So not a lot of headroom, though I guess it should be OK to digitize a phono line output (mine is specified at 200 mV nominal at 1 kHz). We can see that THD minimum is achieved at only ~25mV input (0,006-0,01%) and the ADC starts to clip around 0,8V. Let's look now at the THD vs level sweep at 1kHz: THD is also pretty high at this level, dominated by the 2nd harmonic. Next let's see the spectrum of a 1 kHz sine at -1 dBFS peak:Īs we can see, there's a lot of noise and non-harmonic tones in it, and we can even see pretty high level IMD products around the test 1kHz tone. Good news is that there is no visible ringing in the HF, the response looks pretty smooth there. Let's start with the basics, RMAA measurement summary (input level set to recommended -1 dBFS by reducing RME output level by ~7dB):Īs we can see, performance was not very good - and this is the best I was able to get.Īs we can see the LF -3 dB point is already at 55-60 Hz (not the same for the two channels), and the -6 dB point is in the mid thirties - quite disappointing. If using a 'dirtier' PSU the noise would increase by 5-6 dB and dynamic range would go down by a similar amount. The performance of the ADC varied significantly based on the type of PSU used, and in these tests I used a powerbank to power the ADC and get the cleanest response. Unbalanced/headphone output of RME babyface was used as the signal generator. ADC) and the sample rate was 48kHz (native sample rate of ADC). The ADC was connected to optical SPDIF input of RME Babyface, clock source was the optical input (i.e. The measurements you'll see next were done with the RME Babyface soundcard, first generation - measured here.
My plan was to use an ADC to connect my turntable to a digital input of miniDSP OpenDRC-DI, but I didn't really want to spend much on this and just hoped the cheapest one I find would be satisfactory View attachment 133907 View attachment 133908
Recently I was looking for a cheap ADC and found a generic, unbranded one on eBay for just under 10$ (UPC: 6927373037416). If someone else runs the trials I'd be very interested to see more results! SHA1: 6ee80119abfd3726130e2a7be87a18d28e9ef717į8b9a120470157aac852349a7b3595e22b82220dI have to say I was surprised that the audible difference was smaller that I thought originally (especially considering the relatively extreme difference in performance between the two), though apparently still possible for me to reliably differentiate - so yay! File A: Chain the Sun - BtR - eBay ADC loopback.flac