[Arnold Schwartz]

At the earlier suggestion of @jarnopp, @RCC HD and @Gadget67 I tried connecting my MacBook via optical to the TT2. For the $10 investment in a cable I figured it's worth a shot. I should note, I try to be as objective as possible, if anything my bias is that there should be no audible change.

It wasn't difficult for me to hear a difference.

On the track, all or nothing at all by Frank Sinatra, I could easily hear the reverb from Frank's voice creating a slightly better impression of space. The same reverb could be heard via USB, but it sounded somewhat distant with less texture before fading out completely. Optical sounded a bit clearer as if you could more easily hear the layers or texture of the sounds. Some might prefer the slightly smoother USB because there's a slight (and I'm really splitting hairs here) reduction in clarity. Some people may not notice a change at all, but I found that focusing on nuanced details in the recording makes for easier comparisons. Also, I could quickly and easily switch back and forth between USB and optical to compare.

It was a pleasant experiment and happy to notice a change as it got me excited to listen to some albums this evening.

 

[rkt31]

At the earlier suggestion of @jarnopp, @RCC HD and @Gadget67 I tried connecting my MacBook via optical to the TT2. For the $10 investment in a cable I figured it's worth a shot. I should note, I try to be as objective as possible, if anything my bias is that there should be no audible change.

It wasn't difficult for me to hear a difference.

On the track, all or nothing at all by Frank Sinatra, I could easily hear the reverb from Frank's voice creating a slightly better impression of space. The same reverb could be heard via USB, but it sounded somewhat distant with less texture before fading out completely. Optical sounded a bit clearer as if you could more easily hear the layers or texture of the sounds. Some might prefer the slightly smoother USB because there's a slight (and I'm really splitting hairs here) reduction in clarity. Some people may not notice a change at all, but I found that focusing on nuanced details in the recording makes for easier comparisons. Also, I could quickly and easily switch back and forth between USB and optical to compare.

It was a pleasant experiment and happy to notice a change as it got me excited to listen to some albums this evening.

Exactly my impressions optical vs usb. Usb is slightly smoother but a bit "spread out" optical seem to have very very slightly more depth but less smooth.

 

[rkt31]

Transient Intermodulation Distortion (TID) opens up a big can of worms, as it's much more complex than simply using low feedback - indeed, low feedback can actually make it worse. It's not about the feedback or the open loop HF linearity but how the closed loop system works in totality. The idea that HF components can cause TID in the case of digital is false - because the HF signal is defined - a 44.1k sampling rate source can never create enough overloads to cause TID as my DACs simply do not output HF components to cause any possibility of difficulty. It's relatively easy to design an amp that is linear enough to cover a 22.05 kHz bandwidth, so TID or slew induced distortion (SID) is categorically a non issue.

So does that mean that HF distortion is a non issue too? No of course not - and this is where my analogue noise shaper amp topology steps in. This was invented to solve the crossover distortion issue, and it does this remarkably well. The problem with crossover distortion (when an amp goes from Class A to Class B) is it creates harmonics that extend to infinite frequencies; and this has a major problem with SQ.

And we can see how well TT2 handles this by looking at this distortion plot:


What is remarkable about this is that there is absolutely no distortion above 3kHz - and you can see to -180 dB. As a % that is 0.0000001%, so HF harmonics are well below 0.0000001%. That's actually an extraordinary number for a power amp - I don't know of any other DAC or amp that does anything like this.

Another measurement that shows HF distortion is the 19/20 kHz two tone plot. I don't have one to hand with TT2, but here is Dave:



The problem I have with this measurement is that the APs ADC isn't up to the task - we can't use the high performance sine wave analyser trick of using two ADCs per channel, and so the measurements are hindered by the quality of the ADC. But even so, the intermodulation 1kHz product of -152dB is state of the art.

To have such low levels of HF distortion is by doing two things - making the open loop (no feedback) distortion as low as possible - that's why I have discrete OP stages - and using the analogue noise shaper technique. This actually increases the feedback available for high frequencies. The problem with conventional amps is that open loop they are non-linear (poor OP stages) and there is insufficient feedback at HF. We can see how much feedback there is from the gain bandwidth product (GBP); conventional power amps typically have only 2 MHz GBP; a high quality DAC would be 20 MHz GBP; but with TT2 we are looking at 20 GHz GBP at 20kHz - that's 120 dB of feedback available to eliminate OP stage distortion. With Dave it's 500 GHz or 0.5 THz GBP or 150 dB of feedback at 20 kHz.

The extraordinary 0.5 Tera Hz gain bandwidth product is why Dave has such low high frequency distortion, and why TID and SID simply is not an issue.

@Currawong may like to see the post of rob watts.

 

[ZappaMan]

i think @rkt31 and @Rob Watts may be the same person, as you never see both of them at the same time.....

anyway, i have some Kontak electrical contact cleaner, has anyone used this on the bnc cable connectors or usb connectors ? Or now that I have, where should i use it.... I've done my headphone plugs already.

 

[Rob Watts]

i think @rkt31 and @Rob Watts may be the same person, as you never see both of them at the same time.....

anyway, i have some Kontak electrical contact cleaner, has anyone used this on the bnc cable connectors or usb connectors ? Or now that I have, where should i use it.... I've done my headphone plugs already.

Definitely not! I only post as Rob Watts in all forums and newspapers' comments.

 

[rkt31]

Definitely not! I only post as Rob Watts in all forums and newspapers' comments.

i think @rkt31 and @Rob Watts may be the same person, as you never see both of them at the same time.....

anyway, i have some Kontak electrical contact cleaner, has anyone used this on the bnc cable connectors or usb connectors ? Or now that I have, where should i use it.... I've done my headphone plugs already.

i think @rkt31 and @Rob Watts may be the same person, as you never see both of them at the same time.....

anyway, i have some Kontak electrical contact cleaner, has anyone used this on the bnc cable connectors or usb connectors ? Or now that I have, where should i use it.... I've done my headphone plugs already.

I think the admin can verify the location. I just googled and found the rob's post which incidentally from this thread itself. Imo chord dacs and all the posts of rob are about technical ability of chord dacs which certainly is the reason behind more life like sound. isn't technical ability about better measurements ? Measurements avoid subjectivity.

 

[Vyyy]

Nice topics are there regarding double Rob

By the way, wondering How many -db i have to put in Amp mode to have aroud 1,9V-2V output level for amplifier? Becouse dac mode has 3V which is too much for my system.

Thank you.

 

[rkt31]

Nice topics are there regarding double Rob

By the way, wondering How many -db i have to put in Amp mode to have aroud 1,9V-2V output level for amplifier? Becouse dac mode has 3V which is too much for my system.

Thank you.

-3L is 3v in se out in low gain. So -9L will be 1.5v.

 

[jarnopp]

-3L is 3v in se out in low gain. So -9L will be 1.5v.

And I believe the TT2 is calibrated so that low gain and high gain output the same voltage at the same setting. So, -9 is 1.5v on both low and high gain.

 

[Articnoise]

Definitely not! I only post as Rob Watts in all forums and newspapers' comments.

I'm almost certain he was joking and that we can all tell the difference between you two pretty easy.

 

[bpcans]

Or … audiophiles who have yet to (or cannot afford) Dave or DCS so compromised and bought the TT2

Tanalasta, of course you’re joking I hope? I specifically chose my audio gear for the sound signature that I wanted in the type of music that I enjoy listening to, and not because there was any financial impediment to acquiring either the Chord DAVE or a DAC from dCS.

 

[teknorob23]

Exactly my impressions optical vs usb. Usb is slightly smoother but a bit "spread out" optical seem to have very very slightly more depth but less smooth.

In my experience choice of cable is totally source and cable dependant. For example I find with my set up usb is considerably better in all aspects than the optical cables I’ve tried. Comes to that spdif is also an improvement but not as good as usb.

 

[Tanalasta]

Tanalasta, of course you’re joking I hope? I specifically chose my audio gear for the sound signature that I wanted in the type of music that I enjoy listening to, and not because there was any financial impediment to acquiring either the Chord DAVE or a DAC from dCS.

Yes. I made that clear in a following post. Unfortunately, written forums do not always convey the non-verbal nuances that alter the intent.

I agree with you wholeheartedly and am fortunate enough to be in a similar position. And am enjoying the Chord TT2 tonight with the Utopia as I type this

 

[bpcans]

Thanks Tanalasta

 

[Arnold Schwartz]

In my experience choice of cable is totally source and cable dependant. For example I find with my set up usb is considerably better in all aspects than the optical cables I’ve tried. Comes to that spdif is also an improvement but not as good as usb.

Objectively, I can’t understand why the cable or input matters - it’s carrying a digital signal that still has to be converted by the DAC, the dac should be able to compensate for any variance - that in theory should not be audible if the spdif and USB are carrying 0s and 1s