Headphone Amplifier
Symetrix
SX204
Headphone Amplifier
Owner’s Manual
Symetrix Inc.
14926 35th Avenue West
Lynnwood, Washington 98037
Voice: (206) 787-3222, (800) 288-8855
Fax:
(206) 787-3211
Copyright 1988, 1994 Symetrix Inc.
All rights reserved.
Subject to change without notice.
Batteries not included.
This manual will not play in reverse.
Revision: 2.0, 10/01/94
Part Number: 530104
Table of Contents
___________________________________________________
1. INTRODUCTION ................................................................................................2
2. USING THE SX204..............................................................................................3
2.1 IMPEDANCE, SENSITIVITY, LOUDNESS ..................................................................3
2.2 MAXIMUM AMPLIFIER LOAD .................................................................................3
3. REAR PANEL ......................................................................................................5
4. FRONT PANEL ...................................................................................................6
5. BLOCK DIAGRAM.............................................................................................7
6. SPECIFICATIONS ..............................................................................................8
7. REPAIR INFORMATION ..................................................................................9
7.1 RETURN AUTHORIZATION .....................................................................................9
7.2 IN-WARRANTY REPAIRS........................................................................................9
7.3 OUT-OF-WARRANTY REPAIRS ...............................................................................9
8. LIMITED WARRANTY ................................................................................10
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1
1.
Introduction
______________________________________________________________
The Model SX204 Headphone Amplifier is a 1-in 4-out amplifier
designed to drive multiple headphones of any impedance. Symetrix'
proprietary high voltage converter technology gives the SX204 the
ability to drive high impedance headphones with the equivalent
output voltage of a much larger power amplifier, yet provides more
than ample current for low impedance phones. The four stereo
outputs automatically adjust output power to match the load
impedance.
Controls provided are input level, output level for each individual
amplifier, and a stereo/mono switch.
The STEREO/MONO switch allows the amplifier to be used several
ways. As a "normal" stereo amplifier (with four outputs), the left and
right inputs are used for stereo signals, which feed the left and right
outputs. Switching to mono with a stereo input provides a quick
check of the mono compatibility of a stereo mix.
As a mono amplifier, one signal fed to either input will feed both outputs. Also in mono mode, when two different mono signals are fed to
the left and right inputs, they will be combined to feed both the left
and right outputs.
The inputs are electronically balanced, but will operate normally in
an unbalanced configuration when 2-conductor 1/4" plugs are
inserted. The outputs are 1/4" stereo connectors.
2
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2.
Using the SX204
_____________________________________________________
CAUTION: Do not use any AC adapter other than the
Symetrix PS-2. Do not short the outputs. Do not stick
your finger in a light socket.
2.1 Impedance, Sensitivity, Loudness
Loudness is directly related to the impedance and sensitivity of the
headphones. Impedance determines how much power the
headphones will draw, while sensitivity indicates how much of the
electrical signal delivered to the headphones is converted into sound.
Because low impedance headphones draw more power from the amplifier they will sound louder, at the same control settings, than high
impedance headphones. Also, headphones of higher sensitivity will
sound louder than those of lower sensitivity. Check the
manufacturer's spec sheet for impedance and sensitivity information.
Proprietary high voltage converter technology allows the SX204 to
drive even high impedance head headphones to maximum levels, because the amplifiers are capable of very high output voltage swing.
However, to get a loudness equivalent to that of low impedance headphones, the controls will have to be set much higher with high
impedance headphones. This is normal.
If low and high impedance headphones are combined on the same
channel, the low impedance headphones will be much louder. As a
result, when a combination of high impedance and low impedance
headphones is used, only those of like impedance should be used on
the same channel. This allows each listener to properly adjust
loudness, without regard to the impedance and sensitivity of the
other headphones.
2.2 Maximum Amplifier Load
The minimum operating impedance, or maximum load, for each
output of the SX204 is 8 ohms. Use as many pairs of headphones as
desired, as long as the total combined impedance (per output) does
not fall below 8 ohms. Table 2.1 shows how many headphones of
various impedances may be used with each output of the SX204.
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3
Table 2.1 - Combined Impedance Values (approx. 8:)
Impedance of Headphones
8 (see note 1)
16
32
100
200
400
600
Maximum Number/Channel
1
2
4
10
20
40
60
Note 1:
The quantities given above reflect usage with typical
wide-range musical signals. If you are driving low-impedance
phones (16-ohms or lower actual impedance), and you intend to drive
them to the brink of amplifier clipping, then you should revise the
number of headphones possible (per SX204) to 2 8-ohm phones or 4
16-ohm phones (for the 8-ohm case, you'll have two amplifier
channels that aren't doing anything). It is OK to use any remaining
amplifier channels with higher impedance phones (50 ohms or
higher).
For maximum output with all channels driven, try to restrict the
lowest combined load impedance to 50 ohms per channel. Lower
impedance loads simply reduce the maximum output possible.
Note 2:
Many headphones are spec'd as being suitable for
eight-ohm outputs. They are, but this does not mean that their
actual impedance is 8-ohms. In most cases, the actual impedance is
substantially higher. This is good (rather than bad). For whatever it's
worth, most decent phones have actual impedances ranging from 50
ohms and up.
Note 3.
When multiple headphones are required with each
output, use headphone type "Y" cords, or a "breakout box." A
breakout box may have as many paralleled 1/4" stereo jacks a
necessary, as long as the numbers in Table 2.1 are not exceeded.
Breakout boxes are available from:
ProCo
Sescom
Whirlwind
4
800-253-7360
702-384-0993
800-772-9997
Rev 2.0, 10/01/94
3.
Rear Panel
______________________________________________________________
204 HEADPHONE AMPLIFIER
BALANCED/UNBALANCED
INPUT RIGHT
INPUT LEFT
S/N
POWER
16VAC
MANUFACTURED BY SYMETRIX INC. SEATTLE, WA USA
THIS PRODUCT CONTAINS NO USER SERVICABLE PARTS.
Feature
Description
Power
5mm coaxial jack for power input.; Use only the
Symetrix PS 2 16 volt AC power supply. Other
similar looking "power adapters" may damage the
SX204. Accepts plugs with 2.5mm center pin
(Switchcraft 760).
Input A
(Left channel) 3 conductor 1/4" jack for line level
balanced or unbalanced input signals. Tip = high
(+), Ring = low (), Sleeve = ground. Maximum
input level = +18 dBv. Input impedance is >30
kilohms.
Input B
(Right channel) 3 conductor 1/4" jack for line
level balanced or unbalanced input signals. Tip =
high (+), Ring = low (), Sleeve = ground. Maximum
input level = +18 dBv. Input impedance is >30
kilohms.
Rev 2.0, 10/01/94
5
4.
Front Panel
HEADPHONES
PWR
HEADPHONE LEVEL
0
0
+12
0
+25
INPUT
LEVEL
MONO
STEREO
1
2
3
4
10
1
0
10
2
0
10
3
0
10
4
SX204 HEADPHONE AMPLIFIER
Feature
Description
INPUT LEVEL
Sets the input signal strength. Fully
counterclockwise, no signal. Fully clockwise,
input signals are boosted by 20 dB.
PWR
Yellow LED indicates power "on".
MONO/STEREO
Combines stereo, or two mono, input signals
into one mono output signal (fed equally to both
left and right headphone outputs).
HEADPHONES
1/4" stereo jacks for headphones. The minimum
impedance is 8 ohms (see Table 2.1 for
combined headphone impedances).
HEADPHONE
LEVEL
Volume controls set the signal strength at the
corresponding output jack (1-4).
6
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Rev 2.0, 10/01/94
INPUT B
INPUT A
STEREO
MONO
MASTER
VOLUME
CHANNEL
LEVEL
Rev-B
OUTPUT
CHANNEL 1
CHANNEL 2
CHANNEL 3
CHANNEL 4
5.
____________________________________________________________
Block Diagram
7
6.
Specifications
____________________________________________________________
Inputs
Type
bridging, balanced/unbalanced,
transformerless
Input impedance
>10k ohms each leg
Maximum input level
+18dBv
Connector
3-conductor 1/4" (tip-ring-sleeve)
______________________________________________________________
Indicators
Power
yellow LED indicates power "ON"
______________________________________________________________
Audio Performance
Frequency Response
20Hz to 20kHz, +0dB, 1dB
THD
.01% (1kHz, 0dBm, 600
ohms)
.02% (1kHz, +24dBm,
600 ohms)
Signal to Noise Ratio
95dB
Gain
20dB
______________________________________________________________
Outputs
Type
Output impedance
Maximum output level
low-Z
160 ohms
>50 volts p-p into 2000
ohms,
Connectors
1/4" stereo (x4)
______________________________________________________________
Power Requirements
16 volts AC, 200mA
(Symetrix PS-2,
included)
______________________________________________________________
Accessories
RM-2................................. Two-unit standard 19" rack mount
SC-2.................................. Security Cover
PS-2 .................................. Spare 16 volt AC power supply
______________________________________________________________
8
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7.
Repair Information
Should you decide to return your SX-204 to Symetrix for service, please
follow the following instructions.
7.1 Return Authorization
Symetrix will service any of its products for a period of five years from the
date of manufacture. However, goods will not be accepted without a Return
Authorization number.
Before sending anything to Symetrix, call us for an RA number.
just ask, we'll gladly give you one! call (206) 787-3222,
weekdays, 8am to 4:30 pm pacific time.
7.2 In-Warranty Repairs
To get your unit repaired under the terms of the warranty:
1.
2.
3.
4.
5.
Call us for an RA number.
Pack the unit in its original packaging materials.
Include your name, address, etc. and a brief statement of the problem.
Your daytime telephone number is very useful if we can't duplicate
your problem.
Put the RA number on the outside of the box.
Ship the unit to Symetrix, freight prepaid. Our address is printed on
the title page of this manual.
Just do those five things, and repairs made in-warranty will cost you only
the one-way freight fee. We'll pay the return freight.
If you don't have the factory packaging materials, then do yourself a favor
by using an oversize carton, wrapping the unit in a plastic bag, and
surrounding it with bubble-wrap. Pack the box full of Styrofoam peanuts.
Use additional bubble-wrap if you must ship more than one unit per carton.
We won't return the unit in anything but original Symetrix packaging. Of
course, if the problem turns out to be operator inflicted, you'll have to pay
for both parts and labor. In any event, if there are charges for the repair
costs, you will pay for return freight. All charges will be COD unless you
have made other arrangements (prepaid, Visa or Mastercard).
7.3 Out-of-Warranty Repairs
If the warranty period has passed, you'll be billed for all necessary parts,
labor, packaging materials, and any applicable freight charges.
Remember, you must call for an RA number before you send the unit to
Symetrix.
Rev 2.0, 10/01/94
9
8.
LIMITED WARRANTY
The Symetrix SX204 is designed and manufactured for use in professional and studio audio
systems. Symetrix, Inc., warrants that the SX204 manufactured by Symetrix, when properly
installed, used and maintained in accordance with instructions contained in the manufacturer's
operator's manual, will perform according to the specifications set forth in the operator's manual.
Symetrix expressly warrants that SX204 will be free from defects in material and workmanship for
ninety (90) days. Symetrix' obligations under this warranty will be limited to repairing and
replacing, at Symetrix' option, the part or parts of the SX204 which prove defective in material or
workmanship within ninety (90) days from the date of purchase, provided that the Buyer gives
Symetrix prompt notice of any defect or failure and satisfactory proof thereof. Products may be
returned by Buyer only after a Return Authorization number (RA) has been obtained from Symetrix
and Buyer will prepay all freight charges to return any products to the Symetrix factory. Symetrix
reserves the right to inspect any products which may be the subject of any warranty claim before
repair or replacement is carried out. Symetrix may, at its option, require proof of the original date
of purchase (dated copy of original retail dealer's invoice). Final determination of warranty
coverage lies solely with Symetrix. Products repaired under warranty will be returned freight
prepaid via United Parcel Service by Symetrix, to any location within the Continental United
States. Outside the Continental United States, products will be returned freight collect.
THE FOREGOING WARRANTIES ARE IN LIEU OF ALL OTHER WARRANTIES, WHETHER
ORAL, WRITTEN, EXPRESS, IMPLIED OR STATUTORY. SYMETRIX, INC. EXPRESSLY
DISCLAIMS ANY IMPLIED WARRANTIES, INCLUDING FITNESS FOR A PARTICULAR PURPOSE
OR MERCHANTABILITY. SYMETRIX, INC.'S WARRANTY OBLIGATION AND BUYER'S
REMEDIES HEREUNDER ARE SOLELY AND EXCLUSIVELY AS STATED HEREIN.
The Symetrix SX204 is designed and manufactured for use in professional and studio audio
systems and is not intended for other usage. With respect to products purchased by consumers
for personal, family or household use, Symetrix EXPRESSLY DISCLAIMS ALL IMPLIED
WARRANTIES, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE.
This limited warranty, with all terms, conditions, limitations and disclaimers set forth herein, shall
extend to the original purchaser and anyone who purchases the product within the specified
warranty period.
Warranty Registration must be completed and mailed to Symetrix, Inc. within thirty (30) days of
the date of purchase.
Symetrix does not authorize any third party, including any dealer or sales representative, to
assume any liability or make any additional warranties or representation regarding this product
performance on behalf of Symetrix.
This limited warranty gives the buyer certain rights. You may have additional rights provided by
applicable law.
LIMITATION OF LIABILITY
The total liability of Symetrix, Inc. on any claim, whether in contract, tort (including negligence) or
otherwise arising out of, connected with, or resulting from the manufacture, sale delivery, resale,
repair, replacement or use of any product will not exceed the price allocable to the product or part
thereof which gives rise to the claim. In no event will Symetrix, Inc. be liable for any incidental or
consequential damages including but not limited to damage for loss of revenue, cost of capital,
claims of customers for service interruptions or failure to supply, and costs and expenses incurred
in connection with labor, overhead, transportation, installation or removal of products or
substitute facilities or supply sources.
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Rev 2.0, 10/01/94
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