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Sensitivity 86 v 90

I am considering an upgrade from speakers with a sensitivity rating of 90 db, 4 ohms, to larger speakers rated at 86db, 8 ohms nominal.  Same brand, PMC. My tube integrated amp is 80-112 watts triode/ultralinear, and it’s fine for my 90 db speakers.  Although, it is sometimes at around 4 o’clock on the volume control, approaching the max at 6.  I am aware of the “amp power must double for each 3db increase in volume” rule of thumb, but really have no practical experience with this.  I do like having 90 db efficiency, always assumed that meant a less powerful amp would suffice. 

   My question is, would the decreased efficiency be a concern? 

128x128lloydc
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lloydc OP
751 posts
 

I went ahead and bought the less sensitive speakers (PMC 25.26 @ 87db, replacing PMC FB1i Signature @ 90db sensitivity) and if anything, they seem to produce more volume at a given setting.  I can only speculate as to why, but now I’m certain that speaker sensitivity has very little predictive value, given my level of (mis)understanding of these things. I suppose there are just too many variables involved.

@ atmasphere

Roger says the circuit is designed to use any 12a_7 in that spot.  I don’t know how he does it.  Apparently the 12au7 is the quietist (and lowest gain) and perhaps, the best sounding, but 12au7, 12ax7, and 12at7 all work fine in that spot.

 

mesch
3,484 posts
 

The reason is that the impedance spectrum across the frequency range of the new speakers represents an easier load to your tube amplifier in addition to the fact that the true sensitivity is only 1dB difference, as per @atmasphere.  

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