High impedance array question

[graaf]

Hi to all!

I wonder is it better to have an 50W/8 Ohm amplifier working with 8 Ohm and 90 dB/W loudspeaker or 500W/8 Ohm amplifier working with 80 Ohm and 90 dB/W loudspeaker?

In other words would it be of any advantage to have a more powerful amplifier and a higher impedance loudspeaker?

higher impedance means proportionally less current and less distortion. Or it is not? I am not sure

such a higher impedance and and at the same time high efficiency loudspeaker can be build as an array of ten 8 Ohm speakers wired in series
but an array of 10 drivers per side means quite a lot of money for quality speakers and a lot of woodworking in any case

so – is it worth trying? what do You think?

best,
graaf

[sreten]

Hi,

Whilst a 500w / 8ohm amplifier is a 50W / 80 ohm amplifier the obvious
question is why ? You want utter overkill current capability ? Whilst at
full power 500W/8R vs. 50W/80R distortion for the latter will be lower,
ignoring noise there would be not much difference for 50W/8R case.

It will be "better". Just not very sensible. Poor way to get 50W.

/sreten.

[graaf]

Originally posted by sreten
Hi,
the obvious
question is why ? You want utter overkill current capability ?

I want better sound, this is why
audiophiles are told that less distortion means better sound
is it not true?

Originally posted by sreten

Whilst at
full power 500W/8R vs. 50W/80R distortion for the latter will be lower,
ignoring noise there would be not much difference for 50W/8R case.

You mean that those lower distortions would make not much difference audibly?
They wouldn't be significantly lower?

Originally posted by sreten

It will be "better". Just not very sensible. Poor way to get 50W.

in fact I would like to get the cleanest first Watt

You mean "better" = not better that is not "truly better"?

why not? difference in distortion levels would be insignificant?

best,
graaf

[graaf]

Originally posted by sreten

ignoring noise there would be not much difference for 50W/8R case.

"not much difference" - but how much?
what exactly does it mean "not much"?

we are talking about 10x difference in nominal impedance

a 4x difference (2-8 Ohm) in case of typical solid state amplifier can result in 3x difference in THD+N % or even more
is it significant? can it be?
is it mainly a change in "N" and not in harmonic distortions?

best,
graaf

[LineArray]

Hi graaf,

how do you construct a speaker with high impedance ?


Regards

[graaf]

Originally posted by LineArray
Hi graaf,

how do you construct a speaker with high impedance ?

as an array of multiple speakers wired in series

best,
graaf

[LineArray]

I do not think that series wiring drivers, especially
fullrange drivers, is a good strategy.

Drivers - even of same type - differ, because
there are tolerances.

Drivers are not precision mechanics like clockwork ...

Resonance frequency differs, Q differs, cone breakup
patterns differ.

This is why impedance vs. frequency differs.

By series wiring you loose averaging over the differing drivers.

At each frequency the driver with highest impedance has
the greatest voltage across the voice coil.

Which means, the driver with highest cone velocity gets
the most power.

If you choose 4 same type drivers randomly and compare
the impedance curves series vs. parallel, the curve for parallel
wiring is much smoother even when using logarithmic scaling.

Concerning stability of (some) amps your idea is worth thinking.

But concerning the behaviour of the speaker array itself, series
wiring is no good idea to me ...

Kind regards

[graaf]

Originally posted by LineArray
I do not think that series wiring drivers, especially
fullrange drivers, is a good strategy.
(...)
But concerning the behaviour of the speaker array itself, series
wiring is no good idea to me ...

well, perhaps, I don't know

on the other hand the fact is that series wiring is quite common in line arrays, after all it is a part of "series/parallel wiring"

Dr Griffin writes in His paper:

In a line array various combinations of series and parallel connections can be used to give choices for the overall impedance and SPL values.

so we can safely wire 4 of them in series - says Dr Griffin (and others)
"the speaker never knows that there is another speaker wired in series with it"
see: http://www.monstercable.com/mpc/sta...ing_Woofers.pdf

see also this (from Martin J. King):
http://www.quarter-wave.com/General/Two_Drivers.pdf

so why not wire them all in series? for example 10 of them to get 80 ohms of overall impedance?

perhaps measurable problems of "tolerances" are not a real world audible problems? just like "comb filtering" ("a measurement artifact" - conclusion of Dr Toole's research)

best,
graaf

[LineArray]

Poison is a question of the dose rate.

When wiring series parallel, parallel is to
be preferred. 20 Ohms is not enough ?

[graaf]

Originally posted by LineArray
Poison is a question of the dose rate.

When wiring series parallel, parallel is to
be preferred.

Dr Griffin in His paper writes about wiring speakers in series groups first and than connecting those series groups in parallel

He writes about wiring of 6 speakers in series as something quite normal
see: http://www.audioroundtable.com/misc/nflawp.pdf
at page 22

so 6 "Ok" but 10 "no - overdose"?

Originally posted by LineArray

20 Ohms is not enough ?

I don't know what is enough
perhaps nothing is enough when the aim is "the best"

in audiophile audio "the tendency is to push it as far as You can"

best regards,
graaf