Given that my active XO has a couple of unity gain opamp buffers used in filters and the system still sounds very musical I am thinking about adding another opa627 for volume control with a gain of 3. It should not degrade the sound by that much so that I could eliminate my big 12B4A preamp - I am only hoping.
I have previously compared my 12B4A tube preamp to a piece of wire, i.e. interconnect cable connecting directly from the Shanlin SACD player (with volume control) to a 845 power amp.
Both were very listenable. The wire sounded cleaner with higher resolution and more intelligibility, but definitely thinner and flatter. The 12B4A sounded much fuller, slightly warmer with very good depth of the music but less clear. There are only two possibilities that a 12B4A preamp can "enhance" the sound: (1) The Shanlin CD player had a higher output impedance than the 12B4A and the 845 power amp had a lower input impedance than the 12B4A, etc, so that inserting the 12B4A provides a much better impedance matching; and (2) A small amount of "good" distortions introduced in the 12B4A made it appear to sound more musical.
I don't know which. If the better sound was due to better impedance matching, adding an opa627 as a gain stage into my XO is the way to go.
Has anybody actually built an opamp preamp and conpared it to a good tube amplifier in a low distortion system?
Regards,
Bill
I have previously compared my 12B4A tube preamp to a piece of wire, i.e. interconnect cable connecting directly from the Shanlin SACD player (with volume control) to a 845 power amp.
Both were very listenable. The wire sounded cleaner with higher resolution and more intelligibility, but definitely thinner and flatter. The 12B4A sounded much fuller, slightly warmer with very good depth of the music but less clear. There are only two possibilities that a 12B4A preamp can "enhance" the sound: (1) The Shanlin CD player had a higher output impedance than the 12B4A and the 845 power amp had a lower input impedance than the 12B4A, etc, so that inserting the 12B4A provides a much better impedance matching; and (2) A small amount of "good" distortions introduced in the 12B4A made it appear to sound more musical.
I don't know which. If the better sound was due to better impedance matching, adding an opa627 as a gain stage into my XO is the way to go.
Has anybody actually built an opamp preamp and conpared it to a good tube amplifier in a low distortion system?
Regards,
Bill
HiFiNutNut
Seeing you are a Sydney person, why don't you grab one of those little Silicon Chip designed ,multi purpose little Jaycar
preamp kits? They also have a suitable little dual regulated PSU kit that you could use if need be.
You could then try out your idea at minimal cost. Don't forget a quality 8 pin DIL socket too (if not in kit) to allow you to experiment with different opamp types. I think they may even have OPA2134, although not listed in their cattledog.
SandyK
Seeing you are a Sydney person, why don't you grab one of those little Silicon Chip designed ,multi purpose little Jaycar
preamp kits? They also have a suitable little dual regulated PSU kit that you could use if need be.
You could then try out your idea at minimal cost. Don't forget a quality 8 pin DIL socket too (if not in kit) to allow you to experiment with different opamp types. I think they may even have OPA2134, although not listed in their cattledog.
SandyK
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