Fungus
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how to double amp when there is no amp in the mojo?
I think there is an amp in the mojo
how to double amp when there is no amp in the mojo?
I think there is an amp in the mojo
Please no worries!
However, iwas wondering if you could answer, the Mojo on line level mode - does this still run thru the Mojo's amp? from how i understand your earlier descriptions, buth the amping and DAC is done in the FPGA?
thus there is no way to truly use it as a dac without double amping?
Line level mode is just a volume preset for the volume control - nothing else changes.
Mojo has an FPGA (which is digital logic only) a discrete DAC (turning digital signals to analogue via flip-flops and resistors) and a single output amplifier - and that is it.
Conventional DAC headphone amps use differential outputs and have two I to V converters (current to voltage), a differential to single ended converter, and an output amplifier. Wrapped up with that is a analogue filter. So that's a lot of passive components and four amplifiers in the signal path.
Because Mojo's FPGA has extensive digital filtering (at 2048 FS) and has a noise shaper that runs at a very high rate (104MHz) and uses a discrete DAC, I can keep the analogue section radically simpler, and this is one reason why Mojo is so transparent compared to all other DAC amps.
Rob
I guess my original quetsion, is all we can do is set Mojo to line level output, or is there a way to actully bypass the Mojo's amp and turn the outputs into true line OUT directly from DAC?
Are DAC and amp integreated in the same chip?
Lastly there is any chance of a non battery powered Mojo to be released as a desktop only device.
mojo desktop -> polaris -> yamaaha m4 could be amazing.
@xtr4
i understand the FPGA designs makes the dac and amp essentally the same... what im really trying to get at is, can the FPGA's amp functions be bypassed so it is used simply as a DAC, and the two 3.5mm outs are true line outputs to prevent double amping
Paste
Conventional DAC headphone amps use differential outputs and have two I to V converters (current to voltage), a differential to single ended converter, and an output amplifier. Wrapped up with that is a analogue filter. So that's a lot of passive components and four amplifiers in the signal path.
@xtr4 i understand the FPGA designs makes the dac and amp essentally the same... what im really trying to get at is, can the FPGA's amp functions be bypassed so it is used simply as a DAC, and the two 3.5mm outs are true line outputs to prevent double amping
Paste
No, you need at least one amplifier to do the critical I to V conversion. Now it is possible to design a voltage only DAC (no amp at all), but they sound poor due to lots of problems - the largest being the huge amount of distortion you get doing it that way. Believe me, if I could make it simpler I would. The key that Mojo has is extremely low distortion and noise (0.00017% 3V 300 Ohms) but only one single amplifier in the signal path - and this amp combines headphone drive, filtering and I to V conversion in a single stage.
Rob
No, you need at least one amplifier to do the critical I to V conversion. Now it is possible to design a voltage only DAC (no amp at all), but they sound poor due to lots of problems - the largest being the huge amount of distortion you get doing it that way. Believe me, if I could make it simpler I would. The key that Mojo has is extremely low distortion and noise (0.00017% 3V 300 Ohms) but only one single amplifier in the signal path - and this amp combines headphone drive, filtering and I to V conversion in a single stage.
Rob
how to double amp when there is no amp in the mojo?
Perhaps that's the point i was stuck on. when he said the amp are one and the same as the dac, i didn't imaigne they were both part of the fpga. thus when i asked if anyone tried it with a separte amp with the mojo in lineout mode, seems they would be effectivly double amping.
i plan to get this either way... i just want to know the clear picture on wherether or not true line out is possible