Impedence & DC Resistance

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I have a pair of old wharfedale dovedale SP's. Thats the ones with the double 6.5" mid bass drivers as appose to the single larger driver. Anyway, i have replaced the tweeters with "ScanSpeak D2905/950000 8ohm" and the bass drivers with "H1215-08 CA18RNX 8ohm". The midranges are origonal as i was able to re-centre the cones.

Now my question is, how can i find out the origonal impedence of the old speakers, so that i can make sure i have chosen the correct drivers to replace the old ones. When i measured the DC resistance accross the old wharfedale Mid/bass drivers i got a reading of 12ohms, and the tweeters measured 4 & 5 ohms. The midranges measured 6ohms.

I assume that the midbass drivers would therefore likely be of 16ohm impedence, and the midranges to be 8ohm impedence. However i am unsure as to what the origonal tweeters would be. Can anyone suggest what impedence the tweeters would likely have been, also, seen as though i have 4x 8ohm H1215-08 CA18RNX speakers how would i go about adjusting the wireing so that i can as closely replicate the old 16ohm impedence that existed on the origonal speakers. FYI, the 2 mid/bass are wired to the crossover in a parallel connection therefore reducing the total resistance/impedence by half that of a single speaker.

Sorry for such a long winded post, but i have been trying to work out these issues for some time, and i didnt know what else to do other than post them all at once here.

Thanks in advance to any suggestions.

 

[Anonymous]

Unless you are going to do it properly...with sig gens and such like....the best approximation you can use is a multimeter across the speaker terminals......(not through the crossover). Measured this way you should see a drop in the quoted nominal impedance value....for eg....8 ohm speakers will measure something like 5.6 ohms......A 16 ohm will be around the 12 ohm mark. Not an exact science but as close as you will get with just a meter. Hope that helps.....

 

[Anonymous]

Great, thanks for the help, I have now found out that my tweeters were 6ohms impedence so ive replaced those with similar spec scanspeaks, My midrange were 8ohm and my old bass drivers were 16ohms.

I was wondering if anyone could tell me how i can now wire my bass drivers so that the two 8ohm speakers i have wired into the crossover in parallel could be altered to replicate the old 16ohm speakers.

The origonal 16ohm drivers used to be wired into the crossover in parallel. So i hav copied this, but seen as though the new drivers are 8ohm the impedence is incorrect. Is there any way of altering the wiring so that i can get the overall impedence to 8ohms as it would have been origonally with the two 16ohm drivers.

Thanks,
Andrew.