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In Reply to: OK, thanks, but I guess I asked the wrong question posted by mhardy6647 on February 17, 2007 at 11:19:11:
mrhWhen you hook up a speaker to a tap of lower rated impedance
the impedance variance of the speaker becomes less of an issue
whether at crossover points or at the bass resonance point.
If you were to draw the associated loadlines you would see that
the lower impedance tap would give up a more horizontal line
which the % deviation of the variable impedance of the speaker
would have less affect on the gain (slope of the loadline).
This also explains why the bass is less bloated on the lower tap
because as the imp of the woofer increases the gain changes less.
If you have your 16 ohm speaker hooked up to the 8 ohm tap and
you have plenty of gain/dynamics then don't change it because
the gain/dynamics are the only improvement you'll get IMHO.
Follow Ups:
Hi.I measured for the first time last fall the impedance of my re-built bi-wired KEF speaker systems & found the lowest dip is about 10R across the 20Hz to 20KHz spectrum.
Basing on this observation, I tried to tap the speaker load up to 16R instead of 8R, the way it has been hooked up & audtioned it with
my LPs, test CDs & DVD-audio disks.Guess how it sounded like, the HF get brighter & bass get thinner.
It sounded like the entire response was tilted gently upwards toward HF. This did not sound right to me ears.So, I tapped it back to 8R & the response get back level with HF & LF pretty balanced sonically to my ears.
So how did my speaker impedance measurement & its sonic effect go along with what you just commented?
c-J
CJSounds like you had zobels installed
Which negates the "normal" imp curve of a driver
And sometimes reverses it - if done incorrectly
'found the lowest dip is about 10R across the 20Hz to 20KHz spectrum'That doesn't seem right . Re of 10 ohms would be a nominally 15-16 ohm speaker . What model is it ? If your Kefs are like the Cadenzas I used to have , impedence dropped to a minimum of 4.8 ohms , the drivers on their own had Re of 4.5 ohms making it an overall 6-8 ohm load .
cheers
Hi.You did not read it right: I said I "rebuilt" & "bi-wired" it.
All your assumption is wrong as it is no longer a KEF technically.
It was a Celest, rated 8R. But its lousy aluminum dome tweeter rang like hell so I replaced it with the much much more musical sounding Norway SEAS midrang-tweeter with 1.5" impragnated soft fabric dome diaphram, rated 4-8R, 91dB/m with pretty flat & smooth response from
1.5Khz - 15KHz.The goddamed micky mouse X-over was a cheapie joke, so I modified it to bi-wiring (which has improved the sound big bigtime), & replaced all the tiny 'lytic caps with huge non-polar PP film caps, & rebuilt it on a large fibreglass PCB to provide abundant copper surface to carry large currents. Only the tiny traces of copper gapped in between current carrying copper conducting surfaces were etched out to provide the necessary insulation.
To avoid vibrating which most X-over networks suffer bigtime when installed inside the air-turbent cabinet, I have the large X-over PCB installed outboard in a plastic box (non-magnetic), located just behind my power amps, floated on the floor with semi-rigid foam lifter. Nothing taken for granted.
This also serves as DISCRETE bi-wiring application.
I actually measured the speaker systems impedance. NO guessing like you.
c-J
Hi ,
What model was it ?cheers
Hi.it was a Celeste? As I said clearly it is technically no longer a KEF after I rebuilt it.
BTW, do you have a formula/software to calculate the mean effective impedance of a speaker system given its impedance chart?
Dan is correct. Exchanging better damping factor for reduced power O/P is a GOOD bargain, most of the time.
Eli D.
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