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Topping D70 DAC

Krunok

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However, a pot in the middle, placed somewhere between the gain stage and output buffer will definitely lower the output background noise and very sensitive IEMs will feel better with pots instead of DAC's digital volume control.
Really? And how exactly pot lowers the "background" noise?
 

trl

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By interposing between the gain stage and output buffers. Of course, I'm not speaking about an amp having 1 or 1.5X of gain.
 

trl

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By lowering the volume that enters in output stage. Isn't what all pots do?

Each stage has it's own noise: DAC itself, I/V, LPF, Voltage-Gain and Buffers. Adding a pot in front of the Buffers or at least in front of the Voltage-Gain will lower the noise (and the volume) when pot's knob is at a lower value (between 7 o'clock and 12 o'clock). This is the only way when a pot will actually help in reducing the output noise of an amplifier, otherwise, the built-in DAC's volume should do just fine, maybe even better than an analogue pot.
 

Krunok

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By lowering the volume that enters in output stage. Isn't what all pots do?

Each stage has it's own noise: DAC itself, I/V, LPF, Voltage-Gain and Buffers. Adding a pot in front of the Buffers or at least in front of the Voltage-Gain will lower the noise (and the volume) when pot's knob is at a lower value (between 7 o'clock and 12 o'clock). This is the only way when a pot will actually help in reducing the output noise of an amplifier, otherwise, the built-in DAC's volume should do just fine, maybe even better than an analogue pot.
Lowering the volume actually decreases signal to noise ratio as signal is pushed down to noise floor when volume is lowered. In this process it is totally irrelevant if volume is decreased by pot or by digital volume control.
 

trl

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A 120dB/V 16 Ohms IEM connected to a 10V RMS amplifier makes lot of sense to lower the background noise somehow. Besides getting a pot-in-the-middle, I don't know how.
 

trl

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Now I’m confused. Maybe we should start a “digital vs. analogue control” thread and debate there, OK? O2’s schematic could be a very good starting point and we can calculate there the noise generated by each stage.
 

Krunok

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Now I’m confused. Maybe we should start a “digital vs. analogue control” thread and debate there, OK? O2’s schematic could be a very good starting point and we can calculate there the noise generated by each stage.
It has been discussed in detail on this forum in a dedicated thread. IIRC it has also been measured. Use search and educate yourself..
 

Veri

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let's stay friendly guys :p I think your debate was pretty interesting honestly.
 

amirm

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IIRC it has also been measured. Use search and educate yourself..
I plan to measure at some point but what @trl said can be true. Analog attenuation brings both signal and noise value down. Upstream digital attenuation can obviously do nothing to reduce the noise of downstream stages. But then again it is a more noise-free operation.
 

Krunok

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I plan to measure at some point but what @trl said can be true. Analog attenuation brings both signal and noise value down. Upstream digital attenuation can obviously do nothing to reduce the noise of downstream stages. But then again it is a more noise-free operation.
Analog attenuation between say DAC and amp will bring both signal and noise down but amp is anyhow more noisy than DAC so if you measure noise at the amp outputs chances are you will see no difference in noise between analog pot and digital volume control in DAC chip. Chances are also DAC volume control will have both channels equal in levels while pot may screw things up a little. :p

P.S. Sorry @trl, wasn't trying to be rude.
 

trl

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Kruno, If you could post here the link to the dedicate thread it would be awesome. Thank you!
 

tired_guru

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Price is very high comparing to any other topping products for only a DAC, so it better be great (is topping going now into "high-end audiophile territory" ?). Taking into account about +30% VAT & customs when buying from other countries + international shipping cost, there is a lot of competition in this range. We also have no idea how realiable it be ... Time and users as testers will tell. Personally I would never pay this much. Still interested in measurements but if you believe in all these measurements, you should be set for your life with something like D10 or grace sdac for a small fraction of this price still not being able to tell any difference (even between something like D10 & DCS ring dac).
 
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Krunok

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Price is very high comparing to any other topping products for only a DAC, so it better be great. Taking into account about +30% VAT & customs when buying from other countries & international shipping cost, there is a lot of competition in this range. We also have no idea how realiable it be ... Time and users as testers will tell. Personally I would never pay this much. Still interested in measurements but if you believe in all these measurements, you should be set for your life with something like D10 or grace sdac for a small fraction of this price still not being able to tell any difference (even between something like D10 & DCS ring dac).
I am set with my D10, probably for a long time. :D
 

tired_guru

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I am set with my D10, probably for a long time. :D
I am set with grace sdac, all I miss is changeable digital filters. Default one is not slow roll-off which is a must for my preferences for classical recordings to handle transients exceptionally fast. Maybe I will check out chip spec and mod it to communicate with DAC chip on the bus to be able to switch filters - for me it would be end of the road dac. I would pay even 2-3x for grace if they do it within this small, lovely box.

A few days ago was checking out X1S as DAC only (because built-in amp was step aside from atom performance IMHO) and I was like changing digital filters during playback 5 times. I figured It was always set to 2nd filter - I was not sure which one is that, but after I got home and checked specs just out of curiosity, it was of course slow roll-off. It gives a bit sparkle, speed and aggressiveness instead of being smoothed out and boring. Must be something with it, because I can easily detect which filter it is or at least if it's slow roll-off or not with almost 100% probabilty during AB tests.
 
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