ATI Technologies P100S Operating instructions

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
© Copyright 1997-2005, Audio Technologies Incorporated - Printed in USA
P100S
STEREO TURNTABLE AMPLIFIER
OPERATING AND MAINTENANCE MANUAL

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
GENERAL
A turntable preamplifier is a deceptively simple device which, although it has
major effects on your sound, has been the victim of an amazing amount of poor
design. One problem frequently encountered results from the use of
oversimplified design techniques for the RIAA equalizer network and/or loose
tolerance equalizer components. Equalizer errors can have major audible effects
on your sound because the result of shifting an equalizer corner frequency
slightly is to boost or cut a wide band of frequencies. For example, dropping all
levels from 2kHz all the way up to 20kHz buy only one dB due to a ten percent
tolerance equalizer error is far worse audibly that flat response up to 15kHz with
a droop of 1 dB between 15 to 20 kHz; however both fit within the typical +1 dB
response specification on the data sheet. A professional preamplifier should hold
these midband equalizer response errors to + .25 dB using precision film
resistors and polystyrene capacitors for long-term stability. The P1000 preamp
will typically run + .1 dB from 50 to 15000 Hz.
Another chronic problem is insufficient input stage headroom. Headroom
limitation can result from making the first stage gain high to overcome a high
noise level in the following output stage. With digitally mastered and direct to
disc recordings regularly exceeding 50cm/sec peaks at midband, a high output
cartridge can readily overdrive the 80 mV maximum input level limit of many
preamps.
The preamp will comfortably accept 350 mV peaks (250mVrms) at mid
frequencies and up to 2 Vpk levels at 20 kHz. These levels are so far in excess
of the velocity capability of both cutter heads and playback cartridges that you
can forget about input headroom as a limitation for the foreseeable future.
The RIAA feedback equalizer, when scaled down in impedance to minimize input
noise generation, forms a low impedance, high capacity load for the input stage
and can readily overload almost all low noise IC op-amps. A high slew rate
specification for the input IC amplifier although very necessary is no guarantee of
protection from slew rate problems. Equally important, the amplifier must have
sufficient output current swing capability to drive the high capacity of the
equalizer network. ATI preamps use the 5533 IC, which has a 35 mA peak
output current and can drive the equalizer with full rail to rail output swings at its
rated internal slewing rate of 13 volts per microsecond.
The headroom can also be satisfied by a reduction in the output stage noise floor
thus allowing average output levels to be used. For example, your P100S will
easily meet 80 dB S/N performances at nominal outputs below –10 dBm because
it has an output stage noise floor at only –98 dBm. Operating at –10 dBm out is
a good match for many console inputs and provides 28 dB or preamp output
headroom. This is the functional equivalent of a +36 dBm clipping point above a
nominal +8 dBm out.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
Another important consideration is the presence of high amplitude, subsonic
input signals which originate in record warp, eccentric center holes and seismic
pick up from small earthquake and dancing DJ’s. These signals are strongest in
the neighborhood of the cartridge and tone arm resonant frequency, typically 6 to
10 Hz. In studio applications these signals can overload amplifiers, saturate
console transformers, overdrive limiters, and damages loudspeakers. The
preamp input stage is the optimum location for a subsonic filter. That filter should
ideally remain in the circuit at all times. However, previous attempts ay “Rumble
Filters” noticeably rolled off low frequency audio and had to be switched out most
of the time. Your P100S preamp incorporates an active, tow pole subsonic filter
bridged around the RIAA feedback equalizer. This filter follows the RIAA curve
within .5 dB down to approximately 28 Hz, rolls off only 6 dB at 20 Hz then
plunges quickly -30 dB at 7 Hz. Excellent subsonic rejection is thus attained
without loss of low frequency audio.
The high-end sound of many cartridges can be noticeably altered by adjusting
the resistive and capacitive loading. You may jumper program the cartridge
loading from 47 pf up to 294 pf and from 50 to 100K ohms.
INSTALLATION
MOUNTING
Your Encore preamp won’t win any beauty contests and should be hidden away
under the turntable. Mount it vertically on the side wall of your turntable cabinet
with screws through the keyhole slots on either end of the preamp. Avoid strong
magnetic fields from the turntable motor and make sure your cartridge leads
reach the preamp before final mounting.
WIRING
Our insurance company insists on three wire grounded plugs. The third wire
ground can cause a ground loop with your studio ground. If you are very sure
that your studio ground will provide adequate protection to your personnel in
case of an AC line short to the chassis, a 3 to 2 AC line adapter can be used to
isolate the power line ground. E recommend that the adapter be removed and
the power line ground be reconnected prior to any service work requiring removal
of the studio ground from the preamp chassis.
The four inch, low inductance copper strap that you are, of course, using for your
studio ground is not going to fit over the #6 ground stud on the P100 chassis.
Run copper strap to within a few inches of the chassis and jump to the chassis
with shield braid. Connect the tone arm ground lead to the same stud.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
Plug cartridge leads into the phone jacks. Convention is white for left channel,
red or black for right channel.
Your Encore preamp is decorated with more beads that Bo Derek (Who?). Well
our beads are ferrite and although we don’t have nearly the movie stars capacity,
what we do have is tuned for good FM and AM rejection. Any RF shielding and
suppression system is no better than the ground system into which it is trying to
dump the unwanted RF. If you have a decent ground system and still have RF
problems give us a call and we will hold a telephone prayer meeting. If you don’t
have a ground system you will still be okay as long as you don’t turn on your
transmitter.
Output connections are indicated on the liable. DO NOT GROUND either HI or
LO output terminals. If you are driving a single ended (unbalanced – one side
grounded) high impedance or 600 ohm load it should be connected between
either HI to GND or LO to GND. If you are driving a balanced load connect it
between HI and LO output terminals. It is generally unnecessary to terminate the
P100 with a 600 ohm load if it is driving a high impedance input although placing
a terminating resistor across a hi Z input at the receiving end will occasionally
reduce RF pickup between the preamp and the console input.
ADJUSTMENTS
Your P100 has sufficient gain and output to overdrive some console inputs,
particularly those providing preamps for high level inputs. Full clockwise settings
of the level set pots will provide app. +10dBm balanced output at a reference
5cm/Sec, KHz recording level from a cartridge providing 1mV/Cm/Sec. Two
o’clock on the level pots is app. 0dBm while Twelve o’clock equals –10dBm,
however for lower nominal output levels a fixed attenuator pad should be placed
between the preamp and console input.
Trimming the cartridge loading can optimize the response, brighten a dull
sounding cartridge or smooth out a peaky high end. You can trim by ear, use a
test record or just putt out J7 and J8 which leaves the cartridge terminated with
200 pf, a good nominal value. If you lose the little jumpers, replace them with
#26 wire (.015 DIA) or flatten some cut off resistor leads to .015 thick so that they
can fit comfortable in the DIP socket.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
MAINTENANCE
Power supply voltages are + and – 15VDC nominal.
IC output DC Voltages under no signal, shorted input conditions should remain
with .1V of ground. Greater deviation is an indication of IC or circuit problems.
MODIFICATIONS
230 VAC OPERATION
Your preamp is wired for 115 VAC, 50/60Hz operation unless otherwise
requested at the time of ordering. It can be modified for 230 VAC operation by
removing the power transformer primary jumpers J11 and J13 and inserting a
jumper in J12.
NEW RIAA CURVE
The RIAA has proposed a modification to its standard curve to help roll off
subsonic rumble. This modification adds a roll off corner in the playback
response at 20Hz. Although the active two pole subsonic filter in your P100 is
more effective at blocking subsonic inputs than the proposed RIAA curve
change, that change will also affect low frequency audio response by about
1.6db at 30Hz.
When the new curve becomes more generally used you will e able to precisely
math its low frequency response to 30Hz simply by clipping out capacitors C39B
and C40B, thus adding an additional matching 20Hz corner.

Audio Technologies Inc. | 154 Cooper Road #902 | West Berlin, NJ 08091 | Voice 856-719-9900 | Fax [phone] | www. audio.com
TECHNICAL SPECIFICATIONS
TECHNICAL SPECIFICATIONS Jumper programmable, 50 to 100 ohms
INPUT IMPEDANCE 47 to 394 pf in 47 pf steps.
INPUT LEVEL 250 mVrms maximum @ 1 KHz
5 mV nominal @ 1 KHz for+4 dBm out.
OUTPUT LEVEL +18 dBm into 600 ohms, balanced or
unbalanced, 10 Vrms single ended into high Z
load.
OUTPUT IMPEDANCE 400 ohms balanced, 200 ohms single ended,
split and RF bypassed.
GAIN 54 db maximum, continuously adjustable.
SLEW RATE 13 V/uSec. Assures minimum TIM.
CHANNEL SEPARATION 80 db or better.
SUBSONIC (RUMBLE) FILTER Two pole active input filter, Flat to 30 Hz, -6
@ 20 Hz, -18 @ 10 Hz, -30 db @ 5 Hz in
addition to RIAA specified roll off.
NOISE PERFORMANCE S/N=80db min, ref 10mV, 1KHz, Unweighted
over 20KHz measurement band with input
terminated in 600 ohms. S/N=90 db min, ref
10 mV, 1KHz, with A weighting filter, 600
ohm input term.
HARMONIC DISTORTION .10% max. THD, 20-20000 Hz @ +18 dBm.
INTERMODULATION DISTORTION .05% maximum, SMPTE measurement.
FREQUENCY REPONSE +.5db, 30 to 20,000 Hz ref. Old or new RIAA
curve, either curve available by jumper
change.
POWER REQUIREMENT 115 or 230 VAC, int. jumper select, 50/60 Hz
@ 6VA. 3 cond. RF filtered.
CONNECTORS Input – RCA type phono jacks Output – Screw
terminal block, 3/8 ctrs.
DIMENSIONS 9 ¼ L x 5 3/8 W x 1 5/8 H, 5 lbs. Ship