To djk

[rune]

To djk:

You wrote :"I think the Bakgaard patent

http://164.195.100.11/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F4031321

referenced by PWK in

http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1='4237340'.WKU.&OS=PN/4237340&RS=PN/4237340

when used with a LaScala produced the most coherent sound with more 'slam' than anything I have ever heard."

What is the Bakgaard patent?I have tried to read those links,but I can't figure what it's all about.Can you explain in simple words?Is it a different x-over design or what?

Thanks,

Rune

[WMcD]

I'll give some comments.

First, the links show the text of the patent documents. You should view the graphical presentation of the actual documents. If you want to be able to do this, you'll have to visit the USPTO website and follow directions regarding downloading special plug-in software. It is the TIFF viewer available as free shareware from Alterna-tiff. Clever names.

The Bakgaard patent treats a specific problem with crossover design.

Assume a two way system, two speakers, woofer and tweeter. There is a "crossover network comprised of two filters.

At the cross over point, the low pass filter for the woofer rolls off. The high pass filter for the tweeter rolls on. As you can imagine, the distribution of power to the speakers "cross over". This is typical.

For a lot of reasons, this process may result in imperfect summing.

Bakgaard proposes a solution of a third speaker and filter network. The combined effect of the network and the third speaker is to compensate for the imperfection in summing. It is like having a midrange speaker to fill in between a woofer and tweeter.

I can't comment on slam or modifications to the LaScala.

The Klipsch patent is a different concept.

Let me take a side trip here first. The original patent application claimed two (2) inventions. One was the bass horn alone. But it showed a three way system with woofer, mid, and tweeter. The second invention was the crossover network to use with the three drivers.

U.S. patent law allowed two inventions to be "claimed" in one patent application and grant, if they were "related." An example might be the bass horn and a crossover for the bass horn. However, that was not the case here. The claim for the crossover applied to the tweeter. The USPTO probably demanded that the application for the tweeter cross over be "divided" out. So if you look close at the legalese, you'll see the patent you're looking at is a "division" of the earlier application.

So, what is the claim of the Klipsch patent we're looking at?

It appears the technical issue was that the bass horn and mid horn, in combination with their drivers, had more output than the tweeter. What do we do with the tweeter?

You may recall that the autotransformer in the K-Horn reduces the output of the mid. You see the autotransformer in the A and AA schematics. In the Heresy, using an E crossover, the autotransformer reduces the output of the mid AND the tweeter.

The autotransformer does this reduction by being wired as a "step down" transformer regarding voltage, in that configuration. The input impedance seen by the amp is high, and the crossover, in those frequency ranges draws less power.

It must have been that the bass horn in the invention was very efficent and matched the midrange. But the tweeter was weak. Therefore, the autotransformer in the crossover was reversed in connection to "step up" voltage. This would result in a lower impedance presented to the amp and more power is drawn in the treble range.

Gil

[rune]

Thanks Gil!

[djk]

The Bakgaard patent requires a complete re-vamping of the speaker. You can read a much better account in the JAES. A 24dB/oct Linkwitz Riley crossover is the next best thing. And it can be implemented without modifing the cabinet.