We were just talking about another super low cost option: https://quantasylum.com/collections/frontpage/products/qa401-audio-analyzer
If it were similar to AP, it would be priced 10X higherIs the Averlab comparable to AP? I believe this is Jonathan Novick’s new product. $3,000 seems like a reasonable price for high performance test gear.
https://www.avermetrics.com/products/averlab/
My understanding is that is behaves like a soundcard so can be used with various software:Had not seen that one before. Nice to see very high voltage input capability. But does it not have autoscaling? I see those presets in front and worry that you are one wrong click away from damaging in the inputs.
And yes, I can do a loopback on AP.
That graph is the output from Room EQ Wizard it seems. Is that they software they use or did they just use this as a soundcard?
Looks like DIY had a group buy where cost was $1199 for 10 of them or $999 for 50. Also some people later in that long thread received them and posted some test results with them.
http://www.diyaudio.com/forums/group-buys/306322-gb-rtx6001-audio-analyzer-ak5394a-ak4490.html
You can do that but one wrong signal or turn of the volume control will blow up the input of the sound card. It is just too high of a risk for a good sound card. In the extreme case, it could even travel upstream to the system driving it and damage that!Been meaning to for some time, but haven't done so. Why not just build a resistor box to attenuate the input of high voltage sources like from amps? That seems all you are missing with regularly available ADCs.
You can do that but one wrong signal or turn of the volume control will blow up the input of the sound card. It is just too high of a risk for a good sound card. In the extreme case, it could even travel upstream to the system driving it and damage that!
BTW, that is all that the one we are talking about has right now. The Quantum Asylum though like my AP has both protection and auto-switching. You need both as the latter takes time to switch.
How would you do distortion vs power test?
Just going back to my cock-up with dBFS v dBV above. The QA FS input is 6 dBV = 5.6 VPP = 2 VRMS. The Motu has a lot higher FS (with input preamps set at 0dB) of 20 dBV = 28.2VPP = 10 Vrms. So clearly we are not comparing apples with apples.
I calibrated the input of the Motu in ARTA and the results are as follows for an input of -12 dBV:
QA -12dBV (-18 dBFS)
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Motu -12dBV (-32 dBFS)
View attachment 10056
View attachment 10057
So the Motu is 32 dB away from its FS input, the QA is 18 db away. When the motu is calibrated to dBV you see the noise floor rises as we are adding about 20dB on.
I then set the mot0 to -18dB FS. In all of these tests the motu shows no harmonic distortion visible above the noise floor.
Motu -18 dBFS
View attachment 10058
All this shows how we do need to cross check our measurements with a known transfer standard. The distortion shown on the QA, is it the ADC or is it the DAC signal generator?
I will hook my meridian explorer up and see how that fairs - we could use that as the DUT to compare our systems, I have no problem sending it to you guys.
BTW, there is a lot of value in standardizing on a known unit beside my AP for these measurements instead of each one of you getting a different unit.So if Quantum Asylum is it, that would be good and maybe a group buy can be made. I can also lean on them for marketing value they may get on our forum.
I do agree with this, minimising variables is important. I am very tempted to get an AQ just for kicks whatever, but if you could persuade them of the marketing value of its use on the forum then perhaps we could get a better deal
I think my only concern is its input FS voltage. Many DACS, although notionally output 2 V RMS FS, they will often be a bit above this which means having to switch in the 20dB attenuator on the QA. This could leave us maybe 15 -to 18 dB below the ADC FS. This is both good and bad. Whilst we wont make the most of the dynamic range and spuria might disappear into the noise floor, we also will reduce the harmonic distortion of the ADC as it approaches 0 dB FS. This could also lead to discrepancies in comparing one DAC to another. Oh dilemmas !
Amir, how does the AP cope with this. I gather its auto scaling input amps, and I assume that is in discrete steps. How large are they? Small enough to keep very close to the ADC FS? I have found on my Motu if I start using the input amps to scale say a 2 v rms input close to FS that noise and distortion also rises.
Alan