all come in and fill the hall - not that loud, but you hear the air thick with sound - hard to describe. Always reminds me of Stravinski... Anyway, the LS like the bigger room, a lot. Listening distance is about the same as before...

Pauln

[ben.]

I don't know... I would think the fuller bass is due to acceptable room volume more than anything else.

[oldbuckster]

I think La Scala's and Khorns like the bigger rooms....................isn't that really what they were designed for, to fill big rooms with sound?

[mark1101]

I am using ALK extreme slope nets in my Khorns, and I use ALK Jrs. (modified A network) in my Lascalas.

I find the Lascalas to be fine really at any distance, but since there is such frequency overlap between the drivers you get a nice ambience up close too. The Lascalas also sound great as you increase the listening distance. But I find that true with most of the Heritage line with any of the networks. The horns like distance. The issue I have though is that the gentle slope neworks tend to cause harshness at louder volumes. In bigger rooms where you would tend to turn it up louder, this then becomes a disadvantage.

In my Khorns I have found that with no overlap between drivers, there is diminished (loss of) dynamics. My Lascalas can jump you right out of your chair with some passages, and my Khorns just don't do that at the low and mid volumes (with the ES networks). But as the volume is increased the dynamics improve. The main reason for my use of the extreme slope networks is greatly improved imaging and especially improved clarity and removal of harshness at higher volumes. The bass is much more clearly articulated and the harshness from the top section is completely gone. The sound stage opens up dramatically. It's a whole new way to use the Khorns if you ask me. They are relegated to my 2 ch. stereo "turn it up" system, and are used for music listening only.

Whereas I set my Lascalas up into HT duty. I love the Lascalas in this application because they are great with voices and with the large amount of music on TV. They are also great for concert DVDs, and movies in general. With the gentle slope networks I get all the dynamics and can listen at whisper levels if I want to and it still sounds great. I also found that they mate well with the right subs for HT duty.

[Deang]

My experience mirrors the two Marks.

Great post above -- exactly how I see it.

[pauln]

Thanks all for the reality check. The slope / distance thing I read just did not sound like my experience, and I too notice more dynamics at low to moderate volume (the level I listen) with BEC's A's. I guess that's because of their simplicity (less component count = less signal loss) ?

[Deang]

It mostly has to do with the greater overlap between the tweeter and midrange driver, and the lower end of the tweeter's range is 'more in play' in a first order type, which also changes the power response/off-axis behavior. Also, consider that the K-55-V is almost 20dB down at the crossover point, and that the K-400 is starting to beam at that point as well -- so having the tweeter coming in earlier/faster isn't such a bad idea. Finally, the greater the slope, the more attenuation applied to the driver ...

"A tweeter with a third order high pass filter with a crossover frequency of 5000 Hz driven by the 100 watt amplifier ... will recieve about 1.6 watts at 2500 Hz versus 25 watts with a first order filter at full output."

First order sounds the best (to me), but the drawback is higher distortion levels at any given power level compared to higher order types. The answer here is a better tweeter. Think BEC CTS-125, Beyma, and JBL.

[pauln]

At what level does the distortion begin to show with the first order? When I listen "loud" the meter peaks hit 90dB. I'm just guessing that the audible onset of distortion might not come into play until quite a bit higher than this?

[Deang]

In your room, you're fine there. I'm just over 12 feet back in my room, and I begin noticing 'audible distress' from my Beyma's at a little over 100dB with peaks of 110dB at the chair. That is 'damn loud' territory. Keep in mind that this is relative, because it's strongly tied to power levels, which is tied to room size and distance from the speaker. Personally, I think most ears are very sensitive to driver distortion, especially from the tweeter -- it's not very difficult to hear things falling apart with a Klipsch speaker using a first order network.

[sfogg]

Dean,

"The answer here is a better tweeter."

Better drivers overall. Then you don't need to worry about overlap trying to fill in for a driver that is rolling off well before its actual crossover point (k55v @6k). That or change the crossover points to something more suitable for the drivers being used. The stock heritage are basically constrained in what they can do as they have a tweeter that can't handle a lot of power, and can't go very low coupled to a squawker that can barely get up high enough to meet the tweeter.

As far as what crossover slope sounds better for whatever listening distance I think that is going to depend upon how well the rest of the system has been implemented too. Things like driver level matching is more critical the higher the slope as is matching dispersion patterns and such. Because of less overlap there is less of the sort of acoustic 'soft focus' crossover area that lower slope crossovers give and help to blur the differences between drivers/patterns and such. OTOH the 'soft focus' causes other problems like you mentioned such as off axis response, combing (esp with very different path lengths), power handling and so on.

Pick your prefered poison/trade offs.

Shawn

[mark1101]

That's why I have two active systems (actually 3) because of the trade offs.