dbx Visionary Design 704x Manual de usuario
8760 South Sandy Parkway
Sandy, Utah 84070
Phone: (801) 568-7660
Fax (801) 568-7662
Int’l Fax: (801) 568-7583
Questions or comments?
or visit our World Wide Web home page at:
www.dbxpro.com
A Harman International Company
Part No: 18-6315-A
Important Safety Instructions
The dbx 704X should only be used in a dbx 786, 160S, or a
160SL. Please follow the safety instructions contained in the man-
ual for the product in which the dbx 704X is installed.
704X
®
Notes
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Congratulations on your purchase of the dbx 704X Digital
Output Card. The 704X interfaces with your dbx Blue Series prod-
uct for a premium analog to digital conversion. Below is a list of
the features found on the 704X:
• Sample rates at 44.1, 48, 88.2, and 96 kHz
• Wordlength output at 16, 20, or 24 bits
• Dither to 16, 20, or 24 bits using TPDF or SNR2algorithms
• dbx Type IV™ A/D Conversion System
• Sync input/output using low jitter phase-locked loops
• Two user selectable noise shaping algorithms for lower perceived
noise floor
• Digital output on gold plated connectors
• Can be installed in a dbx 160S/SL Compressor or a dbx 786
Precision Microphone Preamplifier
If you require technical support, contact dbx Customer
Service. Be prepared to accurately describe the problem. Know the
serial number of your unit - this is printed on a sticker attached to
the rear panel. If you have not already taken the time to fill out
your warranty registration card and send it in, please do so now.
Before you return a product to the factory for service, we rec-
ommend you refer to the manual. Make sure you have correctly fol-
lowed installation steps and operation procedures. If you are still
unable to solve a problem, contact our Customer Service
Department at (801) 568-7660 for consultation. If you need to
return a product to the factory for service, you MUST contact
Customer Service to obtain a Return Authorization Number.
Service Contact Information
Introduction
Digital Output Card
704X Digital Output Card
®
1
No returned products will be accepted at the factory without a
Return Authorization Number.
Please refer to the Warranty below, which extends to the first
end-user. After expiration of the warranty, a reasonable charge will
be made for parts, labor, and packing if you choose to use the fac-
tory service facility. In all cases, you are responsible for transporta-
tion charges to the factory. dbx will pay return shipping if the unit
is still under warranty.
Use the original packing material if it is available. Mark the
package with the name of the shipper and with these words in red:
DELICATE INSTRUMENT, FRAGILE! Insure the package prop-
erly. Ship prepaid, not collect. Do not ship parcel post.
This warranty is valid only for the original purchaser and only
in the United States.
1. The warranty registration card that accompanies this product
must be mailed within 30 days after purchase date to validate
this warranty. Proof-of-purchase is considered to be the burden
of the consumer.
2. dbx warrants this product, when bought and used solely within
the U.S., to be free from defects in materials and workmanship
under normal use and service.
3. dbx liability under this warranty is limited to repairing or, at
our discretion, replacing defective materials that show evi-
dence of defect, provided the product is returned to dbx WITH
RETURN AUTHORIZATION from the factory, where all
parts and labor will be covered up to a period of two years. A
Return Authorization number must be obtained from dbx by
Warranty
704X
704X Digital Output Card
2
®
telephone. The company shall not be liable for any conse-
quential damage as a result of the product's use in any circuit or
assembly.
4. dbx reserves the right to make changes in design or make addi-
tions to or improvements upon this product without incurring
any obligation to install the same additions or improvements
on products previously manufactured.
5 The foregoing is in lieu of all other warranties, expressed or
implied, and dbx neither assumes nor authorizes any person to
assume on its behalf any obligation or liability in connection
with the sale of this product. In no event shall dbx or its deal-
ers be liable for special or consequential damages or from any
delay in the performance of this warranty due to causes beyond
their control.
1. Remove lid of the 160SL or 786 by removing 6 phillips head
screws (2 each side, 2 on the back) and 1 hex screw (top and
center of front panel).
2. Remove the 4 silver screws holding the option cover plate on
the rear.
3. Place the 704X in the 160SL/786 from the inside and note
mounting holes labeled "A", "B", and "C".
4. Remove the 704X and then remove the 3 screws mounted in
the 160SL/786 main board directly below points "A", "B", and
"C" when the 704X is installed.
5. Install the 3 taller threaded standoffs where the three screws
were removed.
6. Install the ribbon cable onto the blue header in the 160SL/786
next to the power supply housing.
7. Install the 704X by placing it in the 160SL/786 and then
replacing the 4 silver screws into the rear option slot.
Installation
Digital Output Card
704X Digital Output Card
®
3
8. Install one of the three screws removed from the main board at
point "C" on the 704X.
9. Install the two shorter standoffs at points "A" and "B" on the
704X.
10. Insert the ribbon cable from the main board to the blue con-
nector on the 704X.
11. Install the upper 704X PCB by lining up the two standoffs with
the mounting holes on the upper PCB.
12. Install the last two screws into the standoffs holding the upper
704X PCB.
13. Replace cover.
dbx 704X installed in a 786 Mic Preamp
Now you’re probably wondering, “What’s the catch? I can’t get
something for nothing so what did I give up?” You may be worried
that your A/D noise floor got 4 dB worse because we borrowed the
top 4 dB of your converter. This is certainly a valid concern.
Fortunately, we have the answer! Without going into the confi-
dential technical details, by using our proprietary analog and digi-
tal Type IV™ processing, we reclaim the original A/D noise level!
So what you get is free headroom!
The benefits of the dbx Type IV™ Conversion System can eas-
ily be heard by switching it in and out while listening to signals
with high-level peaks captured in the Type IV™ Over Region. You
will notice an obvious audible difference. With Type IV™
bypassed, you can’t help notice the harsh, edgy sound of the A/D
converter clipping. With Type IV™ enabled, those nasty artifacts
disappear revealing a more open and natural sound. With Type
IV™ enabled, you will get a more accurate and pure representation
of the original wide-dynamic-range signal. You will absolutely
agree that we really do give you “something for nothing.” We give
you peace of mind knowing that you never have to worry about
A/D Clip Level
TYPE IV™ Over Region
Figure 3d - Type IV Mapping Preserves High-Frequency Information
Amplitude
Time
}
TYPE IV™ Over Region
}A/D Clip Level
0 dB FS
0 dB FS
-4
-4
dbx Type IV™ White Paper
704X
704X Digital Output Card
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704X Digital Output Card
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17
AES/EBU OUTPUT Connector: The 704X provides AES/EBU
digital output format through the XLR connector. Be sure to use
short lengths of 110Ω digital cables rather than standard XLR to
XLR cables. Using the correct cables will prevent digital dropouts
and other interconnect problems.
SYNC IN and OUT Connectors: BNC connectors are provided
for both sync in and out. The 704X uses low jitter phased-locked
loops to synchronize to another unit’s wordclock output
through the 704X’s SYNC in jack. The 704X will accept a 44.1,
48, 88.2, or 96 kHz wordclock input, or a 44.1 or 48kHz superclock
(256X sample rate). You also may use the 704X as a master
clock through the SYNC out BNC jack to supply stable clocks
to other processors that accept a sync input. See "Sync Input" for
further information.
SYNC LED: The SYNC LED will light red when the 704X is
locked to an external clock through the SYNC IN BNC jack. Note
that one of the RATE LEDs will light to indicate the clock fre-
quency of the external source.
Rear Panel
Digital Output Card
704X Digital Output Card
®
5
S/PDIF OUTPUT Connector: The 704X provides S/PDIF digital
output format through the RCA coaxial connector. Be sure to use
short lengths of 75Ωdigital cables or 75Ωvideo cables rather stan-
dard audio RCA to RCA cables. Using the correct cables will pre-
vent digital dropouts and other interconnect problems.
NOTE: Although digital information is coming out of both XLR and RCA
jacks simultaneously, the correct format will only appear at the output for the
format type selected. For example, if you have AES/EBU format selected, an
AES/EBU formatted signal will appear at the output of both the XLR and the
RCA connector. Or, if you have S/PDIF format selected, an S/PDIF format-
ted signal will appear at the output of both the RCA and XLR connectors.
AES/EBU / S/PDIF Switch: Selects either AES/EBU format or
S/PDIF digital output format. The LED will be red for AES/EBU
and green for S/PDIF.
TYPE IV Switch: Engages dbx’s proprietary Type IV™ analog to
digital conversion system. See page 9 for more information on Type
IV™.
RATE Switch: Selects output sample rate of 44.1, 48, 88.2, or 96
kHz. The upper LED will light red for 44.1 kHz and green for 48
kHz. The lower LED will light red for 88.2 kHz and green for 96
kHz.
SHAPE: Selects noise-shaping curve of SHAPE 1, SHAPE 2, or
none. Noise shaping essentially takes the noise floor and reshapes
it in a fashion such that the ear perceives the noise floor to be qui-
eter than it really is. See "Noise Shaping" graph on page 20. The
LED will light green for Shape 1 and red for Shape 2. When the
LED is off, there is no noise shaping taking place.
704X
704X Digital Output Card
6
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WIDTH Switch: Selects output wordlength of 16, 20, or 24 bits
output resolution. The upper LED will light green for 16 bits. The
lower LED will light red for 20 bits and green for 24 bits.
DITHER: Selects dither type of TPDF, SNR2, or None. Dither is
random noise that is added to the audio signal which effectively
eliminates the harmonic distortion created by truncation. See
“TPDF Dither” and “Truncation” graphs on pages 19 and 20. The
LED will light red for SNR2and green for TPDF. When the LED
is off, there is no dithering taking place.
The dbx 704X comes with the sync input 75Ωterminated. For
certain configurations, you may wish to have the sync input be
unterminated. Certain "house sync" configurations will require you
to change the default position of the termination jumper on the
main circuit board. For example, if you run your sync to several
pieces of equipment using a tapped configuration (using BNC T’s)
as shown on the next page, only the last box, box C, would be ter-
minated (marked "Terminated" on the circuit board).
Unfortunately, some equipment does not allow the user to change
the termination setting. These pieces of equipment are usually pro-
vided with a permanent termination. If you use the 704X with
another piece of terminated equipment in tapped configuration,
you should unterminate (marked "Unterminated" on the circuit
board) the 704X’s sync input. The same is true if you wish to use
several 704Xs in a tapped configuration. The dbx 704X can also be
used in a daisy chain fashion where each piece of equipment can
remain terminated so the termination can remain in the default
"terminated" position. See figure on the next page for location of
the termination jumper.
Sync Input
Digital Output Card
704X Digital Output Card
®
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