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Foam board speakers / exciters ???


Emile

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@garyrc thank you so much for the awesome help / suggestions :D  Getting late in Florida, so will try "all" tomorrow.  Many, many thanks!

Cheers, Emile :D 

 

add-on ... used to be easier when we just had "our ears" to listen ... now we have hi-tech for inexperienced amateurs ... Haha :D  

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OK; glued the panel to a fiberglass screen ... hoping I can glue this contraption to a 16x20 inch frame; eliminating any unwanted feedback / oscillations :D "Blue" spot is where I will attach the exciter.

 

IMG_2129.JPG

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1 hour ago, rebuy said:

foam

foam?  genuine carbon fiber panel prototypes ... designed by an astrophysicists, they are "out of this world." :D  The bidding starts at $1000 ... can be covered by cloth or a painting of your choice ... $5 million with a Picasso, $100M with a Rembrandt :) Oh; forgot ... I'll include a Klipsch label :D 

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  1.  How does the carbon fiber panel sound compared to your Cornwall?  At high SPLs?  Low SPLs? How is the detail?
  2. Do the advocates talk about 1) Distortion: IM, THD, Total Modulation Distortion?  At what SPL? For instance, PWK, with the same drivers, found the Klipschorn to have approx. 1/3 of the Total Modulation Distortion as the Cornwall, with the Khorn at 10 dB higher SPL.  To the ear, I hear (no pun) the difference was not overwhelming with most music, but it was obvious enough for him to withdraw his recommendation of the Cornwall or Heresy as a center speaker when mated with flanking horns, and recommend the La Scala or Belle Klipsch for that duty.
  3. These things are tricky.  Although your curve (below) doesn't look very good, with about 45 dB peak/trough (+/- 22.5 dB) it might sound O.K. to some ears.  Good, but not accurate.

 

  

image.png.d39800bdfba760da52bcc4e4fa3e208c.png

 

Below is a manufacturer's curve on one of the most popular "extended range" speakers of the 1960s ☮️🍄  My friends and I auditioned one that was just like it above about 200 Hz (can't find the graph of that one; the only difference was it was 15" instead of 12" therefore had more bass, so only look at the part above 200 Hz).  Many people preferred it to speakers with much smoother high ends, i.e., with real tweeters.  My guess is that it filtered out most high frequency distortion (of which there was plenty in those days).  It was very clean, could take a lot of power, producing relatively high SPL;  I think it's sensitivity was about 103 dB, 1w, 1m, between 500 Hz and 2K Hz.

 

Notice, though that their graph divisions are the standard 5 dB, rather than the 10 dB you have been using recently.

image.png.fe43edf770e46b8185bb07490e7d2b46.png

 

The Grateful Dead used quite a few on stage, maybe 70 of the 15' extended range, 30 or 40 of the 12" extended range, and about 70 of the bass only 15."  We kept trying to count them, but had to start over too many times ... you know how it was🍄.

 

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11 minutes ago, garyrc said:

 How does the carbon fiber panel sound compared .... [edited] etc ...

Thank you Dr. @garyrc ... learning and it's fun :D  Taking the dog out ... will be trying your recommendations shortly. Thanks a million!

Cheers, Emile

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@garyrc ... OK; tried some things :D 

1. Compared it to my Cornwall's ... playing Tchaikovsky's Violin Concerto.  At both SPL levels, the carbon fiber (CF for short) speakers are badly missing the lower range of my Cornwall's.  But ... did a miniDSP adjustment and set the Cornwall's to 200HZ and up ... actually the CF's now were very compatible ... very "clear."

2. Distorsion ... no clue sorry :(  but harmonics seem to fall off naturally

distortion.jpg.9174988839c8d70518cfdfc04c13fb36.jpg

3. Yes; tricky :D  but when I equalized them through miniDSP it became pretty good ... but really no clue :D 

2 exciters.jpg

 

Think they would be awesome for surround speakers :D 

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2 hours ago, Emile said:

@garyrc ... OK; tried some things :D 

1. Compared it to my Cornwall's ... playing Tchaikovsky's Violin Concerto.  At both SPL levels, the carbon fiber (CF for short) speakers are badly missing the lower range of my Cornwall's.  But ... did a miniDSP adjustment and set the Cornwall's to 200HZ and up ... actually the CF's now were very compatible ... very "clear."

2. Distorsion ... no clue sorry :(  but harmonics seem to fall off naturally

distortion.jpg.9174988839c8d70518cfdfc04c13fb36.jpg

3. Yes; tricky :D  but when I equalized them through miniDSP it became pretty good ... but really no clue :D 

2 exciters.jpg

 

Think they would be awesome for surround speakers :D 

 

Above 200, the equalized curve looked pretty good to me until I noticed that the dB increments  on the y axis are still 10 dB, rather than 5 dB.  Still not too bad. 

 


 

           
            

 
            

 

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Looking at your readings ( which I am no expert in by any means), things seem to look pretty good all in all. It makes sence to me that it is probably unrealistic to expect a pair of these panels to operate as full range, this is probably why in the demo video, the guy had differing sized ones. To my ears that sounded good. I fully expect that in time cones, domes and horns will be viewed as quaint relics of the past as new tech will eventually be realized and surpass them. Time and tide wait for no man  as the old proverb says.

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5 minutes ago, YK Thom said:

I fully expect that in time cones, domes and horns will be viewed as quaint relics of the past as new tech will eventually be realized and surpass them.

YK; agree fully :D  Antigue (haha) speakers are limited to cone design/materials ... think a lot more can be done with panels.  But ... still keeping my various Heritage speakers :D  

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On 6/13/2018 at 11:38 AM, Don Richard said:

Turn up a pair of Klipschorns loud enough and the whole house turns into a radiant speaker😁

They may not be Klipshorns but my 1977 La Scalas do a pretty good job of that! In the basement of a 2 story!

Rockin DA HOUSE!! :-)

John Kuthe...

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Did I say this before?  I first saw vibrating panel speakers in Thos Tenny Audio in Berkeley CA, in c.1961.  They had membranes that looked like wood, but probably were not, framed in fine hardwood frames.  They sounded well balanced, but, in comparison with the JBL speakers they also had, no high treble detail, treble attenuated, and the deepest bass was nonexistent.  I played in the high school orchestra at the time, so I brought in Lp records of some of the stuff we played.  With some selections they sounded fine, but they flunked the 1812 Overture and The Great Gate of Kiev.  They couldn't handle the high SPL, and after that even the soft parts and the micro-dynamics didn't sound too good.  Either we had undergone some auditory training hearing the JBLs, or the salesperson had wrecked the speakers.  My dad and I left with the JBLs

 

 

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