Acoustat X Owners Manual

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Acoustat X Owners Manual

Extracted text from Acoustat X Owners Manual (Ocr-read)


Page 9

THEORY OF OPERATION

in order to understand the operation of the Servo-Charge amplifier, it is very
usefull to have at least a rudimentary understanding of the load which it was

designed to drive,
Acoustat uses what are referred to as constant charge electrostatic transducer
panels in which the electrostatic "plates" are driven in a push-pull format and

the driven diaphram is biased in such a manner that its electrostatic charge
remains constant despite the application of high voltage audio signals to the

electrostatic plates .

l C =q/V

I 1 J =CV2/2
e E is ‘ _
s l l1 l‘ w ' F =_Eq

I l
o _

l I Where: C capacitance in fared:
* . + 41 ' V voltage in volt:
‘ l + l ' J energy in ioules
. * V F Force in newton;
4 l ' l _ E electric field in

I | newton: per coulomb '
‘ I * " “ q charge in coulomb:

I t

i

measure at e lectvic
field

newtons per coulomb
and volts per meter
[ are alternate units at
l
I

While we admit that the physics is not "obvious at a glance" we will, for the
purposes of this amplifier service manual, simply state the electrical requirements
to drive the electrostatic loudspeaker panels that we use at Acoustat Corporation
and not dwell on the physics of electrostatic loudspeaker design.

Page 27

SYMPTOMS

Unit shuts down
to standby, but
comes back on
immediately .

of

Unit will not

shut down to

standby mode.
or

Unit will not
turn on from

CAUSE

Defective LC.
or Arcing tube

Detective LC. ,
Q5 Transistor or

CURE

A detective integrated

circuit can cause this problem.
The OP-ll device was found

to be particularly prone to this
rare problem. An arcing tube
can also affect proper operation
of the turn on circuitry.

The attending tube will

usually arc at the shutdown

to standby point and bring
back the amplifier to the

full 0n condition. This tube
can sometimes be spotted in a
darkened room. The simplest

standby. bad Relay solution is to replace all
four tubes.

White noise in Leaky 2N3440 Be sure the noise isn‘t

background below (Ql,Q3) originating Upline in the

level of music

preamp or elsewhere by removing
the input to the servo charge
amplifier. It noise persists

replace QI or Q3.

Amp distorts ,
weakened output

sometimes accompanied
by a low level hum.

Detective 02,04,
Ql or Q3 transistor

Check/Repiace detective
transistor.

Intermittent drop

in volume, about
50%, accompanied
by low level hum.

Intermittently open
iunction mm4003
transistor(2N5416 on
later units)

Replace Q2 and Q4

Unit turns on from standby

due to AC line surges-

sometimes induced by an
air conditioner,ilourescent

lights etc.

Earlier production amplifiers
are sometimes found to do this.
Eliminate the problem by
installing a 680 ohm resistor

in series with the cathode
(banded end) of CRI4. This
resistor is factory installed
_-eginning with s/n I700.