USB DAC

USB-DAC

ADL GT40  |  24-bit/96KHz GT40 USB DAC with Phono Stage

GT40_description finally_here

The GT40 is finally here, built for enthusiasts with growing music collections on their computer hard drives. It’s a high performance 24-bits/96kHz USB DAC that’s amazingly affordable. Looking to convert your LPs or other analog sources to digital? The GT40 will take you to the podium with every album you archive.

The seriously-shielded audiophile-grade GT40 features a low-latency USB 2.0 audio driver that plays and records at 96 kHz. A likely first for this category, the GT40 includes a built-in low-noise MM / MC phono preamp! Record your favorite vinyl to hard disk via the USB output.

The ADL GT40 features L/R analog outputs, and switchable line or phono inputs with a vivid, captivating sound that is simply unheard of in this category. The ADL GT40 (wired with Furutech’s GT2 USB cable of course!) brings Furutech’s signature sound -- smooth, detailed clarity -- to desktop systems, especially with high resolution 24-bits/96kHz files, but even 16-bit/44.1kHz files sound impeccable and very musical.

Product Specifications

GT40 USB DAC Specifications

  • USB & Analog Playback and Record multimedia audio system
  • Connectivity: USB B Interface, Analog input/output RCA jack
  • USB Playback Resolution : 24bit/96KHz
  • USB Recording Resolution: 96kHz (Max) supports 32kHz/44.1kHz/48kHz
  • Frequency response: 20Hz ~ 20kHz (40Hz: +0.5 dB, 15kHz:-0.5dB)
  • SN ratio:-90dB (A-wtd) / Line Output
  • Line Output Level: 1 Vrms
  • Line Input Level: MC 0.4mV / MM 5mV / Line 1V
  • Headphone Output Level: 80mW ( 32 ohm ) Max.
  • Power Supply AC Adaptor Rating: AC 9V 0.5A
  • Dimensions: 150 (W) x 111 (D) x 57 (H) mm
  • Weight: 785g Approx.
  • The load (Input impedance) for the ADL GT40 is as follows:
  • Line 50K ohm Approx.
  • MM 46K ohm Approx.
  • MC 10K ohm Approx.
  • Maximum Input Level for MM: 5.0mVrms at 1K Hz
  • Maximum Input Level for MC: 0.4mVrms at 1K Hz
  • Maximum Input Level for LINE: 1Vrms at 1K Hz
  • The Gain setting for the ADL GT40 is fixed at 62.5dB for MC and fixed at 48.5dB for MM.
  • (MC input to LINE output) => 62.5dB @ 1K Hz , +6dB(Line)
  • (MM input to LINE output) => 48.5dB @ 1K Hz , +6dB(Line)
    GT40 has no setting for gain to match different impedance headphones. We recommend using 16 ohm to 300 ohm impedance headphones.
    IMPORTANT NOTE FOR RECORDING:
  • The TENOR chip used in the GT40 has a bandwidth limitation of 12Mbps (USB 2.0 full speed operation), and due to this limitation only one I2S input or output can be set for 24bit/96KHz application at one time. Therefore, under this condition, for simultaneous multiple-channel applications other I2S interfaces must be configured at 16-bit/48KHz or 16-bit/96KHz. In other words, when recording it is necessary to set the audio Input on the computer to 24bit/96KHz (PC-Sound application; MAC-MIDI application), but do not set not the audio Output to 24bit/96KHz. The Output should be set to a lower 16bit resolution until recording is done. Then when you want to playback your 24bit/96KHz files through the GT40 you need to reset the output to 24bit/96KHz and reset the input to a 16bit resolution.
features
  • High performance 96KHz/24bit USB DAC and ADC IC chip
  • Enjoy audio in high resolution at 96KHz/24-bits surpassing conventional 44.1KHz/16-bit standards
  • Incorporates the most trusted driver in professional audio for 96kHz recording and playback
  • External power supply: while a USB-powered device might be convenient, it won’t develop the power required for high resolution playback, so we designed the GT40 with an external power supply to solve the problem.
  • Headphone Amplifier: It contains a high performance headphone amplifier with ample drive for good headphones
  • Analog-to-Digital Converter: The GT40 sports a high-performance ADC IC chip for high resolution recordings via analog inputs including phono, AM/FM radio, or other analog signals.
  • Phono Preamplifier: A first for this class, the GT40 features a phono equalizer for recording your precious LPs. Switch between Moving Magnet (MM) and Moving Coil (MC) or Line input
  • Highest Quality Parts: The GT40 features a high quality amplifier and condenser supporting its high performance analog circuit
  • High End Audio Grade Connections: The GT40 is equipped with gold-plated Fluoropolymer-insulated RCA jacks with an extremely high quality aluminum chassis and machined volume knob



USB-DAC rear


REVIEWS

November 2011

hifi review
June 2011

stereo review
November 2010

digifi review
2010 May

GT40 USB DAC Q & A

Q1. Computer does not recognize the GT40

A1-1. Not connected correctly
(Refer to manual and check if the GT40 is connected correctly to the computer via USB cable.)

A1-2. There is a problem with a USB Hub
(ADL does not recommend the use of a Hub when connecting the GT40 to a computer)

A1-3. Computer does not recognize the GT40 as both the playback and recording USB device
(Disconnect the USB cable and reconnect after 10 seconds. If it still does not recognize the GT40 restart the computer.)

Q2.System error occurs when switching between settings on the GT40

A2. Switching between settings during playback
(There is a small possibility of an OS system error when switching between settings on the GT40 during playback. Avoid switching during playback.)

Q3.There is no sound

A3-1. The sound has been muted
(Open the volume control tab on the computer and unselect mute.)

A3-2. Volume output setting is too low
(Open the volume control tab on the computer and set the volume to maximum.)

A3-3. Another device is set as the default playback device
(Open the Sound and Audio Device properties tab and select USB Audio Device GT40 USB DAC as default playback device.)

A3-4. There is a problem with the external amp or speakers
(Check the connection between external components and the GT40 LINE OUT RCA jacks.)

A3-5. Headphones are plugged into the 6.3mm phone jack on the front panel of the GT40
(When headphones are plugged in, there will be no signal output form the Line Out jacks.)

Q4. No sound from computer internal speakers

A4. USB device is set as the default for playback
(When the GT40 is selected as default audio device for playback, there will be no sound from the computer speakers which is perfectly normal.)

Q5. No sound through headphones

A5-1. The volume is set too low on the GT40
(Adjust the volume on the front of the GT40 to the appropriate level)
(When adjusting volume level for headphones the Line Out RCA jack’s volume level is also adjusted)


A5-2. The GT40 power is not switched on
(Push the power button on the GT40 front panel. It will show as blue when switched on)

Q6. Uneven sound balance during playback

A6-1. Balance is not set a neutral
(Open the volume control tab on the computer and set the balance to neutral - centered.)

A6-2. There is a balance problem with the external amp or speakers
(Check the balance settings on external components.)

Q7. No sound from CD's in the CD-ROM drive

A7. CD-ROM drive does not have digital output
(If the system does not stream digital output from the CD-ROM drive、then there will not be sound output via USB. CD-ROM drives and CD transports must be connected to the LINE IN RCA jacks for listening with headphones)

Q8. No sound via LINE IN RCA jacks

A8-1. Check that the connections are correct
(Check the connection between external components and the Phono/Line Input. If there are no problems with the external components, then check the cable connection.)

A8-2. There is no sound output from external components
(Check if there is sound output from external components.)

A8-3. The selector switch on the front of the GT40 lights up green
(If the selector switch is green, the computer is set as the sound source via USB.)

A8-4. Incorrect setting of the rear panel Input Selector Switch (Phono (MC)・Phono (MM) ・Line)
(Select the appropriate setting for your analog input source.)

Q9. Not able to record

A9-1. Another device is set as the default recording device
(Open the Sound and Audio Device properties tab and select USB Audio Device GT40 USB DAC as the default recording device.)

A9-2. Check that connections are correct
(Check the connection between external components and the Phono/Line Input. If there is no problem with the external components, then check the cable connections.)

A9-3. Check if recording software (not supplied with GT40) recognizes the GT40 as the default recording device
※ Recording software is required to record using the GT40. Furutech recommends free-to-download software Audacity: http://audacity.sourceforge.net/

A9-4. Check to see if both Input and Output settings in the Sound or MIDI application are not set to 24bit/96KHz
The TENOR chip used in the GT40 has a bandwidth limitation of 12Mbps (USB 2.0 full speed operation), and due to this limitation only one I2S input or output can be set for 24bit/96KHz application at one time. Therefore, under this condition, for simultaneous multiple-channel applications other I2S interfaces must be configured at 16-bit/48KHz or 16-bit/96KHz. In other words, when recording it is necessary to set the audio Input on the computer to 24bit/96KHz (PC-Sound application; MAC-MIDI application), but do not set not the audio Output to 24bit/96KHz. The Output should be set to a lower 16bit resolution until recording is done. Then when you want to playback your 24bit/96KHz files through the GT40 you need to reset the output to 24bit/96KHz and reset the input to a 16bit resolution.

Q10. Sound cuts out

A10-1. During playback or recording the computer’s CPU overloads
(Especially during recording make sure all other computer applications are closed.)

A10-2. During playback or recording another USB device is connected to the computer
(The sound will cut out during playback or recording if another USB device is connected to the computer.)

A10-3. CPU is unable to process data fast enough
(If the CPU does not meet the required specifications the expected results may not occur. If the CPU meets the requirements, but the sound cuts out, close all other applications or adjust settings in the recording software)

A10-4. Check to see if both Input and Output settings in the Sound or MIDI application are not set to 24bit/96KHz.
The TENOR chip used in the GT40 has a bandwidth limitation of 12Mbps (USB 2.0 full speed operation), and due to this limitation only one I2S input or output can be set for 24bit/96KHz application at one time. Therefore, under this condition, for simultaneous multiple-channel applications other I2S interfaces must be configured at 16-bit/48KHz or 16-bit/96KHz. In other words, when recording it is necessary to set the audio Input on the computer to 24bit/96KHz (PC-Sound application; MAC-MIDI application), but do not set not the audio Output to 24bit/96KHz. The Output should be set to a lower 16bit resolution until recording is done. Then when you want to playback your 24bit/96KHz files through the GT40 you need to reset the output to 24bit/96KHz and reset the input to a 16bit resolution.

Q11. Noise and interference

A11-1. The GT40 is placed too near appliances with strong magnetic fields like TVs
(Place at a distance from appliances with strong magnetic field)

A11-2.  Check the computer’s AC adaptor
(There is the possibility that the adaptor is not providing stable quality power: Noise at 60Hz or 120Hz or both)

A11-3. Connections are not correct
(Check all terminals for correct connection)

A11-4. Check to see if both Input and Output settings in the Sound or MIDI application are not set to 24bit/96KHz.
The TENOR chip used in the GT40 has a bandwidth limitation of 12Mbps (USB 2.0 full speed operation), and due to this limitation only one I2S input or output can be set for 24bit/96KHz application at one time. Therefore, under this condition, for simultaneous multiple-channel applications other I2S interfaces must be configured at 16-bit/48KHz or 16-bit/96KHz. In other words, when recording it is necessary to set the audio Input on the computer to 24bit/96KHz (PC-Sound application; MAC-MIDI application), but do not set not the audio Output to 24bit/96KHz. The Output should be set to a lower 16bit resolution until recording is done. Then when you want to playback your 24bit/96KHz files through the GT40 you need to reset the output to 24bit/96KHz and reset the input to a 16bit resolution.

If noise is experienced while using GT40 with a turntable:
A11-3. Step one: Disconnect phono cable from GT40 analog line-in jacks momentarily and then reconnect.
A11-4. Step two: Connect power sources for GT40, turntable and computer to the same power strip / Power distributor

Q12: Can the ADL GT40 be used directly with active speakers via the speaker’s RCA inputs?

A12: Yes, Please note that when pairing the GT40 with such actives speakers, before playback the GT40 volume should be set at its maximum and the speaker volume at its minimum. Volume would then be adjusted at the speakers.

Q13: Can the ADL GT40 be used as a preamplifier

A13: The GT40 has been designed to work with a preamp, but it puts out enough voltage to be paired with an amp and sensitive speakers and used directly with its high quality volume control

A13-1: The volume control will adjust volume for both the headphone output and RCA line out output.

Q14. Can the GT40 be used with 64bit operating systems?

A14: Yes

Q15. Is the GT40 compatible with WASAPI?

A15: WASAPI is an OS application and may not be compatible with some playback software. Foorbar2000 software is known to be compatible with WASAPI.

Q16. Is it possible to connect linear PCM recorders directly to the GT40 via USB for playback?

A16: The GT40 USB DAC is compatible with computer based sound data only. Please upload PCM recorded data to your computer and then playback via the GT40.

Q17: The manual packaged with the GT40 does not show set-up instructions for Windows 7. Is the GT40 compatible with Windows 7?

A17: the GT40 is compatible with Windows 7 and the set-up instructions and the same as those of Windows Vista shown in the manual.

Q18: I would like to record LPs to hard drive. Is it necessary to install a driver?

A18: Installation of a driver is not necessary. However recording software is necessary.
software Audacity: http://audacity.sourceforge.net/

A18-2. Important note when recording: Check to see if both Input and Output settings in the Sound or MIDI application are not set to 24bit/96KHz.
The TENOR chip used in the GT40 has a bandwidth limitation of 12Mbps (USB 2.0 full speed operation), and due to this limitation only one I2S input or output can be set for 24bit/96KHz application at one time. Therefore, under this condition, for simultaneous multiple-channel applications other I2S interfaces must be configured at 16-bit/48KHz or 16-bit/96KHz. In other words, when recording it is necessary to set the audio Input on the computer to 24bit/96KHz (PC-Sound application; MAC-MIDI application), but do not set not the audio Output to 24bit/96KHz. The Output should be set to a lower 16bit resolution until recording is done. Then when you want to playback your 24bit/96KHz files through the GT40 you need to reset the output to 24bit/96KHz and reset the input to a 16bit resolution.

Q19: Why will the GT40 only work with an AC 9V 500mA adaptor? Why won’t an AC 9V 2000mA adaptor work?

A19-1. Please check the “No Load” output AC voltage of the AC9V2000mA adapter. The “No Load” voltage of an AC9V500mA adaptor is under AC11V (necessary) and this must be the same for an AC9V2000mA adapter. If the “No Load” voltage is greater than AC12V then the IC4 LM7806 and IC8 LM7906 may overheat.
We don''t suggest replacing it if the no load output AC voltage over AC12V.

A19-2. The GT40 has a linear power transformer, not a switching mode power supply. Also the GT-40''s adaptor is an AC 9V 500 mA and cannot be replaced with a DC 9V 2A adaptor.

Q20: Is it possible to connect linear PCM recorders directly to the ADL GT40 via USB for playback?

A20. The esprit USB DAC is compatible with computer based sound data only. Please upload PCM recorded data to your computer and then playback via the Esprit.

Q21: Does the ADL GT40’s front panel volume control adjust volume for the headphone output only or does it also adjust volume output for the rear panel Line Out jacks?

A21. The volume control adjust volume output for both Headphone and Line Out jacks, so the ADL GT40 can be used as a preamplifier.

Q22: When the GT40 is connected to a preamp is it possible to adjust the headphone output volume at the external preamp?

A22. No, the headphone output volume can only be adjusted with the GT40’s volume control.

Q23: Is it possible to listen via external speakers (line out) while headphones are plugged into the GT40’s headphone jack?

A23. yes, there will be signal output from the lineout jacks while headphones are plugged into the GT40 headphone jack.