What’s the most robust option for phantom power protection with AC-coupled transformerless line outputs? And does it matter if we’re talking single or dual supply? Trying to cover all the bases of what happens when people inadvertently patch into a mic pre input in a global phantom scenario on longframe and TT bays.
This will be a line amp for 24V single supply but I am getting held up after the driver. Pretty standard dual driven differential stage with 47R isolation, big bipolar caps, and 10K bleeders to 0V.
BAV99 or similar from signal to 24V & 0V, for starters, same as dual supply?
Do capacitors absolutely have to be 63V, or is there some zener/TVS trick to allow a lower rating? It would be wonderful to be able to use 16V, as the interstage coupling is that. Input is 100V C0G, no worries there.
Nichicon UES seems to be the only game in town, so I’m sort of stuck with 50V and crossing my fingers that nobody’s gonna leave the output patched into a mic pre for more than a few minutes. My height limitation is a firm 25mm, and UES 50V in that case maxes out at 220u. It would be really great to find a wide base low profile 470u/63V, but it doesn’t look promising. I’m fine with paralleling. I’d like to avoid polar caps here.
Regular -2dBu single ended / +4dBu differential nominal levels. Max signal is +20dBu/8Vrms/11Vpk single ended, +26dBu/16Vrms/22Vpk differential. I believe typical external load is a little under 1K when feeding something 10K, but of course 600R is possible. Driver is based around an OPA1656 if that matters, but i’m still looking at BJT RRIO options.
And yeah, you guessed it, it’s a Neve line amp replacement for monitoring, but people will probably want to use it for other summing and gain staging applications, outside of the Neve realm. 66dB gain maxed out, not optimized for mic pre purposes, but could be used that way. Mainly just an incredibly flexible, clean drop-in replacement for the 3415, 3416 & associated parts.
Thanks!
This will be a line amp for 24V single supply but I am getting held up after the driver. Pretty standard dual driven differential stage with 47R isolation, big bipolar caps, and 10K bleeders to 0V.
BAV99 or similar from signal to 24V & 0V, for starters, same as dual supply?
Do capacitors absolutely have to be 63V, or is there some zener/TVS trick to allow a lower rating? It would be wonderful to be able to use 16V, as the interstage coupling is that. Input is 100V C0G, no worries there.
Nichicon UES seems to be the only game in town, so I’m sort of stuck with 50V and crossing my fingers that nobody’s gonna leave the output patched into a mic pre for more than a few minutes. My height limitation is a firm 25mm, and UES 50V in that case maxes out at 220u. It would be really great to find a wide base low profile 470u/63V, but it doesn’t look promising. I’m fine with paralleling. I’d like to avoid polar caps here.
Regular -2dBu single ended / +4dBu differential nominal levels. Max signal is +20dBu/8Vrms/11Vpk single ended, +26dBu/16Vrms/22Vpk differential. I believe typical external load is a little under 1K when feeding something 10K, but of course 600R is possible. Driver is based around an OPA1656 if that matters, but i’m still looking at BJT RRIO options.
And yeah, you guessed it, it’s a Neve line amp replacement for monitoring, but people will probably want to use it for other summing and gain staging applications, outside of the Neve realm. 66dB gain maxed out, not optimized for mic pre purposes, but could be used that way. Mainly just an incredibly flexible, clean drop-in replacement for the 3415, 3416 & associated parts.
Thanks!
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