Belle AB-2 and LaScala AL-3 exactly the same xover

[Guest " "]

Belle AB-2 and LaScala AL-3 exactly the same xover

[Guest " "]

unless I have the wrong schematic for the AB-2

[Mike 585]

Hi Fritz,

Yes there's an older post around where in the midst of some other discussion Bob Crites made that point.

You recently explained to me precisely what this xover was doing, (slopes, etc). I believe there is also an AL-4 but no AB-3. Do you happen to know what the purpose of that update was? I'm curious because I like Bob's A4500 better than AAs ( unrecapped) but I much prefer the AB-2 to the A4500. I attribute it to the steeper slopes. Worth note, my center is a LaScala (K-400, AL-3) and it sounds significantly different to my L&R Belles (currently AB-2 K-500). K-500 Belles preferred.

I'm getting ready to build a set of Belle(ish) speakers and am trying to decide what to do about networks. I'd like to try actives and experiment but a factory or measured, proven solution is likely hard to beat. I can't tolerate any noise at idle and from the little bit I've read (and no first-hand experience) actives seem to be a bit noisy--hit or miss. I'd appreciate your comments.

Thanks,

Mike

[Guest " "]

I believe there is also an AL-4 but no AB-3.

yes...there is an Al-4 and an AB-3...I'm thinking they are pretty close if not the same.

[LarryC]

Wasn't the AL-4 the same 2004 (or so) more elaborate XOver as the AK-4 for that era of the K-horn? The Xover for the LaScala II is very similar in appearance and complexity to the AK-4.

The back story is that around 2002 Klipsch could no longer get their usual MR drivers and tweeters. They had to find or have made a new MR driver and tweeter to keep Heritage speakers in production. I think it took over a year, so Heritage wasn't back in production until 2004 or so.

As part of those revisions, as I recall, they designed the new, much more complicated AK-4 for the new MR and tweet (which now could go down to 4500 Hz) in the K-horn, and likewise the similar AL-4 for the redesigned LaScala. I don't recall if there was an AB-4, but probably would have been if they'd continued the Belle.

My hazy recollection, anyway.

[Guest " "]

Wasn't the AL-4 the same 2004 (or so) more elaborate XOver as the AK-4 for that era of the K-horn?

the AK-4 is more elaborate than the AL-4....AK-4 is much bigger in size and substantially higher parts count.

[LarryC]

Wasn't the AL-4 the same 2004 (or so) more elaborate XOver as the AK-4 for that era of the K-horn?

the AK-4 is more elaborate than the AL-4....AK-4 is much bigger in size and substantially higher parts count.

OK -- I was thinking both the AK- and AL-4 have quite a few more coils, yellow caps., and wiring than their much simpler-looking AK- and AL-3 predecessors. They look like they're both from the same later, -4, design generation. I didn't mean to suggest that they were that close in detailed design.

[Guest " "]

I'll post pic's and schematic tomorrow.

[WMcD]

FWIIW:

PWK had early on gained the thought that simple crossovers were better.

He also had this thing about keeping the mid to tweeter X-over away (higher) from 3200 or 3500 Hz where the ear is sensitive. Maybe keeping as much energy out of the K-77 made sense too.

I think the glitch in the K-400 and K-55 is the source of problems. It is a matter of debate.

In most cases his mid X-over was just a high pass.

Further, he was a fan of efficiency over frequency response.

Eventually over the years there were some inroads toward more complicated x-overs. The LB is an example, where there are peaking circuits in the mid.

After PWK's passing, engineers at Klipsch had more freedom to redesign the crossovers and depart from the PWK's dicta.

Additionally, the LMS and LEAP systems by Linear-X provided a very sophisticated way of measuring response and also modeling crossovers. The crossover circuits are modeled in a SPICE-like manner. In short, this allowed design, prediction, and optimization of crossover filter circuits, and acoustic output. to obtain a flatter response based on crossover topology and values.

While not mentioned therein, this appear to me to be shown in the descriptions of the design of the Palladum crossovers. My guess is that LMS/LEAP was used on the high-part-count crossovers of the recent Heritage units, some years earlier.

It is also interesting that autotransformers were used in the Chorus, Forte, Quartet units. I take it that PWK insisted. We don't see an autotransformer in the newer crossovers. People are a fan of "The Trouble With Attenuators" where PWK spoke of their virtues over L-Pads. Yet in a footnote to a later article, PWK indicated that autotransformers are not needed in his midrange horns. -- at least for electrical damping control.

Maybe he kept using them because, as shown in a Dope From Hope, they reduced distortion from amplifiers.

WMcD

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