I have a preproduction unit and I'm collecting some measurements with the latest software. Here is its performance using Victors 1KHz oscillator as a source. What is notable is the low distortion at -1 dBFS and at -11 dBFS. The THD+N number doesn't make sense but the D+N number seems to.
The box is connected to a big noisy desktop chassis. I'm getting pretty similar results with AC powered sources. The isolation really does work.
This is driving the input differentially with the source floating. (Its battery powered.) I'll try it with an amp in the next few days. I hope this verifies that its real and will be useful.
The box is connected to a big noisy desktop chassis. I'm getting pretty similar results with AC powered sources. The isolation really does work.
This is driving the input differentially with the source floating. (Its battery powered.) I'll try it with an amp in the next few days. I hope this verifies that its real and will be useful.
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You are seeing the intrinsic distortion of the ADC. The source harmonics are at -150 and THD+N measure about -117 dB on the 725. Its not as good as the AK5394A but more than good enough for real audio. The differential input is a huge benefit.
I hope to test the loopback both single ended and balanced today + a small power amp which will give a much better idea of its capabilities with real products.
The floor is about 10 dB better than the QA400 and with the diff in + balanced out + attenuator its far more flexible.
I hope to test the loopback both single ended and balanced today + a small power amp which will give a much better idea of its capabilities with real products.
The floor is about 10 dB better than the QA400 and with the diff in + balanced out + attenuator its far more flexible.
$200 was a great price.The new
Hi Demian, you do not think that harmonics are so high?
5397 is not a champion in THD, even worth then 5394.
P.S. I got a nice results with PCM1804 chip : OLIVINE-2 Measurement - ALTOR AUDIO
I second Dave's suggestion.
http://www.diyaudio.com/forums/equipment-tools/288824-quantasylum-401-405-a.html#post4657094
How doe Q401 compare to the EMU1616m?
The latter seem to use best technology
A/D converter: AK5394A
D/A converter: CS4398
Also, specification are outstanding, AC coupled out and DC coupled in.
Now granted the Q401 seems to be way more flexible with auto range, input attenuator, dedicated SW.
But just from a perspective of performance, which one is better?
The latter seem to use best technology
A/D converter: AK5394A
D/A converter: CS4398
Also, specification are outstanding, AC coupled out and DC coupled in.
Now granted the Q401 seems to be way more flexible with auto range, input attenuator, dedicated SW.
But just from a perspective of performance, which one is better?
I disagree, but it is just my $0.02. I don't think there is a need for a new thread that will just disperse information on basically the same topic, and may lead to confusion and some people missing the new stuff. I don't think creating a new thread adds any value, and don't think that keeping it progressing on this thread has any downside.
Cheers,
Bob
The distortion at -1 dBFS looks similar to what I measured with the AK5397. I don’t have all the measurements at hand at the moment though. With a 1 kHz signal at – 1 dBFS I measured a distortion (THD) of -101.2 dB. This was measured with a sample rate of 192 kHz though, which may impact the measurement result slightly.
I can also recognize the relatively low level of the second harmonic and a higher level of the third harmonic. The difference was around 12 dB, reading from the graphs, which looks very similar to the measurement from Demian.
The THD at -10 dBFS does seem to be rather high though. In this case I measured around -114 dBFS, versus -106.4 in Demians measurement.
In the measurements on the QA401 there seems to be some discrete noise frequencies at around 7.4 kHz, 9.4 kHz, 15.7 kHz and 17.8 kHz. Are these from the QA401 (power supply?) or are they from external sources? The noise spikes seem to scale with the input signal level, which is rather strange.
I made a few more measurements. Collecting graphics from measurements is a real pain but I'll get some up. The noises are coming from inside the box and are present with even a 50 Ohm source. They are also present with the battery powered victor oscillator. When I have everything right and around -20 dB the harmonics are -110 dB. All the junk is in the -120 dB or less range.
The reason I was given for the AK5397 is the ability to work up to 394KHz and even 768KHz. A prototype worked at 394 KHz but there were issues so Matt stopped at 192K for now. Like all this stuff the software will improve. I think the balanced drive and differential input is worth the premium over the QA400. The SFDR of 110 dB in the right circumstances is also a great benefit. Keep in mind its USB powered with full isolation from the host.
You can get better performance from an EMU 1616M (the better of my two stock examples shown) and an opamp upgrade can improve this which I will attempt again. (I have fried 2 so far due to less than perfect reassembly of the two chassis). But its not that easy to use (patchmix is a bitch) and getting all the calibrations etc. sorted out is not trivial either. And you still need software. I find ARTA limiting and clumsy. The QA401 is better in the integration but still has issues and I will revert to the no longer supported Praxis system when I have real work at the extremes to do.
Finally a power amp being tested. This is an HP467 power amp (pretty rare) at 5W into 8 Ohms. You can see that the filter caps are 50 years old but otherwise its not bad for its vintage. And this was done with no external stuff, attenuators, etc., just a load resistor. 5W into 40 Ohms is its rated power so 5W into 8 Ohms is pretty good.
The reason I was given for the AK5397 is the ability to work up to 394KHz and even 768KHz. A prototype worked at 394 KHz but there were issues so Matt stopped at 192K for now. Like all this stuff the software will improve. I think the balanced drive and differential input is worth the premium over the QA400. The SFDR of 110 dB in the right circumstances is also a great benefit. Keep in mind its USB powered with full isolation from the host.
You can get better performance from an EMU 1616M (the better of my two stock examples shown) and an opamp upgrade can improve this which I will attempt again. (I have fried 2 so far due to less than perfect reassembly of the two chassis). But its not that easy to use (patchmix is a bitch) and getting all the calibrations etc. sorted out is not trivial either. And you still need software. I find ARTA limiting and clumsy. The QA401 is better in the integration but still has issues and I will revert to the no longer supported Praxis system when I have real work at the extremes to do.
Finally a power amp being tested. This is an HP467 power amp (pretty rare) at 5W into 8 Ohms. You can see that the filter caps are 50 years old but otherwise its not bad for its vintage. And this was done with no external stuff, attenuators, etc., just a load resistor. 5W into 40 Ohms is its rated power so 5W into 8 Ohms is pretty good.
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