I recently had a good price form a member here on a Marantz AV 7701. I'm familiar with these pre/pros, as I have one at our Eagan residence. I have never used any Audyssey Eq of any nature, as I just did not like the audio results.
My previous pre/pro was a Marantz 8003, now 10 years old. The Audyssey version is Multi Eq. The crossover was global and the lowest cross point 60 Hz. In any event it worked well with all speakers set to large and the global crossover set to 60 Hz.
The 7701 has Audyssey MultiEq XT. It has individual crossover as low as 40 Hz, Dynamic Eq and Dynamic volume.
In order to make sense of this report it is necessary to describe in some detail the speaker system in this AV room.
The front three speakers.
The left and right speakers consist of dual aperiodically damped lines, (not mass loaded). These lines are tuned half an octave apart. The shorter line is MTM with an F3 of 42 Hz. The larger line is essentially an integrated sub plus. The plus is that the two 10" drivers operate as the "Sub" but the upper driver of the two also handles the baffle step compensation for the small drivers above. This is a low Q non resonant design.
When installing the new pre/pro I built and installed a new mixing circuit for the BSC and Sub/LFE that is fed to the upper 10" driver. The Baffle step compensation is completely controllable and can be precisely instrument set to the location. Apart form an active filter deriving the BSC signal which is first order transitioning to second this cross between the MTMs and the upper driver is acoustic. This is a minimal phase design with only a 45 degree phase shift. Powering of the left and right speakers is from three Quad 909, 250 watt per channel power amps.
This is the FR measured before Audyssey set up.
Dispersion is wide.
The center speaker is another aperiodically damped transmission line with an F3 of 44 Hz. It should be noted that these TL lines roll off at 12 db per octave and not 24 db per octave.
The speakers are SEAS Prestige coaxial units built under license by agreement with KEF. The lower driver is just above the screen. The upper driver is a fill driver providing the BSC, powered from a separate amp from and electronic crossover. The tweeter in that unit provides compensation for HF issues, principally a 9 KHz dip due to cancellations from reflections off the woofer cone. Unfortunately there is no good purely passive crossover solution for these drivers.
This is the axis response of this speaker taken just before Audyssey set up.
Although using different drivers to the mains, the sound from the front stage is seamless. As opera singers move across the stage there is no discernable change in their voices.
Of all the speakers I have designed, I have a real soft spot for this center channel speaker. It reproduces human speech just about perfectly. There is no "chestiness" or shout. Dialog is clear and the volume does not have to be excessive. I have never had to increase the volume to this speaker to hear dialog ever.
The speaker is powered from both channels of a Quad 909, 250 watt per channel amp.
The surrounds are speakers from 1984 and the first I designed using software. I bought floppy discs from Bullock and White for my Apple 2e I had just purchased. Drivers are a couple of Dynaudio high power drivers emplying 2.5" VCs with Dynaudio D 28 AF tweeters, in a sealed minimal ripple designed enclosure.
This is the FR.
The ripple at 100 Hz is about double the projected. In those days before the sub era you chose drivers with an alignment that gave some ripple for sealed designs, otherwise the F3 tended to be unacceptably high. For these speakers F3 is 52 Hz second order roll off. The speakers are powered from a Quad 909.
The rear backs are more complex. They are dual TLs with the smaller line non speaking. The design started in 1976 with a major revision in 1984. There is an active crossover at 110 Hz third order. There are first order crossovers at 900 Hz, and 5 Khz using a series rather than the usual parallel crossover configuration. Because of the length of the driver lay out these speakers are very difficult to measure, and their design arduous, especially given the date of the design when tools were very primitive. The speakers are powered by two Quad 909 amps.
This is the response.
As you can see there is a powerful bass response to 25 Hz, but there is a dip at 38 Hz. As I said these speakers are hard to measure and it looks as if the bass Kef B 139s are turned up to high. However by ear this is the optimal level for the bass drivers crossed at 110 Hz.
So that is the system. Audyssey set up was done by the book with three front row and three back row mic positions.
The first problem was that results were inconsistent. Audyssey could not make up its mind about phasing. reporting rears in or out of phase on a whim, and sometimes saying only I rear out of phase. It was inconsistent about phase of the center channel. Careful tests revealed phasing was correct by measurement and seeing nulls at crossover reversing drivers. So Audyssey I think is fond of a coin toss.
An even bigger problem was that it wanted to cross my lovely center at 200 Hz. Then apply massive boost and cut on alternate sides of the crossover. The acoustic result was awful with total ruination of the lovely sound of this speaker. It sounded horribly shouty and hard.
So I investigated.
This is the room response of the center channel at the front row just under 12 ft. away.
There is a slight null in the room response just below 200 Hz.
So I increased the BSC and got this response.
After this Audyssey set the center speaker to large consistently.
This is the response from the center under measurement with the BSC titrated to the minimum so Audyssey would not cross the center over at 200 Hz.
As you can see BSC is clearly excessive. It sounded excessive also with definite "chestiness" to voices.
This is the correct BSC by measurement and listening.
So that was frustrating start to the set up and not auspicious.
In part 2 we will go into the rest of the set up and consider the reasons why Audyssey does what it does.
