Chord Mojo DAC-amp ☆★►FAQ in 3rd post!◄★☆
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betula

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Got my Mojo. But why i dont feel "wow"? Somebody explain?

I have an impression reading your posts in different threads, that you tend to judge equipment superficially and too quickly. Also changing your interest and purchases too quickly.
I'd suggest you to spend a few days with Mojo, discovering the sound it produces. If you don't start to like it in a couple of days, then just sell it, as it is just not for you.
But if that will be the case in a few days, you should really stop for a moment, and find out what exactly you are looking for in audio world.
 
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twiceboss

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I have an impression reading your posts in different threads, that you tend to judge equipment superficially and too quickly. Also changing your interest and purchases too quickly.
I'd suggest you to spend a few days with Mojo, discovering the sound it produces. If you don't start to like it in a couple of days, then just sell it, as it is just not for you.
But if that will be the case in a few days, you should really stop for a moment, and find out what exactly you are looking for in audio world.
I just throw my opinion for the first impression. But meh, i dont need to sell it since Sonicelectronix gives the customer 60 days a full refund guaranteed. Much time to audition it. No worries!!! :wink:
 
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warrior1975

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Ok, I did it. Mojo will be here on Friday!! Hope I like it. I have a good week to use it before my girl gets back. Should be plenty of time to determine if I like it or love it.
 
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bavinck

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I am not debating it, I just suggested it as an option.

This notion of brain burn in is the biggest crock of !!!! I have ever heard IMO!!! :p

I suggest that you stop giving orders on this thread and leave it to the thread starter and moderators.

See now, in general use I am more convinced of brain burn than equipment burn. However, each must decide on their own.

My point about the Mojo is, it is math that makes the Mojo so great (Rob's algorithm that is doing the waveform conversion) . That will be occurring from the first second the Mojo is turned on, so equipment (possible?) burn in is not even a part if that equation. However, as Rob has said several times (and others have noted as well) it does take some time for us to become adjusted to the better waveform generation (brain burn in) .
 
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bavinck

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Ok, I did it. Mojo will be here on Friday!! Hope I like it. I have a good week to use it before my girl gets back. Should be plenty of time to determine if I like it or love it.

I think you will like it, congrats! What iems you using?
 
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warrior1975

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I ordered tralucent-audio-ref 1 too, should have by end of the month. My current collection is rha T10, Sony Xb90ex, and Heir Audio 8.a. Fostex Th900 headphones too. My goto IEMS until the Ref 1 Too arrives are the Sony Xb90ex. I've recently sold most of my IEMS, so time to add new toys.

Forgot about my asg g2.
 
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bavinck

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Mojo rocks:
 
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psikey

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I am extremely dissappinted that mojo sounds worse with bandcamp than my phone. This is no fault of mojo's, which used to sound spectacular with my iphone 5 with bandcamp. Its the damn android upsampling, whatever genius thought this upsampling was a good idea shouod be fired. Unfortunately for all my streaming on android; bandcamp, youtube, etc, I cannot use mojo as the sound of the upsampled output is atrocious. Shame on samsung. The only time I use mojo now is when i'm listening to albums ive downloaded via UAPP. My listening is probably 80% streaming, 20% UAPP.

Won't somone please invent a program for android that bypasses the dac when streaming from other programs? :sob:

Switch to Tidal streaming in UAPP then.

Sent from my SM-G935F using Tapatalk
 
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jincuteguy

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I ordered tralucent-audio-ref 1 too, should have by end of the month. My current collection is rha T10, Sony Xb90ex, and Heir Audio 8.a. Fostex Th900 headphones too. My goto IEMS until the Ref 1 Too arrives are the Sony Xb90ex. I've recently sold most of my IEMS, so time to add new toys.

Forgot about my asg g2.
Where did you order the Tralucent Audio Ref 1 ?
 
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post-12445871
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Joe Bloggs

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I realize that this is a losing battle as the listener in question has made up his mind regarding what he's hearing with the X7 vs the mojo, but--

Yes, in short.

When I first heard Hugo I was struck by several things I had not heard from digital audio before. One was a sense of natural flow, where the rhythms flowed much more naturally - it sounded mechanical before. Second, you could perceive the instruments "talking" to one another - the subtle interactions of timing that turns a mundane performance into a great one. Thirdly you could hear notes starting and stopping much more easily - for example the initial crack of a wood block had much more impact, power and speed. Fourthly, I could perceive a much greater variation in timbre of instruments.

The problem I had at that time was that it was totally unexpected, and I did not know what I had done to get this sound quality. It was not the increase in WTA tap length, as I had heard 32,000 taps before and that did not sound like this.

The Dave project allowed me to understand exactly what I had stumbled upon, and in the case of Dave, further maximize it. Now the job of a DAC is to converted sampled data back into a continuous waveform exactly as was in the ADC converter, and I had improved the filters within Hugo that go from 16FS to 2048FS - this meant that I had recreated the analogue waveform in the time domain to a much better accuracy than before, and it was this better accuracy that gave the subjective improvements. I had done this in order to improve jitter sensitivity, reduce RF noise levels, all to reduce noise floor modulation, which makes a DAC sound smoother - but it also had these subjective timing benefits.

The filtering was a three stage digital filter, and means I can recreate the analogue waveform accurately to a 9.6 nS resolution. All other DAC's work to a resolution of at most 16FS, which is only 1.4 uS. Moreover, getting to this resolution is not good either, as they have very limited tap lengths so it has gross timing errors too. The fact that I have very long tap length WTA filters, plus the fact that filtering is at 9.6nS resolution, gives Mojo this unique timing performance - and its that, above all else, that gives it its musicality.

Hope that explains, Rob 

The only reason DACs need to upsample is to make room for an analogue reconstruction filter with a less steep rolloff than the brickwall filtering a non-oversampled digital sample stream would require. The filter would cut off at the Nyquist frequency of the oversampled sample stream, which is 16x (say) the original Nyquist frequency, leaving plenty of room for the signal to be passed without attenuation at the original Nyquist frequency.

16x upsampling is plenty enough for this--if that were all that the X7 were using. I'm not at liberty to fully disclose the workings of the ES9018S DAC the X7 uses, but what is publicly known is that it upsamples PCM and DSD alike into a high frequency multibit stream for subsequent ASRC jitter reduction, volume control and D/A conversion. Seeing as it does this upsampling for up to DSD512, in the case of 44.1kHz audio the upsampling factor would also be at least 512x.

But back to the central argument. Does a high oversampling factor increase "timing performance" of the reproduced signal? Quite frankly, no, it wouldn't, even if we pretended for the moment that the "timing performance" as a metric made any sense!

Your contention, apparently, is that the "timing performance" of the DAC is equivalent to the sampling period of the upsampled sample stream. At 16FS, sampling rate = 44.1kHz*2048 = 705.6kHz, sampling period = 1/(705.6x1000)s = 1.4μs as claimed.

The thing is, the D/A converter at the receiving end of this sample stream outputs ANALOG signals--and it does this by lowpassing the digital pulse train. An analogue lowpass filter does not dumbly "join the dots" of the digital sample stream--it has particular mathematical characteristics dictated by the fact that it preserves all frequencies in its passband and rejects all frequencies in its stopband. But a picture speaks a thousand words:


On the top, the D/A conversion of your upsampled signal as you would seem to have us believe is going on, wherein adding more points would smooth out the curve;
At the bottom, the D/A conversion of the upsampled signal as actually occurs--output is analog waveform that bears little resemblance to what an imagined "join the dots" curve would look like.

This analog filtering would occur the same way, regardless of how high the sample rate of the upsampled sample stream. As mentioned at the start, a really low upsampling factor (like 2x) would require the use of a steep analog filter, which in turn may lead to small amounts of phase shift at high audible frequencies, but this isn't an issue at all at 16x.

http://www.head-fi.org/t/769647/objectivists-board-room/1635#post_12203380

Elsewhere I detailed technical arguments regarding Rob's "timing" contentions, I have yet to receive a response.

----------
Don't mind me, I'm just taking an early retirement from my position as FiiO rep
 
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Peter Hyatt

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Got my Mojo. But why i dont feel "wow"? Somebody explain?

How much time have you invested?
 
Also, go to something you are very familiar with and listen for detail.  
Go back to the same song, sans Mojo, listening for the same detail.  
 
With the massive amount of data being interpreted by the brain, it is going to take time.  I am enjoying keeping track of songs, specific parts, and the instruments and clarity that is impressing me.  As the days go by, it continues to amaze me.  
 
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bavinck

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I realize that this is a losing battle as the listener in question has made up his mind regarding what he's hearing with the X7 vs the mojo, but--
The only reason DACs need to upsample is to make room for an analogue reconstruction filter with a less steep rolloff than the brickwall filtering a non-oversampled digital sample stream would require. The filter would cut off at the Nyquist frequency of the oversampled sample stream, which is 16x (say) the original Nyquist frequency, leaving plenty of room for the signal to be passed without attenuation at the original Nyquist frequency.

16x upsampling is plenty enough for this--if that were all that the X7 were using. I'm not at liberty to fully disclose the workings of the ES9018S DAC the X7 uses, but what is publicly known is that it upsamples PCM and DSD alike into a high frequency multibit stream for subsequent ASRC jitter reduction, volume control and D/A conversion. Seeing as it does this upsampling for up to DSD512, in the case of 44.1kHz audio the upsampling factor would also be at least 512x.

But back to the central argument. Does a high oversampling factor increase "timing performance" of the reproduced signal? Quite frankly, no, it wouldn't, even if we pretended for the moment that the "timing performance" as a metric made any sense!

Your contention, apparently, is that the "timing performance" of the DAC is equivalent to the sampling period of the upsampled sample stream. At 16FS, sampling rate = 44.1kHz*2048 = 705.6kHz, sampling period = 1/(705.6x1000)s = 1.4μs as claimed.

The thing is, the D/A converter at the receiving end of this sample stream outputs ANALOG signals--and it does this by lowpassing the digital pulse train. An analogue lowpass filter does not dumbly "join the dots" of the digital sample stream--it has particular mathematical characteristics dictated by the fact that it preserves all frequencies in its passband and rejects all frequencies in its stopband. But a picture speaks a thousand words:


On the top, the D/A conversion of your upsampled signal as you would seem to have us believe is going on, wherein adding more points would smooth out the curve;
At the bottom, the D/A conversion of the upsampled signal as actually occurs--output is analog waveform that bears little resemblance to what an imagined "join the dots" curve would look like.

http://www.head-fi.org/t/769647/objectivists-board-room/1635#post_12203380

Elsewhere I detailed technical arguments regarding Rob's "timing" contentions, I have yet to receive a response.

----------
Don't mind me, I'm just taking an early retirement from my position as FiiO rep
Oh man, this is getting good. Rob, can't wait to read your response!
 
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bavinck

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Joe Bloggs, if you read my earlier impressions regarding x7 vs mojo (and assuming my impressions are fair - which could be entirely bs) what is you take on why I am getting such a different experience with these two dacs?
 
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headmanPL

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So having been on the road with Mojo this week, I have listened to a varied range of music. At times it's amazed me. Many classical music pieces have left me open mouthed at how different (good) it can sound.
Beatles tracks have been great fun.

An old favourite has genuinely stunned me. Ocean Colour Scene-Marchin Already just sounds so different. I saw them live many times as they are great musicians and are fantastic live.
This album through Mojo has never sounded so good.I know recently a couple of posters mentioned 3d imaging and width was less than good. Listen to this if you want to hear what Mojo can do.
The album is so much more fun. Energy just oozes. It reminds me of them in concert. I wish I'd played it when I bought Mojo 3 months ago.
I'm off to play it again :grinning:
 
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