Elac Uni Fi UF5 Speakers

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Mickyh

  • Jr. Member
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Elac Uni Fi UF5 Speakers
« on: 16 Jun 2017, 09:22 pm »
I have just received my new pair of Elac UF 5 Speakers
I always check the DC resistance at the terminals with any new speaker I get.
These measure 14.2 ohms !
These are rated at 4ohm impedance  & 14.2 ohms at the terminals seems high to me ?

Anyone know if this reading is correct ?

Thanks. Mick

richidoo

Re: Elac Uni Fi UF5 Speakers
« Reply #1 on: 16 Jun 2017, 10:40 pm »
Welcome to AC Micky

The speaker's impedance rating is a loosely interpreted average impedance of an AC signal over the whole bandwidth 20-20kHz. The impedance varies with frequency due to various reactivities in the speaker system, like port resonance, driver resonance, crossover parts interactions. All the speaker rating means is that you have 95% chance that the speaker will not break an amp rated to handle 4 ohm load.

To really know what's going on you need to see the impedance sweep. It shows the impedance and electrical phase at all frequencies. You can ask the mfg for it, or you can measure it yourself with a tool like Dayton Audio DATS, or similar. You'll see dips below 4 ohms, and you'll see peaks far above 14ohms. The average, in the eyes of the speaker mfg is 4ohms. There is no science to deciding what the speaker impedance rating is. It is part marketing.

The resistance you see with an ohmmeter is the DC resistance at 0 hertz. It really has no bearing on the operation of the speaker. Sometimes the DC resistance of a voice coil is given for a speaker driver, but never for the entire loudspeaker system because it's irrelevant. Well I guess it's good to check it to make sure you don't have a dead short that would hurt your amp.

srb

Re: Elac Uni Fi UF5 Speakers
« Reply #2 on: 16 Jun 2017, 10:54 pm »
The speaker was reviewed and measured at Home Theater Review and had an impedance of ~ 20Ω at 20Hz.  Not sure exactly how that might translate at 0Hz, but I'm guessing there's nothing wrong, particularly if they both measure about the same.

(The review is just for the UF5, so I think the UF6 label on the graph is a typo)

 

Steve

richidoo

Re: Elac Uni Fi UF5 Speakers
« Reply #3 on: 16 Jun 2017, 10:56 pm »
srb beat me to posting the graph.  :thumb:

I guess technically it should be called an 8 ohm speaker since these days residential speakers are rated only either 4 or 8 ohms. It's definitely not a 4 ohms speaker if this impedance graph is correct, because it barely dips below 8 ohms. An engineer, unencumbered by pesky marketing colleagues, would rate it accurately as like a 10 ohm average.

The higher impedance is intended to play well with inexpensive consumer AV receivers that are too weak for low impedance load.

Mickyh

  • Jr. Member
  • Posts: 3
Re: Elac Uni Fi UF5 Speakers
« Reply #4 on: 17 Jun 2017, 02:34 am »
Thanks for all the info,
 Of course i had to dive in & check the crossover out & the 3 Bass drivers in these are connected in series !!!
so with 3,  4 ohm drivers + the resistance of the 2 series inductors , 14.2 ohms is about correct for a quick
resistance check
Yes i do this check to make sure there are no shorts , got caught with that once before with a new pair
Nice sounding speakers but not very sensitive , will need a high power amp to get the best out of them
I'm sure

Russell Dawkins

Re: Elac Uni Fi UF5 Speakers
« Reply #5 on: 17 Jun 2017, 08:00 am »
Elac claims a nominal 4Ω impedance with a 3.4Ω minimum. Home Theatre review says nominal 6Ω with a minimum of 3.8 @ 397 Hz. I think speaker designers are inclined to be conservative so as to avoid liability by not leading naive users astray with their cheap amps that don't like to drive low impedances.

If Elac were to list 8Ω as the nominal impedance when the actual minimum is 3.4Ω to 3.8Ω, then some guy might select "Speakers A+B" on his cheap old receiver and blow his amp when he cranks it and the paralleled pair dips to 1.7Ω to 1.9Ω around 300 Hz—a frequency with a lot of energy in many types of music.

Phil A

Re: Elac Uni Fi UF5 Speakers
« Reply #6 on: 17 Jun 2017, 02:31 pm »
Welcome and congrats on the purchase

richidoo

Re: Elac Uni Fi UF5 Speakers
« Reply #7 on: 17 Jun 2017, 03:38 pm »
Russell is correct, I thought the vertical hashmarks went up by 2s, not 1s.  :duh: Thanks for the correction.

Mickyh

  • Jr. Member
  • Posts: 3
Re: Elac Uni Fi UF5 Speakers
« Reply #8 on: 22 Jun 2017, 12:57 am »
Does anyone have the crossover details for the Elac UB 5 ?
Component values , schematic , type etc
Just interested to compare this with the crossover in my UF 5 's