Chord Mojo DAC-amp ☆★►FAQ in 3rd post!◄★☆
May 6, 2021 at 10:47 PM Post #41,416 of 41,564

theveterans

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Thank you.
The point of this exersise was not to praise various software upscalers, but to investigate what effect, improvements (if any) they produce when connected to a Chord Mojo.
After all, Mojo also upscales, so how could a humble $10 Android software improve the sound?
To me it certainly does, specially at 16X (found a way to keep it stable) - this means upscalling a mere 44.1kHz all the way to 705.6kHz.
I was wondering if it can be replicated by others, and could they notice what I get.
At least with HQPlayer you could replicate some of my findings. BTW , to my ears, poly-sinc-mqa-mp with no dither or LSN15 , does the trick.
Upscaling to DSD slightly improves the sound but requires more CPU.
Neutron does not use that much extra battery processing to 16X. Last night I listened to about 3 hours, my battery was down 15% as a result - perhaps 5% extra.
The more I try to find a way to convince myself, that it isn't so - the more I hear that it is so, while the book says it shouldn't!
If nothing else, at least I found a way to improve the sound of the mighty Mojo, for free.

Regarding the very short eval period on Neutron before nagging starts, I recommend leaving a feedback for them, perhaps they listen.
25 mins is a JOKE - a week is reasonable.

DSD input to Chord DACs is decimated to PCM and then reconstructed with WTA filter anyways. Using PCM as inputs at 16X base will bypass the WTA filter completely. If hearing DSD upscaled sounds better than PCM upscaled through Mojo, it just proves that WTA filter is better than HQPlayer's filters (which would benefit non-Chord DACs than Chord DACs in this case)
 
May 7, 2021 at 1:11 AM Post #41,417 of 41,564

Rob Watts

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Thanks for your explanation, makes sense that Mojo would do a better Job of reconstructing the original signal. I'm curious about something, and sorry if this has been discussed before. Would using EQ effect the transients timing or how mojo reconstructs the source signal? I never had good results when using EQ and I'm curious if it's because of my lack of experience using an Equalizer or If there is more to it.

Yes EQ as currently handled is certainly not transparent; you need much greater accuracy than 64b floating point to make it completely transparent. This is why EQ does not sound as good as keeping it bit perfect - the problem isn't about transients but about noise floor modulation, and how small signals are treated. With conventional EQ very small signals are degraded (the amplitude and phase shift is different to large signals). Making very small signals to be the same as large signals needs very much more capable DSP than is currently available.

DSD input to Chord DACs is decimated to PCM and then reconstructed with WTA filter anyways. Using PCM as inputs at 16X base will bypass the WTA filter completely. If hearing DSD upscaled sounds better than PCM upscaled through Mojo, it just proves that WTA filter is better than HQPlayer's filters (which would benefit non-Chord DACs than Chord DACs in this case)

Just to clarify - DSD is filtered to 16FS or 705.6 kHz and does not go through the WTA filter. The benefits of filtering DSD are huge, as the out of band noise creates immense problems in the analogue conversion.
 
May 7, 2021 at 3:41 AM Post #41,418 of 41,564

alekc

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@alekc Hey, could you share your opinions on the X10T II as a transport for Mojo. For a while now, I've been mulling over getting the X10T II. While I would love to get a Ploy, it costs as much as a new Mojo, maybe some day I'll get it but for now xDuoo is cheaper and available locally (no shipping + customs). I remember someone mentioned that sound quality improved when using xDuoo with Mojo, something to do with less noise or interference... Have you noticed any changes in sound quality between Mojo paired with X10T II and your phone? Have you tried the Bluetooth to USB/SPDIF option, I'm thinking it's a very convenient way to get wireless connectivity when using YouTube or watching movies etc. and not seriously listening to music via Hiby Link or local storage.

@Johnfg465vd absolutely :) First of all, X10T II is a dedicated transport and I strongly believe in devices with clear, main purpose (however some parts of my current desktop system tend to deny this philosophy - namely Mytek Brooklyn Bridge and ifi iCan Pro since they have rather broad functionality). To make the long story short: it works perfectly well with Mojo. The screen is small but this is due device size. User interface is not cute but usable and easy to handle. It has build-in EQ which I never use and looking at @Rob Watts explanation in case of Mojo this is a good idea not to use it. The battery life, if you are not using screen a lot is a lot longer than Mojos. I can't tell you if it is better than the mobile phone, it is definitively in worst case at the same level. I have never met any X10T or X10T II owner who would say it degrades sound. For me this is a very clean, transparent transport - just like a transport should be. It has 3 different outputs and some other features like BT which I never used. Considering price to quality ratio and sound quality I am very happy owner of X10T II and probably anyone who understands the narrow purpose of this device will be. There are not many competitors either.
 
May 7, 2021 at 5:40 AM Post #41,419 of 41,564

Kentajalli

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DSD input to Chord DACs is decimated to PCM and then reconstructed with WTA filter anyways. Using PCM as inputs at 16X base will bypass the WTA filter completely. If hearing DSD upscaled sounds better than PCM upscaled through Mojo, it just proves that WTA filter is better than HQPlayer's filters (which would benefit non-Chord DACs than Chord DACs in this case)
well DSD does not sound better as a general rule.
within HQP , the DSD output sounds slightly smoother than certain combinations of pcm filter/dither , but only within HQP.
at any rate, I am not bothered about that.
HQP is not practical even if it did work better on Mojo.
Yes EQ as currently handled is certainly not transparent; you need much greater accuracy than 64b floating point to make it completely transparent. This is why EQ does not sound as good as keeping it bit perfect - the problem isn't about transients but about noise floor modulation, and how small signals are treated. With conventional EQ very small signals are degraded (the amplitude and phase shift is different to large signals). Making very small signals to be the same as large signals needs very much more capable DSP than is currently available.
This could very well be the answer to my conundrum !
To control the bass bloom of my Sennheisers, I use a -9dB peak filter (75Hz, Q=0.7).
Could it be that oversampling, is allowing the software to EQ more transparantly??
Oversampling is applied first before signal goes to EQ.
Neutron uses 64bit processing core for DSP.
 
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May 7, 2021 at 7:56 AM Post #41,421 of 41,564

Rob Watts

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well DSD does not sound better as a general rule.
within HQP , the DSD output sounds slightly smoother than certain combinations of pcm filter/dither , but only within HQP.
at any rate, I am not bothered about that.
HQP is not practical even if it did work better on Mojo.

This could very well be the answer to my conundrum !
To control the bass bloom of my Sennheisers, I use a -9dB peak filter (75Hz, Q=0.7).
Could it be that oversampling, is allowing the software to EQ more transparantly??
Oversampling is applied first before signal goes to EQ.
Neutron uses 64bit processing core for DSP.

Actually the opposite is true; oversampling means that for bass, if you double the sample rate, the coefficients half. So at 705kHz the values of the coefficients are 16 times smaller - this means the internal values will get truncated earlier, meaning the small signal resolution problem is larger.
 
May 7, 2021 at 8:16 AM Post #41,422 of 41,564

alxw0w

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Actually the opposite is true; oversampling means that for bass, if you double the sample rate, the coefficients half. So at 705kHz the values of the coefficients are 16 times smaller - this means the internal values will get truncated earlier, meaning the small signal resolution problem is larger.
Hence improving noise shaper performance "solves" the issue ?
Or I'm mixing things completely ?
 
May 7, 2021 at 8:39 AM Post #41,424 of 41,564

Johnfg465vd

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Yes EQ as currently handled is certainly not transparent; you need much greater accuracy than 64b floating point to make it completely transparent. This is why EQ does not sound as good as keeping it bit perfect - the problem isn't about transients but about noise floor modulation, and how small signals are treated. With conventional EQ very small signals are degraded (the amplitude and phase shift is different to large signals). Making very small signals to be the same as large signals needs very much more capable DSP than is currently available.
Thank you very much for clarifying. I was starting to get a migraine adjusting different EQ parameters and wondering why it didn't sound nicer. EQ "fixed" problems I had with Headphones like too much Bass, Sharp treble... etc but always ended up sounding off.

First of all, X10T II is a dedicated transport and I strongly believe in devices with clear, main purpose (however some parts of my current desktop system tend to deny this philosophy - namely Mytek Brooklyn Bridge and ifi iCan Pro since they have rather broad functionality). To make the long story short: it works perfectly well with Mojo. The screen is small but this is due device size. User interface is not cute but usable and easy to handle. It has build-in EQ which I never use and looking at @Rob Watts explanation in case of Mojo this is a good idea not to use it. The battery life, if you are not using screen a lot is a lot longer than Mojos. I can't tell you if it is better than the mobile phone, it is definitively in worst case at the same level. I have never met any X10T or X10T II owner who would say it degrades sound. For me this is a very clean, transparent transport - just like a transport should be. It has 3 different outputs and some other features like BT which I never used. Considering price to quality ratio and sound quality I am very happy owner of X10T II and probably anyone who understands the narrow purpose of this device will be. There are not many competitors either.
Thanks for taking the time to share your experience with X10T II. I'm most probably going to order it soon.
 
May 7, 2021 at 8:59 AM Post #41,425 of 41,564

sebek

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Anyone use Focal Clear with Mojo? Opinions?

I haven't listened to them, but they are described as very dynamic headphones and with a fairly aggressive sound. The warmer, softer and more relaxed signature of the Mojo I imagine would be a good match.
 
May 8, 2021 at 4:52 AM Post #41,427 of 41,564

CJG888

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X-10Tii is probably the cleanest source you will find for sensible money. Make sure you use a good quality optical cable (e.g. Lifatec), though. The Mojo is one of the few devices which appears to sound significantly better via the optical input. Presumably this is due to the combination of sensitivity to electrical interference and a good Toslink implementation…
 
May 8, 2021 at 6:15 AM Post #41,428 of 41,564

AtomAmp

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I am selling most of my DACS and headphone amplifiers because of this. I love this combo.

PXL_20210507_144437838.jpg
PXL_20210507_144451711.jpg
 
May 11, 2021 at 6:07 AM Post #41,429 of 41,564

headmanPL

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I don't spend as much time on this forum as I did when I first bought Mojo (end of 2015).
Mojo (with Poly) is still what I use for the bulk of my listening, though with the kids much older, my loudspeakers are becoming attractive again......
Checking into the forum and seeing @Rob Watts actively answering questions on such a mature product (I can't believe mine is 5 and half years old) is incredible.
I can't think of a parallel. I think it shows how important Mojo remains to Rob, Chord & any new or old customers. In the age of disposable tech (wireless earbuds anyone?), longstanding commitment is refreshing to see
 
May 11, 2021 at 2:13 PM Post #41,430 of 41,564

jamca

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I never found the Mojo soundstage to be narrow. It had the same width as another DAC I was using at the time. However with the Mojo instruments at the side of the soundstage had just as much coherernce and prominence as the centre instruments. Whereas with my other (albeit budget) DAC, I found that I was focused only on the middle (maybe 50%) area of the soundstage.

It meant I heard and noticed instruments at the sides of soundstage with the Mojo, that could go unoticed without Mojo. Or rather maybe I registered the sounds on other DACs, but didn't take them in, so to speak.

Secondly, something that the Mojo has over other DACs, that is eveident with all Chord DACs, is depth. There is way more depth. Anything from twice as much and much more. That has the effect of making the soundstage sound narrower than it is.

Other DACs I compared with were Meridian Explorer, and sound from a DAB tuner, that could also run through Chord.


Soundstage depth is nothing gimmicky either. Hearing thedepth of a sound, is just as real as hearing either side of a sound. Off the shelf DAC chips, in cheaper implementations, don't have anything like the resolving power as Chord. Hence the image on those DACs comes across with less depth.

I adore the depth from Chord's DACs.
absolutely, totally 100% agree ... you capture exactly the essence of chord mojo, and the reason it differs with other dacs. I am wondering how it stands (as dac) against more expensive ones like 2qute or qutest....
 

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