Looking for a modern audio spectrum analyzer that won't break the bank

No trobbins, I think this unit is either defective or just plain rubish.
I changed channel, swapped the RCA to BNC cable, set the USB device in DVD quality 48K and same results.
There is no setup involved as the out of the Behringer is going straight to the scope.
I noticed if I increase the voltage out, the signal gets a bit cleaner.

Nevertheless I think this is a bad solution and well, I got what I paid for.

Zoomed is Sin trace:
20190918_131541.jpg

Zoom in 1K square
20190918_131555.jpg

Square at higher voltage
20190918_132202.jpg
 
I have been spending more time with the Pico gear and I have to say, that thing is surprisingly good.
I understand the 8 bits limitation, etc...

But used on a real case, with a classic configuration AWG -> AMP Input A -> Load resistor Input B, I was able to measure pretty much all what I need, adjust the feedback and plotting on the fly, measuring the THD at various frequency and power, all kind of nice things.
The Pico software is easy to work with, like everything it takes some time to adjust.

So IMO, a cheap PICO solution is workable, no doubt.

pico2.jpg
 
Thanks for the updates Brice.

My opinions are still forming about which solution I want to pursue. I’ve read through the entire manual on the QuantAsylum and I like what I see. I was wrong before when I said it had a limit of +/- 6 volts. That’s the DC offset limit but the AC limit is 28 volts peak, which is about 50 watts into an 8 ohm load. You can use it to test amps with greater than 50 watts output but you need to fabricate a voltage divider on the input to the box. This requires just a bit of skill to know how many dB attenuation you’ve added through the voltage divider, but then you can offset for it in the software by specifying the attenuation level you added. The software adds back in that much boost so that the graphs and data are displayed accurately. Of course noise is added when you do that. It’s 24 bits resolution which is nice. Only works with windows 10 though. One apparent omission in QuantAsylum’s software is there is no Bode plot. It does frequency response but not phase. You can write a plugin (a .dll) to do it using Microsoft’s .NET tools (such as C++ or C#).

The impression I get is QuantAsylum is not quite as sophisticated a company as Pico technologies. Probably haven’t been around as long. Pico’s software basically does everything and has a large community following. Their scope management software runs on all scopes from the least to most expensive models and on all major OS platforms (Windows, Mac, and I think Linux too).

I’m a little apprehensive still about a sound card solution because I think I will quickly want more resolution than they typically offer, and the solution is somewhat cobbled together.

Anyway still mulling it over.
 
Brice said:
I finally got the Behringer UCA202 and installed the TrueRTA software, which was effortless.

I first started to measure the distortion of a simple 1Khz sin signal, but plugging directly the signal into my Tek AA501.
THD: 4.6%. !! ? ??

So I looked as the signal straight into my scope and indeed the trace was not clean.

Then I generated a 1K square signal and here is what I got:

View attachment 1620850

So I stopped right there. That USB device is worse than I expected it, even if it is cheap.

Total waste of time and $.

To avoid at all cost :)
Click to expand...

Looks like a good square wave from source limited to 24kHz. Ringing at fronts is a result of using reconstruction filter with sharp cut off. If you want to see REALLY good square wave, find audio interface which can do sample rate of 384kHz or higher. Even then some ringing will still be present. That is why professional ARB generators have sampling frequencies measured in hundreds of MHz to give you square wave up to few MHz.

In audio measurements square wave is rarely needed. That is why sound card with sampling rate of 192kHz is sufficient to do most measurements below 50kHz. And they have low noise and distortion in that range. If you need to see response to square wave, get ARB generator and oscilloscope. But you will be limited to 8-12 bits of resolution.
 
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It's really too bad that the Pico 4262 has a limitation of 1V for its AWG. That's a bummer. Price is also high.

One thing I was thinking, we discarded the Digilent because in this video, some crosstalk was detected by the spectrum analyzer.
But that was with the version 1 of this product. The new version may not have this problem.

Do we have someone here with a newer version and check if the crosstalk is still there?

Because for price/capabilities, it's a clear winner IMO.
 
Brice said:
It's really too bad that the Pico 4262 has a limitation of 1V for its AWG. That's a bummer. Price is also high.

One thing I was thinking, we discarded the Digilent because in this video, some crosstalk was detected by the spectrum analyzer.
But that was with the version 1 of this product. The new version may not have this problem.

Do we have someone here with a newer version and check if the crosstalk is still there?

Because for price/capabilities, it's a clear winner IMO.
Click to expand...

Actually it says in the specs document:

"Improved signal/noise and crosstalk performances for both the scope and waveform generator."

So that changes everything to me.
 
It’s down to the Pico 4262 and the QuantAsylum for me. I won’t have money to throw at it for a while though.
 
Hello all,
Thought I would ping this thread and see if you have made equipment choices since Sept or if anyone has found something new and improved. I have the entire kit of parts for Pete Millett's interface but haven't assembled it yet.
Thanks,
John
 
I've settled on the QuantAsylum only because I recently got an awesome deal on a Rigol digital scope that I absolutely love. But otherwise I would have purchased the PicoScope and killed two birds (scope, spectrum analyzer) with one stone. I can't believe I've lived without a digital scope for all these years, although the Tek and Instek analog scopes I have are very nice for what they do. So now it's just a matter of saving up some pennies for the QuantAsylum.
 
That's interesting kward.
I've been using the cheapest Pico and quite like it for freq response plot with a laptop.

For the scope, I am still using my Tektronix analog scope and I am not really thrilled with the Pico digital one.

For the THD I am still using my Tek gear which most of the case agrees with the Pico.

Now I've been asking myself about digital scope, to save bench real estate.
 
trobbins said:
KentTeffeteller, can you point to an AudioScience product that you consider accurate and transparent (are you talking about the casing or some characteristic of the specifications or your perception of the sound)? I didn't find navigating the AudioScience website very easy to allow assessment of products. I did notice that yes the PC embedded soundcards would need additional divider circuitry to allow the assessment of speaker output signals, and a quality analog interface circuit if a high impedance probe was needed.
Click to expand...

ASI 5810 is a good product for a desktop PC, aimed at broadcast production use. And a good, transparent, clean audio card for this application.
 
Hey everyone. With cyber-Monday tomorrow... any developments in the past couple of years?
I'll admit I didn't read every post in this thread... would something like this get my foot in the door to using my laptop in my car to test and compare some new speakers?

https://www.amazon.com/M-Audio-M-Tr...ocphy=9003511&hvtargid=pla-1147112908967&th=1

Have the mobile apps made any leaps and bounds? I tried a free one and it seemed kind of useless for getting any precise readings.
 
While I would not replace my old analog Tektronics with this gear, I really love the Analog Discovery 2 with the Audio Analyzer suite freeware.

It's so easy to use and gives a very solid report of what you can expect to hear from an audio amplifier. It's also clearly shown to me how really bad some of the made in China audio gear is, that for some unknown reason still get rave reviews from online influencers. I'm still baffled about why amps like the Reisong brand ones are lifted up by these folks, they sound horrible!

 
Still haven’t pulled the trigger on the QuantAsylum. Would like to, but life has become a lot busier recently and I haven’t had time to pull out the soldering iron for a while now.

@StepheK I've been eyeballing an Analog Discovery setup anyway, for "quick and dirty" type measurements, since they are so inexpensive (relatively speaking to the QuantAsylum)
 
kward,
They aren't so different in price at this point but I don't think the QA403 is available due to chip shortages. The QA403 is listed at $549 and AD2 at $399.

The PicoScope 2206B is $419, so in the same ballpark. This is what I have. They each have differences from the other. I wish the PicoScope had some of the software features of the others.
 
Hmm. Still in the chip shortage. Bummer. I haven’t been following the aftermath of Covid so I’m out of touch.
 
A restored boatanchor, the HP 339A and using the monitoring output into a PicoScope 2204A worked for me.

I've since sold the HP339A and have got a Focusrite Scarlett Solo that I intended to use with REW. But health has intervened so that has been shelved for time being. Picoscope 2204A is barely adequate for tube amplifiers. It can be changed to artificially higher resolution with a form of oversampling but for looking at a pure signal (sinus, triangle, square wave) you loose resolution. Not impressed with the AWG output, it has some crossover distortion at low signal levels but who knows, perhaps it is faulty.
 
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StepheK said:
....
It's also clearly shown to me how really bad some of the made in China audio gear is, that for some unknown reason still get rave reviews from online influencers. I'm still baffled about why amps like the Reisong brand ones are lifted up by these folks, they sound horrible!
....
Click to expand...

^^^ This

And not only the Chinese gear.

Not to forget the quality of the build, where e.g. power tubes have sockets on a PCB and the heat eventually causes for PCB issues as a result of the repeated changes of tubes by the "tube rollers". It has all been a race to the bottom of who can make the cheapest most powerfull amplifier without long life and/or failure prevention taken into consideration.
 
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