equalization is typically needed to
optimize the in-vehicle response of
high BL product drivers in an often
resonant environment. In the final
result, it’s always the listener that’s
the judge of what is best and that can
only be attained by giving flexibility.
Back in the late 1980’s, Richard
Clark used a pair of Crown car
audio power amplifiers in his
IASCA-dominating Cadillac. What
can you tell us about the design of
this early Crown amplifier and,
also, what happened to the distribu-
tion?
Crown can be rightfully accused of not
having taken the car audio market
seriously. For a brief period of time,
Crown sold a product wherein we’d
contracted the design and had it made
in Taiwan. It was a conventional class-
AB design with a switch-mode power
supply. Not having been willing to
develop the market, we simply pur-
sued more profitable things, such as
making gradient amplifiers for MRI.
At Autosound 2000, we have a six
amp set of your 10,000-Watt Crown
- Techron power amps in our test
lab. We configure them in series
and parallel for various tests and
they’re incredible. Did you have
anything to do with the design of
those monster amps?
Yes, I was the main designer of these
amplifiers that owe their heritage to an
industrial line of amplifiers made for
medical imaging in MRI machines.
Very large high-performance ampli-
fiers are used to drive the whole-body
gradient coils of such machines. The
BCA technology was also created to
first make gradient amplifiers.
Will Crown-designed car audio
amplifiers use ODEP (Output
Device Emulation Protection) cir-
cuitry? Is so, what will this do for
performance? If not, why not?
Junction temperature simulation or
ODEP can be applied to switch-mode
amplifiers but is of less importance
compared to its value in dissipative
amplifier designs. It’s better to make
less heat than to optimize and protect
dissipative processes.
When will installer-programmed
adaptive signal processing be
included in the design of power
amplifiers? The idea here is that
various speaker parameters could
be programmed into the amp’s
processor so that we could get 100
percent speaker performance —
with no danger of destroyed speak-
ers. Any thoughts here?
As to when, I cannot say. But, it is
true that more can be done with digital
signal processing to protect and
dynamically equalize loudspeakers
than is being done today.
How did you get involved in design-
ing audio components? Can you
tell us some of the highlights of
your career?
If you jump on Google
(www.google.com) and search on my
name you’ll find a couple of interviews
that have been done that give some of
my ancient history. I started in the
vacuum tube era, and moved on to
the dissipative solid-state designs and
am now in the third major generation
of audio power — the switch-mode
era. It’s been fun.
How large do you think car audio
amps will end up in the next 10
years? What are the practical lim-
its?
The adoption of 42-Volt DC electric
systems will be helpful to making larg-
er amps as the 6000 presently uses a
0-gauge power feed. Just as higher
voltage audio output makes the distri-
bution of low-loss audio more practi-
cal, so will higher voltage input power.
Do you think we’ll ever see the day
when the loudspeaker will be in a
“closed loop” with the power ampli-
fier as opposed to running them
“open loop” as we do today?
Yes, there will be some closed loop
systems, but note that they’ll encour-
age “canned” solutions which will
reduce the configuration options that
the customer will have. As an interest-
ing historical note, see U.S. patent
1,822,758. In 1929, after Harold Black
first invents negative feedback, the
patent office issued this patent to
Pierre Toulon wherein is shown the
first use of closed-loop on a loud-
speaker. Toulon’s patent on negative
feedback was actually issued before
Black’s but he did not file first.
Since you started designing high
powered amplifiers, what amplifier
components have experienced the
greatest advances?
The active elements have undergone
the most advancement. All power
designs are limited by the perform-
ance limits of the tubes, bipolar tran-
sistors, MOSFETs, etc.
Many car audiophiles feel that sub-
jective testing of amplifiers shows
that size is the most important fac-
tor in sound quality. Do you agree
or disagree?
Size is a vital part of the system, but
brute size alone is not sufficient.
Fidelity is always required. Switch-
mode amplifiers are very old — the
first instance can be traced to
Burnice Bedford in 1930, U.S. Patent
1,874,159. Not until recent years has
their fidelity been adequate to be
used in high-performance audio. To
that end, the BCA design leads the
charge.
Our thanks go to Gerald Stanley for
taking the time for this interview.
We’re looking forward with great inter-
est to Crown car audio components
and Gerald Stanley designs.
