4 Input A/V Switcher
with Automatic Input Mode and Volume Stabilizer
Model SVS-4
User Manual
Table of Contents
WHAT’S INCLUDED .........................................................................2
INTRODUCTION................................................................................3
IMPORTANT SAFETY PRECAUTIONS.........................................3
FRONT PANEL ...................................................................................4
REAR PANEL ......................................................................................5
IR REMOTE CONTROL, SRC-1 ......................................................5
TYPICAL HOOK UP ..........................................................................6
OPERATION......................................................................................10
POWER ..............................................................................................10
INPUTS ..............................................................................................10
AUTO INPUT MODE ...........................................................................10
VOLUME STABILIZER ACTIVE............................................................11
VOLUME STABILIZATION ADJUSTMENT .............................................11
HOW IT WORKS ..............................................................................12
SIMPLIFIED BLOCK DIAGRAM OF THE SVS-4.....................................12
AUTOMATIC INPUT SENSING .............................................................12
VOLUME STABILIZATION ...................................................................12
VOLUME STABILIZER INPUT / OUTPUT CURVES ................................13
COMPOSITE TO S-VIDEO CONVERSION ..............................................13
TROUBLE SHOOTING....................................................................14
TERMS ...............................................................................................14
TECHNICAL SPECIFICATIONS ...................................................15
LIMITED WARRANTY ...................................................................16
What’s Included
1 - SVS-4 A/V switcher unit
1 - AC power adapter, 15 vdc.
1 - Triple A/V RCA cable, 1 meter long
1 - SRC-1 IR remote control, with batteries
1 - This instruction manual
1998 by Sima Products Corp.
All rights reserved. No part of this publication may be reproduced or transmitted in any form or
by any means without prior written permission from Sima Products Corp.
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Introduction
The Sima model SVS-4, 4 Input Audio / Video
Switcher with Automatic Input Mode (AIM) and
Volume Stabilization has been designed for the
home theater, DSS satellite, DVD, audio recording
as well as for background music applications.
The SVS-4 has the following features:
• Four A/V inputs to allow you to add more A/V
sources such as DVD, satellite dish, VCR,
games, etc. to your TV and home theater system.
The unit supports stereo audio as well as both
composite and S-Video.
• Dual A/V outputs to connect to your TV, your
surround sound receiver and/or a recording
VCR.
• Composite video to S-Video conversion to
simplify hook-up in systems using both
composite and S-Video.
• Automatic Input Mode (AIM) provides
automatic switching to active input without you
having to push any buttons. Simply turn on
your VCR and the SVS-4 connects it
automatically to the TV.
• Volume Stabilization circuitry to maintain
constant audio volume levels for late night
viewing or when channel surfing. It can also be
adjusted to add impact to old movies by
increasing the dynamic range.
• IR remote control when you want to select a
different input or mode without getting up from
your chair.
• Front panel display brightness control allows
you to dim the lights for nighttime use (via the
remote only).
Warnings
Important Safety Precautions
When using this product, basic safety precautions should always be followed to reduce the risk of fire and electric shock,
including the following:
Read and understand all instructions.
Follow all warnings and instructions marked on this product.
Unplug this product from wall outlets before cleaning. Do not use liquid or aerosol cleaners. Use a damp cloth for
cleaning.
To prevent fire or shock hazard, do not expose this product to rain or moisture. Do not use near a bath tub, wash
bowl, sink, or laundry tub; do not use in a wet basement or in a swimming pool.
To avoid electrical shock, do not open the case of this product.
Operate this product using only the power supply included with it or provided as an accessory. If you are not sure of
the type of power supplied to your home, consult your dealer or local power company.
Do not overload electrical outlets or extension cords as this can result in fire or electric shock.
The unit should be situated away from heat sources such as radiators, stoves, etc. The unit should be situated so that
its location or position does not interfere with its proper ventilation.
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Front Panel
Figure 1, SVS-4 front panel
Controls
1 - Power / Stand-by - Press to turn unit on or
off. The Power/Stand by light will be on
when the unit is operational and dim when it
is in the standby mode.
2 - Inputs 1 through 4 - Press to select desired
input. The light above the switch will light
to indicate the current active input.
3 - Auto Input Mode - Press to turn AIM on or
off. If on, the unit will scan the video inputs
and automatically turn on and select the
input to the device you turned on.
4 - Volume Stabilization Adjustment - This
controls the amount of dynamic range you
want. In the middle, at the 1:1 setting, the
input is equal to the output, so there is no
affect on the audio signal. If the knob is
rotated counter-clockwise towards the 10:1
setting, the audio will remain more constant.
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This will bring up soft dialogue and reduce
loud sounds. If the knob is rotated clockwise
towards the 1:2 setting, the unit will increase
the dynamic range and make loud sounds
louder and soft sounds quieter to add impact
to music or movies.
5 - Volume Stabilizer Active - Press to turn
Volume Stabilization on or off. If active, the
light will be on and the audio will go though
the Volume Stabilization circuitry to either
increase or decrease (depending on the
setting of the Volume Stabilization
adjustment) the dynamic range of the audio.
The light will be off when the Volume
Stabilization is bypassed.
Rear Panel
Figure 2, SVS-4 rear panel
6 - S-Video inputs, 1 through 4 from the SVideo output of your VCR, DSS or DVD
devices.
7 - Composite Video inputs, 1 through 4 from
the composite video output of your VCR,
DSS or DVD devices.
8 - Left and Right audio inputs, 1 through 4
from the audio output of your VCR, DSS or
DVD devices.
9 - S-Video outputs, A and B that connects to
the input on your TV or VCR
10 - Composite Video outputs, A and B that
connects to the input on your TV or VCR
11 - Left and Right audio outputs, A and B
that connects to the audio inputs on your TV,
VCR or surround sound receiver
12 - 15 vdc input from the AC wall power
supply
IR Remote Control, SRC-1
Fig. 3, SRC-1
All the buttons on the SRC-1 IR remote control work just like the
buttons on the front of the SVS-4, with the exception of the
DISPLAY button. See descriptions above (under the heading
“Front Panel”) for more information
POWER - Turns SVS-4 on or off.
DISPLAY - Pressing this button cycles through three levels of
brightness on the front panel lights - bright, dim or off. When the
Display is set in the “off” mode, the lights will light for a few
seconds when any button is pressed.
VS ACTIVE - Toggles between the Volume Stabilizer being active or
in the bypass mode.
AUTO INPUT - Toggles between the Automatic Input Selection
mode being on or off.
INPUT 1 through 4 - Selects desired input.
Be sure to install the two AAA batteries in the SRC-1 remote before
using. Slide the cover open on the SRC-1 remote in the direction of
the arrow and install the batteries as shown inside the unit.
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Typical Hook up
This shows a overview of a typical system with the SVS-4 using 4 A/V sources, a TV and Surround
system. The outputs of up to 4 devices can feed into the inputs on the SVS-4. It can then select one of
the devices to watch on your TV and/or listen on your receiver. Refer to the diagrams on the next few
pages for more detailed connection diagrams.
Figure 4, Overview of typical system
Step 1
Connect the AC adapter to 120 VAC and plug the DC cord into the 15 v input on the SVS-4.
Step 2
You need to determine how you want to use your system.
If you want to watch and listen to the video sources on your TV and / or your surround sound receiver,
see figure 5. This diagram only shows inputs 1 and 2 being used. Inputs 3 and 4 are connected in the
same manner.
If you want to be able to watch the video sources on your TV, listen on your surround sound receiver and
tape from the sources plugged into the SVS-4, see figure 6. This shows how to connect one of the
outputs of the SVS-4 to the Audio and Video inputs on the VCR that you will use for recording.
Note: Do not select the same input that the recording VCR is connected to (input 4 in this
diagram) while recording or loud feedback could occur.
If you only have composite video signals or only S-Video signals, then use the one type in your system.
If your TV only has composite video inputs, you must use all composite video signals into the SVS-4 as
it will not convert S-Video signals to composite video.
If you have a combination of standard composite video (RCA type jacks) and S-Video (mini-din jacks)
on your equipment you can only feed one or the other but not both to any given input to the SVS-4.
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In this case you have several options.
Option A: For ease of use, the SVS-4 has a composite to S-Video converter . You can feed a
combination of composite and S-Video to the SVS-4 and feed only a S-Video signal to your TV.
This lets you use just one S-Video input on your TV and all sources will automatically be displayed
there.
Option B: If your TV has 2 video inputs that supports both composite video and S-Video inputs, you
can feed both the composite and S-Video outputs from the SVS-4 to your TV. You will have to
select the correct video input on your TV, composite or S-Video. This will give you the best picture
quality. Note that this only works if the composite video and S-Video inputs are two separate inputs
on your TV. Otherwise the picture may be blank, black and white or have lines and steaks.
Fill in the chart below to help you organize and remember what devices are connected to the inputs and
outputs. Save for future reference.
Inputs
From (VCR, DSS, etc.)
Composite or S-Video?
#1
#2
#3
#4
Outputs
To (TV, Receiver, etc.)
Composite or S-Video?
A
B
Remember both the A and B outputs are identical. The SVS-4 has buffers to prevent one output from
loading the other output for best system performance.
Note: Most systems have a VHF/UHF cable from an antenna or cable company going
into the VCR and then a VHF/UHF cable between the VCR and TV. This is OK but
you still must connect the A/V cables as shown in figures 5 and 6. Having both the
VHF/UHF cable and the A/V cable would allow you to record a program off of the
cable on your VCR (cable input) while watching a different program/movie via the
SVS-4 on your TV via the A/V input.
Don’t forget, you must select the TV’s A/V input (also call video input or line input on
some TV brands) not channel 3 or 4 to view the output of the SVS-4.
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Figure 5 below shows a hook up showing only two input sources. Be sure you use either S-Video or
composite video inputs, but not both on the same input. The one SVS-4 output goes to the TV so you
can watch and listen on your TV. The second output (audio only) goes to the stereo receiver so you can
listen to music or surround sound audio using your stereo receiver.
Figure 5, Hook-up in typically system
Note: Remember to always connect the outputs on your VCR/DSS/DVD/etc. to the
inputs on the SVS-4. Likewise, connect the outputs on the SVS-4 to the inputs on the
TV/VCR/Receiver/etc..
Note: If you have one or more devices that are not stereo and have a single audio
output you have two options: 1) Use just the left connector for the audio of that
source; or 2) the better solution is to use a “Y” adapter (available from any electronics
store) to spilt the mono signal into two signals that you feed into both the Left and
Right inputs on the SVS-4.
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Figure 6 below shows a system with 3 sources. It also shows using the dual outputs to allow you to record
on a VCR, watch the video on the TV and listen to the sound on a surround system. As shown below, you
can select inputs 1, 2 or 3 (not 4 as you would be trying to record to itself) and record on the Recording VCR
the video and audio from the selected source.
Figure 6, SVS-4 with recording VCR
Note: Remember to select the A/V or AUX input on the recording VCR to record the
output of the SVS-4.
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Operation
When AC power is first applied, all outputs will be muted and all the lights will come on for 1 second
and then go out. The Power / Stand-by light will be lit dim red. The Auto Input and Volume
Stabilization modes will be active as default. When the unit detects an active video input (composite or
S-Video), the Power / Standby light will turn on full and the active input will be selected.
Power
As long as AC power is not lost, the previous status (last selected input, Volume Stabilizer mode and
AIM status) will be resumed when Power / Stand-by is pushed. If AC power was lost, the unit will
default with input #1 selected, Volume Stabilization on and AIM on.
Inputs
Pushing an input button on either the front panel or on the IR remote, will cause the current input and
associated LED to go off and the new input to come on. If the Auto Input Mode is on, the selected input
will over ride the current input until another input is selected or another input is automatically detected.
Auto Input Mode
If the Auto Input Mode (AIM) is active, the unit will look for a video signal on the video inputs to select
an input. If a second input becomes active, the SVS-4 will automatically change to the new input. If you
want to go to another A/V source, simply select the input using the front panel button or the remote. If
you don’t want the SVS-4 to automatically select an active input, turn the AIM mode off. Please note
when you activate AIM, it scans the inputs when the SVS-4 is on or in the stand-by mode.
When the unit is in the standby mode, the
Power/Standby light will be dim and all
other lights will be off
When a video device is turned on, like a
VCR on Input #1, the Power/Standby light
will become bright, the input corresponding
to the device will turn on.
If a second device is turned on (say the DVD
player on input #2) the # 2 light will
illuminate and it will be selected and fed to
your TV
If the second device is turned off, after about
5 seconds, input #1 will be selected.
If both devices are turned off, after about 5
seconds, the SVS-4 will turn off and go into
standby mode waiting for an input.
Note: If an input goes off and back on in less than 5 seconds, the SVS-4 may not sense
the input change so no input change may occur.
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Volume Stabilizer Active
If the Volume Stabilizer Active light is on, then the output of the audio switcher will be routed through
the Volume Stabilizer circuitry. When the Volume Stabilizer Active light is off, the audio signal is
bypassed and the Volume Stabilization setting will not have any affect on the audio signal.
Volume Stabilization Adjustment
The Volume Stabilization circuitry lets you control the dynamic range of the audio signal to
accommodate your needs. The Volume Stabilizer light must be on for this to function. The numbers
around the knob show the ratio of the input signal to the output signal in db. Thus, the setting in the
middle of 1:1 mean that the input signal is the same as the output signal. Likewise, if you set the knob
full counter clockwise to the 10:1 setting, it means that a 10 db change in the input volume level will
result in only a 1 db change in the output level. This will tend to keep the volume constant even when
the sound changes form soft to loud and back to soft.
Setting
10:1
2:1
1.3:1
1:1
1:1.3
1:2
Description
Maximum compression
maintains constant volume
level by compressing dynamic
range
Modest compression
Slight compression
Normal volume fluctuations
Slight expansion
Maximum expansion increases
dynamic range
Use
Watching movies late at night
Background music
Making tapes for airplane use
Making tapes for automotive use
Minimal audio compression
Just like bypass (VS off)
Adds some impact to audio sources
Restores dynamics to old recordings
Reduces hiss and noise below noise
“floor”
Can “un-do” compression on tapes
made with 2:1 compression
Hint: If you want the minimal volume changes when changing sources, changing channels or
watching a movie, be sure the Volume Stabilization knob is set to the 10:1 position and the
VS ACTIVE light is on.
Note: It is normal to notice volume variations even with the SVS-4 set to the 10:1 setting.
This is due to the fact the human ear is more sensitive to certain frequencies and these
will tend to sound louder. Some commercials on TV have been modified to sound louder
than the normal program. Although the SVS-4 will not eliminate all of these volume
fluctuations with these types of commercials, it will help a great deal to keep the volume
level constant.
Caution: Very loud sound levels can result when using the 1:2 expansion mode. Keep
your volume levels low to avoid damage to speakers or amplifiers
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How it works
This section has more technical information for the person who wants to learn more about the
SVS-4.
In the block diagram below you can see how the audio and video inputs are selected and fed to the
output buffer amplifiers. (Only the left audio channel is shown) Notice how the Volume
Stabilizer Active switch allows you to bypass the Volume Stabilizer circuitry. The diagram also
shows how the selected composite video signal is fed to the composite video output buffer
amplifiers and into the composite to S-Video converter which then feeds the S-Video output.
Simplified Block Diagram of the SVS-4
Automatic Input Sensing
When the AIM mode is on, the SVS-4 constantly scans the video inputs, both composite and S-Video,
waiting for a video input. When you turn on a device (VCR, DSS, etc.) a microprocessor in the SVS-4
senses the video input, turns on the SVS-4 (when it is in the stand-by mode) and selects the input. If a
second inputs occurs, the unit will switch to the new input. If the second input is turned off, in about 5
seconds, the unit will go back to the first input. If that input goes off, the unit will turn itself off going
back to the stand-by mode in about 5 seconds and wait for an input to become active.
Note: The Automatic Input Sensing only senses the video signals and not the audio
signals.
Volume Stabilization
The SVS-4 monitors the active audio source and depending upon the setting of the Volume Stabilization
adjustment, constantly changes the volume level smoothly to compensate to input volume level changes.
Lets say the unit is set to the 10:1 setting. When the input level increases by 10 db, that is it gets louder,
in just a few milliseconds, the SVS-4 reduces the volume by 9 db so the output only changes by about 1
db. Likewise, if the audio signal gets softer by 10 db, the SVS-4 adds gain to the signal so it is only
reduced by about 1 db. This way, the unit automatically brings up soft dialogue when watching movies.
The diagram below shows the relationship between an input audio signal and the output audio signal.
Normal output level for most consumer equipment is about -10 dbv (aprox. 250 mv rms). This is why all
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the curves intersect at the -10 dbv point. Looking at the 1:1 line, you can see if an input signal is at the 20 dbv level (slightly soft volume wise) it will come out also at -20 dbv. Thus no change. If the unit is
set for 10:1 compression, the same -20 input will come out at about -11 dbv as shown in the diagram
below. Thus this signal is boosted about 9 db. Likewise, if the input signal goes up to 0 dbv, the output
will be -9 dbv. Thus for an input change from -20 dbv to 0 dbv (a 20 db change) the output only changed
2 db (-11dbv to -9 dbv). This results in soft conversations being boosted to a normal level and loud
special effects being reduced to a normal level.
With the SVS-4 set to 1:2 expansion, if the input makes the same -20 dbv to 0 dbv change as above, the
output now goes from -30dbv to +10 dbv. This is a 40 db output change for a 20 db input change. This
results in soft sounds, including tape hiss and soft conversations, becoming even softer and loud special
effects becoming even louder.
Volume Stabilizer Input / Output Curves
Composite to S-Video Conversion
The SVS-4 has special circuitry to convert the composite video inputs to the S-Video outputs. The
SVS-4 sends the original composite and the generated s-video signal to both sets of outputs. However, if
you feed the selected input with a s-video signal, the SVS-4 only sends the s-video signal to the output.
Note: Because the S-Video signal is generated from the composite video signal, the quality
of the converted S-Video signal will not be as good as a true S-Video signal. For best
picture quality use the original S-Video or composite video signals.
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Trouble Shooting
Problem
Power/Stand-by light does not
come on
No video output
No audio output
No input is selected
Picture is black and white
AIM does not detect device
when turned on
Unit goes to standby after 5
seconds
Volume seems to vary too
much between sources
Video stays on when in standby mode
IR remote does not work
Solution
Make sure power adapter is plugged into a working outlet.
Stand-by light is dim (normal in stand-by mode)
Is power light on?
Is input light lit?
Make sure correct input is selected.
Make sure inputs and outputs are not reversed.
Is power light on?
Is input light lit?
Make sure correct input is selected.
Make sure inputs and outputs are not reversed.
Push STANDBY button so unit is in the ON mode.
Your TV is using both composite and S-Video inputs. Use
only one or the other to feed into the SVS-4 or into your
TV.
Is the video cable connected from the device to the SVS-4?
Is the device producing a video picture. Some products do
not generate a video signal (just a blue screen) unless the
tape/DVD/etc. is actually playing.
Is AIM turned on?
Normal if there are no video inputs.
Either turn video input on or turn AIM off.
Make sure Volume Stabilization is active.
Set Volume Stabilization to the 10:1 setting.
Normal, however, audio is muted
Replace batteries in remote.
Terms
Term
composite video
compression
db
dbv
expansion
S-Video
Definition
Standard video signal using RCA style jacks
Reduce the dynamic range of an audio signal by decreasing loud
signals and increasing soft signals.
Short for decibels - Measure of relative sound levels . The
smaller change a human ear can hear is about 1 db.
Measure of absolute voltages. 0 dbv is equal to .775 v rms. Most
consumer equipment operates at about -10 dbv.
Increase the dynamic range of an audio signal by increasing loud
signals and decreasing soft signals
Video signal that separates the color signal from the brightness
signal and uses mini DIN connectors.
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Technical Specifications
Audio
Inputs, (4 stereo)
Input impedance, 47 Kohms
Typical input level, 300 mv
Frequency response 20 to 20KHz, +/- 3db (bypass mode)
Signal to Noise ratio, greater than 70 db
THD less than 0.1% (bypass mode)
Left to right separation, greater than 60 db
Channel to channel separation, greater than 60 db
Outputs, (2)
Output Impedance, less than 150 ohms
Video
Input (4)
Composite Video (RCA style phono jack)
75 ohm, unbalanced, 1 v p-p
S-Video (4 pin mini DIN)
Y: 1 vp-p, 75 ohms, unbalanced
C: 0.286 V p-p, burst signal, 75 ohms
Outputs, (2)
Composite Video (RCA style phono jack)
75 ohm, unbalanced, 1 v p-p
S-Video (4 pin mini DIN)
Y: 1 vp-p, 75 ohms, unbalanced
C: 0.286 V p-p, burst signal, 75 ohms
Power Input: 15 VDC, 500 ma
Size: 13” wide, 8” deep, 2.25” high
Weight: 3 lbs, 10 oz.
Supplied accessories
AC adapter, 15 VDC, 500 ma output
SRC- IR remote control
A/V cable, 3’
User Manual (this document)
Design and specifications are subject to change without notice
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Limited Warranty
Limited Warranty
Sima Products Corp. (“Company”) warrants that is the accompanying product proves to be defective to the
original purchaser in material or workmanship within 90 days from the original retail purchase, the Company
will, at the Company’s option, either repair or replace same without charge (but no cash refund will be made).
What you must do to enforce Warranty
You must deliver, mail or ship the product, together with both the original bill of sale and this limited Warranty
statement as proof of warranty coverage to:
Sima Products Corp.
Att: Customer Service
140 Pennsylvania Ave., Bld. #5
Oakmont, PA 15139
It is recommended that you contact Sima to obtain a return authorization number.
Limitation of Liability and Remedies
Sima shall have no liability for any damages due to lost profits, loss of use or anticipated benefits, or other
incidental, consequential, special or punitive damages arising from the use of, or the inability to use, this
product, whether arising out of contract, negligence, tort or under any warranty, even if Sima has been advised
of the possibility of such damages. Sima’s liability for damages in no event shall exceed the amount paid for
this product. Sima neither assumes nor authorizes anyone to assume for it any other liabilities.
Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above
limitation or exclusion may not apply to you.
This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.
Sima Products Corp.
140 Pennsylvania Ave., Bld. #5
Oakmont, PA 15139 USA
412-828-3700
800-345-7462
412-828-3775 FAX
Visit us at www.simacorp.com
E-mail us at custserv@simacorp.com
Manual # 21595, rev A
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