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The TooleAudio BantamDAC
Technical Highlights
The TooleAudio BantamDAC is based on the Texas Instruments PCM2702, an all-in-one, USB/clock/DAC. Some of the primary features are listed below:
USB 1.0 specification compliant
Supports 12MHz data tranfer rate
Accepts 16-bit stereo and mono data streams
48KHz, 44.1KHz, and 32KHz sampling rates
8X Oversampling Digital Filter
Clock Generator with 12MHz clock source
+3.3V Digital, +5V Analog operation
In addition, the PCM2702 has been tested by TI with the following operating systems for compliance - proper operation with these OS's does not depend on the speed of the PC's CPU:
Windows 98SE/Windows Me
Windows 2000 Professional
Windows XP Home/Professional (Service Pack 1)
Windows Vista Business
Windows 7, 32bit/64bit (tested by several Head-Fiers)
Apple Computer Mac OS 9.1
Apple Computer Mac OS 10.0
Apple Computer Mac OS 10.1 (some Japanese versions may not plug 'n play the USB)
Apple Computer Mac OS 10.5 (tested by Russ Mowszowski, one of the BantamDAC prototypers)
Linux (tested by user Linuxworks)
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(prototype pic)
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(prototype pic) |
The PCB for the BantamDAC is only 1" by 2", uses only two electrolytic capacitors (depending on your choice of output caps). The reduction in electrolytic capacitors reduces cost and reduces the space needed for the board. This is possible through the use of the Texas Instruments TPS793XX-series of SOT23-5 regulators. These regulators are ultra low-noise, high PSRR (Power Supply Rejection Ratio), LDO-type (Low-DropOut) regulators. Only a 2.2uf SMD ceramic is required on the output of each for stability.
As distinguished also from the REG chips used on other DAC's, the TPS regulators come in both 3.3V and 4.75V voltage output, meaning no adjusting resistors are required for either. However, the board is still compatible with REG101/102 in the SOT23-5 package. Refer to their datasheets for proper resistor and capacitor ratings and connections.
Despite the small size, every attempt is made at using 1206 SMD components where possible. There are a few 805 components, but these are limited. This will helps to make the SMD soldering task a bit easier for DIY-ers.
Output caps selected are Wima MKS at 3.3uf. Bass response with these caps coupled with a 50K-pot amplifier is only down 0.5-1.0 dB at 20Hz. Detail is superior to Black Gates in the same position, in the developers' opinion.
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