Regarding preamp drive or DAC drive, the argument that the upstream component driving the amp should have a "low impedance with a lot of drive capability" while technically correct, in practice should be a non issue for any reasonable designed component. The input impedance of most power amps is 50K or higher (I know some are down to 10K), and with current state of electronics it is trivial to design an output stage with 200 ohm or less impedance. In fact if you look at reference preamps schematics they typically have a resistor in series at the output of roughly 200 ohm.I am guessing this is for protection against shorts. Regardless this tells me that reference level designers are not too concerned with having a very low output impedance. Otherwise removing that resistor would be the first thing an audiophile should do to get the best sound. I know that some of you may say that this has to do with impedance matching. Unfortunately physics tells us that for up to 20KHz bandwidth with short distances there is practically no impedance matching involved (unlike in the case of microwave or RF where the wavelength are on the order of the interconnect length or smaller). I believe the critical functionality for a preamp is minimizing noise and distortion that may be introduced due to attenuation or amplification, while presenting a high impedance to the source and reasonably low impedance to the load. I suspect that this is what differentiate a good (line stage) preamp from an average one.
Optimizing Digital Volume Control
Hi,
First I would like to state that I am relatively new to audiophilia (sounds like a disease), however I have a relatively good engineering background.
Presently I am using a traditional CD->DAC->pre->power->speakers setup. I am using a Hegel HD20 DAC that has a digital volume control feature. I recently noticed that without the pre (ARC LS2) in the chain, using the DAC for volume control, I get better results.
Since the DAC is 24b, having a -140db noise floor (close to 144db theoretical limit) this makes sense to me. Since a CD, having 16bit resolution, supports a theoretical maximum of 96db (practical implementation are below 90db). So s properly designed digital attenuation of over 50db (probably in this case over 60db) should not degrade the sound.
Now to my question, assuming a computer as the source, followed by a 24b DAC that doesn't support volume control, one can in theory achieve the same results if the computer converts the 16b original data to 24b and then apply digital volume control. In this case the computer should output a 24b signal to the DAC.
Does anyone know if this is something that a JRiver or Foobar solution is capable of doing? or in general, does anyone know how volume control would work using JRiver or Foobar?
Thank you in advance for your attention.
First I would like to state that I am relatively new to audiophilia (sounds like a disease), however I have a relatively good engineering background.
Presently I am using a traditional CD->DAC->pre->power->speakers setup. I am using a Hegel HD20 DAC that has a digital volume control feature. I recently noticed that without the pre (ARC LS2) in the chain, using the DAC for volume control, I get better results.
Since the DAC is 24b, having a -140db noise floor (close to 144db theoretical limit) this makes sense to me. Since a CD, having 16bit resolution, supports a theoretical maximum of 96db (practical implementation are below 90db). So s properly designed digital attenuation of over 50db (probably in this case over 60db) should not degrade the sound.
Now to my question, assuming a computer as the source, followed by a 24b DAC that doesn't support volume control, one can in theory achieve the same results if the computer converts the 16b original data to 24b and then apply digital volume control. In this case the computer should output a 24b signal to the DAC.
Does anyone know if this is something that a JRiver or Foobar solution is capable of doing? or in general, does anyone know how volume control would work using JRiver or Foobar?
Thank you in advance for your attention.
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- 21 posts total
- 21 posts total