Timbo21

DAC Off Part 2: Qutest vs RME ADI-2 DAC

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Dealer
16 minutes ago, ChemMan said:

I've been reading the RME manual today and I'm wondering about the volume control.  Do you guys thinks it's best to set the amplifier at some arbitrary and reasonable level and control overall listening volume from the RME.  According to the manual, they claim their digital volume control has no limitations.  The Node2 streamer is set at maximum volume.

My signal path looks like this:

BlueSound Node 2 or CD player . --> Coax cable --> . RME DAC . -->  RCA or Balanced XLR cables -->  MA 252  --> Speakers

With amps that have valve input stages I have always found that the better sound is with the DAC set to a fixed highish output level, say 2v or 3v, and to use the volume control on the amplifier. By better I mean tighter, less woolly, better bass, more transparent mids and top end.

This is nothing to do with considerations of the mechanism of the digital volume control of the DAC and is just based on personal listening conclusions. The difference was quite marked though when I tried the different options before. This was with a Chord Hugo TT, a Chord Dave DAC and a Bricasti M1 DAC. Unfortunately I do not have a valve amp at the moment to try it with the RME but I suggest you listen and see what you think.

Edited by Fourlegs
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Super Wammer
5 hours ago, tuga said:

This one from the Benchmark site is much more comprehensive:

https://benchmarkmedia.com/blogs/application_notes/13095789-volume-control-technologies

I like Benchmark, and I've never heard their kit!

"There are four common systems for controlling volume:

  • Digital attenuator - digital signal processing (DSP)
  • Integrated analog volume circuit - (IC)
  • Passive attenuator - resistor network, or passive potentiometer
  • Active gain circuit - amplifier and variable resistance"

I've tried but can't see where TVC (à la Music First and Bespoke Audio amongst others) fits into this: am I misunderstanding some of the terminology used?

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1 hour ago, TheFlash said:

I like Benchmark, and I've never heard their kit!

"There are four common systems for controlling volume:

  • Digital attenuator - digital signal processing (DSP)
  • Integrated analog volume circuit - (IC)
  • Passive attenuator - resistor network, or passive potentiometer
  • Active gain circuit - amplifier and variable resistance"

I've tried but can't see where TVC (à la Music First and Bespoke Audio amongst others) fits into this: am I misunderstanding some of the terminology used?

Resistor network?

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Super Wammer
1 hour ago, TheFlash said:

I like Benchmark, and I've never heard their kit!

"There are four common systems for controlling volume:

  • Digital attenuator - digital signal processing (DSP)
  • Integrated analog volume circuit - (IC)
  • Passive attenuator - resistor network, or passive potentiometer
  • Active gain circuit - amplifier and variable resistance"

I've tried but can't see where TVC (à la Music First and Bespoke Audio amongst others) fits into this: am I misunderstanding some of the terminology used?

You could also add LDR (light dependent resistors) but I suppose that could come under resistor network.

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Digital amps are a good idea. The signal remaining digital but with gain applied  and then D/A done after, permits any noise floor to be disregarded by the DAC. The output noise floor becomes dependent on the DAC converter chip/circuit characteristics and that of the output stage, rather than all upstream devices.
When things stay in the digital domain, it remains easy to separate signal from noise. When things are analog, this is not the case.

TL;DR this is digital attenuator combined with active gain devices, like some of NADs digital integrateds.

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Dealer
6 hours ago, Metatron said:

Digital amps are a good idea. The signal remaining digital but with gain applied  and then D/A done after, permits any noise floor to be disregarded by the DAC. The output noise floor becomes dependent on the DAC converter chip/circuit characteristics and that of the output stage, rather than all upstream devices.
When things stay in the digital domain, it remains easy to separate signal from noise. When things are analog, this is not the case.

TL;DR this is digital attenuator combined with active gain devices, like some of NADs digital integrateds.

A good idea but probably not easy to implement properly. Rob Watts has been talking about them for years and it seems he still  long way off having a product. His end goal is a series of digital amps fed from a digital crossover with MScaler for the ultimate active speakers. 

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Years ago I listened to what was then a very advanced system a couple of times.

It was an all-Lyndgorf setup with the CD transport feeding the Millennium "power" DAC driving the 2-way open baffle satellites and corner woofers. The amplifier handled the crossovers and used the RoomPerfect DSP module for room correction.

They've since partnered with Steinway but I've never listened to any of their current setups.

Edited by tuga

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Super Wammer
7 hours ago, Metatron said:

Digital amps are a good idea. The signal remaining digital but with gain applied  and then D/A done after, permits any noise floor to be disregarded by the DAC. The output noise floor becomes dependent on the DAC converter chip/circuit characteristics and that of the output stage, rather than all upstream devices.
When things stay in the digital domain, it remains easy to separate signal from noise. When things are analog, this is not the case.

TL;DR this is digital attenuator combined with active gain devices, like some of NADs digital integrateds.

Re “The signal remaining digital”: I presume you meant the to open with “Digital amps are a good idea for those using only digital sources”.

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Super Wammer
8 hours ago, tuga said:

Resistor network?

Yes, that was the closest I spotted, though those of us who have spent any time poking around would definitely have called out TVC with that terminology and/or as a specific subset becaus if its known properties.

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Dealer
14 minutes ago, TheFlash said:

Re “The signal remaining digital”: I presume you meant the to open with “Digital amps are a good idea for those using only digital sources”.

 Maybe with an adequate ADC there is no need for your amendment to the text?

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1 hour ago, tuga said:

They've since partnered with Steinway but I've never listened to any of their current setups.

I heard this in Antwerp, and it has all of the detail and DSP of the Kii3 and DandD.  Impressive sound and he said, they can't keep them in stock.  As we know, it's not for everyone however.

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Super Wammer
1 hour ago, Fourlegs said:

 Maybe with an adequate ADC there is no need for your amendment to the text?

My point was that "the signal remaining digital" implies it starts as digital. Outside the amplifier.

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2 hours ago, TheFlash said:

My point was that "the signal remaining digital" implies it starts as digital. Outside the amplifier.

I was referring to a signal being digital before D/A up to the speaker drivers, or at least analog out from an amp.

Source into pre-stage of a pure digital amp has issues if the source is analog, but precisely for the same reasons analog sources can pose problems into analog pre-amps.

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On 15/01/2019 at 18:48, Fourlegs said:

I am using the XLR outputs from the RME direct to my Pass Labs XA60.8 monobloc power amps (ie using the RME volume control)

Make sure to switch the max output level to +1dBu (0.87V) in the settings so you would use as little digital attenuation as possible. If you find you can't get loud enough at max volume then change the max output level to the next higher setting which is +7dBu (1.74V).

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So @Fourlegs
arr you starting to reach any definitive thoughts on the RME yet (especially direct into Pass Labs, since I also own a Pass amp)?

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