I have an AD10 in the music system in my office. The AD10 had circuitry
for B-format input as well as more options on the front switches. I have
also read that the component quality of the AD10 was better than that
for the AD7, but never having seen an AD7 I can't comment on that.
>From some documentation I found a couple of years ago that appears
originally to have been Minim publicity:
*Ambisonic Surround Sound Decoder AD10*
A decoder with a very high technical specification that
incorporates all the currently available facilities in Ambisonic
Surround Sound technology. It will accept UHJ encoded 2 channel
signals from sources such as record, tape or tuner and 3 channel
B format input signals suitable for professional playback
systems. These will be decoded into signals for feeding to
a four speaker system. A layout control compensates for different
speaker arrangements and is continuously adjustable between aspect
ratio 2:1 and 1:2. The circuit elements used are designed for
minimum in circuit crosstalk. Where speakers are placed more than 3m
from the listener a distance button compensates for the different
ways in which wave fronts travel at low frequencies.
Two special controls are included on this model. FOCUS allows the
listener to make alterations in the soundfield as heard in the
listening room which enables him to focus more easily on details in
the front sound stage. POSITION gives more weight to sounds from the
front or back, depending on the switch, so that the listener may,
effectively move himself forwards or backwards in the
'concert hall'. An example of when this might be used is in the
relay of a live concert where FORWARD POSITION would be applied
during the music to reduce the audience coughs etc and BACKWARD
POSITION at the end so that the listener felt more part of the
audience.
With normal stereo sources the STEREO ENHANCE control can be used
to widen the sound stage from a central mono image to a
complete surround picture. With classical music the enhance
control can be used to provide an illusion of ambience which
is most pleasurable. With pop music, effects can be created to
provide greater involvement for the listener in the music.
There is a stereo BYPASS switch so that conventional stereo
playback may be irade through the front two speakers without having
to disconnect the decoder. An omnidirectional signal is available to
feed sub-woofers.
The circuitry used in the AD10 has been optimised for the most
accurate Ambisonic playback and highest quality sound reproduction.
Special versions are available to meet monitoring and professional
requirements and a conversion for six speaker layouts will be
available.
*Ambisonic Surround Sound Decoder AD7 *
For listeners who wish to enjoy the benefits of Ambisonic Surround
Sound but do not require all the available facilities the AD7 will
be suitable. Smaller in size it decodes UHJ 2 channel signals and
B format signals. It also has the stereo enhance facility with
the amount of extra width adjustable by the listener using the
stereo enhance control. So that the listener can return to
conventional 2 speaker stereo without disconnecting the decoder a
stereo bypass switch is fitted.
By minimising the number of controls we have been able to sensibly
reduce the circuitry and not sacrifice the high quality components.
A switched layout control compensates for different speaker layouts.
The AD7 is capable of most pleasing musical results.
Looking inside the AD10 the quality does not seem to be anything
extraordinary, but neither does it use noticeably 'cheap' components.
I read in a review that the AD10 was intended to be sold at a realistic
price of about $600 and the AD7 sold at a bargain $200. That review also
mentioned that the AD10 used closer-tolerance components that would
additionally be hand-selected for closer matching. Since the review
appears to have been written before production was fully under way, I
wonder if that was indeed done for production AD10 units.
Over the years I have found two different circuit diagrams that seem
both to be for the AD7, but none for the AD10. One circuit diagram shows
a B-format input option, like my AD10 has, but lacks several of the
other features of the AD10 (Focus control, Layout control as a pot
rather than a 3-way selector switch, Position selector switch, Stereo
Enhancement control, Distance compensation, 'Set' (sends mono to all
outputs, for level balancing), etc.); the other circuit diagram lacks
also the B-format input.
Does anyone have or know of a circuit diagram for the AD10?
Gerard Lardner
On 30/04/2011 11:58, Richard wrote:
> Hmmm, out of interest, how many more should there be. Also a question, I
> thought on only X & Y were phase shifted +90 degrees during encoding, am I
> wrong in this thinking?
>
>
> The AD-7 was designed to use a small number of components,
> it has just three phase shifters. The AD-7 is not a precision
> reference decoder, but at least for me, it did it's job for music
> listening.
>
>
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