• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

QUAD Artera PRE partial measurements/spec conformation

dougi

Addicted to Fun and Learning
Joined
May 31, 2020
Messages
853
Likes
774
Location
ACT, Australia
Today I'll present mainly a summary of partial measurements of my QUAD Artera PRE analog preamp. The manual is finally available online and you can find it here. Like the rest of the Atera series, it is quite a looker in a clean kind of way:
Artera-Pre-Black-front.png

The back shows it has three sorts of outputs, variable RCA, variable XLR and fixed RCA (aux):
Artera-Pre-Black-back.png

Specs for the unit are:
artera_pre_specs.png


My main use for it is as a phono pre with variable output to put into my NAD C3050LE, either via its line input or via my RME ADI-2 PRO and its optical out.

I'm not going to show many plots, as my focus is on the phono measurements which do not look nice using the RME for measurement due to grounding issues.

Measurements were done using the RME @96kHz and mostly for the purpose of confirming or clarifying the specs.

OBSERVATIONS
GAIN: The specs above are for RCA or phono in and XLR out it would seem, but there is an error in there:
  • Variable RCA out maximum gains are 2dB for line, 53.5dB for mm, 67.5dB for MC.
  • Variable XLR out max gains are 8dB for line, 59.5dB for mm, 73.5dB for mc. Steps are 0.5dB per number e.g. volume 50 is 25dB from full volume etc.
  • Gains at the fixed AUX output are 36.5dB for mm and 50.0dB for mc (quite low). I didn't measure the line stage gains at the fixed output.
PHONO overload at 1kHz:
  • The fixed (AUX) output started clipping at inputs of 62mV for mm and 13mV for mc.
  • For variable RCA @volume 50 it was again 62mV for mm (gain 29dB) and 13mV (gain 42dB) for mc. Outputs at volume of 50 are low though, with 0.133V out for 5mV mm in, 0.161V out for 0.5mV mc in.
  • At much higher volumes the max input is lower, e.g. for mm will clip at 50mV for volume 61 (gain 34dB), 37mV for volume 66 (gain 36.5dB). Output clip is ~2.5V for RCA.
  • Similarly the output will clip at mc input of 5.5mV for volume of 74 (gain 54.5dB).
  • The mm overload matches the spec but the mc overload is 6dB higher than spec. The spec is likely for XLR out, with 6dB higher gain and perhaps then 6dB lower overload compared with RCA.

1kHz THD and SINAD or SNR: End to end RME performance may influence this a bit but I measured:
  • 4V XLR in, XLR out, unity gain (vol=96), DIRECT mode, a wideband THD of 116dB, wideband SINAD 103dB, A-weighted 111dB
  • 4V XLR in, XLR out, unity gain (vol=96), non-DIRECT, a wideband THD of 108dB, wideband SINAD 100dB, A-weighted 106dB
  • 2V RCA in, XLR out, 6dB gain (vol=96), a wideband THD of 109dB, wideband SINAD 95dB, A-weighted 105dB
  • 2V RCA in, RCA out, unity gain (vol=96), a wideband THD of 111dB, wideband SINAD 97dB, A-weighted 112dB
  • 5mV mm in, AUX out, wideband THD 108dB, shorted input noise A weighted 9uV for a calculated SNR of 91dBA
  • 0.5mV mc in, AUX out, wideband THD 77dB, shorted input noise A weighted 38uV for a calculated SNR of 72dBA
  • 5mV mm in, RCA out volume 73 (0.5V out), wideband THD 100dB, shorted input noise A weighted 13uV for a calculated SNR of 91dBA
  • 0.5mV mc in, RCA out volume 86 (0.5V out), wideband THD 83dB, shorted input noise A weighted 117uV for a calculated SNR of 72dBA.
  • (I didn't get round to measuring the noise for mm or mc with the XLR outputs)
CONCLUSIONS
The specs are likely accurate, but noting they are likely for XLR outputs. There is an error in the spec for mm gain, with huge gains possible on XLR output (up to 59.5dB). Again, overload spec for mc is likely for XLR output, with RCA 6dB higher.
Despite the high mm gain, noise performance of mm is very good, but overload fairly poor. It is tricky to get a good balance of a decent output level (i.e. gain) and overload. It may be best to use the fixed AUX output for mm and the XLR output for mc.
As a line stage it seems good.

A COUPLE OF EXAMPLES (as above, ignore noise in phono 1kHz plots due to grounding)

4vXLR.jpg

I didn't summarise but I did measure THD vs freq for the XLR non-direct case at 4V unit gain:

xlr_thd.jpg


2vRCA4vXLR.jpg


mm 5mV in aux out:
5mV_aux.jpg


mm noise of aux out, shorted input:

noise_aux.jpg


mc 0.5mV in aux out:
0_5_mc_aux.jpg


mc aux out noise, shorted input:
mc_noise_aux.jpg
 

Attachments

  • 5mV_aux.jpg
    5mV_aux.jpg
    119.7 KB · Views: 125
A bit expensive compared to other Chinese made audio gear? (although prices seem to be rising in recent times) but I don't think performance is bad at all. I have used the Play version in mk1 form and was impressed how well it (the built in CD player) coped with what are now called 'reverb tails,' the atmosphere and general reproduction of reverb excellent (balanced connection to the 606 based Artera Stereo power amp).

Lovely traditional 'old school' pairing and the sad thing is, high end and snooty gear-enthusiasts totally ignore it, going for bling-boxes and heaven forbid any discussion of Class D in any form ;)
 
Curious to post flawed partial measurements obtained by suboptimal methods. Even curiouser to ignore the Artera Pre's proper use by restricting it to be a phono pre into an integrated amp, and not mentioning its unique features that includes tilt tone controls.
You might be "curious" but I explained my use case for it. i.e. purely as a phono pre with a volume control to manage headroom into the ADC of the amp. Not interested in the tilt control. The only "sub-optimal" method was the phono hum which I explained and which true hum and noise was measured via a different method.
 
Back
Top Bottom