QuantAsylum QA400 Audio analyser

Anyone tried one of these?  Looks ideal as the basis of a general purpose very high quality audio test set and only $200.

http://www.quantasylum.com/content/Products/QA400.aspx

Cheers

Ian

I'm definetly curious! it does fall in the affordable category comparing!

J

I have one, but it doesn't run on my older Win XP computer. Have to wait untill I get the new one up and running.

Samuel

What software are they using?

ruffrecords said:

Anyone tried one of these?  Looks ideal as the basis of a general purpose very high quality audio test set and only $200.

http://www.quantasylum.com/content/Products/QA400.aspx

Cheers

Ian

Click to expand...

Seems extremely interesting! However, like most of existing products, it lacks some essential features for professional audio, such as balanced ins &outs, source impedance selection,  CMR measurement, and so on...
I've been working on the design of a specific interface for the serious hobbyist, where the basic measurement tools would be a soundcard and alternatively an affordable oscillator and voltmeter/THD analyser.
I will start a new thread with the basic specs and block diagram.

I think a high quality front-end and output buffer would be doable - im am working on something similar right now - not finished now but the whole package seems worth a try for that money anyway.....  the input must have a 20dB pad at least, and may bee switchable input impedance. the output driver must drive much higher output voltages of course...

I will be trying some of this fisrt:

http://www.users.on.net/~glenk/

- michael

Graham from PrismSound tuned me onto this today: http://audio.rightmark.org/index_new.shtml

jplebre said:

Graham from PrismSound tuned me onto this today: http://audio.rightmark.org/index_new.shtml

Click to expand...

RMAA has been around a long time. It's a software only. There are several others, even ones that are free.
The big thing in this QA400 is that it provides a quality hardware.

If I wanted a front-end to address this specific box's shortcomings, could I do something simpler than abbey's solution, like this?

Thinking I might put a chunk of my next paycheck into one of these...

dfuruta said:

If I wanted a front-end to address this specific box's shortcomings, could I do something simpler than abbey's solution, like this?

Thinking I might put a chunk of my next paycheck into one of these...

Click to expand...

I believe you could use my solution and depopulate what you don't need (want). As always, the most expensive part in my project is the PCB itself and the case. The rest is almost marginal.

Sure thing!  I was just thinking that if a relatively simple solution would suffice, I could just etch up a pcb myself and be on my way.  It seems (?) like the QA400 wouldn't need the analog filtering, and I probably wouldn't need the extra connections for external signal generators and scopes.  I thought an input impedance switch might be useful, though.

dfuruta said:

I thought an input impedance switch might be useful, though.

Click to expand...

I decided to do without for two reasons:
one is that in more than 20 years living with an AP, I have never used the internal load. I have used the power calculator that takes into account the load that is connected externally, when testing power amplifiers, though.
The other reason is that there's not enough front panel real-estate for another rotary switch. What I have thought about is putting a pair of binding posts to which any desired resistor could be attached.

Interesting, thanks for the details of that.

And, many thanks for sharing your work in the other thread!

Even though abbey road d enfer very graciously shared his/her front-end design in that other thread, I wanted to be an impertinent little turd and try to come up with one on my own.  I'd very much appreciate any advice, even (especially) if it's just, "give up and get one of abbey's!"

Going to place my order for a QA400 this afternoon.

ruffrecords said:

Anyone tried one of these?  Looks ideal as the basis of a general purpose very high quality audio test set and only $200.

http://www.quantasylum.com/content/Products/QA400.aspx

Click to expand...

This is a USB box, right? The web page makes no mention of the interface to the computer, nor does it show the rear panel.

=a

dfuruta said:

try to come up with one on my own.  I'd very much appreciate any advice

Click to expand...

The input impedance switching is unduly complex IMO.
In the 600 ohm position, the level is attenuated 3dB.

Andy Peters said:

This is a USB box, right? The web page makes no mention of the interface to the computer, nor does it show the rear panel.

Click to expand...

They mention it in their presentation, saying that they couldn't use the more expe,nsive codec because of the USB power limitation.

abbey road d enfer said:

The input impedance switching is unduly complex IMO.
In the 600 ohm position, the level is attenuated 3dB.

Click to expand...

Excellent, thank you!  Would it be better to put resistors to ground, or just strap a resistor across + and -?  I thought I would try to use the 1200's common mode input, but I probably don't need to.

abbey road d enfer said:

Andy Peters said:

This is a USB box, right? The web page makes no mention of the interface to the computer, nor does it show the rear panel.

Click to expand...

They mention it in their presentation, saying that they couldn't use the more expe,nsive codec because of the USB power limitation.

Click to expand...

Having done a USB audio device with phantom power, I'm not quite sure what their issue is.

The PCM4222 uses a 4.0V analog rail and a 3.3V digital rail; maybe their concern was the regulator for the 4.0V?

Also the PCM4222 is only an ADC; they'd need a separate device for the DAC. The Cirrrus part has both, and can also run everything off of a 5V rail (which would make interfacing to a 3.3V micro dicey).

OK, well, I actually do think I know what their issue is -- per spec, the bus can source up to only 100 mA before a device is enumerated, at which time the device may sink whatever current it tells the host during enumeration (up to 500 mA). If you blithely ignore that detail and just try to pull whatever your device needs immediately on power-up, you'll bump up against the current limit pretty quickly. Your device will keep resetting itself, or the host will throw a message saying "current limit exceeded." Of course, some USB hosts (in cheap products) don't correctly implement the power switching so your device will work on some computers but not on others.

Anyways, there's a solution to the power issue but it costs a couple of bucks in parts and your USB interface micro needs to know when enumeration completes and be able to twiddle an output pin to control a power switch.

-a

Andy Peters said:

Having done a USB audio device with phantom power, I'm not quite sure what their issue is.

Click to expand...

Are you allowed to share this with us?