I have an all original PAS 3X (not a 2 or 3) that I would like to use for phono stage only using the tape out into a line level input on my NAD C326BEE integrated amp. In the manual for the PAS 3X it states that, unlike the PAS 2 or PAS 3, the 3X preamp is designed to be used into a terminating impedance of 100k ohms or greater. The NAD spec sheet shows that the input impedance for it's line level inputs (R+C) is 100k ohms +320 pF. The NAD power amp input impedance is given as 20k ohms but I'm not considering using that.
Will the PAS phono to tape out work properly into the NAD line level input?
Also, can the 3X be safely used using only the tape out with nothing hooked to it's Audio Output (to power amplifier) outputs?
If I can use the PAS this way I may do some upgrading to it.
No, less the 250k load will affect the riaa negativly. You need a buffer here.
And no, using an PAS without connecting anything on the output does no harm.
BUT, the output is less sensitive to loading, and may be modified to accept 100k load. Thus
using the riaa and using the audio out to the NAD might be a better option, in addition you have
a volume control to adapt signal level. Test this, it might be what you need.
It's taken me while to think about your comment.
Are you saying that I should use the PAS 3X "Audio Output" (to power amp) rca's connected to the 100k input impedance line level inputs on the NAD?
If I do this I will have volume control from the PAS 3X and also from the NAD since I would be coming into the line level input on the NAD. If I keep the volume low on the PAS output would this be safe for the NAD?
Sorry to be so slow, but my knowledge is limited and I don't want to do anything that could cause harm to either piece.
my message are that using the "tape-out" is not an option, it will sound bad unless you connect an
external buffer between.
Using the "audio out" ( normal output) will work better, but has a number of caveats :
- the level might be high, can be cured by setting volume downwards
- all tonecontrols / loudness are in effect unless specifically turning them off (loudness is out
of the circuit if "off", tonecontrols are out if set in their "middle position".
- even if the manual states that it might drive 250kohm that is to be on the edge and not producing the best sound. You still would need a buffer.
Give these limitations i would recommend to sell the pas3x unmolested and get a decent phono for the money. As long as the PAS3X is unmolested it will represent a decent price. An alterative would be
to get an poweramp that has > 500k input impedance ( a st70/vta70 ?? ) and sell the existing gear. This last is probably the alternative that gives best sound.