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Thoughts of Pass XA30.5, 60.5

After having read numerous reviews & rave about XA30.5 versus 60.5, some would prefer a 30.5 over the doubling power 60.5, some would have contraditory point of view, believing higher power always having a merits of getting fuller sound, better soundstage or remarkable improvement of overall presentation.
But i just wondering why there is not much or none would like to try bi-amping two 30.5 to feed your speakers?! That maybe the way still processing the sweetness of 30.5, but never overdriven your speaker. Provided you're not using a full-range unit speaker with one pair of terminal on each side. A friend of mine has told me that should yield a unbelievable improvement over the pair of 60.5.
Firstly, your pair of speakers would be driven with more ease since each unit of 30.5 has just need to serve half of your speaker system.
Secondly, it would be more flexible & easy to sell one out if extra power is not needed anymore for getting an easy driven speaker at a later time. Your speaker wouldn't be over driven as well as receiving a bill of less electricity payment too.
More importantly, driving ability would be better than a pair of 60.5, so you could even have more choice of less sensitivity speakers.

But the drawbacks is, your preamp should possess two pairs of output, in addition you need an extra pair of interconnects & speaker cable.

Please share your comments. Thanks!
samhvcc
koestner
670 posts
 
If your preamp is solid state with an output imp. of 100 or so Ohms then you should be just fine with the 2 amps.
almarg's avatar
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almarg
9,670 posts
 
What would the sound become if the impedance drops to 15K balanced or 10K unbalanced?
The rule of thumb for proper matching of preamp output impedance and power amp input impedance is that the power amp input impedance (or the combined impedance of two amp inputs, if they are driven by the same preamp output stage) should be at least ten times the output impedance of the preamp, at the frequency within the audible frequency range for which that output impedance is highest.

That requirement will be met by most (but not all) solid state preamps under most circumstances. However, many tube preamps have output impedances of a few hundred ohms at mid and high frequencies (which is also ok under most circumstances), but which rise substantially at deep bass frequencies, often reaching a few thousand ohms at 20Hz. That rise occurs because of the coupling capacitors that most tube preamps (and some solid state preamps) have between their output stage circuits and their output jacks. That rise in output impedance at low frequencies will roll off the deep bass significantly when connected to a load impedance as low as 10K or 15K.

If the 10x rule is not satisfied, frequency response irregularities can also occur in other parts of the spectrum, to the extent that the impedances vary as a function of frequency. Under extreme circumstances, distortion can also worsen significantly.

If the preamp has been reviewed by Stereophile, John Atkinson's measurements which are usually included with the review will indicate the preamp's worst case output impedance, and whether or not this may be an issue.

Regards,
-- Al
pubul57
3,712 posts
 
Jafox's suggestion seems to make a lot of sense XA highs/mids X bass.
rtn1
535 posts
 
Why not ask Mr. Pass for his opinion? That's what I'd do.
pubul57
3,712 posts
 
Some folks trust users more than sellers, though NP does have a reputation of being a straight shooter.
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