Electronics > Beginners
Changing the impedence of a speaker driver
radiolistener:
--- Quote from: soldar on May 11, 2019, 01:45:17 pm ---Designing an audio transformer with a good, flat response over the entire range is quite a challenge. It is not trivial.
--- End quote ---
yes, it's not easy. But all depends on requirements :)
On the other hand active amplifier always add some noise, has very limited dynamic range and IMD.
Designing amplifier with high dynamic range and low IMD is also quite a challenge and requires expensive components :)
soldar:
Again, a proper crossover filter should take care of the problem. Getting or building audio transformers is the least practical solution. I would rather put a couple resistors in series. What power are we talking about? Who cares if half is wasted?
Again, "4 ohm" is strictly nominal. The impedance varies over the range of frequencies. Search for -- speaker impedance curve-- and you will see what I mean.
Zero999:
It's also highly likely the amplifier will be able to drive 2Ohm loads with no problem, especially if it's a modern amplifier with over-current protection. The downside is it won't be able to delver as much power, as it would into the rated load.
It's quite likely cheaper to buy new speakers with the correct impedance, than a transformer, which will be more expensive.
Calvin:
Hi,
"...and I believe it creates a net impedance of 2 ohm when connected through a crossover."
That won't happen if a proper xover is used.
Within its passband the branch of a xover shall not change the speaker drivers impedance.
In its stopband the filters impedance rises and dominates the combined driver/filter impedance the amplifier sees.
As for example the tweeters passband falls into the stopband of the woofer (and vice versa) the amplifier will only see the woofer impedance up to the transition frequency point and the tweeter impedance above, hence 4Ohms over the whole frequency range.
Due to this no impedance matching transformer is required.
regards
Calvin
dietert1:
A contemporary solution with much better results is activation, i. e. another amplifier for the second pair of speakers. Then digital filters can be used as crossover and for room correction, resulting in high sound quality. Let's mention miniDsp as a supplier. Twenty years ago that could be obtained only using extremely expensive analog equipment ("high end"). That kind of analog equipment is obsolete nowadays.
Regards, Dieter
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