Wilson MAXX musicallity and sound

Like Dave says in his descriptions of the Sumiko Master Set procedure, getting the focus right in bass, mid, treble and everything in between is very difficult but achievable. If you want to DIY, you can use mono recordings to assist in getting balance and focus correct. In my particular setup, when my Wilsons were in the incorrect position, the bass would shift around 1 foot to the left of center even with mono recordings. Or the bass would sound like it was a coming from a different speaker and not contiguous with the rest of the music. I guess this is the result of an unlevel frequency response caused by the cancellation or doubling effect of sound "nodes" occurring in the room.

However once I hit that sweet spot, suddenly, the image became dead center, the bass, mid, treble and all in between grouped together in the center and played as one (remember it's a mono recording, I use one of Ella Fitzgerald's earlier works). Forget testing with stereo recordings, there are just too many variables and unknowns.

Don't forget that your sitting location is important too. You have to choose your favourite sitting location and then optimise the speaker setup for that one location. I find that speaker setup is dependent on the sitting location and even hifi components. I had my sofa too close to the back wall by 4 inches and just couldn't get the speaker focus right. When I moved the sofa forward, the focus eventually snapped into place.

If this sounds all too complicated, just call someone and pay for a proper setup. For me, it's part of the hobby and learning process.

Based on what I see all your equipment is excellent,but there has been significant improvements in digital recently. Two years ago I purchased an MSB Tech Platinum CD Player II and I am on my second upgrades and I can tell with each one there was a significant improvement in sound to do with range,clarity and depth of the music. Stereophile has rated the MSB DAC the second best in the world. The best one was for over $30,000 and the MSB sells for around $6,000 ,it probably as good as it gets. MSB Tech is a neat little company in California and all they really care about is are DAC's they do have other stuff to go along with it but their main focus is the Dac. Upgrades are always available when they make the next significant improvement.Plus they have the new ilink which will tolally Plow you away it make any cd player obsolete. I now sit for hours listening to music that I haven't listen to in years.
From what I here Accuphase has fallen way behind in technology in this area.

"I wonder how we'd measure the intermodulation distortion at the listening position, do you have any ideas? This is about way more than frequency response."

Dave- Forget ID measurements, just try to borrow a TacT RCS unit which will measure frequency, pulse response and allow you to EQ the system. They also have a feature call
XTC(see: http://www.ambiophonics.org/Ambiophiles.htm), which should work wonders on a set up like yours.

How and why would I forget IM Distortion???? It's way more important than EQ in making the system "listenable". You're shooting at the wrong target when you put all your focus on EQ.

Dave

I wonder how we'd measure the intermodulation distortion at the listening position, do you have any ideas? This is about way more than frequency response.

I don't think you mean IMD. IMD comes from an amplifier driving a bass signal (amps) and a midrange signals (milliamps) at the same time. The huge demands from the bass signals will cause new frequencies to be intermodulated around a vocalists voice or other midrange instruments (called sidebands). These intermodulations are totally unrelated to the voice of the vocalist and are very intrusive. For example, a kick drum at 80 Hz played at the same time as 500 Hz, 1000 Hz and 2 and 4 Khz harmonics from a vocalist creates all kinds of additional frequencies....920 Hz, 1080 Hz, 2080 Hz, 1920 HZ, 4080 HZ and 3920 Hz and many more multiples of the 80 Hz. such as 1160 Hz and 840 Hz and so on and so forth. This results in a loss of clarity and makes it harder to hear detail - it can also be fatiguing. Think of it as a blurry lens...or camera shake on a photo...the amplifiers huge efforts at big power hungry kick drum bass is "shaking" or "blurring" the midrange vocalist.

However, this is not what I think you mean. I suspect you are referring to Comb Filtering. This is where one reflected wave interferes with another. For example: bass frequencies are omnidirectional up to about 600 Hz so these frequencies radiate backwards from your speakers, bounce off the wall behind them and selectively reinforce or destroy all of what you hear in the lower midrange.

There are only three known solutions to properly hear the lower midrange primary signal;

1) Place speakers at least 6 feet from the wall behind them and sit close to the speakers (this reduces the effect dramatically and it is exactly how near-fields are used in studios to get an accurate mix)
2) Soffit mount the speakers (eliminates the issue altogether)
3) Headphones

Above about 600 Hz this is a non issue as the rear wall behind the speakers no longer has any effect as sound only raidates forward from typical box speakers at these frequencies. So this issue is most noticeable on male vocals. If you find female vocalists very tightly placed in the soundstage and beautifully transparent and crystal clear but male vocalists do not sound quite as clear, transparent ot tihtly focussed in the same way => then "comb filtering" or rear wall quarter wave cancellation is typically the problem....move your speaker well out into the room if you observe this!