Passive volume control vs attenuators

[olds1959special]

12dB attenuators or passive volume control? Which is better to reduce hot DAC output without bit loss?

 

[pogo]

The fixed attenuators are better (fixed channel matching, ...).

 

[Blumlein 88]

12dB attenuators or passive volume control? Which is better to reduce hot DAC output without bit loss?

So is this about reducing output of your DAC to feed your preamp with gain you don't need? So you can run the DAC wide open, reduce the level, and then feed the preamp. I guess in such a case I'd go with attenuators. I would do a few simple measurements so you pick the right value attenuators.

 

[antcollinet]

But regardless, bear in mind there will be no quality loss using the digital volume control, if you are unable to hear the noise floor of the DAC during the quiet/silent parts of the music.

You might be trying to solve a non problem.

 

[olds1959special]

But regardless, bear in mind there will be no quality loss using the digital volume control, if you are unable to hear the noise floor of the DAC during the quiet/silent parts of the music.

You might be trying to solve a non problem.

So there should be no improvement using attenuators? Right now I play around 50 on the volume, I'm hoping I can play between 75-100 with the attenuators, so that there is less bit loss.

 

[Salt]

What exactly do you mean with 50 and 75-100 "on the volume"?

 

[Blumlein 88]

Is the DAC volume -50 db or is it 50%? Your DAC has 2.5 volt max output. Your speakers are a bit more sensitive at the input than the modern average. You don't need gain from the preamp. Do you prefer to control volume from the preamp?

I would probably figure out what volume setting is unity gain for the preamp and control volume at the DAC. The volume on the preamp will likely be pretty far down, but set it and forget it.

 

[olds1959special]

What exactly do you mean with 50 and 75-100 "on the volume"?

the DAC has a volume setting that goes between 1-99. I canceled the order for the attenuators, and just turned down the pre-amp (just 2 notches from bottom) and turned up the DAC to 99. I'm not noticing any distortion right now, which is good. I can reduce the volume with the DAC remote if needed, or play full power for the best quality. I think this might be the way to go, instead of turning up the pre-amp and turning down the dac, or using attenuators or adding passive volume control. (unless I get distortion)

 

[Blumlein 88]

If you don't have multi-meter to set unity gain here is a simple way to get pretty close as in close enough.

Run one channel directly to an amp from the DAC. Run one channel thru the preamp. Set the volume at a nice comfortable sound level for the direct DAC channel. Adjust volume on the preamp until they match (start with the preamp turned well down). You'll be within a db or two of unity gain. Then run everything thru the preamp and you'll be good.

 

[olds1959special]

The Modulus 3 pre-amp states Maximum Input: 9v rms for high level section. Although I have the earlier Modulus 2, it makes me think I shouldn't worry about this if I'm not hearing distortion.

 

[antcollinet]

So there should be no improvement using attenuators? Right now I play around 50 on the volume, I'm hoping I can play between 75-100 with the attenuators, so that there is less bit loss.

Bit loss in the way you are thinking of it is not a thing.

The DAC uses 24 bit or higher (normally 32 bit or floating point for the DSP and volume control). All the bit depth brings you is lower noise floor.

If you can't hear the noise floor when listening at the lower DAC volume, then you don't have a problem with bit loss.

 

[olds1959special]

I found out the input sensitivity of the AI Modulus 3 is 9 volt RMS (I have the 2c, but this should be comparable?) so I shouldn't need attenuators. I simply turned the two volume knobs down 3 notches from 9 o'clock to 2 notches from the bottom. This is the maximum volume I need, and then I just lower the DAC volume when needed. It works great this way.