16-01-2021, 07:55 AM
You're right about balanced outputs, I certainly don't need balanced and floating. It's a while since I read Bill Whitlock's article: https://www.jensen-transformers.com/wp-c...eminar.pdf
The Alesis balanced input is about as simple as it can be, half a TL082 with 4 resistors. They've had the decency to put in 100p caps to stop entertaining bats.
I've used various tricks for split rails in the past. If I know one rail will have a higher current draw than the other I've used (for example) a 12V reg and a 7805 or 7905 to give me a 5V and 7V rail. As often as not the mismatch hasn't mattered. If I'm using coupling caps it might be easier not to bother with split rails. Then I don't have to fit bipolar caps.
The Quad 34 output impedance is too high for comfort. I've attached a screencap of the relevant bit. If I use the 34 there's nothing to stop me putting an opamp buffer inside, using available power rails. I lose the anti-thump circuit. At least I assume that's what T14 and T15 are for.
The 5534 and 5532 opamps are remarkable designs. They're ancient but have hardly been bettered for audio use. I know there are expensive modern opamps that give a fraction less noise and possible lower biad current but they are still the standard choice for audio.
Coming back to speakers, Mark, have you used and/or measured the Alesis ones? They seem to be well liked in the industry but that's not the same as being really good.
The Alesis balanced input is about as simple as it can be, half a TL082 with 4 resistors. They've had the decency to put in 100p caps to stop entertaining bats.
I've used various tricks for split rails in the past. If I know one rail will have a higher current draw than the other I've used (for example) a 12V reg and a 7805 or 7905 to give me a 5V and 7V rail. As often as not the mismatch hasn't mattered. If I'm using coupling caps it might be easier not to bother with split rails. Then I don't have to fit bipolar caps.
The Quad 34 output impedance is too high for comfort. I've attached a screencap of the relevant bit. If I use the 34 there's nothing to stop me putting an opamp buffer inside, using available power rails. I lose the anti-thump circuit. At least I assume that's what T14 and T15 are for.
The 5534 and 5532 opamps are remarkable designs. They're ancient but have hardly been bettered for audio use. I know there are expensive modern opamps that give a fraction less noise and possible lower biad current but they are still the standard choice for audio.
Coming back to speakers, Mark, have you used and/or measured the Alesis ones? They seem to be well liked in the industry but that's not the same as being really good.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
