Dynavector SuperStereo Adapter SS ADP-3

 
Specs:

Model: ADP-3 analog/digital SuperStereo processor with built-in 20-watt stereo power amp

Impedance: Line In 50K ohms; Speaker 300 ohms

Input Voltage: Line In 1.0 volt

Speaker Input Sensitivity: High 10.0 volts; Low 20.0 volts

Output Voltage: Adaptor line out 4.0 volts

Speaker Impedance: 4 to 8 ohms

Amplifier Output: 4 ohms load = 24w per chan.; 8 ohms load  = 20w per chan.

Mode: 3 SuperStereo modes selectable

Polarity: Reversible against front speakers with switch on front

Power Consumption: 90 VA

Dimensions: 430W x 70H x 282D mm

Weight: 6.2 kg

Provided accessories: AC power cord, speaker cables (2 pairs, 1m & 7m length), Operation manual, Warranty card

 

Dynavector Systems Ltd., Tokyo
https://www.dynavector.co.jp

U.S. Distributor: Toffco
toffco-usa@yahoo.com
 

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Intro


Since stereo first came on the scene there have been various attempts
to gain a more immersive surround sound experience that involved more
than just a flat frontal sonic proscenium.  One of the earliest
was the Haefler circuit, which basically just tapped the two + outputs
on a stereo amp and fed the resulting L – R difference information
signal to one or more efficient speakers placed on the sides or rear of
the listening area. It didn’t even require another stereo amp. There
are current processes which continue this often very effective ploy of
achieving surround effects out of two-channel sources, such as NAD’s
EAR.  Processors such as Dolby Pro Logic IIx and Circle Surround
II start with the same difference information but process it heavily to
achieve generally excellent results with most stereo material.

Then there is the entirely different approach of adding various delays
and sometimes equalization to the original two-channel signal and then
feeding it to additional speakers.  The Audio Pulse was an example
of such early devices.  The problem was that the delay was not
very adjustable – only in volume level. And in those days of the LP any
tick or scratch on a disc was heard not once but twice due to the delay
circuitry. Later Yamaha and others carefully measured the reverberation
in various sized halls and venues and built these options into their
receivers and processors.  One approach was to feed the delayed
sounds thru a pair of small speakers mounted high and in front of the
front trio of speakers.  Ambiophonics also uses delays and
multiple additional speakers to simulate the sonic immersion of the
concert hall environment.

Theory of the SuperStereo Approach


The late Dr. Tominari of the Japanese analog tonearm and cartridge
makers Dynavector worked for 18 years and received patents on his
individual approach to achieving a more three-dimensional sound out of
standard stereo sources.  He developed two earlier SuperStereo
models and the sophisticated ADP-3 had been produced by Dynavector
since his passing.  An important finding of Dr. Tominari’s
research was that the low frequencies are not absorbed in a hall nearly
as much as the high frequencies, causing them to bounce around many
more times and undergo a longer delay. Also, the higher frequencies are
reduced and scattered more on their way to the listener. The delay
cannot just be turned up, because at around 30 milliseconds it turns
into an echo.  This is why a single delay time for all
frequencies, as in the Audio Pulse, was unsuccessful.


SuperStereo uses differential time delays across the audio spectrum and
the high frequencies are attenuated.  Thus the 30 ms barrier is
broken and the third and highest of the ADP-3’s three modes allows a
maximum of 343 ms.  As far as I can determine from the extensive
white paper on the Dynavector site, the circuitry does not make use of
the L – R difference information; it processes the left and right
channel signals separately.  That actually qualifies it as what I
have ruefully called the Yamaha approach – a “boingerizer.” But wait a
minute – the SuperStereo is unique and a great deal more sophisticated
in its proprietary processing than the “hall simulators.”


The white paper is titled “Why the Current Standards for Hi-Fidelity
Reproduction are Inadequate and How Dynavector’s SuperStereo System
Addresses the Problem.”  It speaks about how the goal of high
fidelity reproduction has been to realize an ideal transfer function of
one (the relationship between the input and output of an audio
system).  It says that for the most part the technology has now
achieved that with virtually perfect frequency and phase response, but
most people would agree that there is still a huge gap between live
music and its playback on an audio system.


Dynavector observes that the accepted criterion of high fidelity are
only valid in special situations such as an anechoic chamber or an open
space outdoors.  In an enclosed environment the propagation of
music signal waves is entirely different and much more complex. In real
music many signals of many different frequencies occur at the same
time. Some differ only slightly from the fundamental tone, thus
generating beats due to the frequency differences. The beats tend to
propagate differently from the fundamental tone, even to traveling at a
different, slower velocity.  The complex sound waves of music are
shadowed by these later-arriving beats caused by the side frequencies.
Such time misalignment makes the sounds of music in a concert hall more
rich, colorful and enjoyable.


Dynavector feels that no loudspeaker can recognize and reproduce
separately both the phase velocity and the group velocity from the
input signal (which are different), no matter how accurate in frequency
and phase it may be. Their opinion is that multichannel surround
systems completely ignore this concept. “The character of the sound of
music played in a concert hall is very much dependent on the state of
the shadows at the listening point…to enjoy the playback of music in
a listening room…as if one were at the original concert, the group
and phase velocity should be reproduced separately.”

Setup and Controls


And the SuperStereo processor does this by producing from the L and R
channel signals numerous group delays thru the entire audible frequency
spectrum.  These signals are played thru two additional small
speakers which are placed not at the sides or rear of the listening
room, or even high in front as with the Yamaha approach, but located at
the same height as the two front speakers, a few feet in front of them
and to the outside.  The idea is that there is a mixing or
interaction acoustically in the room between the front and the
additional speakers. (Dynavector calls them sub-speakers, which I find
highly confusing.)  While the group delays thus produced in the
listening room are not identical to those in the original venue, the
feeling of life-life reality is enhanced by the system when playing
standard two channel sources, whether they be optical discs, movies,
vinyl, cassettes or even FM.


The ADP-3, by including the stereo amp in the processor, is designed to
require only the two additional small speakers. I used a pair of the
inexpensive Paradigm Atoms on their metal stands, which brought the
mini-monitors to exactly the height of the tweeter and the high
frequency of the two woofer drivers on each of my Von Schweikert VR-2
frontal speakers.  Due to a tight situation near the picture
window on the left, I had to angle the Atoms in toward the VR-2s, which
is also suggested as an alternative in the ADP-3 manual. I placed them
about 2 12 ft. in front of the VR-2s. The diagram above show the hookup
and location of the speakers, although these are not angled toward the
main speakers.


I found only the level control really useful in operation. The phase
switch always sounded better in phase with the main speakers, and the
middle of the three modes nearly always sounded best with most
sources.   The first mode is for small group recordings or
studios with little reverb and the third mode adds a huge amount of
reverb which would only be useful on recordings in a large cathedral
where the original two-channel recording probably has plenty of reverb
already. There is a red overload LED which never let except when
turning the processor on and off.


On the rear of the ADP-3 are line input jacks, which I used from my
Sunfire Theater Grand preamp. There are also speaker input terminals if
you prefer to feed the unit speaker-level signals. I would think that
could only degrade the sound since you are then processing the signal
with distortions added by the main amplifier. The ADP-3 also has output
jacks for a larger amp in case you want to use some higher-quality,
less efficient speakers. It occurred to me that there would be an even
better timbre match if I mounted a pair of Von Schweikert VR-1
mini-monitors as the additional speakers instead of the Atoms, and I
don’t believe a more powerful amp would be required for them.

A/B Evaluation of the ADP-3 Adapter


I started with some standard stereo CDs I was reviewing.  There
seemed to be little effect until the level control of the ADP-3 was
turned to about the 3 o’clock position. Then a richness and bloom was
added to the sound that made it extremely pleasurable.  A greater
feeling of the particular venue’s environment was definitely
provided.  With proper setting of the level control – which I
arranged close at hand since there is no remote – I was able to obtain
a wider soundstage, with more “air” around the individual instruments
and a more solid sonic picture. I found a setting around 4 o’clock
position to be the most-used.


I was curious if the ADP-3 suffered from the double-click problem of
the old Audio Pulse and thus got out a few of my more
“actively-appreciated” LPs.  Even on a serious groove click there
was not a doubling of the sound – in fact fairly scratchy vinyl sounded
less so.  I was also curious about the processor’s effect on mono
sources, since a mention of that ability was made in the unit’s manual.
I tried a recent First Edition Music reissue of some mono recordings of
works by Villa-Lobos: Erosion, and Dawn in a Tropical Forest, with the
Louisville Orchestra.  The Louisville series was not known as
being in the highest fidelity, and the mono sound was rather dry and
dull.  Bringing up the volume control to about the 3 or 4 o’clock
position brought a tremendous lift to the music, adding a depth and
feeling of the orchestra playing in a real hall.  Few would have
been able to identify the recordings as mono.  Dynavector suggests
bringing up the level slowly until it is about the same as issuing from
the front speakers or even a trifle louder.  It is critical to get
the level just right – too little has little effect, and too much
buries the music in excessive reverb. The manual says to try the higher
and lower positions of the Mode switch after getting the level right,
but I disagree.  The lower setting usually needs the level
increased and the higher setting has such strong delay that the level
has to be reduced somewhat.  Once the mode and level are set for
any recording, the main volume control of the preamp or receiver
becomes the master level control, obviating the need for remote control
of the ADP-3.


The next mono source I tried was one of the very few which didn’t fare
well with the ADP-3.  It was the excellent reissue on an Italian
label of the mid-1930s Pablo Casals recordings of the Bach Sonatas for
Unaccompanied Cello.  No matter what mode or level I selected on
the ADP-3 the cello either became much larger than life or sounded like
a cello duo – one instrument at the left and another at the right
frontal speaker. It also sounded more like a string bass than a cello.
Changing the phase made it worse.  I also selected a bunch of
vinyl – both mono and stereo – and found all of them benefitted from
the SuperStereo treatment when the proper level was achieved.  One
of them happened to be one of those “rechannelled for stereo” LPs, and
it struck me that SuperStereo creates a 100% better spatial impression
out of most mono sources than directing highs to one channel and lows
to the other ever accomplished.


I got out a 1989 Philips CD of four Carlos Chavez works conducted by
the composer.  These stereo recordings were made on 35mm film by
Everest in l958 but had some hiss. Unfortunately this was the first
iteration of the No Noise digital noise reduction system, and Philips’
and other label engineers made rather ham-handed use of it – overdoing
the reduction of high frequencies to the point of dulling the life out
of the music.  Inserting the ADP-3 signal at Mode No. 2 brought
life back to the music and made it most listenable. Most of the others
in this series were mono and the SuperStereo brought their
dead-sounding sonics back to life in every case.

Multichannel Uses


The ADP-3 is designed for two-channel diehards who have a pair of high
quality speakers, or at least high enough quality to warrant spending
$2000 on a processor to improve their fidelity and create a more
natural sonic image.  However, since the improved dimensionally it
creates  does not extend much past the frontal soundstage, there
is no reason it cannot be added as well to a standard 5.1 surround
system, which is what I did.  On many multichannel SACDs it
expanded and widened the frontal soundstage and seemed to begin a
filling in toward the sides which blended perfectly with the surround
speakers – even though mine are a bit further to the back than the
recommended 5.1 speaker placement diagram.  I found the best
balance was often with the level slightly lower than when using only
the front two speakers. Hi-res sources often have more detail in the
reverb tails and thus may not require as much of the SuperStereo signal
to be mixed in.


There is one problem with using SuperStereo with the normal
left-center-right arrangement of the front channels: The addition of
the signals from the two additional speakers mixes with the left and
right main speakers and thus achieves a higher volume level on those
two speakers. Whereas the center speaker has no added effect speaker
directed at it, and thus recedes in level compared to the left and
right.  Usually being a smaller speaker than the left and right
also works against a balance.  I found raising the level of the
center speaker in relation to the left and right helped a bit but was
not a perfect solution. It is obvious the processor is designed to be
used with basically two frontal speakers.


I think the best multichannel use of SuperStereo would be a 4.0
surround system without a center channel.  One extremely welcome
feature of the process is a major widening of the sweet spot, which is
part of the reason for being of the center channel speaker.  In
fact, the sweet spot created is so large that listening in an adjoining
area is much more enjoyable than without the SuperStereo.  My
dining room area is off my listening room space and the front speakers
are at a 90-degree angle to it.  With the ADP-3 I get a greatly
improved sound while at the dinner table.  In fact this is the
feature I believe I will miss most of all when the unit is returned
after reviewing.


The ADP-3 is recommended for use on video soundtracks as well as
straight audio, so I used it while viewing several DVDs.  
With music DVDs it was as effective as with audio-only discs.  On
some I had to raise the level on the surrounds a bit to match up with
the higher levels in the frontal area.  However, I found even the
Position 1 setting of the Mode control and a fairly low setting of the
Level control resulted in an unnatural echo being added to most of
dramatic films’ dialog tracks.

Conclusions


The Dynavector white paper states that SuperStereo can improve
difficulties in listening room size and acoustics, and that no special
room-tuning treatments are needed with it.  I can see that could
be true, but I must disagree with their statement that it does not
interfere with room decor. I should think the presence of two more
speakers on stands placed out into the room some distance in front of
the two front speakers with the backs facing the listening area would
be considered a major interference by most users – meaning this is not
just a W.A.F.  Those proudly owning a pair of really striking and
expensive high end front speakers might not be happy to have a pair of
underfed monkey coffins on stands facing them. Dynavector reports they
have had good results with the small Gallo spherical speakers, which
would certainly be less imposing.


SuperStereo does work quite successfully.  I could imagine
a staunch two-channel audio buff interested in getting a more natural
and immersing effect going for the ADP-3 in a big way.  Especially
if he or she concentrates on classical and jazz genres.  I didn’t
find the process added that much to most pop music, which is already
pretty processed and doesn’t occur in a natural venue with normal
reflections of the sounds.  Recordings with natural acoustics
provide the very best sources. It also brings new life to old mono
recordings for those into historical recordings by past masters in the
classics or jazz. I would think an especially synergistic combination
would be someone with such a collection and the very specialist Helicon
mono-only cartridge – a combination made in heaven!  


But the ADP-3 could transform a very basic entry-level audio system as
well – expanding the soundstage greatly and improving the bass
reproduction, even without a subwoofer. Even smaller additional
speakers could be used facing the main two speakers. The super-wide
sweet spot provided by SuperStereo plus the improved sound in adjoining
rooms and areas would be other major pluses for the processor. Anyone
who appreciates the advantages of surround sound for music but doesn’t
want to deal with side or rear surround speakers or the extra
electronics involved would find the ADP-3 a much simpler solution whose
enhancement to any two channel audio system is certainly not subtle by
any means. It would be best to try out the unit with one’s home system
first, but unfortunately there are few dealers as yet.


– John Sunier