Advent 300 Brochure

The new Advent Model 300 is a unique stereo receiver
that, within its power capabilities, is designed to sound as
good as the best combinations of separate-chassis pre­amps, tuners, and power amplifiers.
At a suggested price of $269.95, the Model 300 receiver is
designed for people who can appreciate but generally not
afford the level of sound quality produced by the finest
audio components. We think there are a lot of people in
that category.

The Holman Circuit.

A major reason why the Advent Model 300 sounds the way
it does is an entirely new phono preamp section that is
audibly equal or superior to any separate preamp at any
price. Designed by Advent’s Chief Electrical Engineer, Tom
Holman, the new circuit is the product of exhaustive listen­ing, testing, and rethinking.
It came about largely because our checking of preamps of
all kinds and prices kept turning up no reliable correlation
between test measurements and audible quality. That
turned out to be because standard measurements for pre­amps weren’t checking their performance under actual
conditions of use - a fact that became the center for our
own development effort.
We found, for instance, that frequency response measure­ments weren’t being made with signals from phono car­tridges, but simply with the use of test generators. This
meant that important impedance interactions between pre­amps and various cartridges of different design-causing
very audible differences in actual high-frequency perform­ance-weren’t showing up in standard tests. Phono noise
measurements also didn’t cover the effects of cartridges.

And asymmetrical waveforms representative of music
weren’t being employed to check overall performance
under in-use conditions.
If you would like a full technical description of how the
Holman Circuit came about as a result of findings like
these, we will be happy to send you a reprint of a paper
prepared by Tom Holman for the Audio Engineering
Society. (please see our coupon.)
The main facts about the new preamp, however, are
these:

• It provides the full performance potential of any cartridge
used with it.

• Its effective noise is as low as any preamp’s.

• It handles actual asymmetrical musical signals flawlessly.

• It incorporates a unique subsonic filter that eliminates the

often severe performance problems (such as acoustic
feedback, amplifier instability, added IM distortion in power
amps and speakers, and loudspeaker damage) caused by
ultra-low-frequency pulses generated by warped and
eccentric records and by subsonic turntable rumble. This
unique filter is far more effective than a rumble filter, with
absolutely no audible effect on wanted low frequencies.
And the preamp sounds, as you will hear, the way we say
it does.

The Tuner.

Like the Model 300’s preamp, its FM stereo tuner is
designed for optimum performance under real conditions
of use.
That means it is deliberately not designed for the highest
possible sensitivity rating. Our tests of receivers and sepa­rate tuners (and subsequent checks of in-use perform-

A Very Different Stereo Receiver

From Advent

ance) indicated to us that the race for on-paper sensitivity
was causing audible problems for many people in the typi­cal urban and suburban reception areas across the coun­try. The straining for impressive sensitivity specs tended to
result in severe overload problems in many cases -causing
strong stations to show up at several points along the dial
and interfere with (or entirely blot out) other stations. The
loss of effective reception quality for listeners is very real
and important.
The Model 300 is consequently designed for the best com­bination we can manage of sensitivity, selectivity, and
overload margin. It shows up virtually one-to-one in this
crucial combination in direct comparison with most sepa­rate tuners costing far more.
The tuner section also offers Phase-Locked-Loop multiplex
circuitry that provides excellent stereo separation and
unusually effective suppression of the very common
“birdie” interference from stations that broadcast back­ground music and other subsidiary SCA signals along with
their regular stereo transmissions.
And the Model 300’s unique vernier tuning system and
LED tuning indicator make for consistently easy, precise
tuning year after year, with no chance for dial-cord slip­page and apparent changes in station location on the dial.
Perfect tuning is indicated when the two LED’s light with
equal intensity.

The Amplifier.

The Model 300’s amplifier will provide ample acoustic out­put levels with virtually any speaker we know of (including
all Advents) under the usual home listening conditions ­with no sense of strain or constriction. Yet it’s rated very
conservatively at a minimum of 15 watts per channel into 8
ohms, 40-20,000 Hz, with less than 0.5% THD. The facts
here are well worth going into.
Because of the emphasis on power output in audio adver­tising, manufacturers in the highly competitive receiver
market are under pressure to offer the highest rated power
per dollar. To do so, the usual design approach operates
output transistors at or near their limits and then protects
them with voltage/current limiting circuitry.
A receiver designed that way will deliver its rated power
into the usual test load (a resistor connected across the
output terminals) without difficulty. But a speaker presents
a more complex load than a simple resistor, and when a
receiver of such design operates into a loudspeaker, the
protective circuitry usually triggers at well under rated
power. The result is that a receiver of that kind just isn’t as
powerful, in real use with a speaker, as its rating indicates.
The Model 300 approaches things differently. It uses out­put transistors of the type usually found in units of twice
the rated power. It doesn’t operate them near their limits,
and so doesn’t require the usual protection. It will deliver
its full rated power into a speaker load, and the actual
loudness it can achieve before clipping is more than ample
for driving speakers under home conditions.
We realize it may be hard to believe that a receiver rated
at 15 watts per channel can do the full job with a pair of
speakers. But this one will- and we say this as a speaker
manufacturer with a good knowledge of what’s needed for

satisfying overall sound. It does so well, in fact, that when
we introduced the Model 300 to audio salesmen and
asked them how powerful they thought it was after hearing
it, they averaged a guess of twice its rated power, and
some guessed it at four times the reality.
Equally important, the output design of the Model 300
insures that there will be no audible side effects during
clipping at maximum output. The protective circuits in
many receivers can and often do cause disturbingly audi­ble side effects during clipping, and some of them gener­ate high-frequency pulses that can damage loudspeakers.
The Model 300 doesn’t.

The Model 300 As A Tuner-Preamp.

If there ever comes a time when a Model 300 user wants
higher power output (for super-loud listening in a very big
space), the logical direction to go is toward one of the
high-power separate amplifiers rated at upwards of 60
watts. (A 30 or 40 watt receiver just doesn’t offer that much
more actual acoustic output than the Model 300.)
In that case, and in lots of others, the Model 300 can serve
as a separate tuner-preamp of superb quality- fully as
good as separate-chassis units in audible performance, at
a fraction of the cost. It won’t offer quite as much flexibility
as the separate units, but the sound will be every bit as
good.
Not only does the Model 300 offer a tuner-preamp output
jack for this use, but it also has an input jack to its power
amplifier, so that it too can be used separately-with other
speakers, or with one of the new generation of time-delay
devices now starting to appear.

The Mobile Model 300.

In addition to the standard Model 300, we are also manu­facturing a special version, the Model 300/12, with a
switching-mode power supply for use on a 12-volt electri­cal system in a van or boat or where-have-you away from
home. The unique power supply of the Model 300/12
allows it to provide full rated power in portable use, so that
you can enjoy the same level of sound quality away from
home as in your living room.
If you would like more information before going to hear the
Model 300, please send us the coupon.
Thank you.

Advent Corporation, 195 Albany Street,
Cambridge, Massachusetts 02139

Please send :
Your literature on the Model 300.
A copy of Tom Holman’s paper on the
300 for the Audio Engineering Society.
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Address
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