It's an unfortunate situation to be sure. It's a small market, and AP seems to have cornered it.
What really blows for me is the limited number of options between the QA401 and the APx515. I have no problem spending more than the QA401 costs, but I'm also not in a position to spend $12k on an analyzer. There are lots of good used analog analyzers, as was mentioned, but they're just a THD+N analyzer- no FFT.
The lack of options that satisfy my needs led me to start working on my own solution, as documented in this thread:
Measurement Interface for Sound Card
I got it working sometime in December of 2020, but since that time I've been extremely busy with work and haven't had the time or motivation to finish it. There's some more programming work to be done yet, plus putting it all in a box and doing the needed calibration.
What really blows for me is the limited number of options between the QA401 and the APx515. I have no problem spending more than the QA401 costs, but I'm also not in a position to spend $12k on an analyzer. There are lots of good used analog analyzers, as was mentioned, but they're just a THD+N analyzer- no FFT.
The lack of options that satisfy my needs led me to start working on my own solution, as documented in this thread:
Measurement Interface for Sound Card
I got it working sometime in December of 2020, but since that time I've been extremely busy with work and haven't had the time or motivation to finish it. There's some more programming work to be done yet, plus putting it all in a box and doing the needed calibration.
I am not sure which analyzers you know, but pretty much all do FFT. As mentioned, FFT is a software function, not hardware.
For instance, in de AP series you have either an analog system, meaning analog generator(s) and analog analyzer(s), or the dual-domain version. The dual domain version adds digital inputs and outputs so you can directly test DACs and ADCs.
But the analog i/o version does FFT happily just like the dual domain, because FFT is software operating on the signal samples that are read into the system. Even analog inputs are eventually internally converted to digital by an ADC.
So if you are not planning to use digital i/o directly on ADCs and DACs, an analog-only machine will be fine for FFT and a lot cheaper, some at the same price as you would have paid for an AverLab system.
Going the sound card way, all the software packages that run soundcards - ARTA, TrueRTA, Audiotester, REW - all do spectacular FFTs.
Jan
For instance, in de AP series you have either an analog system, meaning analog generator(s) and analog analyzer(s), or the dual-domain version. The dual domain version adds digital inputs and outputs so you can directly test DACs and ADCs.
But the analog i/o version does FFT happily just like the dual domain, because FFT is software operating on the signal samples that are read into the system. Even analog inputs are eventually internally converted to digital by an ADC.
So if you are not planning to use digital i/o directly on ADCs and DACs, an analog-only machine will be fine for FFT and a lot cheaper, some at the same price as you would have paid for an AverLab system.
Going the sound card way, all the software packages that run soundcards - ARTA, TrueRTA, Audiotester, REW - all do spectacular FFTs.
Jan
By a lack of FFTs I'm referring to the HP8903s, Boonton, Shibasoku, Panasonic, Neutrik, etc. I'm not including the older APs or R&S units in that.
I got a good deal on a Lynx L22 a few months back, and I figure that, ARTA, plus a decent front end and it should be an acceptable measurement system.
I got a good deal on a Lynx L22 a few months back, and I figure that, ARTA, plus a decent front end and it should be an acceptable measurement system.
Hi Jan
I was using a Creative Professional E-MU 0404 external sound device for a while but none of the tests I was doing was automated in any way. Also I did a J-test jitter test on it using the dScope and found it was very average compared to the built in dScope DAC. I like the dScope III because it operates like an all in one toolbox. It may not dig as deep as an APx555 when it comes to THD+N but what you lose out there you gain with the other features. Of course this depends on what model you have too as just like the AP you pay more for more features. All in all I wouldn't be without one now
Also Prism is also now offering a suite of loudspeaker tests just like the AP software.
cheers
david
I was using a Creative Professional E-MU 0404 external sound device for a while but none of the tests I was doing was automated in any way. Also I did a J-test jitter test on it using the dScope and found it was very average compared to the built in dScope DAC. I like the dScope III because it operates like an all in one toolbox. It may not dig as deep as an APx555 when it comes to THD+N but what you lose out there you gain with the other features. Of course this depends on what model you have too as just like the AP you pay more for more features. All in all I wouldn't be without one now
Also Prism is also now offering a suite of loudspeaker tests just like the AP software.cheers
david
Hi Jan
I just happened to be in the right place at the right time and snagged a dScope III at a really good price. I think their price may have risen quite a bit in line with AP's price rises. However they have the lower cost M1 series which leverages a lot on sound cards.
Spectral Measurement dScope M1 (analogue and digital audio test system) - YouTube
Like any bit of test equipment it's not uncommon to have many pieces of gear each having its strength and weaknesses.
cheers
I just happened to be in the right place at the right time and snagged a dScope III at a really good price. I think their price may have risen quite a bit in line with AP's price rises. However they have the lower cost M1 series which leverages a lot on sound cards.
Spectral Measurement dScope M1 (analogue and digital audio test system) - YouTube
Like any bit of test equipment it's not uncommon to have many pieces of gear each having its strength and weaknesses.
cheers
Ironically, I was wondering what it'd be like to put a new A-D on the front end of the Dscope, with your auto-ranger. Something with the same A-D performance of the RME will give a noise floor of around 4dB lower. My gripes with the DScope are input noise (and the fact that L/R do not measure exactly the same THD+N, which I have observed on multiple DScopes, as well as the newer model), and refresh rate (our UPV enables us to screen components much faster than the DScope, simply by virtue of screen refresh rate).
For obvious reasons, I've been working from home a lot. I took a DScope with me, but having become used to the quieter noise floor of the UPV, I had to get a UPV sent over here in a cab after less than an hour. Once you get used to the cleaner noise floor, it feels weird going back. And the UPV gives symmetrical L/R readings. But it does look as if the UPV is destined to be discontinued... So UPV ownership is not a bed of roses!
I was able to improve the noise floor of the input side of the dScope III by about 3dB just by upgrading the opamps from NE5532 to LME49720 on the ADC board since they are installed in sockets. Here's the result dScope III Performance Upgrade
Unfortunately to upgrade the ADC is not such an easy job
Unfortunately to upgrade the ADC is not such an easy job
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Thank you for that information, much appreciated. I shall try it out and let you know how I get on!
If you look inside the UPV, you'll see that every facet of its design shouts 'EMC' at you. There are shields and flange folds all over the place, each with specific contact points. When I look at the DScope (I haven't had the lid of our one yet) in the photos I've seen, it looks to be designed more like a conventional piece of audio than a test instrument. TBH, I'm amazed that it gets the performance that it does! I wonder if the performance would improve further, were you to fit it into a larger case, with more internal shielding.
If you look inside the UPV, you'll see that every facet of its design shouts 'EMC' at you. There are shields and flange folds all over the place, each with specific contact points. When I look at the DScope (I haven't had the lid of our one yet) in the photos I've seen, it looks to be designed more like a conventional piece of audio than a test instrument. TBH, I'm amazed that it gets the performance that it does! I wonder if the performance would improve further, were you to fit it into a larger case, with more internal shielding.
I was using a Creative Professional E-MU 0404 external sound device for a while but none of the tests I was doing was automated in any way. Also I did a J-test jitter test on it using the dScope and found it was very average compared to the built in dScope DAC. I like the dScope III because it operates like an all in one toolbox. It may not dig as deep as an APx555 when it comes to THD+N but what you lose out there you gain with the other features. Of course this depends on what model you have too as just like the AP you pay more for more features. All in all I wouldn't be without one now
david
Real expensive point on AP555B is the tracking notch since SYS-1. For the dScope I do not read any about tracking notch.
Keep in mind that even AP555B uses the AK5394a ADC. With additional input HW (as discrete OPAMP) to deal with 180dB will not be cheap.
So HW to come who deals with tracking not, otherwise build simple fixed freq. notches what is not that simple in terms of noise or self oscillations.
Even the AP SW & HW deals with limited FFT size and may simple mouse dranging is may unknown, see just the fs/2 plots where the beef (jitter / PN) is below 10Hz to draw. Even DSD is for Godfather unknow...
All work is not free even the SW & HW gear... means ROI
Just my 2 cents
Hp
The two channels of my AP 2722 also have slightly different (1-2dB) THD performance.
Jan
Real expensive point on AP555B is the tracking notch since SYS-1. For the dScope I do not read any about tracking notch.
Keep in mind that even AP555B uses the AK5394a ADC. With additional input HW (as discrete OPAMP) to deal with 180dB will not be cheap.
So HW to come who deals with tracking not, otherwise build simple fixed freq. notches what is not that simple in terms of noise or self oscillations.
Even the AP SW & HW deals with limited FFT size and may simple mouse dranging is may unknown, see just the fs/2 plots where the beef (jitter / PN) is below 10Hz to draw. Even DSD is for Godfather unknow...
All work is not free even the SW & HW gear... means ROI
Just my 2 cents
Hp
The APx555 uses two ADC's
Amir Buys a New Audio Precision Analyzer (APx555)!!! | Audio Science Review (ASR) Forum
I found this with the dScope too when you approach its lower limits !! The same with any DUT as well
cheers
The APx555 uses two ADC's
It is a clever way to be able to display the full dynamic range of the signal, and at the same time lower the distortion measuring ADC dynamic range requirement.
Before this, if you looked at the distortion spectrum, you saw the spectrum with the fundamental notched out, literally. With this dual path they can later add in the fundamental so you get these displays that show a fundamental at 0dB and distortion at -150dB.
Jan
The AP solution is really useful for tunable notch filters. It eliminates having to do manual calibration for the notch frequency. Great approach. To me, AP certainly is at the very leading edge of audio test gear.
But, if you're OK with fixed notch filter frequencies, there are software approaches to working around the notch level display of the fundamental.
Notch Filters – QuantAsylum
The obvious trade-off is flexibility versus cost. Ain't that always the case? I think a new high performance AP system costs about the same as a new BMW around here. (To be fair, a BMW toward the bottom of their range, not the higher priced offerings.) As with the car, it's a question of what your budget is and your priorities. And, if you use it for a business, there's other considerations, too.
But, if you're OK with fixed notch filter frequencies, there are software approaches to working around the notch level display of the fundamental.
Notch Filters – QuantAsylum
The obvious trade-off is flexibility versus cost. Ain't that always the case? I think a new high performance AP system costs about the same as a new BMW around here. (To be fair, a BMW toward the bottom of their range, not the higher priced offerings.) As with the car, it's a question of what your budget is and your priorities. And, if you use it for a business, there's other considerations, too.
I do not know the AP details but why can't you tune the notch filter precisely, measure its transfer automatically, and calibrate the DUT measurement with the notch transfer characteristics? Using two ADCs along with band passing the fundamental in digital domain is a better solution, no doubt, especially when the analyzer has several channels, i.e. already has multiple ADCs.
I just think the stream from the direct/band-passed path must be properly time-aligned with the sampled data from the notch-filtered path, likely involving sub-sample resampling for precise time shift.
I just think the stream from the direct/band-passed path must be properly time-aligned with the sampled data from the notch-filtered path, likely involving sub-sample resampling for precise time shift.
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