Overdrive® DAC User Manual
Contents
1. 7 6 7 7 7 8 Empirical Audio Overdrive USB DAC Input select toggle switch Selects between USB 12S and S PDIF coax digital inputs Digital Filter Select toggle switch Selects between Low Medium and High frequency roll offs High setting is the high frequency roll off It is recommended to use High setting always De emphasis Enable toggle switch When enabled it applies an equalization at the high frequencies that eliminates harshness due to high frequency pre emphasis in some recordings Normal position is recommended The function does not take effect until a new track is started High Low Gain switch recessed This selects between high and low gain Only changes on power up Volume Line Out toggle switch recessed This selects between volume control and line out Only changes on power up USB Fault Indicator USB fault is illuminated when the USB cable is unplugged at either end Data Error Indicator Illuminated indicates that there is no valid data coming in on the selected digital input DC Power Indicator Indicates that DC power is applied to the DC input connector 8 USB installation and use 8 1 PC installation for 24 bit 96kHz 1 2 3 N 10 11 12 13 14 15 16 To play a music file simply double click on the filename in the playlist and it should play 18 Power on the Overdrive DAC first and then connect the USB cable to the computer Next install D2. USB cable or Overdrive power during music playback you must hit the stop button on the Foobar2000 player first If you pull the USB cable or Overdrive power while Foobar is playing you will need to close Foobar and re open it To change to 24 bit 44 1kHz Configure Foobar2000 by clicking on Foobar2000 Preferences and make the following selections a On the left side select DSP Manager and on the right click on Resampler SRC in the left field to highlight it and move it to the right field by using the gt button Nothing should be in the left field b Always select 24 bit fixed point in Foobar preferences even for 44 1 You must bypass Kmixer if you are using XP This can be achieved by Unmapping the device ASIO4ALL or Kernel Streaming To unmap the device this is what we do Go to Control Panel System Hardware Device Manager Sound Video and Game Controllers Empirical Overdrive Right Click and select Properties Audio Devices Empirical Overdrive Properties Set Do not use audio features and set Do not map through this Device You will need to reboot and then if you change it back to mapped then you must re boot 8 2 Mac installation instructions Off Ramp and Freeway work with Mac OSX operating systems and iTunes The only settings are e Device select System Preferences Audio and Sound and select the Empirical 1 1 as output device e Sample Rate Utilities MIDI options select eithe
3. button Only Resampler SRC should be in the left field f On the left side select Resampler SRC and on the right set Target sample rate to 96000 and on the right set Quality to Sinc Best Click on Save all and Close in the Foobar Preferences window To make your first playlist click on Playlist then Create new playlist on the top Foobar toolbar To name the playlist double click on the tab labeled New playlist and rename it to Jazz or Classical etc To add tracks to Foobar2000 click on Playlist then Add files It will open a window where you can select highlight the files in a particular folder and then click on open and the files will be added to the playlist that is currently active Create a dummy playlist by creating a playlist and naming it Default Open Foobar Preferences Core and select the checkbox Always send to playlist Default This prevents accidental erasure of playlists Close Foobar by selecting Foobar2000 and then Close If you are using Vista you must go to sounds and audio in Control Panel and select Empirical Overdrive for your output device If you are using Vista highlight Empirical Overdrive from 14 above and right click and go to properties and then select advanced Then set the sample rate to 24 96 or 24 44 1 if you don t want to upsample Open Foobar2000 again by d
4. Empirical Audio Overdrive USB DAC Empirical Audio Overdrive DAC User Manual 2009 2010 mpirical Audios Overdrive DAC User Manual Empirical Audio Rev 1 3 Critical read all red warnings first to prevent equipment damage 1 Technology Design 1 1 The Overdrive DAC incorporates our excellent low jitter USB interface technology and breaks new ground for D A converter technology The Overdrive design philosophy is less is more with one of the simplest analog paths ever devised The Overdrive provides solutions for the three most important issues with digital sources e Jitter e D A noise distortion e Volume control noise distortion This high performance triple solution is unprecedented and delivers a totally new sound quality level The Overdrive is a non upsampling DAC no ASRC that has an ultra simple analog signal path reducing background noise and harmonic distortion to unprecedented levels It incorporates a preamp function that has never been tried in ANY audio product before This preamp function adds no devices whatsoever to the signal path leaving it simple and ultra low noise It has selectable digital filters that allow one to tailor the sound to your personal taste You can effectively eliminate them if you want The sound of the Overdrive is simply indescribable and utterly magical The clarity is unlike anything you have heard before particularly driving amps directly Other DACs sound mud
5. XLR outputs simultaneously For best performance this is best avoided however this is sometimes necessary in order to drive a subwoofer or other ancillary electronics Each of the 4 output drivers is shared between the balanced XLR and single ended RCA outputs However there is some isolation with small resistance between the XLR and RCA outputs If one uses all outputs simultaneously to a system it is recommended that either the XLR cables or the RCA cables be short and low capacitance and drive a high impedance buffer or preamp DC Power Connector The DC power connector is a professional 5 pin high current locking connector The power inputs are e 12VDC Digital Power Digital Ground Return 18VDC Analog Power Analog Ground Return 18VDC Analog Power Cooling Fan A cooling fan is mounted inside and in the center of the top of the chassis The fan runs whenever the Overdrive is powered on A slow very quiet fan was chosen with a filter but some may still find it audible from the listening position Here is one recommendation to reduce the fan noise Place the Substation on top of the Overdrive and put a U shaped piece of foam from the packing between them with the cut out slot facing to the rear Remove the front panel and use a thin plastic screwdriver to adjust the fan down using the blue pot that is visible just behind the volume range jumpers 7 Overdrive Front Panel Switches and Indicators 7 1 7 2 7 3 7 4 7 5
6. d and shorter is better The output drive is sufficient for all preamps and amps and even high impedance headphones like Sennheiser 1 2 Design Choices A number of design decisions were made in order to optimize performance and sound quality over all other criteria 1 2 1 1 2 2 1 2 3 1 2 4 Small Chassis size This was critical to reducing both digital and analog signal path lengths Long signal paths add distortion due to circuit board dielectrics and also introduce more noise due to ground plane coupling and crosstalk Op Amp I V conversion This was necessary in order to optimize the loading of the D A converter Some D A chips require certain loading and voltage on their outputs in order to guarantee best linearity and low distortion AC coupled output This was chosen because the alternative of DC coupling would not allow a pure Class A operation throughout which delivers lower distortion The coupling capacitors available now are very close to a copper wire in performance AC power cords eliminated Wall type power supplies were chosen for best sound quality They eliminate the need to purchase a 1200 2K power cord and locate the magnetic and electric fields well away from the DAC chassis 2 Break in All electronics needs a period of break in New capacitors and dielectric insulators must stabilize with voltage and current applied The Overdrive is broken in by Empirical Audio for approximately 5 days before shipp
7. d on the circuit board The default factory setting is Max for widest adjustment arc Make sure the Overdrive is powered off for this adjustment The front panel must be removed to access these Power System The Overdrive DAC power is provided by a DC umbilical from a second chassis which can be a Substation or a Battery Power Supply The Substation stores a massive amount of energy and has a very low output impedance It is essentially a Hoover Dam to provide power to the Overdrive The Substation receives DC power from three wall type power supplies These are high current switchers If you use after market power supplies please insure that Empirical Audio has approved them first to prevent equipment damage 4 1 Substation The Substation provides three DC voltages to the Overdrive 12VDC 18VDC and 18VDC The Substation will not allow power to the Overdrive if all three voltages are not present and the correct values In standby mode all capacitors and relays are powered in the Substation but there is no DC output It power on mode it applies all three voltages simultaneously to the Overdrive If there is a short in any of the three supplies in the Overdrive the Substation will not power on the Overdrive Danger never connect the Umbilical to the Overdrive with the Substation power on 4 1 1 Substation Front Panel E Audio SUBSTATION 4 1 2 Substation Back Panel 4 2 Wall Power Supplies Three Wall type pow
8. dy in comparison The bass is tight and the detail and imaging is more than first rate it s breathtaking Drums are rendered with more realism than any other DAC is capable of The leading and trailing edges and harmonics of percussion strings and woodwinds are delivered with true realism Even with this level of detail and dynamics it still gets vocals right The Overdrive USB DAC resets the bar for the term accuracy in digital to analog conversion Performance The performance of the Overdrive DAC is a result of several innovative design breakthroughs Low jitter USB interface module Ultra Simple pure Class A analog Path D A Volume Control Ultra Linear Output Stage Fully Balanced Analog Path aRWN gt 1 1 1 Low jitter USB interface module This USB module is the same device that we use in our popular Off Ramp 3 USB converter This is a 3 generation USB converter and rates 1 against all other converters on the market Very low jitter no drivers or ASIO to load and it converts 16 44 1 to 24 44 1 automatically This enables bit perfect playback from XP or Vista PC s and allows for 8 bits of digital volume control without any loss in resolution USB also handles up to 24 96 1 1 2 Ultra Simple Analog Path The analog path consists of an I V stage op amp driving a single output transistor through a coupling cap All stages are run Class A so it gets a bit warm There are no resistors at all in the analog signal paths excep
9. er supplies are required for the Substation 12VDC 18VDC and 18VDC For the 18VDC supply the current requirement is lower These supplies are compatible with all international voltages Optimum performance of the Overdrive will be achieved with all three power supplies plugged directly into the AC mains outlets of a single AC circuit If your location does not have sufficient outlets for this the next best thing is to plug the 18VDC supply into a wall outlet and the 18VDC and 12VDC supplies into an outlet strip or power conditioner Plug the ground wire from the DC umbilical cable into the earth ground of the AC circuit Make sure that you use the same circuit from the AC panel for all three wall supplies and that you power all of the Wall Supplies first and then connect the DC cables second Power the Substation AFTER you connect the umbilical Different circuits will potentially originate from different phases and may cause ground reference voltage differences with resulting high currents in the ground This can potentially damage other components in your system Use the same phase and the same circuit if possible for the entire system including the computer Power conditioners can have high impedance in the ground connection to the AC service so if you use a conditioner it is best to plug all three wall supplies into this conditioner Conditioners with filters generally limit the transient current flow so we advise against using
10. ing An additional 25 days of 24 7 break in is required for full break in with all inputs driven Each input breaks in independently so all should be driven with a signal Outputs do not have to be connected in order to break in 3 Volume settings 3 1 3 2 3 3 3 4 3 5 Volume Control The volume control can be selected by using the recessed toggle switch on the front panel The switch activates the volume or line out on power up only not on the fly To make a change you must power off the Substation and back on using the front panel power switch As with all systems at initial power on the volume should be rotated to its lowest setting before playing music Optimum Manual Control Manual control can be optimized for performance if the volume knob is near maximum The gain should be selected so that the volume knob is near maximum at normal listening levels Optimum Remote Control Remote volume control capability can be achieved quite easily by using a combination of the manual volume control a digital volume control such as iTunes volume and the USB interface Because all 16 bit 44 1kHz sampled files native CD sample rate that are streamed using the USB interface are converted to 24 bit 44 1kHz sample rate bit perfect data this provides 8 bits or 30 digital volume control before the data bits are affected If one adjusts the volume to a comfortable listening level with the manual control then only small reducti
11. irectSound2 by copying the file foo_out_dsound_ex dll from the CD R provided to the file folder C Program Files foobar2000 components Next Install the SRC resampler by copying the file foo_dsp_src dll from the CD R provided to the file folder C Program Files foobar2000 components Next Install Foobar2000 version 0 8 3 by copying Foobar2000 exe from the provided disk to any folder on your hard disk Execute the file by double clicking on it after you copy it After Foobar2000 version 0 8 3 is installed open it by double clicking on the Foobar Icon on your desktop Configure Foobar2000 by clicking on Foobar2000 Preferences and make the following selections a On the left side select Core and on the right move the slider for Process priority class to the far right to realtime b On the left side select Playback and on the right set Output data format to 24bit fixed point c On the left side select Output and on the right set Output method to DirectSound2 d Onthe left side select DirectSound2 and on the right set Device to Empirical Overdrive e Onthe left side select DSP Manager and on the right click on Volume Control in the left field to highlight it and move this to the right field by using the gt button Then click on Resampler SRC in the right field to highlight it and move itto the left field by using the lt
12. ons of the digital control from maximum are necessary to adjust the track to track amplitude variation This is even better than having yet another remote control Most of us already have too many of those It allows you to use the player software for everything song selection muting and volume control without any loss of resolution This is the best possible scenario Gain Switch A two position gain switch is recessed into the front panel It is marked H and L This can be switched at any time but will only take effect after powering down the Substation and back up again using the front panel power switch For driving most amplifiers directly with 1V sensitivity for full power the switch should be in the L position Range Jumpers Two jumpers are provided to set the volume range Three volume ranges are possible The range setting provides a lower volume extreme It does not affect the maximum volume only the minimum volume If the range jumpers are set for Min the volume will have the least range so the lowest volume will still be loud If the range jumpers are set for Max the volume control when at the minimum will be very quiet This allows the volume to be tailored so that a fairly wide arc can be used in adjustment for track to track amplitude variation The range jumpers are located just inside the front panel to the right of the volume control as you look at the front panel The settings are illustrate
13. ouble clicking on the Icon this sets the thread priority There are many skins and different UI s or User Interfaces for Foobar These can be found at the hydrogenaudio forums or contact us by email Pitfalls to avoid e Don t use iTunes on a PC Mac only e Don t use the other USB ports on the computer only one for audio e Don t use Dell Laptops for audio the USB ports have a history of problems Pops and ticks If you experience pops and ticks because you have an older PC or have a lot of applications running close all extraneous applications including e Screen saver e Virus scanner e Anything on the lower right toolbar that is not critical many of these can be eliminated by removing the links from C Documents and Settings All Users Start Menu Programs Startup e Disconnect from the internet set priority of your player to real time or at least highest e If your Primary IDE Channel C drive is set for PIO mode and not DMA mode this can cause pops This is found in the Advanced Properties of your Primary IDE Channel under Device Manager PIO mode is not desirable DMA is what you want Windows can change from DMA to PIO on it s own Go to Device Manager uninstall Primary IDE Channel and reboot If experiencing ticks on Vista do the following e Set buffer length to 300msec rather than 500msec e Run Foobar as admin USB disconnection or Overdrive power down If you plan to disconnect the
14. r 24 44 1 or 24 96 e Make certain that you change the sample rate in the MIDI settings when iTunes is closed and then re open iTunes every time you change the sample rate 9 Specifications Inputs 1 USB 1 1 or USB 2 0 Mac or PC up to 5 meter USB cable up to 24 96 supported 2 S PDIF coax RCA Canare BNC or WBT NextGen up to 24 192 supported 3 12S Empirical standard RJ 45 up to 24 192 supported 4 DC power 12VDC 18VDC 18VDC from included Substation Outputs 1 RCA left and right channels 2 XLR left and right channels Controls Input Select De emphasis Select Digital Filter Select High Medium Low Line Volume Select Volume knob Internal jumpers for 3 volume ranges and two gain settings Oo GB D Electrical 1 RCA output Level 1VRMS or 2 3VRMS XLR output level 2VRMS or 4 6VRMS 2 Frequency response 20 20kHz 0 5dB 3 Output impedance each channel 40 ohms Included 1 Overdrive DAC 2 Substation DC power supply over 60 000uFd of energy storage 3 DC power supply umbilical cable 4 5 meter USB cable 5 AC power supplies 6 CDROM with PC installation software including SRC upsamplers 7 RCAto Phone jack Headphone adapter only high impedance headphones supported Specifications are subject to change without notice 2009 Empirical Audio all rights reserved af pirical Audios
15. t for very small damping resistors on the output Resistors add noise so they are best avoided D A Volume Control The revolutionary volume control is accomplished without any added parts to the line output signal path It is not an entirely digital or entirely analog volume control Itis a little of each actually The volume is adjusted by changing the behavior of the D A conversion It does NOT adjust attenuation of a resistor divider change the gain of an amplifier stage or truncate bits in the digital data All of these would add noise and or distortion to the signal Ultra Linear Output Stage The output stage is a single transistor in Class A mode It is well known that this simple configuration results in some compression distortion but also sounds most natural In order to effectively eliminate this compression distortion we incorporated a compensation circuit in the Overdrive The output stage impedance is low enough and the power output high enough to drive most high impedance headphones easily so we provide an adapter It can drive either normal or balanced headphones such as Sennheiser Fully Balanced Analog Path There are 4 analog paths all identical They connect from the D A converter chip to the outputs All 4 are used for the balanced outputs 2 of the 4 are used for the Single Ended outputs Resistors provide some isolation so all outputs may be used We recommend low capacitance interconnects if all 4 outputs are use
16. tage settle out The line output level from these is 2 3VRMS in high gain mode and 1 0VRMS in low gain mode The volume control reduces this On power down the outputs disconnect from the output drivers and short to ground When there is no valid signal the outputs are disconnected from the output drivers and shorted to ground When active the outputs can withstand short to ground without damage to the Overdrive 5 3 1 Headphone adapter A headphone adapter is provided The red plug on the adapter goes into the left channel RCA output Never use standard Headphones and the balanced outputs to speaker system at the same time this may cause system or speaker damage Also avoid high static charge on the headphone cable when plugging it in Ground yourself and the cable contacts first XLR Balanced outputs The balanced outputs are designed to drive a preamp amplifier or high impedance balanced headphones These are AC coupled so there is a delay in the power output from them on power on in order that the DC voltage settle out The line output level from these is 4 6VRMS in high gain mode and 2 0VRMS in low gain mode The volume control reduces this On power down the outputs disconnect from the output drivers and short to ground When there is no valid signal the outputs are disconnected from the output drivers and shorted to ground When active the outputs can withstand short to ground without damage to the Overdrive Using both RCA and
17. them in general A low impedance power strip such as the PS Audio JuiceBar Il works well in this application however a good power cord is required to feed it from the AC wall outlet The ground wire should be plugged into the outlet bank where the 12VDC supply is plugged or use the alligator clip Overdrive Back Panel Connectors 5 1 Digital Inputs 5 1 1 5 1 3 I2S input The Overdrive 12S input is compatible with the Empirical Audio 12S standard It can be driven with a Pace Car or an Off Ramp S PDIF coax input The S PDIF coax digital input can be driven from any audio device with digital output conforming to the S PDIF standard IEC 60958 The input impedance is 75 ohms It is recommended that stock transports and devices other than that manufactured by Empirical Audio use a 1 5m minimum 75 ohm digital cable in order to minimize the jitter caused by reflections Devices manufactured by Empirical Audio can use a 1m 75 ohm digital cable length USB input The USB input can be driven with a 5m 16 foot USB cable from any USB1 1 or USB2 0 port on a computer The USB port supports up to 24 96 sample rate and uses the native drivers in Windows or Mac OS 5 2 5 3 5 4 5 5 5 6 Analog Outputs RCA Single ended outputs The RCA outputs are designed to drive a preamp amplifier or high impedance headphones These are AC coupled so there is a delay in the power output from them on power on in order that the DC vol
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