Calibrating C1 DAC?

[zbub]

While reading some old C1 reviews, there was a mention that the C1’s DAC chips can be recalibrated (?!) by the user. I went back to the manual and in the beginning of the manual, under “Technical Highlights,” it did mention the need to recalibrate the chips periodically, but the manual didn’t say exactly how this procedure can be carried out.

Recalibrating the DAC????? This is super hard core stuff!!!!!

I played through the C1 menu, and sure enough, under “Factory Setting” that’s where “Calibrate” was hiding…


So, did the calibration made a difference? Sound-wise, I thought it was a little smoother, the leading-edge not as sharp as before, and a little more transparent. Not night-and-day difference I thought, and I like the sound both before and after calibration. However objectively, something DEFINITELY was changed. The preamp I use is a Soulution 721, and whenever a DC-offset of >15mV was detected, a capacitor is switched into the signal path to protect the preamp. For the entire time I had D1/C1 in my system, that capacitor always kicked in when the C1 was turned on. After calibration, that capacitor is mostly OFF the signal path. So what had changed and what’s the theory behind this? I don’t know, but something definitely was changed.


Then I thought, is there a need to recalibrate all DACs that use multiple DAC chips?

 

[rsorren1]

Hi Everyone. I saw this question posted by zbub and wanted to reply with an answer that I received from one of our engineers, Raphael Pasche. I try to calibrate my personal C1 about every year and I calibrate our C1s that we use at shows and dealer events about every six months (before AXPONA and RMAF). Here's Raphael's response:

"The C1 has two channels for conversion, one for Left, one for Right. Each channel contains four 24-bit high precision DAC R2R converter chips. Because each converter has a slightly different gain and offset, an automated calibration system harmonizes their operation. The intrinsic offset and gain of each chip are independently measured during calibration. Pre-compensating functions are automatically computed and the functions are summed to the digital audio signal prior to the conversion stage so when the digital audio signal is converted, gain and offset imperfections of the chips are canceled. A calibration process is performed at the factory before shipping the unit but the calibration is also available from the unit's user menus so end users can re-calibrate their C1 from time to time. We recommend to leave the C1 on until it has reached a stable internal temperature (an hour) before performing the calibration."