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drboar

LaScala Helmholz trap for 140 Hz peak?

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The LS have a peak that seem hard to get rid of.  If one used a HH chamber or a pipe resonator to reduce that peak things would be better for home use of the LS. In PA use I can imagine that any contraption that reduce effiency is a bad thing but at home were the LS hardly goes on at full blast hours on endThe LS has that midbass?

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It’s not a peak - it’s the sagging response below it that causes it to be more noticeable than it otherwise would be. 

 

I’ve been told that using the K-43 helps, but I’ve never seen a curve. 

 

 

BA36B2AB-2DA2-4A18-B0CE-1B7F7777C648.jpeg

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Not knowing too much about this stuff.....  would Roy's PEQ at 148 Hz be of help?

 

148 Hz, Q:8, -7 db

 

This is of course, for active settings 

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My first reaction was, "Sure, why not use a Helmholtz?"

 

Is the peak, or the sagging response below that Dean mentioned, audible from the sweet spot only?  If so, have you tried moving the sweet spot or the speakers? 

 

Have you assessed the room for modes?

 

I have two La Scala graphs that PWK ran and a Belle graph I ran with REW and a calibrated mic.

 

One is the graph Dean posted.  To my eye, the peak looks like it is at about 175 Hz, but relatively narrow, about 1/3 octave, so it might be hard to hear, if that notion still holds.

 

The second graph is the one in PWK's paper presented at the Spring Convention of the Audio Engineering Society, April 1965.  In that one, there is a broad peak relative to average elevation.   It is 2 to 2.5 dB in magnitude, and reaches from 100 Hz to about 250 Hz.  But it is not a peak relative to the 1K area.

 

The Belle Klipsch is advertised as being similar to La Scala, but I don't know how similar.   My Belle center channel, in my room, has a 1.7 dB peak from 100 Hz to just about 140 Hz.

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I thought the peak was caused by the parallel walls in the side channels. Does the Peavey FH-1 also have the peak?

 

Bruce

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21 minutes ago, Marvel said:

I thought the peak was caused by the parallel walls in the side channels. Does the Peavey FH-1 also have the peak?

 

Bruce

Yes, to a lesser degree and it's a bit lower freq. and amplitude, but not much.

 

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Perhaps.  Maybe too much smoothing here.  FH1.JPG

 

Helmholtz resonators usually have very deep cancellation troughs. 

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