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valve amp and speaker impedance
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My old Pioneer valve amp has outputs for 4, 8 and 16 ohm speakers.the
bookshelf speakers that I wish to connect are 6 ohm .( They are
english made denons). Could you please advice a novice on which would
be better?. I know for a solid state, the 4 ohm would be the safest,
but some forums claim the valve "prefers" a lower rating. I am not
cranking up the volume!
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Use only the 4 ohms outlet.
Tubes prefer the use of high ohm speakers on their low ohm outlets.
Don't be misled by ppl saying connect the 6 ohm speakers to 16 ohm
outlet.
The use of 6 ohm speakers on the 4 ohm outlet will give
very close to the specified output power.
There will be lower distortion, lower amplifier output resistance
so a flatter response, than if you connected 6 ohms to the other two
outlets.
Nearly all "6 ohm" speakers may average 6 ohms impedance
but have considerably lower impedances where crossover filters are
active,
and a dip at 300Hz to 3 ohms is not uncommon, and this F is in the
middle of the
power band, so it is imperative to use the 4 ohm outlet.
Your bookshelfs probably have a bass/mid driver ans tweeter with a
crossover at
2kHz perhaps where the Z could be low.
So probably they have no serious dip in the band of frequencies where
most audio power occurs, ie, 100Hz to 750Hz approx, so the amp you have
should sound well.
Many ancient old tubed Pioneer power amps and am/fm receivers develop
a lot of faults unless over hauled after 40 years.
I have see a few with output tubes which may be 20 years old that
have low emission, and can make only 1/3 of max rated power, and they
sound insipid.
But once fully restored they are nice performers.
Patrick Turner.
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