Speaker impedance increase: possible? feasible? [Archive] - Audio & Video Forums


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01-09-2008, 05:53 AM

is it possible to increase the impedance of a pair of stereo speakers from 4 to 8 ohm? (35w).
Is it feasible - reasonably simple and inexpensive - to make such a change?
The reason is simple: the AV receiver I want to purchase drives 6 ohm and above only, and my old and very decent speakers have 4 ohm impedance.

If this question is simple nonsense, my apologies!

thanks in advance,

01-09-2008, 06:24 AM
There's not really a simple way of just changing the impedance. You could wire a 4 ohm resistor in series with the speaker and get 8 ohms total impedance, but you'll cut the volume output of the speaker down to such a point that you'd have to turn the knob on your receiver up higher and send more current to the speaker to get the desired volume anyway.

What is the model of receiver and speakers in question? The manufacturer's specs are mostly useless. Most of the time you can get away with 4 ohm speakers if you're careful. The 6 ohm rating is more to protect the manufacturer than to protect our receiver.
Start at a low volume, turn things up gradually - if things start to sound bad, turn it back down.

01-09-2008, 06:27 AM
it will really depend on the receiver you're looking at, i have some old 4ohm speakers that used to put my old kenwood (read crappy) receiver into protect mode all the time. so i went out and bought a midrange yamaha receiver and never had that problem again.

01-09-2008, 06:47 AM
Receiver: Onkyo TX-SR303 (or TX-SR304), Europe. I checked the manuals, and they are very clear about the protection circuit.
Speakers: Crown (yes!), 24-year old, 7.5kg each, with 20cm woofers... They took everything I threw at them for the past 2 decades, so I have to rate them as decent...


01-09-2008, 06:55 AM
Hmm, that's a small Onkyo receiver, but I've gotten away with powering crappy old Cerwin Vegas on an older, small Sony receiver, which is nowhere near as nice as that Onkyo.

There's no easy answer here - I'd feel more comfortable with a larger receiver, but it might work just fine. I doubt anyone's going to be able to tell you they've had success with that combo. Maybe other Onkyo owners can share their experiences?

01-09-2008, 07:40 AM
As Kex said, you can increase the resistance with an in-line resistor, but it won't solve the problem. Your receiver should be able to drive those speakers at lower levels though. Just not to their full potential.

01-09-2008, 09:41 AM
For reasons already mentioned, you don't want to mess around with your speaker impedence. IMO I would try driving the speakers with the new receiver, but just keep the volume low at first and turn it down if you hear problems (clipping).

I have been running some 6 ohm speakers on a crappy Kenwood (8 ohm) for some time now with now problems except at extremely high volume. That would probably have been an issue even with 8 ohm speakers, given the low quality of the receiver. Keep in mind the speaker impedance value is an average value only, and impedance will be much higher or lower at certain frequencies. Some 4 ohm rated speakers may not go much lower than 4 ohm, while others may get down near 2 ohms at some low frequencies.

The safest bet would be to get a 4 ohm stable receiver or get new speakers. Otherwise it is a roll of the dice. But I think you will be OK at moderate volume levels...

01-09-2008, 12:40 PM
Well, not an issue anymore. Went to a local store and compared the Onkyo TX-SR304 to Yamaha RX-497 (stereo only) and some Denon (st.). Never heard such an awful sound from Onkyo. Hi-Fi? Mid- to hi-range, it seemed that someone put 50 blankets over the speakers. Boy, it's really bad. (My Crown oldie has a high filter that more or less does the same thing...).
So I'm considering some real Hi-Fi instead (the Yamaha, the Onkyo TX-8222, and some NAD), which I think don't have the 6 ohm restriction.
thank you all,

01-10-2008, 12:28 PM
^Much better solution IMHO.

Good on ya'!