DeltaLab_DL2 - Preservation Sound
Contents
1. tion Returning the switch to the center or Off posi tion returns normal operation of the unit The third position of the switch is labeled Sample and with the switch in this position the sustain function alternates between on and off at a rate set by the VCO DeltaLab recommends using the Sample feature with the DL 2 set up for flanging to obtain a digital step flanging effect The sustain function can be switched on and off via a footswitch jack located on the rear of the unit Next to the sustain switch is a two position toggle switch labeled Mode with the positions labeled Parallel and Serial In the serial mode the two channel inputs are mixed and processed through chan nel A and then through channel B The output of A is then delayed by the amount indicated for channel A However the output of channel B is now delayed by the sum of the delays indicated for A and B Switching to the parallel mode the two input signals are mixed through the image contro and then processed inde pendently However the reverberation for the two channels will be interrelated The final control in this group is the reverb program control previously discussed The program indicator is located between the mode switch and the reverb pro gram control Delay times for the two delay lines are adjusted by way of two momentary type toggle switches located one above the other The LED displays to the right of the swi2. With the output level control at maximum this would restrict the output signal level to less than 2 7 dBV Slewing performance for the direct signal path is better The direct output could not be driven into slew limiting because the small signal bandwidth 18 7 kHz is less than the power bandwidth through the direct signal chain If the power bandwidth were just equal to the small signal bandwidth then the slew rate limit would be from calculations 1 3 volts per microsecond Therefore the actual slew rate limit through the direct path is at least 1 3 volts per microsecond Calculating the slew rate ratio based on this slew rate limit it was determined that the slew rate ratio will be at least 0 21 for 0 dB dB headroom signal levels Keeping signal levels below 7 5 dB headroom 7 5 dBV output will insure that the slew rate ratio never drops below 0 5 for the direct signal path The preliminary owner s manual that we received with the DL 2 provided good explanations of the oper ation of the front panel controls and should allow users to get good results quickly Conclusion The DL 2 Acousticomputer by Delta Lab proved to be a highly versatile digital delay sound effects unit It provides high quality flanging and dou bling effects with many subtle variations Although its reverberation is not in the same class as the best reverberators available it does provide a good reverb sound that will be satisfactory in many
3. applications In our listening tests we were impressed with the con sistently high level of audio quality when listening through the unit The DeltaLab Acousticomputer is an excellent delay effects processor LAB TEST SUMMARY Note 0 dBV is referenced to 775 Vrms all tests made with output level control at maximum Input Output Levels Minimum input level required for 0 VU indication unbalanced input 2 2 dBV Maximum input signal before clipping 19 2 dBV Maximum output level at 0 VU unbalanced output 15 0 dBV Output clips at 20 1 dBV Noise Performance 20 kHz filter unweighted With no input signal noise at the output is 73 3 dBV or 88 3 VU Distortion THD plus noise at 0 dB headroom indication delay output Frequency X1 delay X4 delay 10 kHz 1 95 9 4 1kHz 113 36 100 Hz 1 05 1 25 Bandwidth 3dB points 24 Hz to 15 7 kHz delay out 17 Hz to 18 7 kHz direct out Slewing Performance Slew Rate limit 0 4 volts per microsecond delay output at least 1 3 volts per microsecond direct out CIRCLE 19 ON READER SERVICE CARD f MODERN RECORDING
4. are made available to be fed back to the delay line input for reverberation and repeating echo effects The feedback network incorpor ates high and low frequency attenuation controls for coloring the reverberation as well as a mix control for adjusting the balance between the short and long delays fed back to the input In addition the feedback signal can be either phase inverted or not The delay time of the delay line is adjusted in two steps First a pair of momentary toggle switches are used to set the coarse delay time with horizontal rows of LEDs indicating the range of delay selected Then the delay time of the pair of delay lines is fine adjusted over a four to one range using the delay factor con trol A VCO Voltage Controlled Oscillator in the time base generator section of the DL 2 can be used to vary the delay time Both the depth and rate of the VCO are adjustable Mixing the direct and delayed sound while using very short delays 0 1 to about 1 milliseconds and a slow sweep rate provides the familiar swept comb filter sound of flanging A vibrato effect can be created by using a short delay and selecting only the delayed signal in the output mix The depth and rate controls of the VCO then control the depth and rate of the vibrato Reverberation is synthesized in the DL 2 by recircu lating or feeding back to the input the long and short delays of the two channels The fraction of the output sig
5. delays corresponding to sixteen different reverb programs When the desired program is reached the reverb pro gram knob is set to the Hold position and the pro gram sequencing stops where it is If desired the reverb program knob can be left in the sequence posi tion and the reverb character will change continually as the unit sequences through its sixteen reverb pro grams Rotating the reverb program control further clockwise to its Random setting increases the rate at which the DL 2 steps through the program cycle The input controls for the DL 2 are located at the left side of the front panel First there are signal head room indicators which indicate slewing headroom as well as peak level amplitude headroom Each display consists of four LEDs labeled 0 10 20 and 40 dB FEBRUARY 1980 Input level and image controls are located just to the right of the headroom indicators The input level con trol simultaneously adjusts the input signal level for both channels The input image control directs the sig nals to the opposite channel as the control is rotated from normal to reverse Located at the right of the input controls are the reverb program controls The first control in this group is a three position toggle switch labeled Sus tain In the On position of this switch the input to the delay line is disconnected and the signal currently in memory is recirculated indefinitely with no degrada
6. pitch shifting And many more When you consider its road worthy construction highly musical sound quality tremendous flexibility and when you hear for yourself what it can do in the creative process you may find the price of the ACOUSTI COMPUTER surprisingly modest Why wait any longer DL 2 ACOUSTICOMPUTER A true stereo 2 channel delay and special effects unit with highly musical sound quality and extremely flexible versatility 6 Reverb programs 2 Independent pre reverb delays VCO sinusoidal Long delays up to252ms serial mode for special effects Short delays down to 0 25 ms Stereo imaging on input to extract hidden ambience Stereo imaging on output for with 4 1 frequency range for flanging effects left right shifting Sustain non deteriorating Positive and negative reverb Foot switch bypass control repeat with selectable updating and flanging feedback External memory expansion capability HIGH QUALITY DIGITAL DELAY PROCESSING IS NOW AVAILABLE DeltaLab introduces the ACOUSTICOMPUTER a flex ible and rugged all electronic space machine with highly musical sound quality and a surprisingly modest price The ACOUSTICOMPUTER is a combination digital de lay and special effects processor designed for use both on stage and in the studio providing well known functions echo doubling vibrato flanging etc plus some new effects not available in an
7. who have the interests of the small as well as the big wigs at heart have had their thinking caps on and have produced what appears to be one of the best ideas in a long time the DL2 Acousticomputer Basically what it all boils down to is that they ve taken a 19in x fin x 8in box and filled it with enough electronics to give the user access to every type of effect from digital delay ADT flanging reverberation ambient reverberation rear channel ambience extraction digital sample flanging digital random flanging digital random sample flanging echo cardboard tube echo slapback rotating speaker vibrato chorus vibrato simultaneous reverb phas ing simultaneous echo phasing and all of the effects in between the above knob Dave Hastilow is a recording engineer at Eel Pie Recording Twickenham by Dave Hastilow settings which can be pretty mind boggl ing and they re all in stereo How does it work Read on you might be able to afford it Basically and in the simplest words available at this time on Sunday evening the two input channels A and B enter the device and are each routed through two independent side chains which may re main independent or may interact with each other depending upon which mode of operation is selected Channei A may be delayed from 5 to 152 ms and Channel B from 25 to 88 ms with the DL 2 in the parallel mode However in the serial mode the inputs are mixed and processed
8. ACOUSTICOMPUTER a true stereo special effects processor DeltaLab Research Inc 27 Industrial Ave Chelmsford MA 01824 Available at Quality Dealers Your Next Musical Instrument Should be the ACOUSTICOMPUTER by DeltaLab Why wait any longer Many of the leading groups in the U S England and Europe already have theirs as do the most advanced recording studios What is an ACOUSTICOMPUTER Simply the cleanest sounding most flexible widest range digital delay and special effects processor ACOUSTICOMPUTER designed and manufactured by DeltaLab makers of the famous DL 1 Delay Line whose sound was described by Modern Recording as The best we have encountered in any digital delay unit If you are serious about creative music making you need the ACOUSTICOMPUTER now e Especially now that the advent of digital recording demands clean wide range sound from every element in the signal path Is a processor really good enough if it doesn t have the 90dB dynamic range and full 15kHz bandwidth of DeltaLab gear e Especially now when audiences increasingly expect every live performance to sound as good as the record e Especially now when money is tight It only makes sense to buy a device that does it all Doubling tripling chorus effect e Slapback multiple echoes stereo reverberation Flanging tuned resonance R2D2 effects Vocal broadening and enhancement spatial depth Vibrato tremolo
9. e with new information at rate determined by the VCO Reverberation 16 Programs displayed via binary weighted LED s Most programs consist of high echo densities Size 1 x 19 x 10 in 4 45 x 48 3 x 25 4 cm Shipping Weight 12 Ibs 5 5 kg Straight Delay Mode With C Weighted Broadband Filter Manufacturer reserves the right to make improvements without obligation DeltaLab Research Inc 27 Industrial Avenue Chelmsford Mass 01824 Tel 617 256 9034 PRINTED IN U S A 1979 DELTALAB RESEARCH INC DL 2 1 81 5M Tt small studio operator or musician is hit by two facts of life The first one is that producers often take their bands to well equipped studios and the second is that equipping a studio or PA rack costs a lot of money Especially a rack full of what are fast becoming the obligatory ancillaries such as digital delay flanger etc etc However well equipped studios have to update their hourly rates to cover costs so not so well off operators can score a double direct hit if they find one piece of equipment which will do the work of a rack full and is moderately enough priced to justify keeping the hourly rate down The other fact of life is that producers always have their eyes open for less expensive well equipped studios so you might score another hit if a producer looks in your direction after he s heard a few of your demos or happens to be at your gig Delta Lab
10. ee settings Norm Signals pass straight through to their respective channels A B Each channel is mixed with a multiphase signal trom the other channel to extract ambience Rev Signals are directed to opposite channel Stereo reverse PROGRAM Sustain In essence an infinite repeat control When on the input is diconnected and data is recirculated indefinitely with no degration In the sample mode the on off function switches at a rate set by the VCO New data is loaded into the register in the off function and circulated in the on function This facility makes possible a new effect Digital Step Flanging The sustain function may be switched on by a foot pedal Mode Serial Inputs are mixed through Channel A and then B The output of Channel A is delayed by the Channel A indication The output of Channel B is delayed by the sum of the channel A and B indications Also the Channel B indications are twice processed Parallel Each channel is mixed via the input image control and processed independently The reverberation will be interrelated Reverb As already mentioned there are sixteen reverberation programs stored in the DL 2 which create effects varying between sensations of spaciousness flutter and tubey effects depending upon the settings of the Time Base Generator Reverberation and Mix controls The programs are selected by the reverb control Manual Allows user to select delay time sett
11. engths are limited only by the number of modules added signal quality is not compromised at all DeltaLab ACOUSTICOMPUTER DL 2 UNBALANCED IN BALANCED FROM OPPOSITE CHANNEL UNBALANCED OUT BALANCED OUT FROM OPPOSITE CHANNEL FROM OPPOSITE io CHANNEL Block Diagram ACOUSTICOMPUTER One Channel Only SPECIFICATIONS Delay Range Frequency Response 14 dB 1 3 dB Dynamic Range A Weighted C Weighted Broadband Headroom above 0 dB Equivalent Pre emphasis THD Distortion Plus Noise Ref 1 kHz 0dB 10 dB 20 dB 30 dB 40 dB Inputs Balanced XLR Unbalanced Phone Impedance Outputs Balanced XLR Unbalanced Phone Impedance Parallel Mode 0 5 to 160 ms Ch A 0 25 to92ms Ch B Serial Mode 0 5 to 160 ms Ch A 0 75 to 252ms Ch A amp B 20 to 15k Hz X1 Delay factor X4 Delay factor 90 dB min 85 dB min 85 dB min 80 dB min 6 dB 50us X1 Delay factor X4 Delay factor 0 2 max 0 4 max 0 2 max 0 4 max 0 3 max 0 6 max 0 5 max 0 8 max 0 8 max 1 0 max 0 to 18 dBm 0 to 18 dBm 47K ohm Up to 24 dBm Up to 18 dBm 600 ohms Time Base Generator Delay Factor Continuous from X1 to X4 VCO Depth 0 to 100 of Delay Adjustment Range 4 1 VCO Rate Sinusoidal from 0 to greater than 10 Hz Sustain Repeats signal in memory indefinitely without degradation Sample mode is used to updat
12. first through Channel A and then Chan nel B The output of Channel B is delayed by the sum of Channel A and Channel B indicators Also the Channel B data is twice processed I told you it was simple In practical terms imagine the situation where you are trying to get an ambient guitar sound from a dry miked guitar track Had the guitar amp been in the middle of the empty studio or room and had the mic been stereo the sound waves hitting the mic would have consisted of the direct sound from the amp mixed with multiphase delayed sound waves arriving a short time later after being reflected off the walls floor and ceiling This is essentially what the DL 2 is doing in its most basic mode Channel A delay and Channel B delay are in effect the walls around the amp the reflections from the walls are mixing together somewhere in the middle of the room and is the case with the DL 2 when the Image control is in the A B position and the resultant blend of dry plus delayed information gives the ambient effect The reason Delta Lab have labelled the DL 2 the Acousticomputer is that every delay tap within the device has a binary address code or number between 0 and 15 and the DL 2 can select any number and re generate it or it can scan the whole series of fifteen addresses and select randomly at a given sample rate determined by the position of the reverb knob This is a brief description of what the DL 2 Acousticom puter does in its simple
13. have a lot of gain as an input signal level of 2 2 dBV is required for a 0 dB headroom indication Even though this appears to be the equivalent of a nominal 0 VU some caution is necessary in setting levels through the DL 2 as there is only about 5 dB of headroom before clipping above the 0 dB headroom indication However because of the low noise level of the unit about 88 dB below 0 dB headroom it shouldn t be necessary to push the input level The output level at 0 dB indication was 15 0 dBV with the output level control at maximum so there is plenty of output level The THD distortion at 0 dB headroom indication was about 0 1 in the midrange with the delay factor control at the X1 setting Increasing the delay factor to X4 increased the mid frequency distortion to 0 36 Distortion also increases at the low and especially the high frequency extremes The bandwidth through the delay line is better than 15 kHz which is excellent This wide bandwidth was not degraded with any con trol settings The slew rate limit through the delay lines was mea sured as 0 4 volts per microsecond At a 0 dB head room level 15 dBV output level this provides a slew rate ratio of 0 065 volts per microsecond A couple of simple calculations reveal that in order to maintain a slew rate ratio of 0 5 the recommended minimum or higher signal levels through the delay line must be no higher than 17 7 dB below the 0 dB headroom indica tion
14. ings in each channel Locks in program displayed Program changes in a slow counting manner until the knob is rotated to the hold position Random Program changes at a rate determined by position of knob Hold Select DELAY Moving the switches forward or backward respectively increase or decrease the initial delays in each channel by the amount indicated in figures above and below the Light Emitting Diodes Short delays are used for flanging and long delays for spatial or echo effects In the parallel mode channel B behaves in the same manner as channel A but in the serial mode the initial delay of channel B output will be the sum of the delays indicated by both the Channel A LED and Channel B LED This means that Channel B becomes Channel A B REVERBERATION The reverb mix control mixes the long and short reflections to create reverberation In the short position only short reflections will be regenerated In the long position only long delayed reflections are regenerated In the equal position equal amounts of short and long are fed back In practical terms the short position corresponds to the reverberation of a small room and soon Equalisation Low control rolls off low frequen cies in the regenerated delayed signals At full cut passes frequencies above 800 Hertz only High control rolls off everything above 1 5kHz Feedback Determines the amplitude of signals being fed back At max sig
15. ks for interfacing the bypass VCO and repeat foot controls There is also a five pin XLR type connector for inter facing optional memory modules Next to this connec tor is a slide switch labeled Memory with internal and external switch positions Unless external mem ory is used this switch should be left in the Internal position The DL 2 is packaged in a single space rack mount chassis and provides quite a lot of signal processing capability in very little space Field Test We tried out the DL 2 during a leisurely four track recording session and were quite pleased with the wide variety of effects that we could obtain DeltaLab has provided diagrams which indicate con trol settings for some nineteen different effects and we experimented with nearly all of them In addition there are blank control diagrams which allow the user to record control settings for additional effects We tried the suggested guitar reverb control settings and were pleased with the results The effect combined some audibly discrete echos along with more diffuse reverberation to provide a rather tasty combination of echo and reverb The effect identified as ambient reverb provided what seemed to be the most natural sounding reverb for the unit Even though this was a good reverb effect it lacked the quality of lush diffu sion that is generally demanded of the finest and cost lier reverberators However in many applica
16. lts in increasingly more of the delayed out puts being fed back to the inputs except that the out puts are first phase inverted The Time Base Generator is next and employs three rotary controls labeled Delay Factor Depth and Rate The delay factor is adjustable from 1 to 4 and provides fine delay time adjustment in conjunc tion with the coarse delay adjustment already dis cussed The other two controls adjust the depth and rate of the VCO The VCO can be externally controlled via a phone jack on the rear panel The final controls on the front panel are the output image and mix controls The image control inter changes the channels as it is rotated clockwise from the normal to the reverse setting The output mix control allows the direct and processed delayed sig nals to be mixed in the desired proportions At the right of the output mix control is a bypass indicator This LED lights to indicate that the system is bypassed through use of a rear panel foorswitch jack The input connectors for the DL 2 are located on the rear panel The unit accepts balanced inputs by way of XLR type connectors and accepts unbalanced inputs via 14 inch phone plugs Likewise both balanced and unbalanced outputs are provided employing XLR and 4 inch phone connectors respectively A single screw driver adjustable control simultaneously adjusts the output levels of the two channels The rear panel houses three 14 inch phone jac
17. nal fed back to the input determines the decay char acteristics of the reverb The greater the feedback per centage the longer it will take for the reverberation to decay When either the highs or lows are attenuated in the feedback loop the decay time for the attenuated Reprinted by permission of Modern Recording copyright Cowan Publishing frequencies is reduced in comparison to the other fre quencies With the DL 2 the best sounding reverbera tion is typically obtained by using a fair bit of low fre quency attenuation and near maximum feedback The reverberation output for channel A is made up of recirculated delays from both channels A and B Likewise for channel B There is one long and one short delay from each of the two channels available for feed back to the input This gives a total of four discrete delays that can be fed back in various combinations Which of these delays is used for feedback depends on the setting of the DL 2 s program indicator The pro gram indicator is composed of four LEDs that are either on or off The four LEDs indicate the presence or absence of each of the four available delays in the reverberation DeltaLab has a novel way of allowing the user to select any of sixteen possible combinations of these four delays When the reverb program control is placed in the select position the LEDs cycle on and off in a binary counting sequence thus stepping through the sixteen combinations of discrete
18. nals are fed back in phase with input At zero output has no reverbera tion At max reflections are fed back out of phase with input TIME BASE GENERATOR Delay Factor Varies the basic clock frequency which determines the delay thus acting as a variable delay multiplier Variable between x1 and x4 VCO Rate and Depth Rate variable between 0 and 10 Hz Depth control varies amplitude of VCO frequency thus making deep flange and pitch bending possible OUTPUT Image As with the input image control allowing subtle stereo effects to be created Mix Allows the source bypass or the delayed signals only to appear at the outputs or a mix of both when the knob is set in the equal position The DL 2 can be bypassed by using a footpedal which plugs into the back of the unit In the Program section ot the front panel are set four LEDs which are numbered 1 2 4 8 upwards These indicate the binary address codes for the Channel QUIPMEN A and Channel B short and long initial reflections which are recirculated to create reverberation LEDs 8 and 4 indicate the short and long initial reflections of Channel A and LEDs 2 and 1 the short and long initial reflections of Channel B The precise amount of short and long initial reflections recirculated to create the final reverberation pattern is de termined by the position of the Reverb Mix control In operation the Acousticomputer does everything it says it can and more It is n
19. ot possible to describe in words the effects created when the knobs are in the intermediate settings and it is advisable to make slight rather than large adjustments to the knobs when looking for effects to prevent overloading other equipment which may be interfaced with it It is possible to set up quite a simple program and flick the parallel series and sustain switches only to be knocked out by something else so beware of Acousti computeritis or sidetracking The chorus effect is quite astounding so is the rotating speaker and the reverberation is similar in texture to that provided by a reasonably priced spring The input and output connections are balanced and unbalanced which makes for good mobili ty between studio and stage and three sockets allow for the sustain and bypass modes to be switched by footpedal or for insertion of an external control voltage of between 0 and 10v Provision is also made for an optional memory module which increases the DL 2 memory capability to 2 seconds to be inserted via a 5 pin Switchcraft connector The increased delay time will not degrade any of the DL 2 Acousticomputer functions Reprinted by permission from the October 1979 issue of SOUND INTERNATIONAL MAGAZINE SOUND INTER NATIONAL LINK HOUSE PUBLICATIONS LTD 1979 DeltaLab DL 2 Acousticomputer By John Murphy and Jim Ford The DL 2 Acousticomputer from DeltaLab Research Inc utilizes a stereo pair of programmable digi
20. st mode and it is possibly the closest electronic approach to artificial ambience creation short of playing the guitar track back through a speaker in the studio and recording it To complete the picture the Acousticomputer can not only regenerate random selected short and long delayed signals but also feed back or sustain them to simulate the build up of what is described in books on acoustics as equilibrium intensity where the direct and indirect sounds from a sound source have built up to their highest level Sound waves bounce around a room until the energy within them has been dissipated While they ve been bouncing they will have had their frequency content altered considerably by the acoustic properties of the materials lining the walls of the studio This effect is simulated in the Acousticomputer by adjusting the equalisation of the signals which are being fed back to the input for regenera tion The equalisation controls consist of high and low pass filters The front panel can be divided into six sections which are further sectionalised by the nature of the controls under these headings Now that I have described what the Acousticomputer does I hope that these individual controls will make more sense DELTALAB DL2 INPUT SECTION Headroom indicator Two columns of LEDs indicating peak and slew level between 40db and Odb Level Control Adjusts input level of Channel A and B simultaneously Image Thr
21. tal delay lines to produce a wide variety of special effects including echo flanging and reverberation It can provide up to 240 milliseconds of delay while main taining a high level of audio quality and has control features which make it attractive for use on the stage as well as in the studio With more than a dozen front panel controls of operating parameters the DL 2 hasa very strong toy appeal and encourages creative experimentation with its wide variety of delay effects The DL 2 currently sells for 1 750 General Description The DL 2 is not a simple piece of equipment either in its functions or in the con trol of those functions In general it is appropriate for novice users of complex signal processing equipment such as the DL 2 to first carefully learn the operation of the unit Studying a block diagram showing signal flow through the unit see Figure 1 for a block diagram of one channel of the DL 2 is usually the quickest way to learn how it operates Knowing the operation it then becomes easier to use it to maximum advantage The operation of the DL 2 can probably be best understood by viewing it as a pair of digital delay lines that can be used in many different configurations Each of these delay lines has one input and three sep arate outputs corresponding to three different time delays along the line Of these three outputs the mid dle one is used as the main output of the delay line while the other two outputs
22. tches indicate the 4 to 1 range of delay times selected for each channel The range of delay times available is 0 5 ms milliseconds to 152 ms for channel A and 0 25 ms to 88 ms for channel B When used for reverb these initial delays become pre reverb delays Next and just to the right of the center of the front panel is a group of four rotary controls labeled Rever m DeltaLab ACOUSTICOMPUTER DL 2 UNBALANCED IN BALANCEO IN FROM OPPOSITE CHANNEL H LO PROGRAMMABLE DELAY LINE Block Diagram ACOUSTICOMPUTER One Channel Only BYPASS UNBALANCED ouT l BALANCED IMAGE ag our FROM OPPOSITE CHANNEL FROM OPPOSITE CHANNEL Fig 1 DeltaLab DL 2 Block diagram of the unit one channel only beration The first control Reverb Mix sets the mix of long and short delays fed back to the delay line input This control simultaneously adjusts the relative levels of the four long and short delays available for feedback The next two controls are labeled Equaliza tion and provide high and low frequency cuts when backed off from their full clockwise Flat settings The last reverberation control is the feedback control With this control in the twelve o clock position none of the delayed signals are fed back to the inputs Rotat ing the control clockwise provides increasingly more feedback signal to the inputs Counterclockwise rota tion resu
23. tions the DL 2 will provide quite satisfactory reverb Other classifications of effects that we found useful besides reverberation include varieties of flanging DeltaLab provides five control recipes for flanging MODERN RECORDING effects echo four recipes provided vibrato and dou bling chorusing We used the DL 2 to flange the out put of an electric piano with excellent results We were especially pleased with the consistently high level of audio quality when we processed signals through the unit There was never any loss of highs and the unit s noise was never heard The Acousticomputer is really quite a high quality device We performed our usual listening test by incorporat ing the DL 2 into a tape loop on our preamplifier The DL 2 was set for 15 ms delay in each channel with no feedback or VCO employed The output mix control was set to full delay so that we could listen through the delay chain with no other effects When we played a disc back through our reference system we heard virtu ally no degradation when we introduced the DL 2 into the chain I must say though that we allowed the DL 2 a healthy amount of headroom and were careful not to press the signal levels In any event it was quite trans parent and introduced no sound of its own Lab Test We performed the usual variety of tests on the DL 2 and the specific results are provided in the Lab Test Summary We noted that the input section does not
24. y other device PERFORMANCE FEATURES 2 Independent delay channels Delay lengths from 0 25 ms to 252 ms Frequency response 20 to 15 kHz at all delay lengths Dynamic range greater than 90 dB No audible distortion 1 kHz THD lt 0 2 16 Inter channel related reverb programs Foot pedal controlled bypass Variable time base with VCO Stereo imaging input and output controls FOR STUDIO The ACOUSTICOMPUTER is a compact highly versatile true stereo delay line incorporating feedback and equaliza tion circuitry In one package the DL 2 contains what would have previously required a rack full of outboard equipment And the ACOUSTICOMPUTER maintains DeltaLab s no compromise reputation full 20 15 kHz bandwidth large dynamic range and virtually no audible distortion FOR THE PERFORMING MUSICIAN Today s musician knows the problem of trying to recre ate studio effects during a live performance The DL 2 pro vides this versatility in one easy to understand reliable unit Footswitch bypass and external VCO inputs give musicians the option to pre select an effect and also modulate the effect via the external input OPTIONAL MEMORY MODULE Prior to the ACOUSTICOMPUTER long delay times have been available only at the expense of dynamic range and or bandwidth degradation DeltaLab again chooses the no compromise alternative by offering an external memory module with a maximum of two seconds of delay per module Now delay l
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