Dear Fellow SC IVA owners

Every room is different, to say nothing of our differences in personal taste.

When I owned my Princesses, I went through a careful exercise to achieve the smoothest bass response in my living room. Note that was different than seeking the maximum bass response at a given frequency. Using a Stereophile test CD and a calibrated SPL meter and measuring from the listening position, I inched my speakers out into the room by 2" increments while measuring each position. When I found the best distance I then measured again one inch either way from that position. I ended up with the equivalent front plane of the drivers for each speaker 40" out from the front wall. Any distance closer resulted in an increase in bass frequency (<200 Hz) variation.

My point is not to recommend a 40" placement for anyone else, but to suggest that placement too close to the front wall may produce more apparent bass, particularly if this creates a peak at say 50, 63, or 80 Hz, but this will not be the smoothest overall bass response. Be certain of what you are trying to achieve.

Jonathan I have not checked for some time, are you still doing your jazz program?

Pryso, thanks for this data. Yes, I believe your basic concept is the answer. Move the speakers bit by bit until you achieve the highest quality or balance. Each room/equipment relationship is different. I know one thing. My speaker are in the world class realm now with recent changes including a clarity and detail which I did not have before. I have more work to do though. And the musicality is not only still there, it has increased. (Yes, I am on twice a week now with the Jazz program. Friday/Sunday at 7pm unitl 9pm EST. NPR affiliate called Robinhoodradio.com. I think you'll enjoy it. All nonprofit. Just finished preparing tomorrow night's show. Jonathan

Jonathan, I just don't understand how letting your speakers run full range and adding a subwoofer can improve the midrange.

I have heard improvements by using a crossover while adding a subwoofer thereby relieving the main amp of low frequencies and removing bass energy from the main speakers.

What exactly was the improvement you heard? I am curious.

Dear Rrog, I have no idea why adding subs with no crossovers improves the mids, but it does. I put on JL Audio subs crossing over very very low at 25Hz with very little volume (barely on) and the mids opened up and are cleaner and clearer. And the bass is slightly extended. The JLs match well. I have no idea how this can be and would never try to explain or defend it. But I hear it and so does my recording engineer associate who taught me this. I'm so used to it that when I try the system without the subs I don't like it nearly as well.

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