New Audio Analyzer from Prism Sound (M1)

[orchardaudio]

I will be selling my old Audio Precision analyzer soon so that is another option. It nearly matches my new analyzer in performance. It just doesn't support USB audio output.

Send me a PM, I might be interested.

 

[SIY]

I have tried half a dozen software packages to measure things using sound cards but none of them are a painless solution. Many don't have "closed loop" control where they can alter a parameter and measure for example. So graphs like IMD versus Level, etc. would not be doable. They also don't have high-voltage inputs so you can't measure anything with power output. Even a headphone amp many damage the input of the ADC.

STEPS, which is included with ARTA, allows the generation of plots like THD or IMD vs level. Use a signal conditioner like Pete Millet’s soundcard interface or Jan Didden’s Autoranger and your soundcard is safe and you can measure higher voltages and powers.

 

[sergeauckland]

STEPS, which is included with ARTA, allows the generation of plots like THD or IMD vs level. Use a signal conditioner like Pete Millet’s soundcard interface or Jan Didden’s Autoranger and your soundcard is safe and you can measure higher voltages and powers.

I've made an external box with four 4ohm dummy loads so I can configure 1-16ohms mono or two lots of 2-8 ohms for stereo. These go through a pair of 10ks pot out to the sound card with parallel connections for 'scope and voltmeter. The sound card has metering for dBFS, so I can measure any sensible power amp output, limited only to the power handling of the dummy loads. The sound card provides balanced and unbalanced outputs of up to 6v, (+18dBu) so sufficient to load fully just about any power amp.

If I were really clumsy with a very high power amp, then theoretically I could damage the sound card input, but with only 200 or so watts of dummy load capacity, I'm limited in the size of power amplifiers I can fully test, so the situation hasn't arisen. For small signal kit, then there's no problem.

S

 

[Sythrix]

On analyzers below $1K, I think quantum asylum is the only unit there.

What's your professional opinion on this unit? The QA401? I went and looked at it. I want something for personal use and evaluation, mostly to test DIY products. Is this a viable option, or is it too limited?

Also, it says it doesn't include any accessories. Are there any kind of cable kits that are for sale that would work with the analyzer (Not the USB cable, I have that)?

 

[amirm]

What's your professional opinion on this unit? The QA401? I went and looked at it. I want something for personal use and evaluation, mostly to test DIY products. Is this a viable option, or is it too limited?

Also, it says it doesn't include any accessories. Are there any kind of cable kits that are for sale that would work with the analyzer (Not the USB cable, I have that)?

I have not used it. Member @March Audio had one but sold it. Maybe he can comment more.

 

[Sythrix]

I have not used it. Member @March Audio had one but sold it. Maybe he can comment more.

Thank you

@March Audio , same question when you get a few moments.

 

[March Audio]

Unfortunately I can't recommend it. It has a problem with noise floor modulation. Basically, although the unit has a low noise floor with small signals, around -160dBV with a 132k fft, it rises with increasing signal level to around -126dBV with large signals.

Second issue is the software is extremely limited in capability. You are better off with a good sound card, professional audio interfaces can work well. I often use my Motu 8a. Member @Blumlein 88 gets good numbers out of his interfaces, but you will need to check with him what they are. For software Virtins Multi Instrument is very capable.

Hope that helps

 

[March Audio]

Oh I forgot, another great option is the Texas instruments pcm4222evm. Its an evaluation board for their pcm4222 ADC chip. Balanced input and spdif output.

It's performance is brilliant and only $150.

http://www.ti.com/tool/PCM4222EVM

http://www.ti.com/product/pcm4222

With signals below -18dBFS it achieves thd+noise of -120dB.


All you need is a spdif to USB converter and PSU.

https://www.minidsp.com/products/usb-audio-interface/ministreamer

 

[Blumlein 88]

Unfortunately I can't recommend it. It has a problem with noise floor modulation. Basically, although the unit has a very low noise floor with small signals, around -160dBV, it rises with increasing signal level to around -126dBV with large signals.

Second issue is the software is extremely limited in capability. You are better off with a good sound card, professional audio interfaces can work well. I often use my Motu 8a. Member @blumlein88 gets good numbers out of his cards, but you will need to check with him what they are. For software Virtins Multi Instrument is very capable.

Hope that helps

I've been using a Focusrite Forte interface which is discontinued. The current Clarett line is based upon the same circuitry with different features and more channels. I also use an Antelope Audio Zen Tour.

 

[maverickronin]

Oh I forgot, another great option is the Texas instruments pcm4222evm. Its an evaluation board for their pcm4222 ADC chip. Balanced input and spdif output.

It's performance is brilliant and only $150.

http://www.ti.com/tool/PCM4222EVM

http://www.ti.com/product/pcm4222

With signals below -18dBFS it achieves thd+noise of -120dB.

That looks pretty awesome. I'm looking for a standalone ADC and this would fit the bill.

Besides the power supplies, how difficult is the implementation?

 

[March Audio]

You have to make the correct jumper selections on the board for various settings, but nothing beyond the wit of man. Just bear in mind it is a fixed gain input, about 4.2 v RMS FS. Don't know if that's an issue in your application.

 

[maverickronin]

You have to make the correct jumper selections on the board for various settings, but nothing beyond their of man.

That's cool. If everything is documented in the TI user guide I should be able to figure it out then.

Just bear in mind it is a fixed gain input, about 4.2 v RMS FS. Don't know if that's an issue in your application.

That should probably be ok. Shouldn't clip with most line level sources but FS isn't so high that weak stuff will be too lost in the noise.

I want an analog input on my ADI-2 DAC but don't want to spend an extra $1K for the Pro. A standalone analog in, S/PDIF out board looks great for that.

 

[Sythrix]

Thanks for all the info an suggestions. Looks like quite a bit to think about. I don't have extravagant needs. Just want something that can evaluate DIY projects (amps, DACs) I put together. I'm not a designer or anything.

 

[Sythrix]

Just bear in mind it is a fixed gain input, about 4.2 v RMS FS

Sorry for being ignorant, but could you explain what this means with respect to testing DACs and headphone amps?

 

[March Audio]

Sorry for being ignorant, but could you explain what this means with respect to testing DACs and headphone amps?

No problem, questions are good, we like to help . Its simply that the input voltage is fixed. It can accept a maximum of 4.2 v RMS. So if your device outputs a higher voltage the ADC will overload and distort. If your device outputs a lower voltage you will not maximise the SNR of the measurement.

However in the second case it should be noted that, as with most AdCs, it's own distortion starts increasing from about -18dBFS so I wouldn't worry about it too much. Most DACs will be about 2 V RMS.

 

[andreasmaaan]

However in the second case it should be noted that, as with most AdCs, it's own distortion starts increasing from about -18dBFS so I wouldn't worry about it too much. Most DACs will be about 2 V RMS.

And -18dBfs for this ADC is just over 0.5 V RMS.

So in other words, if the device you're measuring outputs anything between just over 0.5 V RMS and just under 4.2 V RMS, this ADC will be operating in its optimum range for measurement.

 

[RayDunzl]

with most AdCs it's own distortion starts increasing from about -18dBFS

Hmmm...

That is probably true with my Behringer UMC202HD, but haven't played with it lately.


It did make me want to check my UMIK-1 (condenser capsule -> internal ADC -> USB -> REW), which I do use often.

Test:

Microphone an inch or so in front of a 25 year old Sony SRS-150 on my desk.

Varying the level in the Microphone Properties in Windows, keeping the speaker volume constant;

---

Windows Level = 0.001 -30.8dB, and -57dBfs. 0.38% THD

For whatever reason the high frequencies come out like this:

Windows level 0.750 +7.3dB, -20dBfs. 0.38% THD again

Now the high frequencies are registering. The 8~12kHz range is just idle noise from the speaker. It goes away when the speaker "times out" - they wake up with signal.

And Windows Level 1.0 (Maximum) +24dB, showing -2dBfs on the monitor now, THD still the same at 0.37%

Conclusion:

Looks like no reported distortion differences present changing the Windows volume level when using the UMIK-1 for in-room speaker measurements with a useful SPL.

Caveat: I suppose this isn't really looking at the higher voltage levels the capsule might present to the UMIK-1 internal ADC at higher SPL, just manipulation of the digits sent toward the PC.

 

[maverickronin]

Spare parts power supply for the PCM4222EVM is pretty much done. Just need to find a box to put it in.

 

[sergeauckland]

That looks pretty awesome. I'm looking for a standalone ADC and this would fit the bill.

Besides the power supplies, how difficult is the implementation?

Some 20 years ago, I bought a pair of Meridian DSP5000 active loudspeakers that only had digital inputs, so needed an ADC for my analogue sources. I bought a Crystal Semiconductors CS5534/5 evaluation board, put it in a box with a power supply, and that was it. A 20 bit ADC with XLR analogue inputs and both optical and coax S/PDIF outputs. At the time the cost was trivial compared with buying a manufactured ADC, the only limitation was a sample rate of 44.1 or 48k, but that was fine as my DSP5000s didn't do more than 48k. It still works fine, although its performance can now be matched or exceeded by a $100 USB interface.

S.

 

[maverickronin]

Some 20 years ago, I bought a pair of Meridian DSP5000 active loudspeakers that only had digital inputs, so needed an ADC for my analogue sources. I bought a Crystal Semiconductors CS5534/5 evaluation board, put it in a box with a power supply, and that was it. A 20 bit ADC with XLR analogue inputs and both optical and coax S/PDIF outputs. At the time the cost was trivial compared with buying a manufactured ADC, the only limitation was a sample rate of 44.1 or 48k, but that was fine as my DSP5000s didn't do more than 48k. It still works fine, although its performance can now be matched or exceeded by a $100 USB interface.

S.

That's exactly the kind of "old-fashioned" ADC I need. There some USB interfaces with coax or TOSLINK out but they all look to be controlled by software on a host computer. I need something completely standalone.