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Dear Fellow SC IVA owners

Dear SC IVA owners. I recently made some improvements to my SC IVAs that were transforming when all were added up together. I thought I'd share these and hope others contribute to what improvements they have made. 1. Added Sunfire IV subwoofers set at the lowest crossover point and very very low volume. This improved midrange noticeably by opening it up while the bass went a bit deeper. Spread speakers out from each other nearer sides of room so at least 2.5 feet farther from each other with major improvement in detail and clarity. Added symposium ultra platforms under each speaker with Walker points under the platforms. Major improvement again. All of these transformed my sound from very good but slightly cloudy to very clear with even deeper and tighter bass, a scary musicality rare in any component and a top to bottom coherence that this speaker is known for. I hope someone else has had similar success and perhaps some other new tips. All of these improvements except the subwoofers came from suggestions from other Audiogon members.
jonathanhorwich

Showing 4 responses by timlub

timlub
2,039 posts
 
Hello all, I have researched D'Appolito designs quite a bit and built my first speakers in 1979.
"A true D'Appolito design requires a 3rd order 18bd per octave crossover allowing the drivers to have the same horizontal dispersion characteristics".
The above statement used to be accurate, but no longer is. D'appolito started that way and used 3rd order electrical slopes. Today, he has changed most of his designs to 4th order acoustical slopes. He specifically found that with the tweeter at ear level, this crossover improved the Symmetrical dispertion pattern maintaining good phase and amplitude summation.
4th order (linkwitz riley) acoustical puts your acoustical slope 6db down at the crossover point. Time alignment and proper phasing are much easier to achieve here and D'Appolito did tons of research of lobing and cancelation effects in vertical alignment.
I am currently useing D'appolito I use 12/18 electrical slopes to achieve 24/24 acoustic.
I am not speaking for Dunlavy in anyway, I have not seen crossover schematic for SC IVa
timlub
2,039 posts
 
Also, Just looked at the SCIVA... The only thing in common with D'Appolito is that they use a wmtmw arrangement. Totally different design parameters. These Dunlavy's are extremely well thought out speakers. Dunlavy achieves time alignment through voice coil alignment, he keeps speakers very cohesive by using 6 db per octave slopes, he handles baffel step compensation by the use of felt...He tackles every problem.... in a different way and by what I can tell with terrific results.
timlub
2,039 posts
 
Hi Pryso, the wool was strictly diffraction control. I agree with you on the subwoofer points also.
timlub
2,039 posts
 
Pryso, you are thinking right. A very basic description would be, Stepped baffle is putting the tweeter behind the same plane of the woofer to align voice coils. (kinda like a stairstep) That is why I called it voice coil alignment in my earlier post, that is stepped baffle. You are actually putting the voice coils in alignment. The idea is that the sound radiates from the same point for correct time alignment of the signal to your ears. The dispersion from the drivers then bounces off the frame of the drivers. The wool felt absorbs part of this to keep the reflections from warping the frequency (defraction). You can also align the signals electronically, this is called stepped baffle compensation for time alignment.
I hope this helps, Tim
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