Best soundcard for low noise THD measurement?

Saw the recent announcement for the APx500 Flex. This basically is the AP software, but without the $30k dongle. Instead, you bring your own sound card.

I was just thinking, if I could find a sound card with AP performance, I could get a top of the line AP system for 10% of the cost.

Any sound cards you know that could fit the bill, performance-wise?

Jan
 
I doubt that there is anything available in the mainstream soundcard market. The commercial implementation of good chips like AK5394A from Creative and preferably Lynx have long stopped production and the ones that could somehow compete with AP, ESS AD chips, where withdrawed far too quick (a handful of recording devices are still advertised) . To my knowledge computer or recording oriented soundcards are out of the game for such a performance
That only leaves measurement oriented implementations not that cheap. But then again, I don't think that AP had cost effective solutions (something let's say below 1k$) in mind when they designed APx500 Flex. It is very interesting for those could afford it
 
:) certainly nothing like this on any soundcard:

Low-distortion transformer-coupled circuit

That is used often these days. There's also an app note on the Lundahl website. The idea is that you provide positive feedback equal to the primary wire resistance. If you do that right, that resistance is cancelled and the xformer becomes distortionless.

Jan
 
That's a very good choice, I've proposed this to a friend of mine for recording purposes. It measures very good and doesn't cost an arm or a leg.

Really? I don't find those measurements particularly hot. Good, but not excellent. I would like at least 20dB better. Minimum. Maybe a Lynx?
How does the RTX do for THD?

Jan
 

dreamth

Member
2010-11-18 9:12 am

dreamth

Member
2010-11-18 9:12 am
Really? I don't find those measurements particularly hot. Good, but not excellent. I would like at least 20dB better. Minimum. Maybe a Lynx?
How does the RTX do for THD?

Jan
An AP or similar meter is a package that offers all you need to make valuable measurements, it's not just a signal generator and a line input...I know you might not need all the things an AP does for any application, but your post made me remember the fact that some time ago i went to a headphones manufacturer who was measuring its 32 ohms mangeplanar headphones by driving them from a Babyface pro soundcard with its maximum 70mw of output at 0.1% thd and 2 ohms Z out ...
Apart from the frequency plot which was very uncertain anyway over 10khz i wouldn't consider anything worth looking at, yet that simple setup was good enough to evaluate almost all the headphones on the market.
 
Saw the recent announcement for the APx500 Flex. This basically is the AP software, but without the $30k dongle. Instead, you bring your own sound card.

I was just thinking, if I could find a sound card with AP performance, I could get a top of the line AP system for 10% of the cost.

Any sound cards you know that could fit the bill, performance-wise?

Jan

$6000+ for a piece of software, this is IMO ridiculous. I don't see anything that the next piece of free (or almost free) piece of software cannot do. This looks like a sales pitch for those engineers that don't want (or cannot, due to commercial/contractual reasons) to step outside the AP ecosystem.

I'm not a sound card measurements fan, but I got a Focusrite Scarlett 2i2 3rd generation for about 150 of your euros and, combined for example with ARTA, I don't think anybody will ever need more than that.
 
Well I do have an AP2722 which until a year ago was the lowest measuring device on the planet. With the APx555B they got another 7dB lower, but a basic 555B sets you back $ 30k.

An APx500 FLEX is 10% of that, plus the soundcard.

Jan

The software has nothing to do with the performance. It only controls the hardware and renders the results.

I can post some Focusrite loopback results, if memory serves it's around 2ppm THD.

I normally use a second hand Rohde UPD which I got a few years ago for slightly over $1000 (was a good deal). With some TLC (including replacing the hard drive with a SSD) shows -130dB THD and -118dB THD+N @1KHz. Even a modern second hand Rohde UPV can be had (if you watch the market) for less than the cost of this software.
 

dreamth

Member
2010-11-18 9:12 am
It's all business and marketing...
Nothing more than -90 db thd +N, TID or SNR is really needed and that is for absolute ear sensitivity.I feel like i'm going to take another 6 months break from this forum if i hear again all sots of bla bla's on this subject, fantastic people that can hear -117 db SNR into tape noise etc...
They measure dacs and amps on resistive loads or ideal signal source while the real world meet a brick wall made out of minimum 0.1 thd given by the best speakers and much higher nonlinear distortions.I don't see high end manufacturers presenting their amps measured on a real speaker of the same kind...they all pretend that their amps deserve extraterrestrial speakers to be evaluated...Really?
 
I still have a 1st generation, which is good as soundcards go, but no match for my 2722.

You are correct, a sound card (probably not even a Lynx) won't beat a 2722 at least because the 2722 is a true instrument, not a piece of harware hanging on a PC PCI Express or USB interface.

But then the question is, what do you really need? Something you can use without any hassles on a daily basis and will cover 99.99% of measurement needs, or the bragging rights for owing the best audio measurement system on the planet?

If the latter, then buying the AP software will never be enough. I don't think you'll find any sound card/hardware that will ever match the AP or Rohde peformance.

For other reasons (namely curiosity that kills my wallet), I will get an (now available) AKD4499 A/D demo board. That could be another option beyond a "sound card" if the performance matches the expectations for a measurement tool (which I somehow doubt, but I'll find out soon enough).
 
Really? I don't find those measurements particularly hot. Good, but not excellent. I would like at least 20dB better. Minimum. Maybe a Lynx?
How does the RTX do for THD?

Jan

Both RTX and Benchmark are using AK5394A but RTX has little better specs, comes down to implementation. IIRC RTX has better THD than Lynx L22 too. Haven't seen any RTX measurements done by AP machines, we have to rely on website (0dBV 192 kHz -121 dB @ 1 kHz) or on the thread here

For good VFM solution I'd have chosen Benchmark for recording and RTX for measuring. Lynx is for the lower bugdet.

But I guess that's not in the same league with AP.
 

dreamth

Member
2010-11-18 9:12 am
Did someone mention hearing? I must of missed that. Seems just a technical challenge to me, why not, it all adds up?
It doesn't really add up to anything else but unjustified price for the built and measured equipment at the end...
If Devialet is selling amps that measure 0.0000000000000000000000000000000000000000000000000000000000000000000001% thd and sound like ....whatever...compared with much "lower performance" amps from Naim, I believe it's Magic, isn't it?