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QuantAsylum QA400 and QA401
QuantAsylum QA400 and QA401
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Old 21st March 2016, 07:53 PM   #1851
mrsavage is offline mrsavage  United States
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QuantAsylum QA400 and QA401
Default Not Happy

The company has stopped selling the QA400. $200 was a great price.The new
version,QA401, is more than double the cost of the original ($429.00). Yes,
it's better, but $429.00 is a still high.
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Old 22nd March 2016, 12:20 AM   #1852
agdr is offline agdr  United States
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mrsavage - PM sent.
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Old 22nd March 2016, 07:46 AM   #1853
acusticlab is offline acusticlab  Mexico
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Default QA400 in school

Somebody has for sell a QA 400?
The idea is buy less expensive and we donate to a small acoustic school in Mexico.
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Old 22nd March 2016, 09:14 AM   #1854
altor is offline altor  Israel
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Quote:
Originally Posted by 1audio View Post
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.
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
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Old 22nd March 2016, 12:09 PM   #1855
B&W_arthur is offline B&W_arthur  Hong Kong
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Quote:
Originally Posted by skidave View Post
Suggestion for a new thread focused on the QA401. I'm sure there will be quite a bit of information shared once these get to the masses...
I second Dave's suggestion.

http://www.diyaudio.com/forums/equip...ml#post4657094
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Old 22nd March 2016, 03:54 PM   #1856
Stefanoo is offline Stefanoo  Italy
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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?
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Old 22nd March 2016, 05:50 PM   #1857
Bob Cordell is offline Bob Cordell  United States
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Quote:
Originally Posted by skidave View Post
Suggestion for a new thread focused on the QA401. I'm sure there will be quite a bit of information shared once these get to the masses...
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.

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Old 22nd March 2016, 06:26 PM   #1858
dennismiller55 is offline dennismiller55  United States
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I agree with Bob. I prefer to keep the discussion here. For search purposes, maybe a moderator can change the title to include QA401.
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Old 22nd March 2016, 06:33 PM   #1859
JensH is offline JensH  Denmark
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QuantAsylum QA400 and QA401
Quote:
Originally Posted by 1audio View Post
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 distortion at -1 dBFS looks similar to what I measured with the AK5397. I donít have all the measurements at hand at the moment though. With a 1 kHz signal at Ė 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.
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Old 23rd March 2016, 02:44 AM   #1860
1audio is offline 1audio  United States
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QuantAsylum QA400 and QA401
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.
Attached Images
File Type: png KH4400 - QA401 1 KHz -20dB.PNG (150.1 KB, 823 views)
File Type: png KH4400 - EMU1616M 1 KHz -11dB.PNG (48.2 KB, 812 views)
File Type: png HP467 5W 1 KHz 8 Ohms.PNG (189.4 KB, 812 views)
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Last edited by 1audio; 23rd March 2016 at 02:46 AM.
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