What was I wrong about...get back to me when you have a good reason to run two phantom sources...
You were wrong when you said the idea of using 2 phantom sources was fucked. Matt and I have both explained that you were wrong and that it is perfectly acceptable and will not cause any problems.
Why use 2 phantom sorces? I defy anyone to give a reason to do this...
Reasons:
1) if the mic splitter is transformer based, you will need to either use 2 phantom sources or will need to insure that the phantom you do use is on the pass through output side, not on the side that is transformer isolated. A transformer based splitter will not allow changes in impedence to change the signal level on either side of the split (as was discussed earlier). For this reason, professional sound companies running sound will use transformer based mic splitter boxes when they need to split the signal. But a transformer will not pass DC voltage, including 48v phantom.
2) Using 2 phantom sources will better insure you have adequate current available for the mics to draw from. For example, Earthworks mics are very power hungry and consume about 10ma per mic, as opposed to most mics that consume 1-2ma per mic. Many phantom power circuits do not have enough juice to power mics like these adequately. Using two phantom power sources in parallel allows power hungry mics to get the current they need to operate at their best.
3) a poor phantom design may not have adequate current available, may not provide the standard 48v, may have unacceptable levels of noise, etc. Using two sources (esp say if one was from a V3 which has good phantom powering) will mask this. The overall phantom power might be worse than using the V3 alone, but would be far better than only using the preamp with crappy phantom. So using two phantoms won't allow you to compare on the basis of phantom power, but at least it allows the mics to perform their best so the rest of your preamp comparison means something.
I guess if you know beforehand you've got one of your two preamps that is known to have good phantom power (eg the V3), you can only run the phantom on that unit alone and avoid issues with 2) and 3) above. But if you don't know anything about either preamp you're running and don't know whether either has good phantom power, by running both together you insure you have an adequate phantom power supply. And since their is no reason not to run two phantom power circuits, why not do it?
Topic: What was I doing wrong? (Read 10751 times)