Line level input voltage for Ultimate Pas Pre

I've built what Roy termed the Ultimate Pas 3 which is the regulated PS, Aikido line stage board and the PH10 Phono board. Very happy with the sound. I just picked up here locally a very nice Pioneer Rt-707 reel to reel player that has adjustable line out pots. From the manual it mentions that the center of the range is 450mV and full scale is 700mV. I'm just running the output at full CW or 700mV because that put's it at roughly the same loudness compared to using other sources.

I'm wondering what the correct line input voltage should be for my set up? Any thoughts?

Line level is normally considered to be 500mv

"Line level" is a nominal signal level in decibels, compared to a reference standard.  

So you have to start from the reference standard, then make assumptions as to what the nominal line level is going to be.


For the reference standard, consumer applications generally use dBV (Decibel volts) while professional equipment uses dBu (Decibels unloaded).

Consumer equipment: 0dB = One dBv = 1 volt RMS across a 1kΩ load  (the voltage needed to develop 1 mW across 1kΩ).

Professional equipment: 0dB = One dBu = 0.775 volt RMS across a 600Ω load  (the voltage needed to develop 1 mW across 600Ω).  

The most common (this is where assumptions come in) nominal line level for consumer equipment is −10 dBV, or 0.316 volts RMS/0.447 volts peak amplitude (double that for peak-to-peak).

The most common (this is where assumptions come in) nominal line level for professional equipment is +4 dBu, or 1.228 volts RMS/1.736 volts peak amplitude (double that for peak-to-peak).

Note that other assumptions can be made than the most common, resulting in possible mismatches between components.

NOTE: I do remember that in the alignment process for some consumer equipment - specific example I can remember right now, TEAC reel-to-reel decks - the manufacturer specified 0 dB at the professional-standard 0.775 volts...or maybe TEAC considered them "professional."