[x RELIC x]

Another review...kinda meh:

http://www.hifiplus.com/articles/chord-electronics-mojo-portable-dacheadphone-amp/

(Sorry if already posted...hard to keep up!)

I like this part that he writes about the sound of Mojo.

"When I say the Mojo sounds natural, I mean that it renders musical timbres, textures, and transient sounds in a wonderfully believable and unforced way. As you listen, there is less a sense of being in the presence of bowls-you-over grade ‘great hi-fi’ and more a sense of effortless connection with the real-world sounds of human and instrumental voices. In short, the Mojo invites listeners to focus less on the constituent elements of sounds and more on the overarching whole. Note that this does not imply any sort of lack of transient or harmonic information, since the Mojo does a terrific job on both counts. Rather, it is more a matter of proportion and balance; instruments and voices simply sound like themselves, without any artificial spotlighting or underscoring of their sounds merely for ‘dramatic effect’. It’s the sort of quality you might not notice in the first 30 seconds of listening, but after enjoying a track (or album) or two one gradually becomes aware that virtually every piece of musical material the Mojo touches seems to come out sounding spot on.

This quality became most apparent to me in listening to pianist Alfred Brendel’s performance of Mozart’s Fantasia in C minor [Mozart: Favourite Works for Piano, Philips]. One of Brendel’s great gifts—especially for this music—is that his performances typically are less about pianistic flash and pyrotechnics, and more about subtlety, fluidity, and masterful touch. The Mojo played right into this schema as it, too, is capable of revealing (but never overplaying) almost infinitesimal shifts in phrasing, dynamics, and—here’s that word again—touch. When you listen through a Mojo, you can’t help but sense that you and your music are in good hands.

The Mojo’s organic quality focuses specifically on the timbres and distinctive attack and decay characteristics that are the defining ‘signatures’ of the instruments we enjoy hearing. To borrow a term from contemporary architectural discussions, I found the Mojo handily reveals the ‘materiality’ of the instruments in play. Thus, acoustic basses sound realistically large and ‘woody’, trumpets sound incisively articulate and ‘brassy’, tubular bells sound, well, believably tubular and ‘metallic’, and so forth. These might seem like perfectly ordinary things that all DACs and amps should do, but in my experience they are not as simple or ordinary as you might think. The difference I mean to point out involves the quality of authenticity; many DAC/amps can give you a fair simulacrum of the real thing, but the Mojo (like the Hugo before it) steps things up several notches in terms of realism, believability, and timbral accuracy."[/i}

 

[x RELIC x]

Interesting and funny-apparently the Mojo was originally going to be called the Trojan:

https://youtu.be/DTWcKLI0g7c?t=6m11s

Nope. :wink_face:

Sorry to say that the name we planned to use was Buddy..... not Trojan until Ken Kessler a kind friend advised me that in the USA buddy was famous a brand name for what every young and hopeful guy carries around in his wallet and that usually stays firmly in his wallet for months or even years if he's unlucky or an audiophile like most of us guys were.

 

[Mediahound]

Nope.

At any rate, Mojo is a much better name than either Buddy or Trojan. 

 

[UNOE]

I just built a SPIDIF cable out of a old TV composite cable.  Then clipped old floppy disc drive power cable from a old power supply (because this was the thickest wires I could fine with normal PC headers connection).  I removed the pins from the header/jumpers.  Then cut one of the heads off the old composite video cable which is rated for 75ohm.  Then recrimped the cut end of the composite to the jumpers and reinserted them into the old floppy drive header.  Then finalized the other end of the cable with a RCA to 3.5mm mono connector (which was less than $1 at moonrise) directly into the Mojo.  This gave me much less noise than using the USB to the computer.  Though feeding the Mojo with DX90 is still much cleaner even with just a standard 3.5mm stereo cable.

 

[jarnopp]

I like this part that he writes about the sound of Mojo.

Yes, but after reading 14k+ posts here, it takes a lot to raise the level of discourse.

 

[dcginc]

How are you connecting?  Apple CCKs can be defective but if you don't have a CCK or one of 2-3 equivalent connectors you will get nothing.

My 6 plus died yesterday and i replaced it w a 6s plus. The old 6 plus ran the mojo fine since buying the mojo 30 days ago. Only change is the new phone. Tomorrow Ill check the mojo on both my laptop and desktop pc's. If it works fine there, I'll assume the cck died.

 

[parkman]

With the micro iDSD you had to make sure that the iDSD was on before you plugged your phone into it, otherwise it would try and use the phone battery to charge itself and often it would cause the music to be intermittent, that's one benefit of two usb inputs, one for power and one for data! I'm assuming then it that it doesn't matter whether I plug my phone in before or after the mojo is turned on?

 

[Mediahound]

  With the micro iDSD you had to make sure that the iDSD was on before you plugged your phone into it, otherwise it would try and use the phone battery to charge itself and often it would cause the music to be intermittent, that's one benefit of two usb inputs, one for power and one for data! I'm assuming then it that it doesn't matter whether I plug my phone in before or after the mojo is turned on?

Doesn't matter since the Mojo does not charge the phone. 

 

[analogmusic]

About the Phone vs Chord Mojo. I tried it in my car, first the Mojo then Phone, then Mojo and Phone
 
I could hear the downgrade in sound quality (to Phone) clearly each time. 
 
Anyway don't take my word it, what hi-fi says this about the Chord QBD 76 DAC compared to some of the very best CD players in this world.
"The QBD76 doesn't always sound easy on the ear like Unison Research's Unico CDE does; neither does it produce rich-sounding or warm results. No, it's all about fluidity, naturalness and the kind of cohesion that only the very best turntables can manage.Most digital players, even great ones such as the Naim CDS3/555PS we use as reference, sound slightly stilted in comparison."

Read more at http://www.whathifi.com/chord-electronics/qbd76/review#r3KVXI3iFzSTEUUG.99
 
Now the Naim CDS3 is one fantastic CD player, one of the very best in the world, which can easily make most turntables sound inferior. Every time I play the Hugo vs my entry level project turntable, each visitor to my home says the Hugo beats the turntable.
 
The Mojo FPGA is even better than the one in the QBD 76.
 
So I am quite surprised that some people claim the Phone and the Mojo sound the same, because they don't to me.
 
The Mojo sounds exactly as described by what hi-fi "has the fluidity, naturalness and the kind of cohesion on the very best turntables can manage"

 

[twiceboss]

Damn tried with m50x, WOW. Spotify iPad > mojo > m50x.

It makes m50x sounds damn good!

 

[jincuteguy]

Damn tried with m50x, WOW. Spotify iPad > mojo > m50x.

It makes m50x sounds damn good!

Why did you say the Mojo didn't "WoW" you earlier?

 

[Rob Watts]

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.

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

 
I said from the outset that we are talking about very small differences here being subjectively important.
 
A number of points:
 
1. Mojo has a very simple analogue topology with a single stage analogue section. This keeps the analogue component count small, so improving transparency. But this means the OP from the noise shapers has to be low out of band noise, that is one reason why the noise shapers run at 104 MHz not the usual few MHz. It also means that the filtering has to be done within the digital domain.
 
2. You make the assumption that stop-band performance is not important, that a simple analogue filter is good enough. That is an assumption, my listening tests have revealed that even 120 dB rejection is not good enough - increasing it further gave sound quality benefits - and you can't possibly obtain greater than 120 dB stop-band from an analogue filter.
 
3. The nature of the filtering has very important time domain effects. You can't reconstruct transients perfectly (look at Whittaker Shannon sampling theory) without using an FIR filter with a sinc response - an ideal sinc FIR filter will return the original un-sampled bandwidth limited signal completely perfectly. An IIR filter, or analogue filter can't reproduce the original exactly - there will always be time domain differences.
 
My contention is that these subtle differences are very importantly subjectively, you clearly think otherwise. We will have to agree to disagree.
 
Rob 

 

[warrior1975]

So I am quite surprised that some people claim the Phone and the Mojo sound the same, because they don't to me.

I don't work for Chord, never got any thing from them for saying this, but it is quite annoying to read these ignorant comments comparing a phone to a Mojo and saying they sound the same.

Ignorant comments? Kind of harsh, no? Someone's opinion of how electronic devices annoys you? Are you serious?

 

[parkman]

Ignorant comments? Kind of harsh, no? Someone's opinion of how electronic devices annoys you? Are you serious?

I just opt for ignoring such comments and just hope the intent was better than it seems. 

 

 

[analogmusic]

Ok i have deleted the last sentence, a bit harsh, agreed
 
The thing is when it comes to serious digital audio, companies like Naim who use Burr-Brown DAC chips, disable the digital filter of the DAC chip, and use their own code on a DSP chip that does the Digital filtering, and then have custom designed analog filters (that are hungry for current. I can't see any phone having this kind of hardware that is so hungry for current).
 
These companies like Naim are very serious about not allowing out of band noise into the output as any amplifier does not like to receive 1MHZ Rf noise from a digital source. Rob has posted enough about modulation of RF noise with the musical signal that pumps up and down and adds a certain "digital" brightness to the sound. It may sound more impressive for a few minutes until its starts to bring listening fatigue , but I can't bear to listen anymore to this kind of sound. 
 
So I can't hear that a phone DAC sounds the same as a Hi-end DAC from Naim, let alone, a Chord Mojo or Hugo.
 
A very simple way to know is play some piano music on a chord mojo and then on any phone.