OK, I managed to squeeze in the dual (LF03d) as an upgrade for the I/V converter of a Kenwood DP-1001 CD player (mostly sold in Asia, I don't know if it was ever exported to the EU or North America). It's a high-quality, mid-priced CDP with a fairly beefy PSU, TDA1547 DAC, and a line output stage consisting of a dual opamp with discrete Class-A output current booster. It sounds pretty good even with the stock opamps (I/V, line amp), but the LF03d as the I/V takes it into fairly high-end territory.
The challenge lies in physically fitting the LF03d on the DAC riser card, which has fairly limited clearance to the transport next to it. The second constraint is the relatively low rail voltage for the I/V converter opamp: ~ +/- 5V or lower, which the LF03d can handle comfortably (but is not optimal for numerous otherwise highly-regarded monolithics like OPA627, which choke below about +/- 9v)
There are a number of upgrades I did to the I/V stage, including Black Gates, styroflex caps, Wima FKP2s, small chokes on the opamp rails for LC filtering, etc., but all of those are optional and contributed relatively small increments to the sonics, compared to the opamp upgrade.
Compared to the LME49722 and the 2x OPA627 which were previously in this player, on a scale of 1 to 10, I'd rate both the monolithics (LME49722 and 2x OPA627) at about 6-7 and the LF03d at about 9 on audible sonics - definition, detail and dynamics are distinctly superior with the LF03d.
The challenge lies in physically fitting the LF03d on the DAC riser card, which has fairly limited clearance to the transport next to it. The second constraint is the relatively low rail voltage for the I/V converter opamp: ~ +/- 5V or lower, which the LF03d can handle comfortably (but is not optimal for numerous otherwise highly-regarded monolithics like OPA627, which choke below about +/- 9v)
There are a number of upgrades I did to the I/V stage, including Black Gates, styroflex caps, Wima FKP2s, small chokes on the opamp rails for LC filtering, etc., but all of those are optional and contributed relatively small increments to the sonics, compared to the opamp upgrade.
Compared to the LME49722 and the 2x OPA627 which were previously in this player, on a scale of 1 to 10, I'd rate both the monolithics (LME49722 and 2x OPA627) at about 6-7 and the LF03d at about 9 on audible sonics - definition, detail and dynamics are distinctly superior with the LF03d.
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No, I don't have a OPA1642 in hand. I did try an OPA1612 long ago (though not A-B with the LF03), and didn't like its sonics (a bit harsh) at line level.
Looking for ad797 clones i found this. Id like to implement this into my preamp for it seems like a very noble and unique design. (Much appreciated, Linuxguru!)
Id like to know if as a non inverting 3x gain config i will have to worry about on/off thumps or not. The output is single ended it seems? Thats why i raise the concern.
Id like to know if as a non inverting 3x gain config i will have to worry about on/off thumps or not. The output is single ended it seems? Thats why i raise the concern.
Ive built this circuit successfully and it sounds wonderful. However i managed to easily blow out the output because there is no short circuit protection. So could you describe to me how i would implement that? I put a 68ohm output resistor (i didnt even have that!) but i fear thats not enough