True Manufacturing Company Stereo Amplifier PRECISION 8i User Manual

TRUE  
systems  
PRECISION 8i  
8•CHANNEL PRECISION MICROPHONE PREAMPLIFIER with M/S decoding  
and Direct Inputs  
OPERATION MANUAL  
Version 1.2  
 
CERTIFICATIONS  
Declaration of Conformity – CE  
Sunrise Engineering and Design Inc. hereby declares the TRUE Systems  
PRECISION 8i 8•channel microphone preamplifier to be in material conformity with the  
following directives and related standards:  
 73/23/EEC – Low Voltage Directive  
 89/336/EEC – EMC Directive  
 EN60065:1998  
 EN55103•1: 1997  
 EN55103•2: 1997  
Technical files are maintained at corporate headquarters of Sunrise Engineering and  
Design Inc., 1634 S. Research Loop, Suite 110, Tucson, Arizona 85710, USA.  
Owner’s Record  
We recommend that you record the following information for reference in the event that  
you need to contact TRUE Systems for technical support or repairs. Please return  
your completed Warranty Card today.  
Serial No._____________________  
Purchase Date ______________________  
Dealer _____________________________________________________________  
Address ____________________________________________________________  
Phone _______________________  
3
 
PRECISION 8i  
OPERATION MANUAL  
CONTENTS  
SAFETY and OPERATING PRECAUTIONS  
CERTIFICATIONS  
2
3
3
4
5
5
6
Owner’s Record  
Table of Contents  
INTRODUCTION  
PRODUCT OVERVIEW  
UP•AND•RUNNING IN A HURRY  
INSTALLATION  
Unpacking and Inspection  
Mounting  
7
7
8
8
Ventilation  
OPERATION  
8
8
Connections  
AC Mains Connection  
Output Cable Connection  
Microphone Cable Connection  
A Word About Cables  
Front Panel Controls  
More About M/S Decoding  
8
10  
11  
11  
12  
14  
DESIGN APPROACH  
16  
16  
17  
18  
19  
SPECIFICATIONS  
TROUBLESHOOTING  
REGISTRATION and WARRANTY  
SERVICE and SUPPORT INFORMATION  
4
 
PRECISION 8i  
OPERATION MANUAL  
INTRODUCTION  
The PRECISION 8i is designed to provide the detailed, transparent sonic performance  
necessary for the most critical direct tracking and live sound applications. It includes a  
unique combination of functions that make it useful as a complete input system for  
standalone or PC•based recording systems. And, the PRECISION 8i has special  
features that provide the serious musician or recordist with useful tools to get the best  
sound more quickly and easily.  
We appreciate the confidence you have placed in TRUE Systems by purchasing this  
product. Please feel free to contact us with questions or comments. And, we always  
appreciate hearing about successful projects you have completed.  
OVERVIEW  
In addition to our acclaimed TRUE preamps, PRECISION 8i features two instrument  
direct inputs (DI’s) that offer sonic performance previously thought to be available only  
with dedicated, high•end DI’s. You’ll get incredible articulation and control for electric  
bass, detail and smoothness for stringed instruments and keyboards  
The 5•segment peak•hold level metering with selectable peak reference allows rapid  
optimization of program levels between the PRECISION 8i and devices to which it is  
interfaced. Dual output connections provide easy interconnection as well as the ability to  
act as a mic splitter.  
PRECISION 8i is ideal for location recording due to its compact, 1U rack size, 8•  
channel format, useful level metering and easy interconnect. The integral M/S decoder  
provides creative spatial image control and can be particularly useful in attaining an  
exciting stereo image with minimum effort and microphone re•positioning. The M•S  
microphone technique can be employed effectively in a wide variety of circumstances,  
from classical ensemble, to drum kit overheads, to solo vocal or instrument – whenever  
accurate capture of the performance and its acoustical space is desired. M•S micing  
also eliminates the “hole•in•the•middle” effect.  
In addition to the previously mentioned features, the PRECISION 8i includes:  
 Both 8•channel DB25 and individual TRS output connections • for easy connectivity.  
 Individual Polarity Reverse • to correct polarity inversions caused by mic position or  
cable wiring variations.  
 Individual Phantom Power (48V) – available on the front panel.  
5
 
PRECISION 8i  
OPERATION MANUAL  
UP•AND•RUNNING IN A HURRY  
1. Read the “Safety and Operating Precautions” on page 2 of this manual.  
2. Check the voltage selector on the International Power Supply Module (PSU•P8i) to  
make sure it is set for the appropriate AC mains voltage in your area.  
3. After making sure the main power switch is off, connect the AC power cord.  
4. Connect output signal cables between PRECISION 8i and the analog line level  
inputs of your recorder, mixer, signal processor, etc. Use either the individual 1/4”  
TRS or DB25 eight•channel balanced output connectors. See the section  
“Connections” for wiring details.  
5. Connect mic cables to MIC 1 through MIC 8 as needed.  
6. Connect the interface cable on the International Power Supply Module (PSU•P8i) to  
the main PRECISION 8i unit.  
7. Turn on the AC power.  
8. Set PEAK REFERENCE selector to +26.  
9. Set 48V and buttons as appropriate on each channel.  
10. Depress the RESET button to clear Peak•Hold indicators.  
11. Adjust Gain controls for adequate signal level as indicated on the PRECISION 8i  
level indicators or on the level indicators of the device to which it is connected.  
If you’re using the DI’s for electric instrument input:  
1. Connect your instrument cables to Direct In 1 and Direct In 2 on the rear panel. The  
Direct In jacks are located within the same connectors as MIC 7 and MIC 8. Simply  
plug your 1/4” phone plug into the center portion of the desired connector. NOTE:  
DO NOT use TRS plugs for these inputs as the DI will not function correctly.  
2. Set buttons as appropriate.  
3. Adjust DI•1 or DI•2 Gain controls for adequate signal level as indicated on the  
PRECISION 8i level indicators or on the level indicators of the device to which it is  
connected.  
If you’re using the M/S Decoder:  
1. Connect the cardioid or omni MID mic to MIC 1 input.  
2. Connect the figure 8 SIDE mic to MIC 2 input. Face the SIDE mic toward the right  
side of the sound field (perpendicular to the axis of the MID mic). See Figure 1.  
3. Depress the MID•SIDE ON button. “Left” signal is routed to Channel 1 output. “Right”  
signal is routed to Channel 2 output.  
4. Adjust the Channel 1 gain control for adequate mono signal level.  
5. Adjust the Channel 2 gain control to vary the image width as desired.  
6. See the section “More About M•S Decoding” for more information.  
MID  
Figure 1  
M•S microphone orientation  
SIDE  
6
 
PRECISION 8i  
OPERATION MANUAL  
About the Level and Peak•Hold Indicators:  
1. SIG indicates that a signal is present on the channel. It illuminates when the signal  
level exceeds •24dBu.  
2. +4 illuminates when the output signal reaches normal operating level of +4 dBu.  
3. OL illuminates when the signal level exceeds +26 dBu, which is 5 dB below the  
overload point for the Precision 8i.  
4. The PEAK•HOLD indicators (PK,•3,•6) activate when the output signal level exceeds  
the level set on the PEAK REFERENCE switch.  
5. For example: With PEAK REFERENCE set to +26 the PK indicator illuminates (and  
stays on) at +26dBu, the •3 indicator illuminates at +23 dBu and the •6 indicator  
illuminates at +20 dBu.  
6. NOTE: Only the OL light indicates impending preamp overload. The red PK light  
simply indicates that the signal has exceeded the level selected on the PEAK  
REFERENCE switch.  
7. Push the RESET button to reset the PEAK•HOLD indicators for all channels. (It is  
normal for power•on transients and phantom power transients to activate the PEAK•  
HOLD indicators. Simply depress RESET to clear the indicators.)  
INSTALLATION  
Unpacking and Inspection  
We recommend that you inspect your PRECISION 8i upon unpacking it from the  
factory shipping carton. In the unlikely event that the unit exhibits any physical damage,  
DO NOT connect it to the AC mains power, but contact your dealer immediately.  
In addition to the PRECISION 8i, the shipping carton should also include:  
An International Power Supply Module (PSU•P8i)  
An AC power cord  
A warranty registration card  
A “Caution” sheet  
This Operation Manual  
We recommend that you keep the shipping carton and foam supports in the event that  
the unit must be shipped at some time in the future. DO NOT package the unit in  
“packing peanuts” or similar material as it will settle during shipping and damage will  
likely occur. If original packing materials cannot be located, wrap the unit with a liberal  
amount of plastic “bubble wrap” material extending at least 2” beyond the extremities of  
the PRECISION 8i enclosure.  
7
 
PRECISION 8i  
OPERATION MANUAL  
Mounting  
The PRECISION 8i is designed for conventional rack mounting, or stand•alone  
mounting by use of the adhesive rubber feet supplied. Avoid locating the unit next to  
equipment that emits strong electromagnetic fields. If the unit is to be permanently  
mounted in a high•vibration environment, you may wish to provide additional side or  
rear support to prevent possible distortion of the mounting ears.  
 Do not locate the unit where it is exposed to rain, moisture, or liquid spills.  
 Do not locate the unit where it is exposed to temperature extremes.  
 Do not mount the Power Supply Unit closer than one rack space from the  
preamp unit. This avoids coupling unwanted magnetic interference into the  
preamp unit.  
Ventilation  
We recommend that you provide adequate ventilation so that the air temperature  
surrounding the unit does not exceed 55C (122F). If multiple units are to be mounted  
in a poorly ventilated rack or travel case, a 1 3/4” blank space should be located after  
every two units (two units mounted together, blank space, two more units, etc.).  
OPERATION  
Connections  
PSU•P8i  
1
240  
AC Mains Connection: Prior to connecting the AC mains power cord to the  
Power Supply Unit, verify that the Voltage Selector is set for the AC mains  
voltage in your area. The currently selected voltage appears in the window  
on the Fuse Drawer 1 . It is important that the voltage is set correctly for both safety  
reasons and to insure that the PRECISION 8i will operate according to specifications.  
Note also that the correct fuse type must be used. See Table below. Product damage  
caused by incorrect voltage settings or fuse selections cannot be covered under  
warranty.  
8
 
PRECISION 8i  
OPERATION MANUAL  
To change the AC operating voltage selection:  
This procedure should be performed only by qualified technical personnel. If  
you are not qualified, please consult TRUE Systems or your dealer for  
assistance.  
2
1
1) Using an appropriate AC voltmeter, measure the AC line voltage at the  
installation site.  
2) Make sure the AC power cord is disconnected from the PSU•P8i Power  
Supply Unit.  
3) Using a small screwdriver or similar tool, release the latch on the Fuse  
Drawer 1 and pull it (and the fuses) out of the AC inlet module.  
4) Using a small screwdriver or similar tool, remove the Voltage Selector 2 .  
5) Rotate the Voltage Selector to the appropriate position for the AC voltage  
measured in Step 1) above. See Table below for proper Voltage Selector  
setting. Select the setting that places your measured voltage nearest the  
middle of the Operating Voltage Range.  
Voltage Selector  
100V  
Operating Voltage Range  
90•110VAC 50/60Hz  
110•132VAC 50/60Hz  
201•240VAC 50/60Hz  
220•264VAC 50/60Hz  
Fuses (2)____  
T 500mA L, 250V  
T 500mA L, 250V  
T 315mA L, 250V  
T 315mA L, 250V  
120V  
220V  
240V  
For other operating voltage options, consult TRUE Systems.  
CAUTION: To provide continued protection against fire, replacement fuses should be  
only of the types listed above. Note that two (2) fuses are necessary and that both fuses  
9
 
PRECISION 8i  
OPERATION MANUAL  
must be of the same type. AC mains power cord must be removed to gain access to  
Fuse Drawer 1 for fuse replacement.  
3
4
TRUE Systems • Precision 8i  
Sunrise Engineering and Design Inc.  
Tucson, Arizona USA  
CONNECT  
ONLY  
PSU•P8i  
S/N  
7
8
5
6
3
4
1
2
LINK  
1•8  
(4•40)  
DO NOT DISCONNECT  
WITH AC POWER ON  
BALANCED OUT  
Signal Ground Connection: LINK 3 connects signal ground to earth ground. Signal  
ground is isolated from earth ground if the LINK jumper is removed. This jumper will  
normally be installed. See “Troubleshooting” section for usage tips.  
Output Cable Connection: For ease of connection, we’ve provided two styles of  
balanced output connector: 8•channel DB25 and individual TRS 4 . Both output types  
are electrically equivalent and may be used simultaneously to connect to Line Inputs on  
mixing consoles, recorders, etc. If both pairs of outputs are used, care should be taken  
to avoid system ground loops. See “Troubleshooting” section for tips on avoiding hum  
caused by grounding problems.  
The DB25 and TRS output connectors are not electronically isolated. Therefore, if you  
chose to connect either one of the output connectors to an unbalanced input, the other  
connector will automatically be unbalanced. When connecting an output of the  
PRECISION 8i to an unbalanced input, you must connect the negative signal pin (pin  
3 of the XLR or “ring” of the TRS) to the shield. Failure to do this will result in audible  
distortion.  
The wiring configuration used for the output connectors on the PRECISION 8i is:  
For TRS:  
For DB25:  
This output connector is wired  
according to the Tascam8•channel  
analog wiring configuration. DO NOT  
USE TDIF CABLES.  
 Tip is positive (+)  
 Ring is negative (•)  
 Sleeve is shield  
1
2
3
4
5
6
7
8
S • + S • + S • + S • + S • + S • + S • + S • +  
13  
25  
1
14  
10  
 
PRECISION 8i  
OPERATION MANUAL  
5
6
MIC 8  
MIC 7  
MIC 6  
MIC 5  
MIC 4  
MIC 3  
MIC 2  
MIC 1  
PIN 2 +  
PIN 3 •  
Direct In  
2
Direct In  
1
MS  
Microphone Connection: Microphone connection is made to standard XLR receptacles  
on the rear panel. The wiring configuration used for the microphone connectors on the  
PRECISION 8i is:  
 Pin 2 is positive (+)  
 Pin 3 is negative (•)  
 Pin 1 is shield  
Do not attempt to connect unbalanced microphones (with single•pin connectors) to the  
PRECISION 8i. It is not intended to operate with this type of microphone.  
CAUTION: We recommend that you avoid “hot•patching” microphone inputs  
when using a patch bay at the microphone inputs of the PRECISION 8i.  
Please TURN OFF phantom power and turn down the gain prior to  
connecting or re•patching microphone inputs routed through a patch bay. Failure to do  
so may result in transients that can damage the PRECISION 8i or equipment that is  
connected to its outputs•not to mention your ears!  
Electric Instrument Connection: Dual•purpose input connectors 5 are available on  
channels 7 and 8. Insert XLR microphone connector for normal MIC 7 and MIC 8  
operation. Insert 1/4" phone plug for use as Direct Input for instruments DI•1 and DI•2.  
DI•1 and DI•2 are controlled by Gain and (phase) controls for channels 7 and 8,  
respectively. The gain range for the direct inputs is from •4 dB to +44 dB.  
NOTE: DO NOT use TRS plugs for these inputs as the DI will not function correctly.  
M•S (mid•side) Microphone Connection: You may note the M•S (mid•side) connection  
symbol below the MIC 1 and MIC 2 connectors 6 . This is simply a visual reminder,  
when using an M•S mic setup, to connect the MID mic to channel 1 and the SIDE mic to  
channel 2. See the section “More About M•S Decoding” for more information.  
A Word About Cables.....  
Most users of the PRECISION 8i have invested much time and money in their  
selection of microphones and preamplifiers. We recommend that you give some  
consideration to the microphone, instrument and output cables you select, as well.  
11  
 
PRECISION 8i  
OPERATION MANUAL  
 Use high•quality, low capacitance cable. Braided shielding and “star quad” type mic  
cables will perform better in electrically noisy environments. Manufacturers such as  
Canare, Mogami(and others) make high performance cable of this type.  
 Some “house brand” cables are made by quality manufacturers, but others can be  
inferior. Be careful. Use cables with high•quality connectors (Neutrik, Switchcraft,  
etc.).  
 Our studio testing has shown that some of the more esoteric guitar/instrument  
“super•cables” do, indeed, sound better. Noticeable improvement, but at a stiff price.  
Try before you buy!  
 Avoid excessive cable length.  
 Replace damaged connectors.  
Front Panel Controls  
4
8
3
35  
35  
35  
OL PK  
•3  
OL PK  
•3  
OL PK  
•3  
30  
40  
30  
40  
30  
45  
45  
50  
•6  
•6  
•6  
TRUE  
50  
55  
48V  
48V  
48V  
systems  
55  
64  
+4  
+4  
+4  
16  
64  
16  
16  
Ø
Ø
Ø
ON  
SIG  
SIG  
SIG  
SIDE  
MID  
3
1
2
2
6
1
7
5
1
2
Phase reverse selector. Output signal polarity is reversed when the button is  
depressed.  
Phantom power selector. Phantom power (+48V) is activated when the 48V button  
is depressed. Avoid selecting phantom power if you are using a ribbon  
microphone. While not required, it is advisable to de•select 48V when using a  
dynamic microphone or a DI input.  
3
4
Overload warning indicator. OL illuminates (and holds) at +26 dBu which is 5 dB  
below actual overload. Depress RESET 10 to clear OL.  
Peak•Hold indicators. These are provided to help optimize level setting when the  
PRECISION 8i is remotely located from the device to which it is connected. The  
PK indicator activates (and holds) at the level selected on the PEAK REFERENCE  
selector 9 . The •3 indicator activates at peak level minus 3 dB. The •6 indicator  
12  
 
PRECISION 8i  
OPERATION MANUAL  
activates at peak level minus 6 dB. Generally, the PEAK REFERENCE selector is  
set for the maximum level you want to present to your mixing console, recorder,  
etc. Depress RESET 10 to clear PK.  
NOTE: Only the OL light indicates impending preamp overload. The red PK light  
simply indicates that the signal has exceeded the level selected on the PEAK  
REFERENCE switch.  
Note that the overload level of the PRECISION 8i is +31dBu at the output. This  
level exceeds the input capability of some devices (check manufacturer’s  
specifications). In other words, it may be possible to cause overload distortion in  
the connected device even though the PRECISION 8i level indicator does not  
show a red light. We can provide accessory Output Attenuators in applications  
where this is necessary. Please consult the factory for assistance.  
5
6
Signal Present indicator. The SIG indicator activates at approximately •24 dBu.  
Operating level indicator. The +4 indicator activates when the output level reaches  
+4 dBu normal operating level. When the PEAK REFERENCE selector 9 is set  
to the •10 dBV position, the operating level indicator activates at •10 dBV output  
level.  
7
8
Mid•Side mode selector. When the ON button is depressed, Channel 1 output  
becomes “Left” and Channel 2 output becomes “Right”. The Channel 1 gain control  
adjusts the mono signal level applied to both the Left and Right outputs. The  
Channel 2 gain control adjusts the stereo image width.  
Gain control. This control adjusts the preamp gain over the range of 16 dB to 64  
dB.  
12  
35  
35  
OL  
PK  
OL  
PK  
40  
30  
40  
30  
40  
•3  
•6  
•3  
•6  
45  
50  
45  
50  
45  
50  
P R E C IS IO N  
8
+26  
+24  
+22  
48V  
48V  
55  
55  
55  
+20  
+4  
+4  
64  
16  
64  
16  
64  
+18  
•10  
dBV  
Ø
Ø
SIG  
SIG  
PEAK  
REFERENCE  
DI 1  
DI 2  
RESET  
8
7
9
11  
10  
13  
 
PRECISION 8i  
OPERATION MANUAL  
9 PEAK REFERENCE selector. This sets the level at which the Peak•Hold indicators  
4 activate. It also changes the operating level indication 6 to •10 dBV operation  
when the •10 dBV position is selected.  
10 Peak•Hold reset. RESET clears the peak•hold indicators on all channels. NOTE: It  
is normal for the Peak•Hold indicators to activate when phantom power is applied,  
when AC power is applied, or when a new setting is made on the PEAK  
REFERENCE selector • simply depress RESET to clear the indicators.  
11 Direct inputs DI•1 and DI•2 are controlled by gain controls for channels 7 and 8,  
respectively. The gain range for the direct inputs is from •4 dB to +44 dB.  
12 AC power indicator. The green power LED indicates that the unit is on.  
More About M•S Decoding:  
M•S (Mid•Side) decoding is a particularly creative feature of the PRECISION 8i. While  
the M•S microphone technique has been around for many years, the opportunity to use  
it is frequently limited by the need for specialty microphones and/or decoders.  
MID  
What is M•S?  
It is a stereo microphone placement technique  
that uses a center, forward•facing omni or  
cardioid mic (Mid) and a side•facing figure 8  
mic (Side). The signals from these two mics  
are passed through matrix circuitry that  
combines them in particular phase and level  
relationships to produce a stereo L and R  
output.  
SIDE  
What good is M•S versus the typical XY microphone placement?  
Originally, M•S was used because it provided a stereo signal with good mono  
compatibility. While this is not very interesting for contemporary stereo CD’s, it is still  
valuable for broadcast and film sound production. But there is another significant  
benefit: varying the gain of the Side mic in relation to the Mid mic causes a variation in  
the stereo image • from none, to extreme separation. It is not necessary to change the  
angle or position of the microphones in order to change the stereo image. This feature  
can really speed up the time•consuming process of finding a “sweet spot” that provides  
both good tonal quality and good imaging.  
What are the best applications for M•S?  
M•S does an excellent job of capturing the natural sonic perspective of acoustical  
ensembles.  
 Orchestral and choral recording: use an M•S pair for the central array  
14  
 
PRECISION 8i  
OPERATION MANUAL  
 Drum kits: use an M•S pair for drum overhead micing.  
 Vocal and instrumental ensembles: use M•S to give realistic perspective to backup  
vocals or instrumental groups.  
 Individual instruments or vocals: try M•S on acoustic guitar and in situations where  
you wish to capture room ambience.  
 Broadcast/film sound: use M•S to capture audience noise or background ambience.  
M•S can also be used in TV and film work to match the sonic image width to the  
visual image width.  
Optional Level Indicator Modes  
The Peak•Hold level indicators can operate in two modes. As supplied, only the OL and  
PK indicators will hold (after they are activated) until RESET is depressed. An optional  
mode is available which causes the •3 and •6 indicators to also hold until RESET is  
depressed. This mode can be helpful in live sound and recording applications where the  
PRECISION 8i is remotely located from the device(s) to which it is connected. Jumpers  
inside the unit select this optional mode. If you wish to configure the unit for this mode,  
proceed as follows:  
WARNING • ELECTRIC SHOCK HAZARD. Dangerous voltage exists inside  
the enclosure of this product. This operation should only be performed by  
qualified personnel. NEVER open the product enclosure while the AC power  
cord is attached.  
 Disconnect AC power cord.  
 Remove the twelve screws securing the top cover to the enclosure. Remove the  
cover.  
 Locate the eight upright printed circuit boards along the front panel.  
 Select level indicator mode by setting jumpers (J2) as shown below.  
J2  
J2  
Normal Mode  
Optional Mode  
(OL, PK remain on)  
(OL, PK, •3, •6 remain on)  
 Replace cover and secure with twelve screws. Make sure no tools, loose hardware,  
debris, etc. remain in the unit prior to attaching the cover.  
15  
 
PRECISION 8i  
OPERATION MANUAL  
DESIGN APPROACH  
PRECISION 8i features a high•voltage composite architecture with discrete devices  
plus integrated circuits. The totally balanced, dual servo, dc•coupled design provides  
exceptional transient response, headroom, imaging and noise performance. Critical  
devices have been selected on the basis of extensive listening tests as well as  
engineering tests. Military grade, hand•matched components are utilized in critical  
circuit areas. These design features result in the transparent, detailed sound quality for  
which TRUE preamps have become known.  
SPECIFICATIONS  
Gain, preamp:  
DI:  
15.5 to 64dB  
–4 to 44dB  
Frequency Response:  
(gain=40dB)  
1.5 Hz to 500kHz (•3dB)  
Maximum Output Level:  
Maximum Input Level:  
Noise (Rs=0 Ohms):  
+31 dBu  
+15 dBu  
•132 dB e.i.n.  
>40 V/uS  
85 dB  
Slew Rate:  
CMRR (CMV= +10 dBu):  
THD (preamp) (+26dBu, 100kOhm):  
.0008%  
Input Impedance, preamp:  
DI:  
5.5 kOhm  
2.5 Mohm  
Power Consumption:  
44W  
Preamp Enclosure Dimensions:  
17.5 in. (44.5 cm) W, 13.75 in. (35 cm) D,  
1.75 in. (4.5cm) H  
Preamp Front Panel Extension:  
Power Supply Unit Dimensions:  
Power Supply Unit Height:  
Power Supply Unit Rear Extension:  
Preamp Weight:  
1 in. (2.5cm)  
6.63 in. (16.8 cm) W, 6.4 in. (16.3 cm) D,  
1.75 in. (4.5cm) H  
3 in. (7.6 cm)  
10.2 lbs. (4.6 Kg)  
Power Supply Unit Weight:  
5.0 lbs. (2.3Kg)  
Typical performance. Specifications subject to change without notice.  
16  
 
PRECISION 8i  
OPERATION MANUAL  
TROUBLESHOOTING  
Symptom  
Solution  
 Check AC power source and cord.  
 Check fuses (pull fuse drawer next to power  
cord inlet)  
No signal output. Main power switch  
is on, but no LED’s are illuminated.  
No signal output. Main power switch  
is on and green power LED is  
illuminated.  
 Check status of phantom power.  
 Check continuity of mic and electric  
instrument cables.  
 Check continuity of output cables.  
Output signal is distorted. Outputs  
are connected for balanced  
operation.  
 Make sure gain is adjusted so that the OL  
indicator does not activate during the audio  
program.  
 Make sure the high output capability of this  
unit is not overloading the device or  
monitoring system to which it is connected.  
Set PEAK REFERENCE selector to match  
capability of device or monitoring system,  
then adjust gain according to indications on  
the Peak•Hold LEDs.  
 Check continuity of output cable.  
 Make sure outputs are not connected to a  
load impedance of less than 600 ohms.  
Output signal is distorted. Outputs  
are connected for unbalanced  
operation.  
 Make sure the minus (•) output signal pins are  
connected to the shield and not left  
unconnected. See “Output Cable Connection”  
section.  
 Check troubleshooting tips for balanced  
operation (above).  
Hum can be heard in the audio  
program.  
 Disconnect grounding LINK.  
 Check continuity of output cables (particularly  
shields).  
 Disconnect shields on one end of output  
cables. Connect grounding LINK.  
 If both outputs (TRS, DB25) are in use, try  
disconnecting shields on DB25 only, or TRS  
only.  
17  
 
PRECISION 8i  
OPERATION MANUAL  
Channel 1 signal can be heard in  
Channel 2 output • and vice versa.  
 Check status of M•S selector. It should be  
“out” for individual channel mode and “in” for  
Mid•Side mode.  
Channel 2 seems to have no output  
when used with Channel 1 as a  
stereo pair  
 Check status of M•S selector. It should be  
“out” for individual channel mode and “in” for  
Mid•Side mode.  
 Make sure the selectors for both Channels 1  
and 2 are “out”.  
In M•S mode the stereo channels  
are reversed (Channel 1 is Right  
and Channel 2 is Left)  
 Make sure the front of the bi•directional “Side”  
mic is aimed 90 degrees to the right of the  
axis of the “Mid” mic.  
In M•S mode the stereo channel  
phasing is incorrect  
 Make sure the selectors for both Channels 1  
and 2 are in the same position.  
Electric instrument connected to a  
Direct Input does not produce a  
signal or signal is distorted.  
 Check continuity of electric instrument cables.  
 Check the batteries or AC power source of  
any “foot pedal” effects processors connected  
to the Direct Input.  
 Make sure that the instrument cables have  
standard tip•sleeve 1/4” phone plugs. • DO  
NOT use TRS plugs.  
Radio Frequency Interference can  
be heard in the audio program  
(swishing sound or audio from a  
radio transmitter).  
 Make sure that mic cables are of good quality  
and that the shield is properly connected.  
Avoid excessive length.  
 Make sure that earth ground connection is  
maintained via the AC power cord • DO NOT  
use an isolator.  
 Make sure the unit is located away from  
known sources of radio frequency energy.  
.
REGISTRATION and WARRANTY  
Don’t forget to register your PRECISION 8i by filling out the enclosed Registration  
Card and returning it to us. This allows TRUE Systems to contact you regarding any  
updates, upgrades or applications information that may become available.  
SUNRISE ENGINEERING and DESIGN INC. (“SUNRISE”) warrants the TRUE  
systems PRECISION 8i to be free from defects in material and manufacture, when  
properly installed and used according to instructions in the Operation Manual, for a  
period of one year from the date of sale to the original purchaser. Units returned for  
warranty repair to SUNRISE or an authorized TRUE Systems repair facility will be  
18  
 
PRECISION 8i  
OPERATION MANUAL  
repaired or replaced at the manufacturer’s option, free of charge. Supplementary  
shipping charges will apply to units returned to addresses outside the continental USA.  
All units returned to SUNRISE or authorized TRUE systems repair facility must be  
prepaid, insured and properly packaged. Purchaser must obtain a Return  
Authorization (RA) number from SUNRISE prior to returning a product. SUNRISE may  
require proof of the purchase date in the form of a copy of a dated original retail invoice.  
This warranty is void if, in the sole judgment of SUNRISE, the product has been  
abused, neglected, misapplied, or has been damaged by an accident, modification, or  
attempted repair by unauthorized personnel. This warranty will not apply to cosmetic  
damage incurred due to normal handling and use. SUNRISE reserves the right to  
change or improve the product design at any time without prior notice. Incorporation of  
design changes in future versions of the product does not imply the availability of  
upgrades for existing units.  
This warranty is in lieu of all other warranties, expressed or implied, and SUNRISE  
specifically disclaims all implied warranties, including, but not limited to, warranties of  
merchantability and fitness for a particular purpose. The purchaser acknowledges and  
agrees that in no event shall SUNRISE be held liable for any special, indirect, incidental  
or consequential damage, or for injury, loss or damage sustained by any person or  
property, that may result from the use of, or failure of this product to operate correctly at  
any time. In the USA, some states do not allow the exclusion or limitation of implied  
warranties or liability for incidental or consequential damage, so the previous exclusion  
may not apply to you. This warranty gives you specific legal rights, and you may have  
other rights which vary from state to state.  
SERVICE INFORMATION  
Other than cleaning the exterior surfaces of your PRECISION 8i and occasional  
inspection of the AC power cord and audio cables for damage, no maintenance  
procedures should be attempted by the user. Cleaning can be performed using a lint•  
free cloth dampened with Windex.  
There are no user•serviceable components inside the product enclosure. Many of the  
electronic components are selected and matched at the factory. For this reason, as well  
as personal safety considerations, we recommend that you refer service requirements  
to TRUE Systems or authorized repair facilities.  
All units returned to TRUE systems or authorized TRUE systems repair facility must  
be prepaid, insured and properly packaged. Purchaser must obtain a Return  
Authorization (RA) number from SUNRISE prior to returning a product.  
Sunrise Engineering and Design Inc.  
1634 S. Research Loop, Suite 110  
Tucson, Arizona 85710 USA  
Tel: +1 520•721•2735  
Fax: +1 520•722•4057  
Email: info@true•systems.com  
19  
 

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