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

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To me, the Mojo stock without that gear, with USB, sounds thinner than my laptops onboard sound. More refined with better separation etc, sure, but thinner.
Could be the output impedance. Many laptop's sound cards have a way to hight output impedance, making the bass uncontrolled and over bloated. The Mojo, with it's near zero output impedance, has much better damping control making the bass drier and compared to the laptop's sound leaner.
 
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flyte3333

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I have set up my APX555 so that it uses the USB via ASIO drivers, and I get exactly the same measurements on all inputs - 125 dB DR, THD and noise of 0.00017% 3v 1k 300 ohms. I have done careful jitter analysis, FFT analysis down to Mojo's -175dB noise floor, and can measure no difference whatsoever on all inputs (with the APX always grounded on the coax).
Hi @Rob Watts

Quoting an old post here about Mojo's -175dB noise floor, but this bloke is tapping Mojo and seeing noise floor rise.

As Mojo is designed to be portable, why is it so sensitive to vibrations? Mojo is running on battery here.

 
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Rob Watts

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All analogue electronics are microphonic - try doing that test to a valve/tube electronics and it will be hundreds of times worse.
 
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flyte3333

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All analogue electronics are microphonic - try doing that test to a valve/tube electronics and it will be hundreds of times worse.
Noted but tubes aside he did the test with his own similarly priced DAC. Link below.

Mojo seems more sensitive. And a key difference is Mojo is designed to be portable (experience vibrations) and the other is a desktop DAC (experience less vibrations).

So he raised the question about -175dB noise floor of Mojo, when it's a portable experiencing typical vibrations and the noise floor rises with gentle taps.

Somebody will bring up bias by this other designer but the measurements are shown in real-time video.

I'm a proud Hugo2 and Mojo owner. Just wondering if this is something you fixed or improved with Hugo2?


 
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dakanao

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Hi @Rob Watts

Quoting an old post here about Mojo's -175dB noise floor, but this bloke is tapping Mojo and seeing noise floor rise.

As Mojo is designed to be portable, why is it so sensitive to vibrations? Mojo is running on battery here.

Aha, so this is the reason the Mojo would sound brighter and thinner when it got moved a little bit during my listening sessions a few months ago (it reduced a lot with a galvanic isolator I have now)
 
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Rob Watts

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No - inaudible levels of LF microphonics won't make it sound brighter.
 
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Rob Watts

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It's a lot less with Hugo 2 - unmeasurable using FFTs. I strongly suspect that it is down to the tantalum coupling capacitors in Mojo - these have been eliminated in Hugo 2 with the digital DC servos.
 
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flyte3333

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It's a lot less with Hugo 2 - unmeasurable using FFTs. I strongly suspect that it is down to the tantalum coupling capacitors in Mojo - these have been eliminated in Hugo 2 with the digital DC servos.
Thanks Rob - appreciate the transparency.

Do you still think the user reports of Mojo RFI issues are actually magnetic field issues you mentioned a long time ago?

What are your thoughts now in 2019 - I'm guessing a lot has been learnt along the way.

Hugo2 doesn't have any issues connected to a phone for me - Mojo does for me.
 
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Yes it's not RF pick-up, but the 217 Hz GSM buzz from 2G (it's the TDMA frame rate) - so it's actually direct audio pick-up. 3G and beyond do not use TDMA, so do not create audio bursts - so the problem will disappear as 2G is no longer being used or is rapidly disappearing.
 
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Yes it's not RF pick-up, but the 217 Hz GSM buzz from 2G (it's the TDMA frame rate) - so it's actually direct audio pick-up. 3G and beyond do not use TDMA, so do not create audio bursts - so the problem will disappear as 2G is no longer being used or is rapidly disappearing.
Genius. You're smashing these technical queries out of the ball park.

Last question - for an out of warranty Mojo where someone doesn't want to replace the dead battery - is it still your current position that Mojo should be fine with the battery disconnected, for driving headphone impedance above 33 ohms?
 
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Measurement wise you are absolutely fine - but some caveats - it wasn't designed for battery less operation, and I didn't do any AB listening tests. But judging from comments on this thread it seems perfectly OK to do this.
 
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It's been a while since I used my Mojo at home for critical listening. Have spent more time with Hugo2 at home.

I forgot how insanely great Mojo is... Just with plain simple boring old TOSlink feeding it...

Really glad I kept Mojo. This was my entry into the @Rob Watts designed DAC/Amp world and it still kills most DAC & Headphone amps on the market, at any price (in my subjective opinion).

I don't see (hear) why Chord would be in any rush for a Mojo 2... it's still that great.
 
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Hi,
Does anyone know what kind of IEM’s Rob Watts uses (if any) ? It would be great to know which IEM’s have a good synnergie with the mojo...
I am using mostly shure se846 and I enjoy it quite a lot.
But the “Master” :) could have another opinion...
 
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Deftone

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Hi,
Does anyone know what kind of IEM’s Rob Watts uses (if any) ? It would be great to know which IEM’s have a good synnergie with the mojo...
I am using mostly shure se846 and I enjoy it quite a lot.
But the “Master” :) could have another opinion...
I wouldnt have picked the SE846, thats a hell of a lot of treble roll off when paired with Mojo.
 
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