roggae
Head-Fier
- Joined
- Nov 25, 2006
- Posts
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- 12
My switching power supply is making a high pitched buzz. Anyone have any thoughts/suggestions? Perhaps I should replace it.
I just received my Pure i20 yesterday. I am using it as a doc for a iPhone4, feeding the SPDIF output to an original Benchmark DAC-1. So far so good. It definitely sounds a lot better than the iPhone4 own headphone output on my HD-600s.
Having not previously read these forums I was surprised that there is a volume control in the signal path, only adjustable from the i20 remote. I was hoping for bit-accurate digital output with no processing. However, it still sounds very good. I will be running some tests very soon on the output bit depth and resolution which I will post on my blog. Please stay tuned!
-david BTW
I sent in a tech support request to Pure and after some back and forth trying to find the right words so the tech support engineer got the real question I today received this really pretty clear answer:
Dear David,
The maximum volume control setting on i20 sets 0dBfs digital output level within the DSP which converts asynchronous USB packetized audio data from the iPod to I2S audio data (i20 system) to feed the D/A converter within i20 and also to feed the digital outputs (S/P-Dif).
This can be quickly verified with a digitally generated file of -nndBfs added to the iPod playlist and then played out of the S/P-DIF path on i20 and digitally captured, as digital interfaces pass level in absolute dBfs with 0dBfs being the highest magnitude signal that can be described.
N.B. Additionally, yes, using the digital volume control at a setting other than 0dBfs (maximum) does manipulate the audio stream to reduce volume and hence with large shifts (SNR)
Regards,
David Wilson
I will be confirming this with real measurements when I get my lab (and Audio Precision System Two Cascade) rebuilt in the very near future. In the meantime, it appears that once the iPhone4 is on the doc, running up the volume to full using the i20 remote will provide the best digital output, with the most dynamic range and maybe even bit-accurate when using apple lossless format(we shall see). There is no indication that the volume control is going up or down on the screen, so one just has to keep hitting the up command until convinced it is up all the way.
Have Fun,
-david BTW
Can the Pure i-20 dock an iPhone without removing the phone case?
My snug fitting bamboo wood case from Grove is not easily slipped off & on. Thanks.
I'm very curious to know whether davebtw (or anyone else) has ever measured and verified whether the Pure i-20 outputs bit-perfect data from the iPod/iPhone/iPad when used as a digital transport to an external DAC. I've searched this forum in vain for any conclusive evidence that the output is bit-transparent (by contrast, it has been well-documented elsewhere that output from the iPad via the Camera Connection Kit to certain USB DACs is bit-perfect all the way up to 24/96 files, e.g., http://www.benchmarkmedia.com/discuss/feedback/newsletter/2011/06/1/ipad-streams-high-resolution-audio-dac1).
I am equally interested to know whether anyone has verified that the i-20 will output full 24/96 resolution music files when used as a digital transport to an external DAC, either with an iPhone or iPad using FLAC Player or some other player that can store and access 24/96 files. I realize the iPhone is limited by Apple to 24/48 output (though this is no longer true of the iPad), but if I can store 24/96 FLAC files locally on the iPhone with FLAC Player, and the i-20 is acting as a pure digital transport, shouldn't the full resolution of those files be visible to the i-20 and output to the external DAC? In other words, wouldn't bypassing the iPhone's integrated DAC completely remove any hardware limitations on playing high resolution 24/96 files?
Thanks very much. I have an i-20 hooked up to a Benchmark DAC1-USB via optical with both an iPhone 4S and iPad 2, and it would be great to verify that 100% of the data from high resolution files is being sent unaltered to the DAC1 from one or both devices.