Is Someone Playing Fast & Loose With Measurements?

[Larry Ho]

Few simple facts here...

 

1. Dragonfly do have clipping in -0dBFS. John Atkinson also mentioned in his review. He needs to dial down a few clicks to get normal result.

 

IF there is a need to do a special favorable treatment to Dragonfly. I could do that, actually I did it in our first test. The THD+N is still around -70dB or so.

 

Or if I do that, Meridian and iFi will jump out say: Not Fair? ;-)

 

2. JTEST is only a simulation of the simplest way jitter by toggle LSB... The JTEST doesn't have the 32 bit version yet, at least to my knowledge so I decide to skip it. Also, there are many professions claim that test is not accurate.

 

3. As an US manufacturer, I won't have any special favor for an UK vendor. We did Explore, iDSD and Dragonfly at the same time.

Meridian Explorer is normal there... Machine won't discriminate.

 

4. We have the most advanced 1G bandwidth scope on hand. With the distortion I saw on Dragonfly's output wave, we really don't need the big gun scope there.... Again, even if Audio Precision is NOT good enough, and don't need to see Geek out's test result. Why iDSD is performing much better than Dragonfly? Do I need to favor iDSD? :-)

 

One friend from Google is sending me 3 more good DACs, including Herus, micro streamer and D3.

 

I'm gonna publish that with the original test results.

 

Don't worry. Truth is the daughter of the time.

 

Enjoy!

 

The DragonFly did clip when ran as designed if it was run in the top 3 steps of it's volume control. So ran at FS this could indeed be the case... I believe Gordon even said as much here at CA and then later there was a firmware update if I am not mistaken?

 

You can search for my reviews early on here at CA. The DragonFly sounded no better than the built-in audio in my Mac and went back to Crutchfield. I even tried Kimber interconnects. In the end it cost me a couple hundred bucks for a product that could not exceed the digital format of my Mac (24/96), or support USB 2.0, or DSD.

 

http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/audioquest-dragonfly-24-96-asynchronous-universal-serial-bus-industry-standard-cables-connectors-and-communications-protocols-between-computers-and-electronic-devices-digital-analogue-converter-headphone-amp-12353/index12.html#post184175

 

They were first-to-market but my experience with that product is that the SQ was extremely disappointing.

[Larry Ho]

Hi, Steve

 

Thanks for clear this out. Now we know why.

If possible, I will try to get the Dragonfly V1.2 and test again.

Is that public available now?

 

Larry

 

Hello Junker –

 

As you point out – the original (first production run) DragonFly did in fact clip when a 0db 24/96 signal was presented. Upon discovering this we took immediate steps to resolve the issue. It was only in the first production run (1.0) that the problem existed. the following production runs had a version 1.0c, which we used to identify amended DragonFly's (also measured by John Atkinson in Stereophile's review). Then in late November of last year we released the improved 1.2 version.

 

Regards,

 

Steve Silberman

AudioQuest

[email protected]

[Larry Ho]

Michael Lavorgna at Audiostream has posted on this. Some may find it helpful:

 

Are Measurements Subjective? | AudioStream

 

I already list our testing settings there... Including 90K bandwidth, 300R load and none-weighted there... You could check it out.

 

Of course a lot of media people will get Geek Out and test it. Actually a lot of them already bought it!

 

I'm waiting for their test results show up. Time will tell.

 

Under different testing settings will have different test results. And all the DACs are tested in the same condition, same machine, same cable by the same people during a short period of time. So instead of picking one absolution value, using JA's measuring value compared with mine, the relative values is more important.

 

For example, JA got 3.8% THD from Dragonfly. I got 5%... I would say both are right, because measuring difference between 90K Hz and 20KHz, loading from 100K (200K) to 300Ohm... all possible. And when analog IC got clipping, one could be 4%, one could be more, since that is not a ideal working condition. Using that 3.8% vs 5% as a prove of I'm intentionally against our competitor is a very weak argument.

 

And one thing I'm quite amazing: We publish that testing result inside our Geek Force forum. And we just hope our Geek Out backers knows how good their perk will be. Why suddenly it looks like this becomes a media focus? We didn't quote it here or in Audiostream...(I know Audioquest is a bigger company. Especially when I wrote this message, its big read banner is hanging on top of this forum.)

 

Time will tell....

 

Larry

[Larry Ho]

Thanks for your question.

 

We already published the digital to analog performance of Geek Pulse long time ago, that is USB input vs balanced analog output.

 

The new test there is related to its digital input interface (SPDIF and AES), because this is another important part of the system so we hope our backers know the current progress.

 

Audio digital interface is 'not' like your hard drive transmission, because that is REAL time and NO re-try... If you said this measurement is useless, then basically that means every SPDIF or AES interface performance is the same... which I think a lot of people not only me won't agree.

 

SPDIF and AES signal is based on NRZ protocol and they embedded the clock signal within the audio data. On receiver side, it needs to make sure the input signal as jitter-free as possible, so when we use PLL to recover the master clock from the data, it will have the best performance for the next stage, which is digital-to-analog stage.

 

I have been asked many times for the similar question in USB interface too. People ask since they use USB Hard drive or USB printer that never got a bit of error. Why bother with Asynchronous USB interface or buffer... this kind of stuff. The answer is the same: the real time transmission nature of digital music, and the SPDIF or USB Audio protocol design itself could not guarantee the bit perfect, 100% error free transmission. That is why people are investing their time and money here. :-)

 

 

 

 

Sorry, magnum innominandum, I don’t understand half of the technical stuff you were trying to say about their measurements…

 

[ATTACH=CONFIG]11581[/ATTACH]

 

 

 

Geek Pulse: A Digital Audio Awesomifier for Your Desktop | Indiegogo

 

Are you saying they were measuring the digital to digital transmission lost inside the Geek Pulse?

 

If there is a case, it should have no error at all, so a 24bit signal should be -144dB.

 

This is just like measuring whether there is any error in the 10MB file that I have just copied to my USB thumb drive from my PC, and then say “Everyone look, the copying went perfect without error, not bad at all!"

 

What is the point of this completely meaningless test? A couple cheapest computer sound cards can achieve that …

 

Come on, LH Labs couldn’t be doing this, they must be measuring something else which I don’t quite understanding yet, they are surely more professional than this.