Phase Question

[Chris Fitzgerald]

Thanks Bob. Since the preamp that I own with all of the headroom doesn't have a switch, would using the above-linked Rapco adapter placed on the output of the preamp have the same effect as a switch sonically?

 

[Bob Lee (QSC)]

Yes. It just won't be as convenient and quick as having a switch is.

 

[Tom Baldwin]

BTW (looking through your earlier posts) if you're using both the Presonus and the PMB, then you're effectively using two preamps in series… (not a Good Thing…) (try Googling "gain-staging"…)

I've been aware of the principle that more than one preamp is not recommended. So I googled gain-staging and found Invalid Link Removed which is intended mostly for studio type techies, but it left me with this question. As long as the input and output reference levels are matched, and as long as the input level of the "downstream" unit is set higher than the output level of the "upstream" unit, wouldn't you be apt to get a clean signal? Or am I missing some other potential ill-effect from having two preamps in the signal chain?

One other question, could someone describe what is meant by "unity gain"? Thanks a whole bunch of bunches.

 

[Chris Fitzgerald]

I've been aware of the principle that more than one preamp is not recommended. So I googled gain-staging and found Invalid Link Removed which is intended mostly for studio type techies, but it left me with this question. As long as the input and output reference levels are matched, and as long as the input level of the "downstream" unit is set higher than the output level of the "upstream" unit, wouldn't you be apt to get a clean signal? Or am I missing some other potential ill-effect from having two preamps in the signal chain?

I've been wondering this myself, since it seems to me that even simple devices like the Raven Labs PMB contain two distinct "gain stages": the channel gain, and the master output. But remember, as was once said by someone far funnier than I, "your honor, I'm just a caveman".

One other question, could someone describe what is meant by "unity gain"? Thanks a whole bunch of bunches.

From your own source: "Unity gain is a simple concept.

When the input and output levels in a device are equal, resulting in no net gain or loss (techinically, a gain ratio of one), that unit is operating at unity gain.

The zero mark on a mixer's fader indicates unity gain between the corresponding circuit's input and output."

Oh, and BTW I just called the local studio where I record most often, and they're going to make me a phase reversed XLR cable to fix this problem for me. Thanks to all, and especially to Bob Lee, who finally cleared this up.