Budget preamp with quality volume control
Dear Audiogoners,
I used to be a firm believer that the signal path should be as short as possible and, as such, I have been using the two-channel system without a dedicated preamp. For a long period of time, I have relied on the digital attenuator in DAC for volume control, knowing the digital attenuator would compress the dynamic range of the sound. Therefore, I switch the volume control on DAC to the fixed mode, bypass the digital attenuation and use the unity gain knob in the back of the power amp for volume control. Depending on the music recording level, however, sometimes I need to turn the unity gain control way down to get proper sound level. This is particularly painful when I use the full-balance connection because of the double voltage gain.
In short, I am looking for a budgetary preamp with quality volume control that either has relay switch stepped control or precise potentiometer for left-right channel match to curb the issue. I try to summarize important (to me) performance catgories as best I can for various good sounding preamp I know (with or without headphone amp/dac) as shown below. It is found the Schiit Magnius happens to have the highest performance ratio. However, I am pretty sure that I likely miss other good performers due to my limited knowledge and would like to solicit for your inputs. Your kind assistance is appreciated.
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- 80 posts total
As mentioned earlier, after trying out Schiit SYS, I no longer consider passive preamp. I suspect the degraded SQ, i.e., soften lows and restrainted less airy highs, is resulted from the mismatched impedance. In addition, the headroom becomes fairly limited because of signal loss. Most of passive preamps have pretty high output impedance and unavoidably create mismatch issues with my amp (20k ohms - 33k ohms). I could not locate the specs for Pacette passive linestage even on their website but suspect its output imp. is no exception. But thank you for the thoughts. |
@lanx0003 One thing to consider is the gain stage of your power amp. My pass labs power amp has a gain of 28db and therefore only really requires a buffer preamp. It would be worth looking at the gain of your power amp and use the appropriate preamp. It seems your dac has a gain stage on the output and between that the gain of your amp, you have too much gain. One solution is to replace the potentiometer (s) on your power amp with one with higher resistance. To me, it doesn't make any sense to add yet another gain stage and volume control in front of your amp that has a potentiometer in the signal path. Another solution would remove the potentiometer from the amp and get a SPL Volume 2 which is basically buffered analog Alps RK-27 potentiometer. |
secretguy1,397 posts Like any of you could hear the difference in volume controls
Showing how much you know…….again.
The volume control used in a preamp is more important than the topology.
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@pwayland I could not find that gain stage info in the manual for my Parasound amp. The control on the back are the unity gain control whose function, as you know, is to throw away some of the preamp output to get the main volume control in the region one likes best (gain staging process). I am not sure if I could simply get rid of it but I could max it out so there won’t be any variable resistor in the signal path. Then I could use Active preamp without gain in lieu of with gain (like you said) to adjust the volume. At the mean time, I could also bypass the digital attenuator in DAC by switch the volume to the "fixed" mode to avoid sound degradation. By reading the specs, the SPL Volume 2 as you have suggested or several Schiit products such as Freya, Asgard 3, Jot 2, or Magnius on my list will serve that purpose in addition to impedance matching. These Schiit products also come with active w/ gain so is handy when needed. Thank you that really helps me to eliminate a few other choices.Btw, while reading the tech info. (as shown below) in SPL Volume 2 manual, it really explains what I have experienced with the SYS... It is actually a much better passive preamp compared to the cheap in-line attenutor I purchased for the sub. I therefore decide to retain SYS for my sub. instead.
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- 80 posts total