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CP-1 Digital Audio Environment Processor

1.  Schroeder, M.R., Gottlob, D. and Siebrasse, K.F.,"Comparative Study of
European Concert Halls:  Correlation of Subjective Preference with Geo-
metric and Acoustic Parameters", J. Acoust. Soc. Am., vol. 56, pp. 1195-1204
(1974).

2. Barron, M., and A.H. Marshall, "Spatial Impression Due to Early Lateral
Reflections in Concert Halls: The Derivation of a Physical Measure", J. Sound
Vibration,
 vol. 77, pp. 211, 232 (1981).

3. Griesinger, D., "Spaciousness and Localization in Listening Rooms and
Their Effects on the Recording Technique", J. of the Audio Eng. Soc., vol. 34
no. 4, pp. 255-268 (1986).

4. Griesinger, D., "New Perspectives on Coincident and Semi Coincident
Microphone Arrays", J. of the Audio Eng. Soc., 82nd Convention, Lon-
don(1987) Preprint # 2464 (H-4).

5. Damaske and Mellert, "Ein Verfahren zur richtungstreuen Schallab-
bildung des oberen Halbraumes über  zwei Lautsprecher", Acustica, vol. 22,
pp. 153-162 (1969/70)

6. Bishnu S. Atal and Manfred R. Schroeder, "Apparent Sound Source
Translator" - U.S. Patent Disclosure, Patent No. 3,236,949, Feb. 22, 1966.

7. Borish, J., "An Auditorium Simulator for Domestic Use", J. of the Audio
Eng. Soc.
, 33 (5) p. 330 (1985).

8. Blumlein, A.D., British Patent 394,325, 14 June, 1933, reprinted inJ. of the
Audio Eng. Soc.
, Vol. 6, pp. 91-98, 130 (April, 1958).

9. Schroeder, M.R., "Progress in Architectural Acoustics and Artificial
Reverberation: Concert Hall Acoustics and Number Theory", J. of the Audio
Eng. Soc.
, 32(4) pp. 194-203 (1984).

10. Blauert, J. and Lindemann, W., "Auditory Spaciousness: Some further
psychoacoustic analyses", J. Acoustical Soc. Am. 80 (2), August, 1986.

11. Griesinger, D., "Theory and Design of a Consumer Environment Proc-
essor", presented at the Los Angeles AES Convention, Nov., 1988, preprint
available.

References

Theory

and

Design

Summary of Contents for CP-1

Page 1: ...CP 1 Digital Audio Environment Processor Owner s Manual CP 1 Plus Version 2 0 ...

Page 2: ...nterference by one or more of the following measures Reorient or relocate the receiving antenna Increase the separation between the equipment and the receiver Connect the equipment into an outlet on a circuit different from that to which the receiver is connected Consult the dealer or an experienced radio TV technician for help This triangle which appears on your component alerts you to important ...

Page 3: ... Moisture Do not use the unit near water for example near a sink in a wet basement near a swimming pool near an open window etc Object and liquid entry Do not allow objects to fall or liquids to be spilled into the enclosure through openings Cleaning The unit should be cleaned only as recommended by the manufacturer Servicing Do not attempt any service beyond that described in the operating instru...

Page 4: ...ion Installation 7 Connections to Other Equipment 9 Setting the Main Input and Output Levels 11 Calibrating the Listener Position 13 3 Speaker Set Up and Configuration 15 4 Using The Programs To Load Modify and Store Programs 21 The Modes Panorama 22 Concert Halls 24 Music Surround 28 Movie Surround 32 To Rename and Store a Register 36 5 Troubleshooting 37 6 Theory and Design 41 7 Specifications 6...

Page 5: ...Panorama Ambience Reverb Surround CP 1 Digital Audio Environment Processor Owner s Manual CP 1 Plus Version 2 0 ...

Page 6: ...eaker stereo systems over thirty years ago brought dramatic improvement to high fidelity music reproduction With a care fully designed system and good recording it became possible to produce a good sonic picture of the original event Unfortunately our listening rooms do not approximate the acoustics of a good concert hall an intimate jazz club or a magnificent cathedral our ears tell us where we r...

Page 7: ...verberant decay than on early reflections It is especially good for simulating large highly reverberant spaces such as churches stadiums and cathedrals For films encoded with Dolby Stereo the CP 1 uses a completely digital Dolby Pro Logic Surround decoder with automatic correction of azimuth and channel balance errors the most common problems in currently avail able films The CP 1 also provides mo...

Page 8: ...ameters can be changed to create custom User modes Mode Parameter values are stored recalled in Presets and User modes Some examples are Delay Time Bass Split etc System parameter values are not associated with a particular mode System parameters are not stored in User registers or Presets nor do their values change when a new mode is recalled Examples are display contrast volume etc Register The ...

Page 9: ...l from the remote control The SYSTEM MUTE LED indicates that unprocessed audio is no longer passing through to the CP 1 s main outputs The EFFECT MUTE LED indicates that the CP 1 s processed audio is no longer passing through to its outputs Indicator Lights The alphanumeric display shows both the effect that is running and its modifiable parameters The CP 1 has 24 registers PRESETs 1 12 are config...

Page 10: ...one only after all other channels are calibrated See pages 12 and 19 Main Center and Subwoofer Outputs Center channel output with level control and button Push the button in if you have no center channel leave it out if a center speaker is connected NOTE Leaving this button out with no center channel will cause the Surround modes to malfunction Center Out Phantom In Inputs and outputs for an addit...

Page 11: ...for simulating large highly reverberant spaces Panorama The PANORAMA modes provide enhanced lateral sound and hence greater spaciousness and envelopment for either music or films PANO RAMAcanutilizeleftandrightrearchannelsbutisalsoeffectiveusingonly the two front loudspeakers NORMAL 1 and WIDE 2 differ primarily in their initial Effect Levels BINAURAL 3 is for playback on loudspeakers of recording...

Page 12: ...The number doesn t change if you are using Preset 9 BANK switches to User 9 and vice versa Holding BANK for a few seconds puts the CP 1 into Configuration mode inwhichthethreeParameter buttonsadjusttheLCDcontrastandselectone of the 12 speaker setups illustrated on page 15 The three PARAMETER buttons allow selection and adjustment of variable parameters within each mode Pushing PARAM displays the c...

Page 13: ...ts alone back on Pressing SYSTEM MUTE then EFFECT MUTE allows you to hear only the effect channels of the CP 1 This is particularly useful for making fine adjustments of parameters EFFECT MUTE alternately turns off and on all signals added by the CP 1 Use it to compare the sound with and without CP 1 processing In TEST mode EFFECT MUTE clears all user memories See page 21 Mute ...

Page 14: ...o AAA batteries in the CP 1 s remote control Precautions The CP 1 may be installed on a shelf or in a standard 19 equipment rack Contact Lexicon or your local dealer for hardware sources Connect the power cord to a wall outlet or to a switched outlet on the back of your preamplifier Observe the following precautions Connections to Other Equipment VCR or CASSETTE DECK MAIN OUT TAPE OUT IN AUDIO OUT...

Page 15: ...on Locate the button below the SUB potentiometer marked CENTER OUT PHANTOM IN If you have no center front speaker push it in if you have a center channel make sure this button is in the out position Audio Inputs Note Audio Outputs Ifyouhaveareceiverwithnoexternalaccesstothepreamplifieroutputs or you wish to use the tape monitor loop on your preamp you can use a tape output or external processor lo...

Page 16: ...ht of thedisplayblinkoccasionally thenreducetheINPUTLEVELuntilonlythe green LEDs are lit If there are audible differences between the levels of the source you used for this calibration procedure and other sources you may have to readjust the INPUTLEVELtoaccommodatethem Wherepossible trytousetheoutput level controls on the various sources to equalize levels Push and hold the VOLUME DOWN button on t...

Page 17: ...Push PARAM UP to turn on the calibration signal The sound you hear is a band of noise centered around 1 kHz being sent in sequence to all channels left side plus left front center right side plus right front and rear channel s If you have a center speaker the rear panel CENTER PHANTOM button should be out Since all levels are down except for MAIN you will hear only both fronts left only silence ri...

Page 18: ...ing If the image is off center adjust the CP 1 s BALANCE control The narrower the monaural image the better Panorama will work Perform the following setupfromarelaxed comfortablepositioninyourlisteningchair withyour head facing the center point between the speakers 1 Reducethevolumetoabout 20dB Ifthedisplayreads USER atthetop left push Program button 2 if not push BANK then button 2 to load PRESET...

Page 19: ...nter or use PARAM to get to LISTENER POS and adjust this parameter to move the sweet spot towhereyouwantit UsePARAMtosteptoCALIBRATEandpush PARAM DOWN until the calibration signal goes off The Panorama mode is now calibrated To store it see page 36 Use PARAM to display the final values of LISTENER POS and SPEAKER ANGLE Note these values and use them for all forms of Panorama including the Pano ram...

Page 20: ...this mode operations are carried out using only the three PARAM buttons Configu ration mode will be canceled if any other button is pressed or if 10 seconds pass without a button push Subwoofers are not shown in any of these configurations Consult the subwoofer owner s manual or your dealer for proper placement of subwoofers Sideandrearspeakersmaysoundbetterif mountedabovethelistener Seepage16 1 C...

Page 21: ...optimal performance as your system ex pands If you are starting with a conventional two channel system in what order should you add additional channels The answer depends on whether you are primarily interested in audio or video Best The film enthusiast with only two stereo speakers should place them relatively close on either side of the screen and use the Panorama mode for both music and films B...

Page 22: ... can be as far as 20 degrees behind the listener For film use they should be slightly ahead of the listener Place the sides at or slightly above ear level Ceiling placement is notrecommended asthiswillreducethestereoseparationandwillbequite strange for film where Pro Logic sends the same information to the sides and fronts The rears should be separated as much as possible and kept away from the li...

Page 23: ...rners of the room driven from the rear amplifiers The side speakers however are the most important With Configuration 5 movies can be played with the Pro Logic mode the rear channelsoundwillautomaticallyberoutedtothesidespeakers Ifyou have six speakers Configuration 9 an additional stereo amplifier can power both a center channel and a subwoofer The height of the extra speakers will depend on the ...

Page 24: ... bi amping the main speakers all the low bass is handled by the subwoofer and the main speakers only handle mid bass on up This usually reasults in a better sounding main speaker If you want to run the main speakers full range the subwoofer can be wired in parallel to the main amp using a Y connector Alternatively the CP 1 Subwoofer ouput can be used If there is not enough gain for the subwoofer b...

Page 25: ...Lexicon Page 20 Speaker Set Up and Configuration ...

Page 26: ...e if you are running USER 7 pressing BANK will switch to PRESET 7 When the CP 1 leaves the factory each User register contains a duplicate of the Preset of the same number If you maintain this arrangement the labels on the remote will continue to describe the contents of both registers You can however store a version of any mode in any of the User registers The CP 1 s User registers can be cleared...

Page 27: ...eakers If side speakers are present Panorama disables them and substitutes its own simulation The front speakers are driven entirely from the CP 1 s digital circuits Panorama will also send a stereo difference signal left channel minus right or vice versa to the rear loudspeakers if you have them NORMAL 1 will provide enough expansion for most music while WIDE 2 has a more pronounced effect on the...

Page 28: ...e for recordings with too much of this property LF WIDTH canaddneededspaciousnessandwarmthtoclassicalrecordingsmadewith coincident or near coincident miking See Chapter 5 Theory and Design REAR LEVEL adjusts the loudness of the signals sent to the rear channels REAR ROLLOFF sets the frequency above which the rear channel sound is attenuated It should be high enough to give presence and airiness to...

Page 29: ...ams 5 and 6 It will be easier to hear exactly what the parameters do if the effect level is temporarily turned all the way up Program parameters for Small Club and Concert Hall are identical but vary in the available range of settings to specify room characteristics as well as in their intial settings The parameters for Cathedral are significantly different and are described immediately following ...

Page 30: ...e air in the hall and its initial value is therefore more pronounced the rolloff begins at a lower frequency in the larger halls The Speech Detection circuit distinguishes monaural speech from other inputs Whenever stereo signals are present the right and left input chan nels are used independently as inputs to the ambience synthesis If there is a strong monaural speaking voice present at the same...

Page 31: ... When there are no side speakers it adjusts the amount of ambient signal mixed into the main loudspeakers EFFECT LEVEL is the most important user adjustment in the Concert Hall mode and has been given its own button on the remote It should be set as high as possible without making the extra speakers individually audible ROOM SIZE allows you to change the room size in fine gradations For convenienc...

Page 32: ...fit to some popular music where spoken voice such as rap occurs along with music stereo television and early stereo movies Any stereo material which was not carefully mixed for Surround is a good candidate for playing through Ambience with SPEECH DETECTION On PANORAMA EFFECT adjusts the strength of the signal used to expand the stereo image outward from the front two speakers Its initial value is ...

Page 33: ...m the theatrical optical format Dolby Pro Logic Surround decoding is the licensed consumer version of the professional Dolby Stereo cinema processors which allows the home viewer to obtain all the spatial effects of the soundtrack heard in a theatre over a wider range of seating positions than conventional Dolby Surround playback Program Parameters CENTER LEVEL HIGH PASS SET PROGRAM NAME MEMORIZE ...

Page 34: ...eter should be set to ON for films OFF for music When it is on special patented algorithms continually monitor the input signal and adjust both the relative level and time offset of the two channels to keep the dialog properly centered and special effects properly localized This automatic feature is why the CP 1 does not have or need an input balance control for Dolby Surround decoding REAR DELAY ...

Page 35: ... at thislevel central monaural sourcesarereducedinlevelby6dBinthemain stereo speakers With FRONT and REAR EFFECT both set to 0 STEREO LOGIC becomes the equivalent of a simple non steered Dolby Surround decoder Ifyouhavenorearspeakers REAREFFECTshouldbesetto0 The CP 1 will set this parameter automatically when you specify a speaker configuration with no rear channels See page 15 FILM EQ equalizes t...

Page 36: ...ve or need a front panel input balance control for Dolby Surround decoding REAR DELAY in Stereo Logic is adjustable Generally the correct delay is about20milliseconds butthesettingdependsonspeakerset upandsource material In general the delay should not be so great that the rear sound becomes identifiable as a distinct source Dolby Surround decoding specifications call for a special form of Dolby B...

Page 37: ...nt speakers ACADEMY FILTER is provided to recreate the proper tonal balance of older monaural films which were recorded with a much narrower and duller frequency response than current films MAIN LEVEL controls the level of the mono signal which is reproduced by the main speakers When there is a center speaker configured many films may sound better when this control is set between 6 12 This will sp...

Page 38: ...ally when you specify a speaker configuration with no rear channels See page 15 FILM EQ equalizes the left center and right channel outputs to match the overall frequency balance of the original recording Without this equaliza tion many films and some television programs will sound too bright and become fatiguing to listen to This EQ is a gentle shelving filter REAR ROLLOFF sets the cutoff frequen...

Page 39: ...nct source Auto Azimuth Balance Rear Delay The Modes Movie Surround 40 35 30 25 20 15 10 5 0 0 5 10 15 20 25 30 35 40 Distance in feet From Front Speakers Distance in feet From Rear Speakers Preferable Acceptable 1 5 m s 1 5 m s 1 5 m s 2 0 m s 2 5 m s 3 0 m s 3 0 m s 3 0 m s Dolby Surround decoding specifications call for a special form of Dolby B type noise reduction for the rear surround channe...

Page 40: ...w bass from the center where it is in many film and music mixes and distributes it instead to the left and right front channels and the subwoofer This is valuable because in many video installations the centerspeakerissmallerthanthetwomainstereospeakersandis therefore less capable of handling the lowest frequencies Refer to the graph on page 31 REAR DELAY in Pro Logic is adjustable Generally the c...

Page 41: ...the space Holding either button for one second activates an auto repeat mode to speed you throughthelist Alllettersareavailable inupperorlowercase asaredigits 0 9 a blank space and an assortment of other characters When the first space in the display is correct press button 2 set the second character and repeat until the new name is complete As with all the other parameters a new name composed whi...

Page 42: ...er amplifier preamp or other source Powerturn onwithlargepowerampsmaycausepowersagsthatwill confuse the CP 1 To prevent this plug the CP 1 into an AC outlet on a different branch circuit or turn on one amplifier at a time First verify that signal is coming into the CP 1 by observing the Input Level meters Increase VOLUME using the Remote Control and check the Front Back and Left Right balances Mak...

Page 43: ...s If there is no center channel in the system the center channel output is routed to both the left and right main outputs This means the left speakerreproducesnotonlytheleftchannelinformation butalsothe center channel information If you set the balance all the way over to the right the left channel information will be attenuated but the center channel will still be present at the left speaker In o...

Page 44: ...want to note any settings you wish to re use before proceeding Turn CP 1 power OFF While pressing PARAM on the Remote Control turn power ON Make sure your hand does not block the infrared receiver on the CP 1 front panel Continue holding down PARAM until the display reads TEST MODE PRM Key To Exit Release PARAM and press EFFECT MUTE to clear and reload User registers and to restore all factory set...

Page 45: ...Lexicon Page 40 Troubleshooting ...

Page 46: ...eo image tended to appear entirely inside the head spoiling the accu racy of such recordings as a test of concert halls To overcome this problem Schroeder played his recordings through a pair of loudspeakers in an anechoic chamber using a special electro acoustic technique developed by Atal Schroeder Damaske and Mellert to elimi nate crosstalk between the listener s ears Normally each speaker is h...

Page 47: ...stereo recordings Another reason is that most listening rooms have reflective surfaces to the sides of the listener A popularlisteningroomtreatmentputsabsorptivematerialatthefrontofthe room leaving the walls by the listener reflective This improves the clarity by removing the front reflections while retaining those from the side This also explains the appeal of loudspeakers that produce lots of si...

Page 48: ...o a real hall or larger environment The confusing frontal reflections can be absorbed leaving the essential lat eral ones This is better but not ideal Ambience Extraction ThePanoramaandSurroundmodesintheCP 1extracttheoriginalacoustic cues from the recording and present them to the listener from the correct directions We call this ambience extraction The three Panorama programs can even do this wit...

Page 49: ...ear of the listener then diffract around the listener s head and be heard by the right ear If we take the left channel sound delayitjusttherightamount invertitinphaseandfeedittotheright speaker it will arrive at the right ear just in time to cancel the crosstalk from the left speaker The main problem with a first order device is that the subtracting signal is alsoheardbytheoppositeear Inourexample...

Page 50: ... frequency With wide speaker angles a movement of as little as 1 inch can make a perceptible difference Fortunately the effect is usually fairly good everywhere within a zone about one foot wide To achieve the fullest Panorama effect your main loudspeakers should have good imaging The smaller speakers that tend to be used with video systems may have an inherent advantage here but the most importan...

Page 51: ...ry stereo excites SI is through the out of phase low frequency energy in the recording The Low Frequency Width control allows the amount of out of phase bass in a recording to be adjusted Even when the Effect level of the Panorama control is all the way down the Low FrequencyWidthcontrolisactive allowingtheusertoexperimentwiththis property of sound Recording engineers have only recently become awa...

Page 52: ...nt the Panorama Effect parameter is automatically turned down and no mixing occurs into the front speakers The Ambience Effect Small Club and Concert Hall Presets Theory and Design While the Panorama effect recreates the space that already exists in the recording the Ambience effect actually generates the side and rear reflec tion patterns of a number of ideal concert halls The reflections were de...

Page 53: ...ell as the rear speakers may sound best if placed above the listener The effectiveness of the CP 1 s Ambience simulation is heavily dependent on the source material and the playback room If the playback room is large and reverberant its reflections may dominate those generated by the program Carpet drapesandfurniturecanallbeusedtobreakuporabsorb undesirable reflections making it easier to hear the...

Page 54: ...akers Some of the side energy can also be fed to the front speakers side and rear outputs are generated from the stereo input For the largest possible effect from the Reverb effect consider placing speakers in the front corners of the room and driving them in parallel with the rear speakers Note however that this configuration does not compen sate for the absence of side speakers which continue to...

Page 55: ... as for audio video material The CP 1 is able to optimize the listening experience of any material precisely because it provides such a wide range of processing options This flexibility is readily apparent in the variety of Surround modes available to the user each optimized for maximizing listener involvement in different types of material played on a system whose speakers are laid out primarily ...

Page 56: ...e listening experience of ordinary stereo music In addition with all speakers except the fronts reproducing the same monaural signal no directional effects are possible There may be some senseofthemusiccomingfromallaroundyou buttheviolinsandcellosare equally loud from both sides Music Logic solves this problem in a novel way The side speakers repro duce the left and right front loudspeaker signals...

Page 57: ...r the front and rear outputs of the program simultaneously Music does not necessarily contain a crucial centrally located element analogous to the dialog in films So the Preset version of Stereo Logic has no automatic adjustment for interchannel time delay and balance that is the Auto Azimuth Balance parameter is off The Front Effect parameter which controls the steering among the front three chan...

Page 58: ...Onetime honored solutionistobreaktheincomingsignalintofrequencybands sendingsome toonechannelandtheresttotheother Whenthefiltersarecomplementary whenthesumofthetwooutputchannelsequalstheoriginalinputchannel thissolutioncangivestereospreadwithoutruiningthetonalbalance When the filters are non complementary they can produce an unpleasant fake stereo effect Some effort has been made to design filter ...

Page 59: ...use of the wide variety of recording and processing techniques used in program produc tion and transmission Programs and commercials are recorded in mono stereo and surround sound then subjected to compressors erratic stereo synthesizers sleepyproductioninterns andotherelectronictortures Often all of this can be experienced on one channel within five minutes The TV Matrix mode makes use of directi...

Page 60: ...round Decoding WhenthemovieisshownthetwoDolbyStereotracksmustbedecodedand separated into the original four The Dolby Surround decoder does this in a rather rudimentary way it supplies a signal to the center channel which is just the sum of the two input channels This signal contains the dialog However the left and right signals still contain dialog too so the dialog is spread out among the three f...

Page 61: ... with which this is done is even more important in a home decoder than in a professional model because the small size of the playback room makes decoding errors more audible than they are in a theater The level detection must be very fast and the matrix must adapt very quickly or there will be a time lag between the audibility of a sound and its correct steering Since phase relationships determine...

Page 62: ... incoming material All the time the film is playing the CP 1 is checking balance and azimuth keeping the dialog perfectly centered The result is superior steering An added benefit is that the CP 1 needs no front panel input balance control the user need not bother with this adjustment You can check the quality of the balance and azimuth in a tape or disc if you wish by turning the Auto Azimuth Bal...

Page 63: ...ention in a way that front sound does not Occasional extra wide sound effects can seem peculiar at first for being so much wider than the screen but when the mix is good the emotional impact of the wide sound can be very great The disparity between the size of the video screen and the size of the sound is usually easy to accept and the added impact is hard to give up once you have heard it Afewthe...

Page 64: ...ot the surround to the side speakers When side speakers are present this is a marvelous solution See speaker configurations 10 and 11 on page 15 Much the same effect as separate side loudspeakers can be provided by simply placing the main loudspeakers near the sides of the listeners and using the center loudspeaker to fill in the middle of the front image If the soundstage becomes too wide the sid...

Page 65: ...ts you scroll through the available characters and the 12 numbered keys on the remote allow you to select which characters you change When you ve named your hall press PARAM one last time so the display reads MEMORIZE PROGRAM then immediately press mode 6 HALL This will store your new custom created hall in User Register 6 Lastly hold the B BALANCE button to move the balance all the way to the bac...

Page 66: ...ske and Mellert Ein Verfahren zur richtungstreuen Schallab bildung des oberen Halbraumes über zwei Lautsprecher Acustica vol 22 pp 153 162 1969 70 6 Bishnu S Atal and Manfred R Schroeder Apparent Sound Source Translator U S Patent Disclosure Patent No 3 236 949 Feb 22 1966 7 Borish J An Auditorium Simulator for Domestic Use J of the Audio Eng Soc 33 5 p 330 1985 8 Blumlein A D British Patent 394 3...

Page 67: ...Lexicon Page 62 Theory and Design ...

Page 68: ... 1 kHz max level Subwoofer Less than 05 10 100 Hz max level THD 300 mVRMS Minimum Input Level Maximum Output Level 3 5 VRMS Input Impedance 50 k ohms Output Impedance 500 ohms Signal to Noise Ratio 85dB min A weighted Ref 1 kHz max level Factory set to one of the following 120V 60 Hz 100V 50 60 Hz 220V 50 Hz 240V 50 Hz 30W 17 W x 12 5 D x 2 5 H 11 lbs Voltage Specifications subject to change witho...

Page 69: ...Lexicon Part 070 09113 Printed in the United States of America Lexicon Inc 3 Oak Park Bedford MA 01730 USA Telephone 781 280 0300 FAX 781 280 0490 ...

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