Fubar IV DAC / Headphone Amp

[MasterBlaster]

I splurged and pulled the trigger on a Firestone Audio DAC / Headphone amp.
We ran it at the shop for a while as a DAC into the melos preamp, and it sounded pretty darn good.

I played a little with shop headphones and that wasn't too shabby either.
I found that there is a protection circuit to prevent short/overvolt that will trip if you plug in headphones with the volume up.  


I'm going to do some A/B comparisons between it and the onboard headphone jack on my Macbook Pro.

More to come after I get some time into it....


Detailed Specifications:

Amplifier Structure: Coupling Capacitor Less / Push-Pull
Line Level Output: RCA output 2 Vrms
Gain Control: High setting (normal) / Low setting provides 20dB attenuation
Volume Control: Series / Shunt - user selectable (default is Series)
Headphone Impedance: 32 Ohm to 600 Ohm
Circuit Protection: Output Short / Over Current Protection
USB Support Format: 16 Bit  - 32 / 44.1 / 48 kHz (compatible with Windows, Mac and Linux)
S/PDIF Support Format: 24 Bit / 96 kHz
Upsampling: up to 192 kHz
Input select: Auto Select - USB highest priority
USB Chip: CMedia - CM108
Reciever: Texas Instruments - DIR9001
ASRC Chip: Texas Instruments - SRC4192
DAC Chip: Cirrus Logic - CS4344
LPF OpAmp: National Semiconductor LM4562
Main OpAmp: Texas Instruments OPA2604
Servo OpAmp: Texas Instruments TL072
Audio Performance

S/PDIF (Digital Coax and Toslink Optical input) - RCA outputs - (1 kHz Sinewave) 2 Vrms
Noise Level: (1 kHz A-weighted) -111.9 dB
Dynamic Range: (1 kHz A-weighted) -111.6 dB
THD%: 0.0018%
Stereo Crosstalk: -111.0 dB

S/PDIF (Digital Coax and Toslink Optical input) - Headphone output (1 kHz Sinewave 2 Vrms)
Noise Level: (1 kHz A-weighted) -99.7 dB
Dynamic Range: (1 kHz A-weighted) -99.6 dB
THD%: 0.0020%
Stereo Crosstalk: -90.0 dB

USB Input - RCA outputs (16 Bit / 48 kHz)
Noise Level: (1 kHz A-weighted) -96.2 dB
Dynamic Range: (1 kHz A-weighted) -96.2 dB
THD%: 0.0017%
Stereo Crosstalk: -94.1 dB

USB Input - Headphone output (16 Bit / 48 kHz)
Noise Level: (1 kHz A-weighted) -92.1 dB
Dynamic Range: (1 kHz A-weighted) -91.6 dB
THD%: 0.0020%
Stereo Crosstalk: -90.0 dB

Connectivity

    * USB input (1)
    * S/PDIF Input
          o Digital Coax
          o Toslink Optical
    * Line Outputs
          o RCA Jacks (1 set)
          o Headphone Jack 1/4" (6.4mm)

[rgpit]

I would love to compare it to the Aune headphone amp/DAC at the next meeting. I picked one of these up on Ebay. They seem pretty similar.

Internal component:
*Nichicon capacitors
*Muse Capacitors
*Wima Capacitors
*Alps attenuator
*USB controller chip Burr-Brown PCM2707.
*Digital input receiver chip DIR9001 with
(This chip has better sound quality than the popular CS8412/4/6 commonly used in other DACs. It can play sound with much more detail and accuracy.)
*Main DAC chip is Burr-Brown PCM1793 with
24bit/192kHz Sampling Advanced Segment Audio Stereo DAC
*Dynamic Range: 113 dB and THD+N: 0.001%
*8x Oversampling Digital Filter
*OPAMP chip: Burr-Brown OPA2134
*Headphone AMP: Burr-Brown OPA2604+TIP41C*2+TIP42C*2 (Referencing the SOLO headphone amplifier)
*Digital Coaxial/USB input, RCAx2/6.35mm stereo analog output.

[MasterBlaster]

Sure thing Ron, I will bring it with me to the next meeting.

[SunnyDaze]

Well if you good folks are bringing your HP amps, I suppose I could bring my 325is's again.

We might have to have separate headphone meetings.