I guess I am unfamiliar w/ what "unity" gain is.
Unity gain, if I understand it correctly, is the record level setting on your recorder where its internal preamp is neither boosting the signal nor attenuating it.
My 9100 preamp is at unity around 11:00 on the knob, IIRC. Below that you are attenuating, above it you are adding gain, and at 11:00 it's essentially a battery box. Someone please correct me if I am wrong.
This is essentially correct. Although the concept of unity gain is somewhat blurry with these all-in-one units.
unity gain = no change in signal strength
Amplify/attenuate signal = positive/negative gain
'Unity gain' is more strait-forward when refering to a piece of gear that is in the middle of a signal chain. In that case you can measure the signal voltage going in and coming out. The gain setting on the device that makes those values equal is the unity gain setting. This is important with outboard studio gear where lots of different stuff may be chained together. Optimizing the signal levels through the entire signal chain is called 'gain staging'.
In these all-in-one devices the end result is a digital file. We can't really measure gain between the internal stages of the device, nor would we need to since the gain staging is done by the manufacturer as an integral part of the design.
Instead we look for the 'sweet spot' that is the comfortable zone between the extremes of noise at one end and distortion at the other. We tend to call that unity gain around here, but 'sweet spot' is more acurate since there is no way of knowing if that is really unity or not. Something like unity gain applies more clearly to some all-in-one machines which have settings referencing specific input levels for their line inputs.
The concept of unity gain is simple to apply to external devices such as preamps though. A battery box is a 'unity gain' device since it doesn't change the voltage of the signal going in an out (it only provides power to the mics), unless it has built in pads or filters, in which case it would decrease signal level if those are switched in. In that case it would no longer be a unity gain device but would be applying 'negative gain'. An adjustable gain preamp has a range of gain available, and that range is depends on the design. Some always amplify (they always increase gain by some variable amount), some have a range that starts at unity (they have zero gain at the lowest setting), and others may attenuate or even completely mute the signal at the lowest setting (they can have negative gain or positive gain). With a preamp, the gain can be measured across the device and the unity or zero-gain point can be determined... or you can just ask the manufacturer.
So to bring the discussion full circle, the 9200 can probably be set for unity gain, where it does not amplify the signal and essentially only provides power to the mics like a battery box. Chris Church can confirm that for you.
Topic: HEB DPA4060 > CA-9200 > EDRIOL R09 came out distorted... help! (Read 14217 times)