I need a high quality headphone amplifier. It must be connected to line output, and should have a volume control.
I found this circuit from
(by Dejan Veselinovic)
Based on OP37.
I have two questions about it:
Q1: it lacks a volume control (potmeter), which I need. At the 'preamp' section, the author writes you would need *two* of these circuits, the first one for buffering. But, for buffering only, I think such circuit would not need as complex as the original circuit (no need for transistors). Can someone provide me details of how to add buffer stage and how to add the potmeter? (I know electronics but I am not an expert)
Q1.5: what are the transistors Q1 and Q2 for? Are they power supply? Could they be used for two opamps for stereo use? And why are there 2 additional unconnected lines coming out of the opamp symbol?
Q2: A power supply circuit is not provided. But the author suggests a good one would be a so called 'virtual battery'; this comes from Pioneer, but there is reference to Andrea Ciuffoli's website. I, however, could not find any details anywhere on such a principle... I am very curious about it. Does anyone have a clue? (see the page , Figure 4 on this page seems to be using this virtual battery principle built around the BUX48). I would need a power supply of +- 24 volts.
Alternatively, I could use a simple 78xx/79xx regulator IC power supply.
As a last note, I found another good schematic that relies on the NE5532. It *does* have a level control: Could someone tell which of the two circuits is best for delivering top audio quality (at high volumes ;-) ?