Digital interface for analog audio mixers

Digital interface for analog audio mixers
US007421084B2
(12) Unlted States Patent
(10) Patent N0.2
Jubien et a].
(54)
(75)
US 7,421,084 B2
(45) Date of Patent:
Sep. 2, 2008
DIGITAL INTERFACE FOR ANALOG AUDIO
6,259,957 B1 *
7/2001 Alexander et a1. .......... .. 700/94
MIXERS
6,353,169 B1
3/2002 Juszkiewicz et a1.
.
.
Inventors: Christopher Michael Jubien, V1ctor1a
(CA), Andreas Tennis Martinus
6,466,672 B1
10/2002
6,639,142 B2 *
10/2003 Takahashl .................. .. 84/609
Kappersa Victoria
OlsWang,
Seattle, WA (US);
Benjamin
Daniel
*
St
eers
_
Subramoniam et a1.
Martin Steinberg, Oceanside, CA (US)
(73) Assignee: LOUD Technologies Inc., Woodinville,
WA
( ) Nonce'
(Continued)
S
(U )
OTHER PUBLICATIONS
SutbJetCt.tO altly (gsglalmeé’. thte germdof?glg
Syntrillium Software Corporation, “Cool Edit User’s Manual”,
$518 1155221311); 0 3y: Jus e un er
1992-1996, Versions 1.53 and 95, pp. 1-4, 1530*
(21) Appl. No.: 11/329,838
(
'
(22)
)
P rzmar
'
y Examzneri
'
V~1v1an
'
Ch'1n
Flledi
Jan- 11-1 2006
_
(65)
Continued
Assistant Examinerilason Kurr
_
_
(74) Attorney, Agent,
Prlor Publlcatlon Data
US 2006/0152398 A1
Jul. 13, 2006
or Firm4Christensen O’Connor
Johnson Kindness PLLC
(57)
ABSTRACT
Related US. Application Data
(60)
Provlslonal apphcanon NO' 60/643393’ ?led on Jan'
An analo -di ital interface device is rovided, Which is con
11 2005
’
g
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g
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?gured to be housed Within or removably coupled With an
(51) Int_ CL
H043 1/00
(200601)
(52) us. Cl. ....................................... .. 381/119; 700/94
(58) Field of Classi?cation Search ................. .. 700/94;
381/119’ 61; 369/1’ 4; 84/625, 660’ 697
analog mixer, to thereby form a digital-output analog mixer.
The analog-digital interface device includes analog-digital
Conversion Circuitry and digital transmission ctrtuitry that
Convert 999196 audlo front the analog 11113“ t0 dlgltal fotmat
for transm1ss1on along a d~1g1tal transport mterface to an exter
See application ?le for Complete Search history
nal d1g1tal computmg devlce, such as a PC or MAC computer.
In one embodiment, the analo 8 audio can be taPP ed from any
,
(56)
References Clted
one or more points along a signal path of the analog mixer and
sent to the analog-digital interface device. In another embodi
US. PATENT DOCUMENTS
ment, the analog-digital interface device is further con?gured
4,885,792 A : 12/1989 Christensen et al' ~~~~~~ " 381/119
4,993,073 A
2/1991 Sparkes .................... .. 381/119
5,297,231
A
3/1994
to receive digital signals back from the external digital com
puting device’ Convertthemto analog Signals’ andreturnthem
Mlller
_
-
_
-
-
to the analog m1xer at any one or more po1nts along a s1gnal
5,402,501 A
3/1995 sllfvajt et a1.
ath of the analo mixer
5,524,060 A
6/1996 Silfvast et al.
5,881,317 A *
6,041,080 A *
3/1999 Hampsten et a1.
710/62
3/2000 Fraisse ..................... .. 375/242
p
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4 Claims, 9 Drawing Sheets
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US 7,421,084 B2
Page 2
US. PATENT DOCUMENTS
OTHER PUBLICATIONS
6,686,530 B2
2/2004 Juszkiewicz et 31,
Screen Printout: Cool Edit 1.53 , Feb. 23, 1996 “File Properties”.*
6 888 057 B2
6,969,797 B2
5/2005 Juszkiewicz et 31‘
11/2005 Brinkman etal.
Yamaha, “02R Digital Recording Console” Owner’s Manual, Copy
nght1995’pp'2’ 172 190'
11/2005 Roman et al. ............ .. 369/471
* cited by examiner
2005/0259532 A1*
'
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US. Patent
Sep. 2, 2008
Sheet 1 of9
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US 7,421,084 B2
US. Patent
Sep. 2, 2008
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US 7,421,084 B2
US. Patent
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ANALOG CIRCUITRY
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US. Patent
Sep. 2,2008
US 7,421,084 B2
Sheet 4 0f 9
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US. Patent
Sep. 2, 2008
Sheet 5 of9
US 7,421,084 B2
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US. Patent
Sep. 2, 2008
32_\
Sheet 6 of9
US 7,421,084 B2
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US. Patent
Sep. 2, 2008
Sheet 7 of9
US 7,421,084 B2
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US. Patent
Sep. 2, 2008
Sheet 8 of9
US 7,421,084 B2
US. Patent
Sep. 2, 2008
Sheet 9 0f 9
SAMPLE RATE
44.1 kHZ
LATENCY
6.0ms. I264 samples
0.5ms. I24 samples
1.0ms. / 48 samples
1.5ms. / 72 samples
2.0ms. I88 samples
2.5ms. / 112 samples
3.0ms. / 136 samples
6.0ms. I264 samples
12.0ms. / 536 samples
24.0ms. / 1064 samples
Fig.5.
US 7,421,084 B2
US 7,421,084 B2
1
2
DIGITAL INTERFACE FOR ANALOG AUDIO
MIXERS
auxiliary sends and returns, and a channel volume (fader)
control. The bus section of the analog mixer includes master
auxiliary sends and returns, a master volume (fader) control,
CROSS-REFERENCE TO RELATED
APPLICATION
and one or more mixing (group) buses. The analog audio may
be tapped from any one or more of these points (or before or
after them) forming the channel strip and the bus section.
The present application claims the bene?t of US. Provi
sional Application No. 60/643,393, ?led Jan. 11, 2005.
In accordance With another aspect, the present invention
provides an analog audio mixing system With a digital inter
face. The system includes an analog mixer, an analog-digital
FIELD OF THE INVENTION
interface device coupled With the analog mixer, and a user
The present invention relates generally to an audio system
and, more speci?cally, to an analog-digital interface device
points along a signal path of the analog mixer from Which
analog signals can be tapped and sent to the analog-digital
that permits recording analog audio signals from an analog
interface device.
mixer in a digital computing device such as a desktop com
According to another aspect, the analog-digital interface
device is con?gured to be removably received Within the
interface control that permits a user to select one or more
puter.
analog mixer, to thereby form a digital-output analog mixer.
BACKGROUND OF THE INVENTION
Analog mixers have been used for many years to combine
In another aspect, the user interface control includes one or
more sWitches provided for the corresponding one or more
20
various audio sources (e.g., electric guitars, keyboards, vocal
microphones, etc.) for live and recorded performances. With
activating one or more sWitches, the user can tap analog
signals at the one or more points Which correspond to the one
or more activated sWitches, respectively.
the advent of computers, a need arose to permit a user to
record analog audio from an analog mixer in a personal com
puter or other digital recording device. To date, recording
25
analog audio in a PC has been achieved based on the use of a
dedicated box that may be connected betWeen a PC and an
external analog mixer. An external connection to an analog
mixer has inherent limitations in that the output of the analog
audio to be sent to a PC is accessed (or taken) only at a single
?xed location in the analog mixer, usually at a bus section
(e. g., a ?nal output point) or at an insert section (e.g., an
digital interface device are further con?gured to receive digi
tal audio signals from an external computing device (e.g., a
30
sponding one or more points along a signal path of the analog
mixer at Which the analog audio converted from the digital
35
40
mixer may be con?gured to tap analog audio at any one or
more points along a signal path of the analog mixer and to
send it to the analog-digital interface device. The analog
digital interface device then converts the received analog
to it the independent functionality to carry out analog-to
digital conversion and digital transport of analog audio; and
50
present invention, the analog-digital interface device pro
vides up to 18 independent channels of high-quality digital
audio (e.g., 24-bit/ 96 kHZ) that can be taken from the analog
(3) the ability to selectively add or remove the digital interface
to or from an analog mixer.
BRIEF DESCRIPTION OF THE DRAWINGS
55
The foregoing aspects and many of the attendant advan
tages of this invention Will become more readily appreciated
as the same become better understood by reference to the
purposes.
According to one aspect, the present invention provides an
folloWing detailed description, When taken in conjunction
With the accompanying draWings, Wherein:
analog-digital interface device to be housed Within an analog
mixer. The analog mixer includes at least one signal path
including a channel strip and a bus section. The analog-digital
FIG. 1A illustrates an overall arrangement of an analog
mixer including an analog-digital interface device (not
shoWn), Which is connected to a digital computing device
(e.g., laptop PC), in accordance With one embodiment of the
interface device includes analog-digital conversion circuitry
and digital transmission circuitry, Which convert analog audio
to digital format for transmission along a digital transport
interface to an external digital computing device.
In one aspect, the channel strip of the analog mixer
includes a microphone preampli?er, an equalizer section,
ability to access the analog audio at one or more different
points along a signal path of an analog mixer, (2) the ability to
maintain complete analog mixer functionality While adding
along a signal path of the analog mixer from Which analog
mixer and plugged into a PC or MAC including supporting
softWare, and up to 2 channels of analog audio that can be sent
back from the PC or MAC to the analog mixer for monitoring
Which permits a user to adjust audio sample rates, bit depths,
and latency for data going to or from the analog-digital inter
face device.
As Will be appreciated from the foregoing, an analog
digital interface device formed in accordance With the present
invention provides signi?cant advantages, namely: (1) the
45
face control, Which permits a user to select one or more points
audio can be accessed. In some speci?c embodiments of the
audio can enter the analog mixer.
According to a still further aspect of the invention, the
analog mixer further includes a second user interface control,
To address the limitations of the prior devices, the present
audio to digital audio and sends the digital audio to an exter
nal digital computing device such as a PC. In one embodi
ment, the digital-output analog mixer includes a user inter
PC) and convert them to analog format for mixing and routing
back into the analog mixer. In this connection, according to a
further aspect of the invention, the user interface control may
further include one or more sWitches provided for the corre
invention offers an analog-digital interface device, Which can
be housed or embedded Within an analog mixer, to thereby
form a digital-output analog mixer. The digital-output analog
According to yet another aspect, the analog-digital conver
sion circuitry and digital transmission circuitry of the analog
auxiliary send point).
SUMMARY OF THE INVENTION
points along a signal path of the analog mixer from Which
analog audio can be tapped, respectively. In one example, by
present invention;
65
FIG. 1B illustrates a side of the analog mixer of FIG. 1A,
shoWing an analog-digital interface device of the present
invention being removably received Within the analog mixer;
US 7,421,084 B2
3
4
FIG. 1C is a block functional diagram of the arrangement
of FIG. 1A, consisting of an analog mixer including an ana
section, a plurality of auxiliary send/retum controls, and a
channel volume (fader) control. The channel strip 18 may
log-digital interface device and a digital computing device,
include further controls, such as a control for positioning the
formed in accordance With one embodiment of the present
audio Within a stereo or multi-dimensional audio ?eld, and
invention;
routing sWitches for sending the channel audio to various
FIG. 1D is a block functional diagram of the analog mixer
including an analog-digital interface device, as shoWn in FIG.
destinations Within a bus section. As also Well knoWn and
understood by one skilled in the art, each of the bus sections
(e.g., master bus sections) includes a plurality of controls for
1C;
combining, controlling, and routing the analog audio signals,
FIG. 2A is a block diagram illustrating the concept of
selective tapping and returning of analog signals from and to
such as master auxiliary sends and returns, a master volume
an analog mixer at any one or more points along a channel
(fader) control, and one or more mixing (group) buses.
Speci?cally referring to FIG. 1C, the analog-digital inter
strip of a signal path, according to one embodiment of the
present invention;
face device 20 in accordance With one embodiment of the
FIG. 2B is a block diagram illustrating selective tapping
and returning of analog signals from and to an analog mixer at
present invention is provided in the form of a FireWire board
20'. The analog mixer 17 and the analog-digital interface
device 20 are coupled With each other via a cable 22, for
any one or more points along a bus section of a signal path,
according to one embodiment of the present invention;
FIG. 3 is a block diagram illustrating the con?guration of
an analog-digital interface device of FIGS. 1B and 1C accord
ing to one embodiment of the present invention;
example a ribbon cable, Which inputs analog signals from the
analog mixer 17 and outputs the same to the analog-digital
interface device 20. The analog-digital interface device 20
20
includes analog circuitry 24, a plurality of analog-to-digital
converters (ADCs) 26A, a plurality of digital-to-analog-con
FIG. 4 is a sample hookup diagram illustrating an analog
mixer coupled to various audio sources, Wherein analog sig
verters (DACs) 26B, and a FireWire interface 28. In accor
nals from these sources can be selectively tapped from the
analog mixer to be digitiZed and sent to a digital computing
dance With various exemplary embodiments of the present
invention, the analog signals are taken (or accessed) from one
device (PC), While digital signals can also be returned from
the digital computing device to the analog mixer, in accor
25
or more points along the channel strip or bus section of a
signal path of the analog mixer 17, as Will be more fully
described beloW in reference to FIGS. 2A and 2B, and are
dance With one embodiment of the present invention; and
FIG. 5 is a sample user interface control for permitting a
received by the analog circuitry 24. The analog signals are
then converted into digital signals by the ADCs 26A. The
user to set a sample rate and latency of an analog mixer.
30
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENT
digital audio from the ADCs 26A is then sent along a digital
transport system Which, in the illustrated embodiment, is
provided in the form of IEEE 1394 FireWire interface 28. As
Well knoWn in the art, IEEE 1394 is a very fast external bus
standard, and various products supporting the 1394 standard
FIG. 1A illustrates an arrangement of an overall system 10
including a digital-output analog mixer 12, Which consists of
35
an analog mixer 17 and an analog-digital interface device (not
shoWn), and a digital computing device 14 such as a laptop
PC, Which is connected to the digital-output analog mixer 12.
The system 10 is suited for being able to tap analog signals
from the analog mixer 17 and convert them to digital signals
for recording in the digital computing device 14, in accor
are available under the trademarks such as FireWire, i.link,
Lynx, High Performance Serial Bus (HPSB), etc. Accord
ingly, as used herein, “IEEE 1394 device” refers to any bus
device that supports the high speed data transfer as de?ned
under the 1394 standard. Alternatively, the FireWire interface
40
28 (or any IEEE 1394 device) canbe replaced With other types
of high-speed data interface systems, such as an interface
utiliZing USB 2.0 technology or an interface utiliZing any
dance With one embodiment of the present invention. FIG. 1B
shoWs a side 17A of the analog mixer 17 of FIG. 1A, through
other hi gh-speed data interface system that is currently avail
Which an analog-digital interface device 20 formed in accor
able or to be developed in the future.
dance With the present invention is removably received Within
the analog mixer 17 to thereby form the digital-output analog
45
(e.g., electric guitars, keyboards, vocal microphones, etc.) via
mixer 12. FIG. 1B Will be described in detail later.
FIG. 1C is a block functional diagram of the overall system
10 as shoWn in FIG. 1A, including the digital-output analog
mixer 12 and the digital computing device 14 (e. g., PC or
MAC computer). It should be understood that the digital
Referring to FIG. 1D, the digital-output analog mixer 12
receives audio from a plurality of external audio sources 21
the plurality of channel strips 18 of the analog mixer 17,
respectively. Speci?cally, referring additionally to FIG. 1B,
50
once the analog-digital interface device 20 is coupled With
(e.g., included in) the analog mixer 17 of a table-top format
computing device 14 may be any computing device having
type, for example, to thereby form the digital-output analog
multitrack recording functionality, and thus is not limited to a
mixer 12, connector points 68 of the analog mixer 17 are used
to couple various audio sources to the digital-output analog
mixer 12. At the same time, the analog-digital interface
device 20 in the digital-output analog mixer 12 is coupled to
an external digital computing device. A user can then enjoy
the complete functionality and user interface of the analog
mixer 17, While at the same time being able to record, process,
PC or MAC personal computer. The digital-output analog
mixer 12 is coupled With the digital computing device 14 via
55
a cable 16, such as a FireWire cable. The digital-output analog
mixer 12 includes an analog mixer 17 having analog mixing
functionality and user interface, as Well knoWn in the art, and
the analog-digital interface device 20. Referring additionally
to FIG. 1D, Which is a block functional diagram of the digital
60
output analog mixer 12, the analog mixer 17 typically
includes a plurality of audio channels or channel strips 18
(18A-18M are shoWn in FIG. 1C) and a plurality of bus
sections (e.g., master bus sections) collectively referred to as
19 in FIG. 1D. As Well knoWn and understood by one skilled
in the art of audio processing, each of the channel strips 18
typically includes a microphone preampli?er, an equalizer
and reproduce the audio signals in the digital domain using
the digital computing device 14. As described above, the
analog audio signals can be accessed (taken) from any one or
more points along the channel strip or the bus section of a
signal path of the analog mixer 17, and converted into digital
65
audio signals to be sent to the digital computing device 14.
Also, the digital audio signals from the digital computing
device 14 can be received by the analog-digital interface
US 7,421,084 B2
6
5
device 20 to be converted into analog audio signals and routed
When the analog signals are taken at one or more points
to enter the analog mixer 17 at any one or more points along
along the channel strip or the bus section, as described above,
the channel strip or the bus section of its signal path.
FIGS. 2A and 2B schematically illustrate hoW analog sig
the signals are sent to the ADCs 26A, Which convert the
signals to digital signals. The digital signals are then sent
along a digital transport system, for example according to the
nals are taken from and return to one or more points along the
channel strip 18 and the bus section 32 (e. g., master bus
IEEE 1394 standard via the FireWire interface 28, to the
section), respectively, in the digital-output analog mixer 12 in
digital computing system 14 (e.g., PC, MAC computer),
accordance With various exemplary embodiments of the
present invention. In FIG. 2A, the analog signals may be
Where the digital signals are recorded and/or may be further
processed.
taken at one or more points along the channel strip 18 includ
Still referring to FIGS. 2A and 2B, according to various
ing: (1) after a microphone preampli?er 34, (2) after audio
equalization circuits 36, (3) at auxiliary sends 38 (e.g., before
exemplary embodiments of the present invention, any digital
signals recorded or processed in the computing system 14 can
then be sent along the same transport system in a plurality of
digital audio streams back to the DACs 26B for conversion
back to the analog domain. The analog signals are then routed
to enter any of the channel strips or the bus sections of the
analog mixer 17 at one or more points therealong. For
or after an auxiliary send fader or after an auxiliary send insert
point), and (4) after a fader/volume control 40.
Referring noW to FIG. 2B, the analog signals may also be
taken from the bus section 32 at one or more points including:
(1) after auxiliary sends/retums 42, (2) after Mix Bus l-x 44,
Which is the summation of all channel audio signals, (3) after
equalization circuits (EQ) 46, and (4) after a master fader 48.
For example, if a user Wishes to access relatively “raW”
20
analog signals (not yet processed via the analog mixer 17) to
be digitized and sent to the digital computing device 14, then
the user may Wish to tap the signals earlier in the channel strip
(e. g., after the preampli?er 34 in FIG. 2A). On the other hand,
if a user Wishes to tap analog signals that have been more fully
processed via the analog mixer 17, then the user may Wish to
access the signals later in the channel strip or the bus section.
It should be understood that the various points described
25
(4) before the master fader 48. It should be understood that the
various points described above are merely exemplary, and the
30
analog signals may enter the analog mixer 17 at one or more
of any other points along the input channel or the bus section
of a signal path, in accordance With the present invention. It
to, before a subgroup fader, after a subgroup fader, after a
subgroup insert point, after an input channel insert point, and
after a main bus insert point.
Accessing and taking analog signals from one or more of
such points is possible based on various means, as should be
apparent to one skilled in the art, such as by using a series of
sWitches each coupled to one of these points to thereby
the fader/volume control 40. As further examples, referring to
FIG. 2B, the analog signals may enter the analog mixer 17 at
(1) before the auxiliary sends/retums 42, (2) before the “Mix
Bus l-x” 44, (3) before the equalization circuits (EQ) 46, and
above are merely exemplary, and the analog signals may be
taken from one or more of any other points along the input
channel or bus section of a signal path such as, but not limited
example, referring to FIG. 2A, the analog signals may enter
the analog mixer 17 at: (1) before the microphone preampli
?er 34, (2) before the audio equalization circuits 36, (3) at the
auxiliary sends 38 (e.g., before or after the auxiliary send
fader or after the auxiliary send insert point), and (4) before
should further be understood that a suitable user interface
control may be provided to permit a user to select one or more
35
points along a signal path of the analog mixer 17 at Which the
analog signals from the analog-digital interface device 20 can
output analog mixer 12 may include a user interface control,
enter the analog mixer 17. The user interface control may
include, for example, sWitches that are similar to the sWitches
69A-69D described above and shoWn in FIG. 1A. It should be
understood that the sWitches illustrated in FIG. 1A form
merely one example of a user interface control that permits a
Which permits a user to select one or more points along a
user to select desirable locations to tap (or return) analog
receive analog signals therefrom. In accordance With various
exemplary embodiments of the present invention, the digital
40
signal path from Which analog audio of the analog mixer 17
signals from (or to) the analog mixer 17, and various altema
can be taken and sent to the analog-digital interface device 20.
tive forms of a user interface control should be obvious to one
For example, as shoWn in FIG. 1A, the channel strip 18M
includes a microphone preampli?er 67A, an equalizer section
67B, auxiliary sends and returns 67C, and a channel volume
(fader) control 67C. The user interface control of the digital
output analog mixer 12 includes four sWitches 69A-69D,
Which are located adjacent to and slightly doWnstream from
the channel control elements 67A-67D, respectively, to
thereby correspond thereto. Speci?cally, the sWitch 69A cor
45
digital interface device 20, provided in the form of a FireWire
board, in accordance With one embodiment of the present
invention. The analog-digital interface device 20 includes
50
67D. In this example, by activating one or more of these
sWitches 69A-69D, the user can tap analog signals from the
one or more points Which correspond to the activated
sWitches. Though FIG. 1A illustrates the user interface con
55
60
it should be understood that a similar user interface control
may be provided for each of the other channel strips also. It
bus section (as shoWn in FIG. 2B) also.
22 (e.g., the ribbon cable 22 of FIG. 1C) that takes the analog
signals to and from the analog mixer 17. The analog buffering
52 conditions the incoming analog signals to have the correct
amplitude and offset as required by the ADCs 26A and a
CODEC (Compression/Decompression module) 54. In one
example, the ADC 26A comprises an AK5384 or equivalent,
available from AKM Semiconductor or other mixed-signal
semiconductor company, Which is an audio analog to digital
trol With respect to only one of the plurality of channel strips,
should further be understood that such sWitches may be pro
vided to tap analog signals from one or more points along a
analog circuitry 24 consisting of a connector 50 and analog
buffering 52. The connector 50 is used to mate With the cable
responds to a point after the microphone preampli?er 67A,
the sWitch 69B corresponds to a point after the equalizer
section 67B, the sWitch 69C corresponds to a point after the
auxiliary sends and returns 67C, and the sWitch 69D corre
sponds to a point after the channel volume (fader) control
skilled in the art.
FIG. 3 is a block diagram of one embodiment of the analog
65
converter that takes 4 analog signals and produces a 24-bit
digital replica at a desired sample rate. In one example, the
CODEC 54 comprises an AKM4528 or equivalent, available
from AKM Semiconductor or other mixed-signal semicon
ductor company, Which contains 2 ADCs 26A and 2 DACs
26B. The ADCs 26A convert analog signals and produce a
24-bit digital replica and the DACs 26B convert 24-bit digital
data streams into analog signals.
US 7,421,084 B2
7
8
The FireWire interface 28, Which is one example of a
high-speed data interface that may be used in accordance With
inputs), and keyboard or other line-level input 82 (four
inputs), respectively. The tWo digital channels coming out of
the present invention (see FIG. 1C), includes an interface
processor 56, clocks 58, memory 60, a physical layer device
(PHY) 62, and interface connectors 64. In the illustrated
the PC 14 back to the analog-digital interface device 20 and
then to the analog mixer 17 may be used to output analog
signals via headphones 84 (tWo outputs), so that a player can
monitor the digital signals as recorded in the digital comput
embodiment, the interface processor 56 comprises a DM1000
or equivalent FireWire processor, available from BridgeCo or
other mixed-signal semiconductor company, Which is a full
duplex IEEE 1394 interface processor With an integrated
FireWire link layer controller. The DM1000 receives and
transmits data from and to the (FireWire) PHY 62 and trans
lates the audio data to be sent to and received from the
ADCs26A and CODEC 54 (including ADCs 26A and DACs
26B). The DMlOOO also provides a multi-channel audio data
patch to a PC via the (FireWire) PHY 62 and handles control
information and audio buffering. The clocks 58 are used for
the operation of the ADCs 26A and the CODEC 54, and in one
embodiment the audio clock is derived from the FireWire bus
to be distributed via a CGS2535 clock distributor, available
from National Semiconductor Corporation or other semicon
ductor company. In one embodiment, the memory 60 consists
of FLASH memory and SRAM (Static Random Access
Memory). FLASH memory is used to store program code for
ing device 14.
FIG. 5 is a sample user interface screen that permits a user
to control the operation of the analog-digital interface device
20 as used With an analog mixer 17 in accordance With various
exemplary embodiments of the present invention. The screen
prompts a user to select an analog-to-digital (or digital-to
analog) sample rate in a WindoW 90, and a latency level in a
WindoW 92, each With a pull doWn menu displaying options
available to the user. In the illustrated embodiment, the user
has selected 44.1 kHZ as the sample rate, and 6.0 ms/264
samples as the latency level. The user interface screen may
permit a user to set other parameters, such as bit depths, in a
similar manner.
20
the interface processor 56 (e.g., DM1000) and the SRAM is
used for audio buffering. Lastly, the physical layer device
(PHY) 62, in the illustrated embodiment, is provided in the
25
1. An analog audio mixing system With digital interface,
Instruments. TSB41AB2 provides the digital and analog
30
an analog mixer including at least one signal path compris
ing a channel strip and a bus section;
an analog-digital interface device coupled With the analog
mixer, the analog-digital interface device comprising
analog-digital conversion circuitry and digital transmis
and arbitration and for packet reception and transmission.
sion circuitry that convert analog audio to digital format
It should be understood by one skilled in the art that the
embodiment illustrated in FIG. 3 is merely exemplary, and
The embodiments of the invention in Which an exclusive
property or privilege is claimed are de?ned as folloWs:
comprising:
form of a FireWire PHY, TSB4lAB2, available from Texas
transceiver functions needed to implement a cable-based
FireWire netWork. It supports tWo nodes, or interface connec
tors 64, and includes circuitry to monitor the line conditions
as needed for determining connection status for initialization
While the preferred embodiments of the invention have
been illustrated and described, it Will be appreciated that
various changes can be made therein Without departing from
the spirit and scope of the invention.
for transmission along a digital transport interface to an
35
various different con?gurations are possible to form an ana
external digital computing device; and
a user interface control that permits a user to select one or
log-digital interface device 20 in accordance With the present
invention.
more points along the signal path of the analog mixer
Referring back to FIG. 1B, one advantage of the analog
digital interface device 20 is that it canbe provided in the form
of an interface board option card, Which can be readily
included in and removed from an existing analog mixer 17. In
the illustrated embodiment, the analog-digital interface
device 20 provided in the form of an option card may be
analog-digital interface device, Wherein the analog-digi
inserted into a corresponding hole de?ned in one side 17A of
from Which analog signals can be tapped and sent to the
40
45
the analog mixer 17 and secured therein using suitable means,
such as a pair of screWs 66 to be received Within correspond
2. An analog audio mixing system With digital interface,
ing holes provided in the side 17A of the analog mixer 17.
FIG. 4 is a sample hookup diagram for use in live multi
track recording to a laptop computer 14 using an analog
digital interface device 20 formed in accordance With the
comprising:
50
present invention. The diagram illustrates various audio
55
external digital computing device; and
a user interface control that permits a user to select one or
more points along the signal path of the analog mixer
60
from Which analog signals can be tapped and sent to the
analog-digital interface device, Wherein the analog-digi
tal interface device is con?gured to return analog signals
to several points along a signal path of the analog mixer,
Wherein the analog signals have been returned after hav
analog mixer 17. In this example, the sixteen channel strips of
guitar effects 78 (tWo inputs), a drum machine 80 (tWo
sion circuitry that convert analog audio to digital format
for transmission along a digital transport interface to an
and an analog input for each of tWo channels to be received
from the PC 14, converted to analog form, and sent back to the
the analog mixer 17 to be digitiZed and sent to the PC 14
receive audio signals from an electric guitar 72, a bass guitar
74, six vocal microphones 76, an electric guitar With stereo
an analog mixer including at least one signal path compris
ing a channel strip and a bus section;
an analog-digital interface device coupled With the analog
mixer, the analog-digital interface device comprising
analog-digital conversion circuitry and digital transmis
sources used in live recording, Which are hooked up to an
analog mixer 17 including an analog-digital interface device
20, Which in turn is coupled to an external digital computing
device 14 (e.g., a PC laptop). In the illustrated embodiment,
the analog-digital interface device 20 provides a digital direct
output for each of 16 channels of the analog mixer 17 to be
digitiZed and sent in digital form to the PC 14, an analog
output to be sent to each of tWo (right and left) speakers 84,
tal interface device is con?gured to tap analog audio
from several points along a signal path of the analog
mixer, Wherein at each of said points an analog audio
signal may be tapped at a different stage of processing so
that the tapped analog audio signal is further converted
to digital format by the analog-digital interface device
for transmission to the external digital computing device
to digitally process the converted signal.
65
ing been digitally processed by the digital computing
device and converted from digital format to analog for
mat by the analog-digital interface device.
US 7,421,084 B2
10
3. An analog-digital interface device that is con?gured to
be housed Within an analog mixer, the analog-digital interface
4. An analog-digital interface device that is con?gured to
be housed Within an analog mixer, the analog-digital interface
device comprising:
analog-digital conversion circuitry and digital transmis
device comprising:
analog-digital conversion circuitry and digital transmis
sion circuitry that convert analog audio from the analog
mixer to digital format for transmission along a digital
transport interface to an external digital computing
device, Which is further con?gured to tap analog audio
from several points along a signal path of the analog
sion circuitry that convert analog audio from the analog
mixer to digital format for transmission along a digital
transport interface to an external digital computing
device, Which is further con?gured to return analog sig
nals at several points along a signal path of the analog
mixer, Wherein at each of said points an analog audio
signal may be tapped at a different stage of processing so
mixer, Wherein the analog signals have been returned
after having been digitally processed by the digital com
that the tapped analog audio signal is further converted
to digital format by the analog-digital interface device
for transmission to the external digital computing device
to digitally process the converted signal.
puting device and converted from digital format to ana
log format by the analog-digital interface device.
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