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La Scala tweaks and hacks? Hit me


jimjimbo

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According to the posted chart the notch at 200 Hz seems better but gets funky around 250-350 Hz but its hard to tell without overlapping the two charts for comparison.

 

 

The green is with the padding...

post-5045-0-84660000-1426201870_thumb.jp

Edited by Marvel
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Marvel,

 

From the overlay graph, it seems the foam flattened the response while not effecting efficiency in a negative way.

 

I could be seeing something wrong, but the experiment results seem to contradict the hypothesis Jason made.

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Marvel,

 

From the overlay graph, it seems the foam flattened the response while not effecting efficiency in a negative way.

 

I could be seeing something wrong, but the experiment results seem to contradict the hypothesis Jason made.

 

 

Look at my post regarding reactance annulling on the previous page.  I believe the back chamber may be slightly undersized for the driver and the padding made it seem acoustically larger.

 

I originally decided to study the topic of reactance annulling when JWC was posting various horn designs several years ago and this was an important aspect of his designs to ensure the back chamber volume was appropriate for the drivers he selected in conjunction with the Fc of his horn designs.

Edited by Fjd
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"I believe the back chamber may be slightly undersized for the driver and the padding made it seem acoustically larger."

 

The response looks even better if you undersize the rear volume by 30% (by stuffing with non-porus material), it now becomes reactance annulled (it is not as such in stock form).

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"I believe the back chamber may be slightly undersized for the driver and the padding made it seem acoustically larger."

 

The response looks even better if you undersize the rear volume by 30% (by stuffing with non-porus material), it now becomes reactance annulled (it is not as such in stock form).

 

 

 

Thanks! It does make more sense for the sealed back-chamber and I think I had it reversed in thinking we were pushing the system resonance down to the Fc of the horn when we probably really need to push it up to Fc of the horn by decreasing the rear chamber volume.

 

 

 

 

So there you go...ask about glue and tennis balls and you get reactance annulling....what a forum..... :)

Still laughing...

 

 

 

It is funny since he wanted "tweaks" and "hacks" and I suspect this one, which seems to result in a smoothing of the response, is not commonly known and easily reversible too. B)

Edited by Fjd
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According to the posted chart the notch at 200 Hz seems better but gets funky around 250-350 Hz but its hard to tell without overlapping the two charts for comparison.

 

 

The green is with the padding...

 

 

Very nice job, thank you.

 

Looks like a loss just where i expected but does not look too bad really.

 

Everything has a tradeoff as always.

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Same old same old advice from this end.

 

1. If you have the K-55-V with the spring loaded terminals and the single phase plug, find, and buy a set with the dual phasing plug and replace.

2. Build some Type AAs from scratch using Jensen paper in oil capacitors. I know everyone is tired of hearing about this one. Sorry.

3. If you listen loud, change out the horn. However, if you do #2, you'll be surprised at how loud you can go before it gets harsh, which is probably just your ears giving out.

4. If you hate the K-77, I would try Dave's B&C DE120 set up. There should be enough loss through the high pass to avoid having to use attenuators. Maybe.

 

Has anyone ever seen inside of the chamber of the new LaScala? I ask because Roy packed the chamber of the Jubilee full of that stuff. I know they're not the same, but still similar in some ways I think -- so it makes me wonder.

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"I believe the back chamber may be slightly undersized for the driver and the padding made it seem acoustically larger."

 

The response looks even better if you undersize the rear volume by 30% (by stuffing with non-porus material), it now becomes reactance annulled (it is not as such in stock form).

Got a graph for this one Dennis? I'd be very interested in seeing what happens in the 70-100 Hz region as I high pass mine a lot higher than most...any extra sensitivity in that region would be a welcome addition in my application.

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I used O-Rings on my mid driver just put very small amount of Vaseline on the ring to help with seating . I also got better terminals from PE for the woofer wire going into the dog house. If they sit on hard wood floor install what they use to call grippers for furniture it keeps speaker hooked to floor without transferring vibrations. Then I put metal plate under the veneer I put on so I could put small round magnets in the grill surround trim so I could remove them or not. Base shoe molding is what you use for the grill frame regular 1/4  moldings looks wrong. I got pics some where on the forum...lol.  Rick

trippy answer - o-rings in the mid driver - can I see a picture -    2) furniture grippers - great idea - are these the round or square rubbers - and do you have a picture

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I ran my wire straight from the woofers to the barrier strip. I used hot melt around the wire where it passes through the wood to keep it airtight.

 

The O-rings should already exist between the exit of the compression driver and the entrance to the horn. If you don't have any, or if they are old and compressed -- you can get new ones from Bob for next to nothing.

 

Some people remove the bug screens. I've always been curious about this one since there is quite a bit of metal in that screen for the sound to reflect off of.

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