USB DAC

ADL x1 ADL x1

Alpha Design Labs 24bit/192KHz GT40α USB DAC with Phono Stage!

The GT40α Harmonizes Computer Files and Analog Inputs

IMPORTANT INFORAMTION FOR GT40a and WINDOWS 10 USERS

Please download and follow the NEW guide for the driver installation on Windows 10 Anniversary Update PCs: HERE

For users that upgraded their OS from Windows 7 or 8 to the new Windows 10 and the above installation guide does not work on your PC, it is possible to roll back the Windows 10 Anniversary Update and return to the previous installed version of Windows 10.
(see this video for tutorial: https://www.youtube.com/watch?v=DTGxB0s_HXw )
You will also need to disable the Windows automatic update function.
(see this video for tutorial: https://www.youtube.com/watch?v=m-bmRe0VEeQ )
Then you will be able to install the driver on Windows 10 OS computers and use the GT40a without issue.

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The GT40α built for enthusiasts with growing music collections on their computer hard drives. It’s a high performance 24bits/192kHz USB DAC that’s amazingly affordable. Looking to convert your LPs or other analog sources to digital? The GT40α will take you to the podium with every album you archive.

The seriously-shielded audiophile-grade GT40α features a low-latency USB 2.0 audio driver that plays and records at 24bits/192kHz. A likely first for this category, the GT40α includes a built-in low-noise MM / MC phono preamp! Record your favorite vinyl to hard disk via the USB output.

The ADL GT40α 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 GT40α (wired with ADL’s Formula 2 cable of course!) brings Furutech’s signature sound -- smooth, detailed clarity -- to desktop systems, especially with high resolution 24bits/192kHz files, but even 16-bit/44.1kHz files sound impeccable and very musical.

Product Specifications
  • USB & Analog Playback and Record multimedia audio system
  • Connectivity: USB B Interface, Analog input/output RCA jack
  • USB Playback Resolution : 24bits/192kHz (Max)
  • USB Recording Resolution: 24bits/192kHz (Max) supports 44.1 /48 /88.2 /96 /176.4 /192 (kHz)
  • Frequency response: 20Hz ~ 20kHz (+/-0.5 dB)
  • SN ratio: >90dB (A-wtd) / Line Output
  • Line Output Level: 5 Vrms
  • Line Input Level: MC 0.4mV / MM 4.0mV / Line 2Vrms
  • Headphone Output Level: 1% THD 1kHz (Max.)
    94mW(16 ohm),110mW(32 ohm), 98.6mW (56 ohm), 23mW (300 ohm)
  • Power Supply AC Adaptor Rating: Erp step2 compliant, 2Wire AC Input Type, Class II, AC/DC Switching Adaptor output DC 15V / 0.8A / 12W
  • Dimensions: 150 (W) x 111 (D) x 57 (H) mm 
  • Weight: 650g Approx.
  • GT40a Windows driver supports Win XP, Win 7 and Win 8 (not Win Vista)
  • IMPORTANT:
  • The load (Input Impedance) for the ADL GT40α is fixed at 47K ohm for MM and 100 ohm for MC

    Input Sensitivity Level for MM: 4.0mVrms at 1K Hz
    Input Sensitivity Level for MC: 0.4mVrms at 1K Hz
    Input Sensitivity Level for LINE: 400mVrms at 1K Hz
    Maximum Input Level for LINE: 2Vrms at 1K Hz
    MC input to LINE output (Vol./Max.) => 70dB @ 1K Hz ,( +/-1dB)
    MM input to LINE output (Vol./Max.) => 50dB @ 1K Hz ,( +/-1dB)
    LINE input to LINE output (Vol./Max.) => 8dB @ 1K Hz ,( +/-1dB)

    GT40α has no setting for gain to match different impedance headphones.
    We recommend using 16 ohm to 300 ohm impedance headphones.
features
  • High performance 24bits/192kHz “VIA VT1736 “USB chip and 24bits/192kHz “Cirrus Logic CS4270” DAC /ADC chip
  • Enjoy audio in high resolution at 24bits/192kHz surpassing conventional 16bit/44.1KHz standards
  • Incorporates the most trusted driver in professional audio for 24bits/192kHz 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 GT40α with an external power supply to solve the problem.
  • Headphone Amplifier: It contains a high performance “Maxim MAX9722A” headphone amplifier with ample drive for good headphones
  • Analog-to-Digital Converter: The GT40α sports a high-performance ADC IC chip for high resolution recordings via analog inputs including phono, AM/FM radio, or other analog signals.
  • Convenient Clip signal Toggle switch for Recording Attenuation: Adjust the recording attenuation to avoid any distortion during recording: 0dB, 6 dB, or 12dB (RecAtt/db signal light comes on when input level exceeds circuit Gain).
  • Phono Preamplifier: A first for this class, the GT40α 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 GT40α features a high quality amplifier and condenser supporting its high performance analog circuit (NJM5532 OPAMP: for ADC,DAC,Line in and out and NJM2068 OPAMP: for Phono )
  • High End Audio Grade Connections: The GT40α is equipped with gold-plated Teflon-insulated RCA jacks with an extremely high quality aluminum chassis and machined volume knob



USB-DAC rear


Video




GT40 REVIEWS

November 2011

hifi review
June 2011

stereo review
November 2010

SpryAccordion.js digifi review
2010 May

GT40α USB DAC Q & A

Q1. Computer does not recognize the GT40α

A1-1. Not connected correctly
(Refer to manual and check if the GT40α 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 GT40α to a computer)

A1-3. Computer does not recognize the GT40α as both the playback and recording USB device
(If your computer has Windows OS please download the GT40α driver from the GT40α webpage and install)
(Disconnect the USB cable and reconnect after 10 seconds. If it still does not recognize the GT40α restart the computer.)

Q2.System error occurs when switching between settings on the GT40α

A2. Switching between settings during playback
(There is a small possibility of an OS system error when switching between settings on the GT40α 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 “Furutech ADL GT40α “ as default playback device.)

A3-4. There is a problem with the external amp or speakers
(Check the connection between external components and the GT40α LINE OUT RCA jacks.)


A3-5. Headphones are plugged into the 6.3mm phone jack on the front panel of the GT40α
(When headphones are plugged in, there will be no signal output form the Line Out jacks.)


A3-6. In the case of Windows OS make sure the ADL ASIO driver is installed and “Furutech ADL GT40α “is selected and “Apply” is clicked in the desktop ADL ASIO tool. In the settings the ASIO buffer size should be set to 5 milliseconds

Q4. No sound from computer internal speakers

A4. USB device is set as the default for playback
(When the GT40α is selected as default audio device for playback, there will be no sound from the computer speakers)

Q5. No sound through headphones

A5-1. The volume is set too low on the GT40α
(Adjust the volume on the front of the GT40α to the appropriate level)
(When adjusting volume level for headphones the Line Out RCA jack’s volume level is also adjusted)


A5-2. The GT40α power is not switched on
(Push the power button on the GT40α 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 GT40α lights up green
(If the selector switch is green, the computer is set as the sound source via USB. If the switch is red, ANALOG (Phono/Line) has been selected)

A8-4. Incorrect setting of the rear panel Input Selector Switch “ LINE / PHONO(MC or MM) “
(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 “Furutech ADL GT40α “ 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 GT40α) recognizes the GT40α as the default recording device
※ Recording software is required to record using the GT40α. 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 set to 24bit/192KHz
(It is recommended both Output and Input bit and sample rates be set to 24bit/192KHz)
Note: Both bit and sample rates for playback and recording in the Sound Application must be set the same when recording.

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 set to 24bit/192KHz.
It is recommended both Output and Input bit and sample rates to 24bit/192KHz.

Q11. Noise and interference (USB and Analog)

A11-1. The GT40α is placed too near appliances with strong magnetic fields like TVs or Antennas
(Place at a distance from appliances with strong magnetic field)

A11-2.  Check the computer’s AC adaptor
(There is the possibility that the Computers or Laptop’s AC 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 set to 24bit/96KHz.
It is recommended both Output and Input bit and sample rates to 24bit/192KHz.

If noise is experienced while using GT40α with a turntable:
A11-5. Step one: Disconnect phono cable from GT40α analog line-in jacks momentarily and then reconnect.
A11-5b. Step two: Connect power sources for GT40α, turntable and computer to the same power strip / Power distributor.
A11-5c. Step three: Connect the GT40α ground wire to an earthed object.

Q12: Can the ADL GT40α be used directly with active speakers via the speaker’s RCA inputs?

A12: Yes, Please note that when pairing the GT40α with such actives speakers, before playback the GT40α 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 GT40α be used as a preamplifier

A13: The GT40α 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 GT40α be used with 64bit operating systems?

A14: Yes, both 32bit and 64bit OS

Q15. Is the GT40α 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 GT40α via USB for playback?

A16: The GT40α USB DAC is compatible with computer based sound data only. Please upload PCM recorded data to your computer and then playback via the GT40α.

Q17: The manual packaged with the GT40α does not show set-up instructions for XP/VISTA. Is the GT40α compatible with XP/VISTA?

A17: the GT40α is compatible with Windows XP and the set-up instructions and the same as those of Window 7.
(Note* the GT40α Windows driver is not compatible with Windows Vista)

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

A18-1: No drivers are necessary with Mac computers and a single standard driver is required for Windows OS. The driver can be downloaded from the GT40α webpage. Please note that recording software is also necessary.
ADL recommends Audacity: http://audacity.sourceforge.net/

A18-2. Check to see if both Input and Output settings in the Sound or MIDI application are set to 24bit/192KHz
It is recommended both Output and Input bit and sample rates to 24bit/192KHz

Q19: Why will the GT40α only work with the previous model’s (GT40) AC adaptor?

A19-1. The GT40α is designed to be power by a DC 15V / 0.8A / 12W AC/DC Switching Adaptor only

Q20: Does the GT40α’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?

A20. The volume control adjust volume output for both Headphone and Line Out jacks, so the GT40α can be used as a preamplifier

Q21: When the GT40α is connected to a preamp is it possible to adjust the headphone output volume at the external preamp?

A21. No, the headphone output volume can only be adjusted with the GT40α’s volume control.

Q22: Is it possible to listen via external speakers (line out) while headphones are plugged into the GT40α’s headphone jack?

A22. yes, there will be signal output from the lineout jacks while headphones are plugged into the GT40αheadphone jack.

Q23: I am using Mac OS X Mavericks and would like to update to Yosemite, will the GT40α be compatible?

A23. yes, once you have updated to Yosemite and you find that the GT40α is not recognized, restart your MAC.

Q24: Is the Windows driver for the previous model GT40 compatible with the new GT40α?

A24. No, you must uninstall the old driver and install the new driver which can be downloaded from the ADL GT40α webpage.

Q25: Playback via USB is not stable?

A25. Connecting a Self-power USB Hub between the GT40α and PC/Laptop can sometimes stabilize playback.

Q26: Is it possible to switch between PHONO and LINE during playback of LINE source signal?

A26. NO. Do not switch between PHONO and LINE during playback. Doing so could damage speakers and/or componentry.

Q27: What kind of recording software does the GT40α support?

A27. While recording software is not included with the ADL GT40α, it will support many of the recording software that is available on the market. ADL has tested and can recommend free-to-download Audacity software. Question regarding the use of this software should be direct to the software maker.

Q28: Is it possible to recording instruments using a mic with the GT40α?

A28. If the GT40α is connected via the GT40α’s LINE Input to the Mic recording device LINE output, it is possible.

Q29: When playing back signal through the GT40α LINE Input and the GT40α LINE Output, is the signal processed by the GT40α’s DAC?

A29. No, the signal will bypass the DAC
RCA LINE Input ⇒ Op Amp(Circuit1) ⇒ Variable Resistor ⇒ Op Amp(Circuit2) ⇒ RCA LINE Output

Q30: Is it possible to use a 0.4mV(1kHz、4cm/sec.)MC cartridge?

A30. The GT40α’s LINE Input level is M=0.4mV、MM=4mV, so it is not a problem.

Q31: Is the resolution of payback and recording formats of the GT40α improved over the previous model (GT40)?

A31. Playback and recording of 88.2kHz ・176.4kHz・192kH sample rates is no possible with the new GT40α.

Q32: Is the GT40α compatible with ASIO?

A32. The GT40α is ASIO compatible. Install the ADL ASIO driver and select Furutech ADL GT40α in the desktop ADL ASIO tool and “Apply”. In the settings the ASIO buffer size should be set to 5 milliseconds.

Q33: Is the USB data transfer Asynchronous?

A33. Yes

Q34: What is the USB transfer speed?

A34. The GT40α is USB2.0 High speed (480Mbit/s)

Q35: Is it possible to record digital sources with the GT40α?

A35. No, only analog sources.

Q36: Before using the GT40α is it necessary to uninstall USB audio drivers of other components?

A36. Since other products ID codes will differ from the GT40α’s code it should not be necessary to uninstall other USB audio drivers. However if another product has the same USB chip as the ADL GT40α it may be necessary to uninstall the other product’s USB audio driver.

Q37: During recording the Clip Signal lamp on the front panel of the GT40α is flashing constantly

A37. If the analog input level is too high there is the possibility of distortion in the recorded signal, so it may be necessary to reducing the recording level using the Clip Signal switch (RecAtt/dB switch) on the rear of the GT40α. Switch between 0db, 6db and 12db for the appropriate level.

Q38: Caution regarding the Bit and Sample rates during recording with the GT40α

A38. During recording make sure both Input and Output bit and sample rates at set at the same level

Q39: How about the WAVE MUTE setting for the recording level?

A39. It is recommended that the Recording Level settings be at 50~90% and the WAVE MUTE settings at 5% (-19db). Note* It may be necessary to make other adjustments to these settings if distortion is experienced.

Q40: Is it possible to use USB BUS power to power the GT40α (no AC-DC adaptor)?

A40. This is not possible. The provided 15V switching adaptor must be used.
USB chip independent power: 5V DC from PC USB bus powers USB chip only.

Q41: Is it possible to use the ADL A1 driver with the ADL GT40α and vice versa?

A41. Yes, the GT40α driver is compatible with the A1
A41-1. : In the case you have both the GT40α and A1 and installed the A1 driver first, it is recommended that you connect the A1 to your PC and uninstall its driver. Then install the GT40α driver and the new driver will work for both GT40α and A1.
Note* When installing the GT40α driver do not connect the GT40α to the PC.
Note* Latest drivers for A1 and GT40α are available for download from 2015.01.22

Q42. When using Line Input and Line Output only, does the signal pass through the DAC?

A42. The signal does not pass through the DAC.
Please see the list below for signal paths in the GT40α

ADL GT40α circuit routes:

RCA LINE Input ⇒ NJM5532 OP Amp(Circuit1) ⇒ Variable Resistor (VR) ⇒ NJM5532 OP Amp(Circuit2)⇒ RCA LINE Output


RCA LINE Input ⇒ NJM5532 OP Amp(Circuit1) ⇒ Variable Resistor (VR) ⇒ NJM5532 OP Amp(Circuit2) ⇒ MAX9722 Phone Amp ⇒ Phone Output

RCA Phono Input ⇒NJM2068 OP Amp(Circuit1) ⇒ Variable Resistor (VR) ⇒NJM5532 OP Amp(Circuit2) ⇒ RCA LINE Output
RCA Phono Input ⇒NJM2068 OP Amp(Circuit1) ⇒ Variable Resistor (VR) ⇒NJM5532 OP Amp(Circuit2)⇒ MAX9722 Phone Amp ⇒ Phone Output

PC Playback ⇒ USB Input ⇒ VIA VT-1736 ⇒ CS-4270/DAC ⇒ NJM5532 OP Amp(Circuit1) ⇒ Variable Resistor (VR) ⇒ NJM5532 OP Amp(Circuit2) ⇒ RCA LINE Output
PC Playback ⇒ USB Input ⇒ VIA VT-1736 ⇒ CS-4270/DAC ⇒ NJM5532 OP Amp(Circuit1) ⇒ Variable Resistor (VR) ⇒ NJM5532 OP Amp(Circuit2) ⇒ MAX9722 Phone Amp ⇒ Phone Output

RCA LINE Input ⇒ NJM5532 OP Amp(Circuit1) ⇒ Clip Detection ⇒ CS-4270/ADC ⇒ VIA VT-1736 ⇒ USB Output ⇒ PC Recording
RCA Phono Input ⇒ NJM2068 OP Amp(Circuit1) ⇒ Clip Detection ⇒ CS-4270/ADC⇒ VIA VT-1736 ⇒ USB Output ⇒ PC Recording

Q43. Is it possible to record and playback using MAC Quicktime?

A43. Recording of analog signal with Quicktime is possible. The recording format will 16bit/44.1kHz AAC and it is possible to playback using iTunes.
The files can also be played back using Windows Media Player 12 (Windows 7 or later) - Windows Media Player 11 or earlier will need codecs installed.

Q44. Is it possible to playback music from an iPhone when connecting via the USB port using a camera connection kit?

A44. Yes, this is possible. The switch on the front panel of the GT40α must be set to USB.

Q45. When recording with Audacity only noise can be heard and the sound wave indicator does not change on Audacity. Only noise is heard during playback of the recorded file (experienced on Windows PC).

A45. Close Audacity and restart the PC. This can fix the problem. Also switching the default speaker setting from GT40α to the primary speaker on your PC can fix the problem.

Q46. Is it possible to use the GT40a with LINUX OS?

A46. Yes, it is possible and a driver is not required.

Q47. Is it the GT40a compatible with Windows 10 OS?

A47. Yes, compatible.

Q48. Is it the GT40a compatible with MAC OS El Captain (10.11)?

A48. Yes, compatible.

Q49. Experienced noise when recording at 24bit/192kHz after updating to Audacity 2.1.1 on Mac.

A49. There is an incompatibility issue with the 2.1.1 version of Audacity when recording at 24bit/192kHz on Mac. The issue is not evident when using Audacity 1.3.14.

Q50. Error message “Enumerate filter failed” during driver installation.

A50. This error means the USB device is not being recognized. Try reconnect the USB cable or try another USB cable or another USB port. Once the GT40a is recognized as the USB device in the sound application, uninstall the driver and reinstall.

Q51. The ASIO component of Foobar 2000 does recognize the GT40a as the ASIO device.

A51. Go to Preference/Output/ASIO and uncheck “use 64bit ASIO drivers”. Also under “Components” click on “ASIO Support foo_out_asio and update