Chord Mojo 2 Thread ___ [product released January 31, 2022 -- starting on page 95 of thread]
Mar 25, 2022 at 11:00 AM Post #3,364 of 10,898
I get a little apprehensive, when any manufacturer starts to quote the opamp model numbers, DAC chips series etc. To me, it says "we are filling the void of low-design by exotic components".
A LOT of audiophiles want and expect those technical specs. When not provided by the vendor - they start complaining.
I guess you cannot satisfy everyone... :wink:
But seriously, it is better to provide all the info, and let people (like you) filter out what they do not care for.

ifi is a respectable company, they should avoid that, but these are Covid days, economy not what it used to be.
Yup - great company, and following some of their product threads, people ask for that stuff. iFi is doing the right thing providing it (IMHO).
 
Mar 26, 2022 at 12:08 AM Post #3,371 of 10,898
Hey @Rob Watts, can you confirm if Mojo 2 draws power directly from the plug when in desktop mode? Thx.

When in desktop mode the battery is completely isolated, so power only comes from the charger circuit, in this case a low impedance high current regulator replaces the battery and provides power to the device.

@Rob Watts , if dsp is 104bit, does it mean volume control and other processing like digital filtering also is 104 bit accurate ?

Short answer yes. Long answer is more complicated than that - as different digital circuits have very different requirements for transparency. So the IIR filter needs noise shaping and 104 bits to be transparent, but an FIR filter (like the WTA filter) needs smaller DSP bit depth. This is because an IIR filter (which is doing the EQ) is recursive (that is the signal is being fed back continuously so small consistent errors end up being huge) and so has different requirements to the WTA filter.

But IIR filters and FIR filters and all digital modules processing audio have a common requirement for transparency - that is being able to reproduce a -301dB signal with perfect amplitude and phase accuracy compared to 0dB. It's just that to do this you require different bit depths to maintain this accuracy. In the case of Mojo 2, I used the 104 bit UHD DSP core to do the volume control too, but that doesn't mean that you have to use 104 bits for volume control - but you do need to ensure that when the volume control is functioning, that the -301dB signal is perfectly reproduced if you want a transparent volume control.

In the case of the EQ - the IIR bi-quad filters - you do indeed need 104 bits plus noise shaping of all the internal nodes - to perfectly reproduce -301dB when the filters are active.
 
Mar 26, 2022 at 12:17 AM Post #3,372 of 10,898
When in desktop mode the battery is completely isolated, so power only comes from the charger circuit, in this case a low impedance high current regulator replaces the battery and provides power to the device.



Short answer yes. Long answer is more complicated than that - as different digital circuits have very different requirements for transparency. So the IIR filter needs noise shaping and 104 bits to be transparent, but an FIR filter (like the WTA filter) needs smaller DSP bit depth. This is because an IIR filter (which is doing the EQ) is recursive (that is the signal is being fed back continuously so small consistent errors end up being huge) and so has different requirements to the WTA filter.

But IIR filters and FIR filters and all digital modules processing audio have a common requirement for transparency - that is being able to reproduce a -301dB signal with perfect amplitude and phase accuracy compared to 0dB. It's just that to do this you require different bit depths to maintain this accuracy. In the case of Mojo 2, I used the 104 bit UHD DSP core to do the volume control too, but that doesn't mean that you have to use 104 bits for volume control - but you do need to ensure that when the volume control is functioning, that the -301dB signal is perfectly reproduced if you want a transparent volume control.

In the case of the EQ - the IIR bi-quad filters - you do indeed need 104 bits plus noise shaping of all the internal nodes - to perfectly reproduce -301dB when the filters are active.
Thanks for clarifying !
 
Mar 26, 2022 at 1:18 AM Post #3,373 of 10,898
Still waiting Mojo2 and HiBy R3 combo case :frowning2:
That case for Mojo + R3 was my design work.
If someone would be willing to lend me the Mojo 2 for 2-3 weeks please send me a PM, then I can adapt the case design.
I’m in Austria, and I’d provide the lender a 3D printed combo case and transport box as a thank you.
 
Mar 26, 2022 at 1:55 AM Post #3,374 of 10,898
When in desktop mode the battery is completely isolated, so power only comes from the charger circuit, in this case a low impedance high current regulator replaces the battery and provides power to the device.
Rob,
Am i correct in thinking that removing the battery and powering the M2 with an external 5V battery pack is essentially equivalent to the desktop mode, and that the charging circuit would power the device?
 

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