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In Reply to: RE: Any interest in a 32 ohm speaker? posted by Duke on May 02, 2014 at 13:45:47
I'd like 32 Ohm drivers to parallel 4
for an 8 Ohm load.
(8" please) ... :)
Follow Ups:
I should have been more clear... I'm talking about a 32-ohm speaker system, not the individual drivers. Eminence makes a 10-inch 32 ohm bass guitar speaker that is meant to be used in multiples, wired in parallel.
If your end goal is an 8-ohm load, is there any particular reason why you prefer four 32-ohm drivers in parallel over four 8-ohm drivers in series-parallel?
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Drivers in series don't really work together.
I've had this demonstrated both aurally and instrumentally.
I.E...
2 drivers with slightly different Fs if paralleled will
measure with Fs that is the average of the 2
BUT ..
The same 2 drivers in series will measure the 2 Fs's separately.
"Drivers in series don't really work together."
That has not been my experience. I received a Golden Ear award from Robert E. Greene of The Absolute Sound, who does extensive measurements which are not included in his reviews, for a speaker that had woofers wired in series as well as tweeters wired in series.
"I've had this demonstrated both aurally and instrumentally.
I.E...
2 drivers with slightly different Fs if paralleled will
measure with Fs that is the average of the 2
BUT ..
The same 2 drivers in series will measure the 2 Fs's separately."
I did extensive measurements before using series connection, to find out for sure what happens to the T/S parameters (there are inconsistencies in the information available on the 'net from professional sources). Fs, Qms, and Qes don't change. Re and Vas both double as expected. The slight wiggle in parameters that I observed in my measurements was within the margin of error of the test equipment I was using.
And subjectively I and an associate whose ears are better than mine have both preferred series over parallel connection when we had a preference. With one beefy Class A solid state amp that he tried, to his ears the difference was inconsequential, as I recall. I think it was a Plinius. To the best of my recollection, every other test either of us have done where the amp wasn't driven into clipping, we have preferred the series connection.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
You're not the first to refute my 'knowledge' on
this subject, though perhaps the best qualified :)
I myself (on more than one occasion), using a
'woofer tester', have observed the 'double hump'
impedance response as opposed to the 'averaging'
response of the same drivers paralleled.
I have also heard a sort of 'phasing' effect of
series drivers 'supposedly' caused by the 2 resonating
at different frequencies and beating.
Perhaps you have used drivers better matched than I.
Well matched drivers take away the double hump for sure
and thusly perhaps the phasing.
As a 'purist' I prefer not to use series-parallel, but
as a realist (should I really need the array) I will ...
What kind of woofer tester?
I'm also curious about this: a sort of 'phasing' effect of
series drivers 'supposedly' caused by the 2 resonating
at different frequencies and beating.
The term 'beating' sounds like you are suggesting intermodulation. Is this the case?
> What kind of woofer tester?The Dayton DATS now, but started with WT-1
> The term 'beating' sounds like you
> are suggesting intermodulation.
> Is this the case?Right. The differance frequency of the 2
Fs's. Too low to be heard as a tone, but
discernable as slight phasing effect .
Edits: 05/05/14
Do you have any idea why that would not happen when the drivers were in parallel? Wouldn't the two midrange drivers express their own individual resonances anyway?
> Do you have any idea why that would not
> happen when the drivers were in parallel?
Sorta metaphysical, but evedently because the
signal 'wave' travels (in the case of series)
accross the drivers one at a time, while crossing
both at once in parallel ?
Actually I was referring to the midrange drivers with the intermodulation.
But with regards to the woofers if we are talking about a resonance, it is mechanical in nature and so would seem to manifest either way. That is not your experience?
I can tell you that I have seen a number of very successful speakers using a series woofer arrangement.
> That is not your experience?
Yes. That is not my experience.
> I can tell you that I have seen
> a number of very successful speakers
> using a series woofer arrangement.
No doubt .
Well our experiences have been different, so we've come to different conclusions... like that never happens!! I will look for that difference in resonant frequency impedance bumps that you observed next time I run measurements though - I hadn't noticed it, but that may well be because I wasn't looking for it.Unfortunately there are some significant technical hurdles when it comes to building a practical 32 ohm woofer: When we increase the voice coil's DC resistance, the Qes will go up proportionately... UNLESS we also increase the BL.
There are two ways that we can increase the BL: We can make the magnet more powerful (which is expensive and has practical limits); or we can increase the number of turns of the voice coil inside the magnetic gap.
If we increase the number of turns in the magnetic gap by making the wire thinner, thermal power handling goes down rapidly. If we increase the number of turns in the magnetic gap by making it a multi-layer voice coil, the voice coil inductance and moving mass both go up, the former inevitably rolling off the top end, and the latter trading off efficiency but gaining low-end extension in return.
My point being, like everything else in speaker design, high impedance woofer design is a juggling of tradeoffs. The best we can hope for is to be informed jugglers, and/or catch our mistakes early!
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 05/03/14
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