[ubs28]

Currently listening to the Chord Dave with the HD 800. Very impressive that the Chord Dave is able to deliver a big soundstage that the Chord Hugo can only do with high-end amplifiers like the Auralic Taurus MKII. An outstanding one in all solution for headphones so far based on my first impression.

I hope I will have some new USB B cables for the Chord Dave in the weekend. The performance will probably go up then.

 

[Arpiben]

Dave, in common with all electronics, is (very slightly) microphonic. You can hear this using the AP - set it up so the -128 dB background noise from Dave is a roar from the AP loudspeaker monitor (that would be about 120 dB of gain), then tap Dave's PCB and you can hear tiny clicks through the loudspeaker. On headphones you can't hear it with the Nighthawks but you can just hear it with Noble Kaiser K10 IEM. Note if this was a valve or tube DAC or pre-amp the clicks would have been extremely audible.

So using Dave with loudspeakers one can reasonably expect it would be (slightly) sensitive to vibration - after all I can hear the effects of noise shapers at -350 dB affecting depth, so this is way bigger than that. Also I experimented a lot in the 1980's with vibration control - my turntable was in an 1 inch thick oak double glazed (with half inch thick plate glass) enclosure, and this made a huge difference to turntable sound. My electronics were on stainless steel springs and Italian slate - so I know vibration is important. That is one reason why Dave is in a solid aluminium billet, so I can control vibration. Reducing vibration gives smoother sound, with better depth.

So I am not surprised about it being slightly sensitive with loudspeakers. But I admit I was very surprised to hear reports about it being sensitive with headphones - this I can't see making a difference. That said I have two favorite quotes relating to audio - "There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy." And somewhat more recently "You know nothing Jon Snow". So yesterday I puzzled over what may be a reason and thought of skirts. When a DAC or oscillator creates a sine wave, when you do an FFT you do not get a straight line indicating a pure tone - it will have skirts. Now these skirts are important subjectively - you hear them as a hardening of the SQ, so reducing the skirts and making an individual sine wave more pure and sharper on an FFT makes it sound smoother. And the ear/brain is very sensitive to this problem. Skirts are caused by low frequency jitter problems, and if you can measure a skirt it is audible. This is why I do not use fempto S clocks or atomic clocks; these have low cycle to cycle jitter, but lots of low frequency jitter, as these oscillators use PLL's - which have poor low frequency jitter performance. So using a fempto clocks measurably increases skirts, and sound much brighter - and its easy to confuse the brightness as more transparency. With Dave, I have no measurable skirts - at least I am at the residual level of skirts that you get with the windowing function of the FFT within the AP.

But the action of low frequency vibration may add more skirts, and so this is a potential mechanism for making very small changes to the SQ when you are just using headphones - but it would only have the effect of making it sound a little smoother with lower vibration levels.

I am in Moscow tomorrow, then Dusseldorf, Singapore, Shanghai, Tokyo and finally Ho Chi Min. When I finally get back I think it will be worth investigating, as I am intrigued.

Rob 

Very interesting point about wander effects in audio. Wander is the term used for low jitter frequency (f<10Hz).
There are different parameters for wander: MTIE/TDEV/...As per Rob comments, depending on time of observation,time deviation varies from ns to hundreds ns range even with atomic clocks.
Patiently awaiting Rob's return for more.
Rgds

 

[JaZZ]

Currently listening to the Chord Dave with the HD 800. Very impressive that the Chord Dave is able to deliver a big soundstage that the Chord Hugo can only do with high-end amplifiers like the Auralic Taurus MKII. An outstanding one in all solution for headphones so far based on my first impression.

I hope I will have some new USB B cables for the Chord Dave in the weekend. The performance will probably go up then.

I'm curious about Rob Watts' reaction to this – hope he will chime in. Actually he has already expressed his opinion.

 

[ubs28]

I'm curious about Rob Watts' reaction to this – hope he will chime in. Actually he has already expressed his opinion.

Well, let's not do this again. It has been discussed many times in the Chord Hugo thread and it went nowhere. I can only say that it is also highly dependant on the interconnects you use. With cheaper interconnects the soundstage is less impressive.

Let's keep it to the Chord Dave in this thread

 

[lovethatsound]

Currently listening to the Chord Dave with the HD 800. Very impressive that the Chord Dave is able to deliver a big soundstage that the Chord Hugo can only do with high-end amplifiers like the Auralic Taurus MKII. An outstanding one in all solution for headphones so far based on my first impression.

I hope I will have some new USB B cables for the Chord Dave in the weekend. The performance will probably go up then.

YES the hd800 sound fantastic with the Dave.ive been trying out different headphone cables out with the Dave and the hd800,and do you know what?,the hd800 stock cable sounds the best to me.At some point this year i hope to be able to home demo the focal utopia.

 

[Kakki]

Dave does indeed have a unique amplifier section - it is actually a 2nd order analogue noise shaper (a conventional amp is a first order noise shaper).

The reason I do this is two fold - firstly, whenever you load a headphone amp you get more distortion, and its audible and all amplifiers suffer from this. By using a 2nd order noise shaper approach allows me to eliminate this problem - when I load the outputs there is zero change in distortion (apart from a small increase in 2nd harmonic). This means when you load the OP, there is no change in sound quality (all other amps harden up and to mask this they add a lot of 2nd harmonic to fatten the sound up).

The second reason this is done is high frequency distortion. All conventional amplifiers have higher distortion as frequency rises, and this has important SQ consequences, in terms of making things sound hard and un-musical. This is due to insufficient feedback available at high frequencies with poor open loop distortion. Now the distortion with modern high performance op-amps is down to the output stage - and that's one reason why all my DAC's have discrete OP stages, so I can eliminate this weakness. But my second order system has excellent open loop distortion performance plus no HF feedback problems too. A indicator of this is the gain bandwidth product - the best audio op-amps are 100 MHz, but with Dave it is 1 GHz.    

You can see this HF distortion problem with the 19k/20k test. All DAC's make a mess of this but Dave has the lowest distortion of any other DAC using this test:




This level is actually the residual performance of the APX555, so Dave is probably much better than this (one reason why Davina is happening - I need better ADC's to measure).

By using the second order approach does not affect transparency - it is still a single global feedback path, so the effective number of passive components is the same as before.

Rob 

Rob, thank you for very interesting post as always.

I often hear that "NFB is bad" and "NFB kills musicality" but your post suggests that Dave is having very very deep NFB utilizing the amazing 1GHz gain bandwidth.

I'm right now listening to my Dave ... and as many of the owners pointed out, Dave is with such a great musicality.

So I'm really wondering why some people hates NFB so much and believe that NFB kills musicality.
Really wondering why, on the other hand, your products are with great musicality when having very deep NFB.

Do you have any thought on this?

 

[bigfatpaulie]

If hunting for a ps300 and being in line for a Stellaris qualifies as "just" going to go back to enjoy music, then I think we're all in the same boat

I'm grateful to be in good company that understands me oh so well

 

[ubs28]

Is it possible to use the balanced outputs for headphones or is it strictly for amplifiers? (My HD 800 S has the balanced cable installed so I haven't tried it with the Chord Dave yet because I'm not sure if it's safe to do so).

 

[EVOLVIST]

Is it possible to use the balanced outputs for headphones or is it strictly for amplifiers? (My HD 800 S has the balanced cable installed so I haven't tried it with the Chord Dave yet because I'm not sure if it's safe to do so).

No, it's not. Don't even try, per Rob Watts.

 

[ubs28]

No, it's not. Don't even try, per Rob Watts.

Ok thanks. I won't then. The HD 800 (non S version) sounds really good and well behaved with the Chord Dave anyway so I will keep using the non S version for now.

 

[ecwl]

Ok thanks. I won't then. The HD 800 (non S version) sounds really good and well behaved with the Chord Dave anyway so I will keep using the non S version for now.

Hmmm... Can't you just unplug the regular headphone cables from the HD800 and plug them into HD800S?

 

[romaz]

Hey Roy... now you're throwing out the baby with the bathing water.

Hey Jazz, this opening line was not meant for you. If you haven't noticed, the natives have grown restless with all the vibration control talk. This isn't an area I claim any expertise in but I do find the conversation stimulating and educational. I will pursue it further with you through PM.

I wonder how you seem to avoid the greatest potential for sonic improvements (as I see/hear it): at the weakest link in every chain, the sound transducers. If there's one thing that's relatively easy to fix, at least to a large degree, it's the notoriously uneven amplitude response.
.

Not trying to avoid it, just mostly ignorant of it but also not wanting to leave Roon. I will pursue this further with you in private. Thanks for bringing it up.

 

[JaZZ]

Hey Roy... now you're throwing out the baby with the bathing water.

Hey Jazz, this opening line was not meant for you. If you haven't noticed, the natives have grown restless with all the vibration control talk. This isn't an area I claim any expertise in but I do find the conversation stimulating and educational. I will pursue it further with you through PM.

I wonder how you seem to avoid the greatest potential for sonic improvements (as I see/hear it): at the weakest link in every chain, the sound transducers. If there's one thing that's relatively easy to fix, at least to a large degree, it's the notoriously uneven amplitude response.
.

Not trying to avoid it, just mostly ignorant of it but also not wanting to leave Roon. I will pursue this further with you in private. Thanks for bringing it up.

I have my own limitations built in my system in that I insist in using a FiiO X5 II as transport for the DAVE, despite theoretical downsides in terms of galvanic connection. (So no need for excuses, just in case!)

 

[bigfatpaulie]

I think my sentiment may have been poorly conveyed. I meant nothing negative by it, and I greatly appreciate all the diligent testing and comparing done by Roy and others.

My intention was I really like DAVE as-is and that if an improvement can be made with vibration control or otherwise I'm all in: after you've done all the hard stuff (testing and research). In the mean time I have luxury of enjoying the music.

I meant in no way to knock or discredit what your are doing.

 

[EVOLVIST]

Back to the music: Day-Two with my DAVE was yesterday, and it was even more blissful than the day before.

Say, has anyone listened to the DAVE and because it's so truthful, you've been able to equally revel in a recording's imperfections just as much as you would audiophile grade tracks?

I found myself doing this last night.

I put on Neil Young's classic "Harvest" album in 24/192. It was a revelation! This is an album I have heard many times, yet now I can hear all of the flubs, a little sloppy playing, and even poor recording techniques. This doesn't mean that the album sounded bad. It just means that I can now more appreciate the musical signature of the album as a whole. Actually, that should be signatures, plural, because I was asking myself, why does the production in these couple tracks sound so different than these other tracks. Then it dawned on me! Wow, historically, and now for the first time, I can hear the difference in the studios, because the album was recorded at several different ones! I knew this, but I had never HEARD this. I can now tell which songs were recorded at a different studio, at a different time! All of these factors really heightened my joy for the album, warts and all.

I think some of these older recordings can give more of an insight into what the DAVE can actually do, besides just rendering every intrument as a clean entity in the mix. There were even times where I heard some distortion in the background harmonies, and my trained studio brain immediately thought, "Oh, they hit that too hot," meaning they pegged into the red and left it as the final take. Had they had a DAVE in 1972, they might have heard that and rerecorded it.

Anyway, I think tonight will be Springsteen's "Darkness on the Edge of Town" album. This should be fun!