Audio Precision alternative

[Sawdust123]

I'm a former AP employee and left to help launch a low-cost alternative (that failed). In a nutshell, nothing comes close to an AP in terms of feature breadth and technical specs. Of course, you may only a subset of the capabilities in which case there are many alternatives. For instance, an AP can handle 300 Vrms at the input. How often do you need that? If you need to test a high voltage load, you can always measure across a small sense resistor and convert your results. I wrote an article on this. https://audioxpress.com/article/practical-test-measurement-attenuators-for-measurement

There are plenty of other features aside from specs that separated AP from the pack. This includes their breadth of digital interfaces (I2S, PDM, HDMI, etc) and their automation software and some really specialized measurements not commonly used in consumer gear. Their dominance is so strong that Rhode & Schwarz exited the audio business. Prism (Spectral) is a shell of its former self and I think the only reason Stanford still sells the product is to clear inventory. I have a friend that reps the brand and he tells me the SR1 gets no interest.

People that don't need all the hardware specs of an AP can still benefit from their 50+ man-years of software development by using APx-Flex. This allows their software to be used with the hardware of your choice. Echo Test & Measurement sells boxes that are compatible with this.

 

[Rja4000]

People that don't need all the hardware specs of an AP can still benefit from their 50+ man-years of software development by using APx-Flex. This allows their software to be used with the hardware of your choice.

If only that was not crazy expensive !
For hobbyist like me, $8000 to get the required options is just insane.

Would they bundle the required options to run Amir's set of tests (with automation and a little flexibility around it) in a $1000 package and I'd probably buy it immediately.

 

[Sawdust123]

I didn't realize the pricing for APx-Flex was that high. A new APx-515 used to sell for less than $8K. I guess I should acquaint myself with Amir's tests. AP had some pricey software options and have introduced more since I left.

 

[jae]

Something like Motu M2/M4 in combination with the Cosmos could also do you quite well if you are willing to give up some spec to save 80% the cost...?

 

[tomelex]

I didn't realize the pricing for APx-Flex was that high. A new APx-515 used to sell for less than $8K. I guess I should acquaint myself with Amir's tests. AP had some pricey software options and have introduced more since I left.

I really enjoyed your tech article. Do you have some link to where someone would go who was designing audio gear and wanted to test it to current standards, for example I think consumer cd output level was 2 VRMS etc. Thanks

 

[Rja4000]

I wrote an article on this. https://audioxpress.com/article/practical-test-measurement-attenuators-for-measurement

Very interesting, indeed.
Thanks.
I'm also struggling to optimize noise performance of attenuator BEFORE DUT.
(To measure performance at a few mV , as an example)
My trials so far show I'd rather have a higher DAT output and a higher passive attenuation.

 

[Piere]

Sub ppm levels are no problem with common stuff these days. Ease of use is another thing. It all depends on what you want. IMHO the already mentioned https://quantasylum.com/ looks an affordable set up. Supported by useful software.

 

[al2002]

I use this one.

This grew out of a project and group buy on DIyaudio.com. Unobtanium, as is the Quantasylum 403.

 

[jhenderson0107]

This grew out of a project and group buy on DIyaudio.com. Unobtanium, as is the Quantasylum 403.

I believe the RTX6001 is still sold through Virtins. It's still listed on their price sheet.

 

[Piere]

IMHO concerning lowest distortion together with affordability, your best bet for the moment looks the E1D AD/DA combo combined with the Virtins pro suite. But I hate Virtins licence construction! You get a lifetime licence but moving to another PC/Laptop or even changing your HDD/SSD is a time consuming nightmare. Alternatively there is ARTA. You have to do a lot yourself, but that is part of the game and for hobby use not a big problem and part of the fun.

 

[restorer-john]

I wrote an article on this. https://audioxpress.com/article/practical-test-measurement-attenuators-for-measurement

Very useful article - thanks for sharing.

 

[al2002]

I believe the RTX6001 is still sold through Virtins. It's still listed on their price sheet

TTBOMK neither the designer nor Virtins had any actually for sale as of about a year ago due to the AKM factory fire and other supply chain issues.

 

[Sawdust123]

I really enjoyed your tech article. Do you have some link to where someone would go who was designing audio gear and wanted to test it to current standards, for example I think consumer cd output level was 2 VRMS etc. Thanks

There are many Standard Development Organizations (SDOs) out there. I was part of AES and CTA standard committees at different times. Each SDO has their own policy on standard distribution. Some are free for members, others charge a pretty penny (though usually under $100). The beauty is that there are so many to choose from. In one of my old talks, I show the spec page from a consumer amp. There were 6 sets of power ratings for the same amp, all to different standards and the results ranged from 95w to 240w. The FTC (Federal Trade Commission) method was the most stringent and thus had the lowest reported power. The defunct IHF standard showed the highest power (albeit at lower impedance).

I found that most consumer companies don't really care too much about following standards. There is almost no enforcement. In fact, 15 years ago, I had lunch with the fellow at the FTC that was responsible for the amp standard. He had said it had been more than 10 years since they handled a complaint about bogus power specs They know vendors lie but as long as the amps aren't blowing up, they don't really care. When the standards were written in the late 60s, amps were failing in spectacularly impressive ways (sparks, smoke, flames). These days amps self-protect pretty well and you may not be happy with the output level but at least you still have something that functions.

 

[Piere]

Did some measurements of what can be archived with an affordable "Poor man" measurement set up. Did some null measurements with the E1AD and Topping D30Pro balanced as a set, as well as the with the E1AD with the Topping E30 as a set. This was the old E30 with the original AKM chips and fed by a linear PSU. Software used was ARTA. ARTA has the disadvantage that it can only handle one ASIO interface at a time. And here we have two, one for the output and one for the input. So I used WDM which worked fine. Connection of the DA and AD to my laptop was by USB.


Topping D30Pro Balanced--> E1AD:

Topping E30 Cinch --> E1AD:

They do not differ much. Both sets perform below ppm level (-120dB). Looks E30 has slightly better jitter performance.

For what can be done with such a set-up I tested my LM3886 Composite Amplifier at 50 Watts into 8 ohms, which is on the edge of what could be measured with a PCI semi-pro soundcard 10 years ago (M-Audio Audiophile 192). I used the E30-E1AD combo for this.


LM3886 Composite Amplifier 50Watts into 8 ohms:

Here we see an other advantage of CA apart from virtually eliminating all cross-over distortion: A tremendous increase in PSRR. No sign of mains hum.

 

[Bonzoro]

I love my QA403.

Too bad they have no product to sell.

 

[Deschu]

Too bad they have no product to sell.

I’ll sell my QA401. The global IC shortage is a pain, not much they can do.

 

[sarumbear]

If only that was not crazy expensive !
For hobbyist like me, $8000 to get the required options is just insane.

Would they bundle the required options to run Amir's set of tests (with automation and a little flexibility around it) in a $1000 package and I'd probably buy it immediately.

Why not use the REW system then?

 

[Bonzoro]

I’ll sell my QA401. The global IC shortage is a pain, not much they can do.

Whats the diff between the 401 and 403?

 

[Rja4000]

Why not use the REW system then?

I use Virtins Multi Instrument, because it allows me to build my own layout and to automate measurements (IMD vs level, as an example)

I think this

Is easier to read than this

 

[Piere]

REW, ARTA, Virtins, all work well to my experience. It is more a matter of taste. And don't forget our own ASR development: Multitone It's free easy to understand and can do a lot more than only multitones. I wonder if there is still work in progress about it going on?