Yamaha 4-track question - signal levels

[pchorman]

If there were a Yamaha only forum I'd post there, but I assume this is the right place - please help me understand something that may apply to most 4-tracks:

It is recommended "for best performance" that I set the input fader between approx 7 and 8. Would anyone know exactly why? What is the advantage? Not only that, does this optimal setting apply whether I'm switched to mic level, line level, or the setting in-between, or either?

Thanks much.

[atomictoyz]

The area on the fader your reffering to is the unity gain...its like the sweet spot on the fader. Its gives you the best signal to noise ratio if I were to keep it simple. When tracking...keeping the fader postioned within the 7-8 keeps the signal the strongest and the most quiet. The mic/line should be adjusted to whatever is plugged in the input....a microphone or a keyboard... Play around with it some to learn what impact it has on the recording... I still have my 1st analog 4 track laying around..MT-120 from Yamaha I got great results by keeping the fader at unity and adjusting the mic/line until I got the signal hot enough without clipping.


Peace,
Dennis

[pchorman]

atomictoyz: thanks for chiming in with an explanation. I have heard this once before (the unity gain explanation) and am still stuck on a point:

If I run the faders above 7-8 and don't happen to clip, I should be amplifying both signal and noise levels equally for the later stages within the 4-track. If I run the faders below 7-8 and happen to be at the right input level according to the LED indicators, it seems that I would be amplifying the noise less, but getting the signal level where I want it (desireable). Can you see my confusion? Bail me out please. Why does this unity gain setting result in optimal SNR?

[atomictoyz]

The fader is like an amplifier, so when you move the fader up it amplifies whatever is on that channel. If you move the fader past the 8 mark for instance, there is more noise introduced by the fader, which decreases the quality of the signal. When you move the slider down, you lose the signal and the noise. Most of the amplification of the signal should happen prior to being on tape, which is at the mic/line stage. If you think of it like gas milage on a car, there is a certain place where the pedal needs to be for the car to cruise effectively. If the pedal isn't pushed far enough it bogs down, if its pushed too far it smokes the tires and wastes gas...so you move it where its just right. The manufactures of recorders put meters and faders that mark this spot for you. I always keep the faders at the 7-8 mark and adust the incoming signal through a mic preamp or the mic/line preamp in the mixer until the meter is just below clipping. If the fader is at 5 and the meter is being pegged than back off the preamp. If the source signal is still to hot then your only choice is use a preamp to reduce the signal some. Ive tried recording with the faders too low because of a hot signal and the noise is higher. The reason for why unity gain gives you the best SNR is that the self noise of the cicuitry within the preamps is pushed downward from the main signal your recording. I can't really give you alot of technical jargon to explain it.


Peace,
Dennis