“I don't really understand the minimum impedance business—this receiver's is 6 ohms—so are my 8 ohm speakers compatible?”
Answer This Question
1-2 of 2 Answers
Impedance is the total resistance (reactive & DC) that a speaker or any electrical component has to electrical current flow. The less impedance, the less resistance to current flow, or put another way, the more current will flow through the device. Higher impedance "impedes" current flow, so the amplifier will deliver less current through the speaker. Impedance varies depending on frequency, so a quoted ohm rating for a speaker is just an average - although good speaker design should have the impedance curve without sharp peaks or substantial variations. These can cause an amplifier to overload, cause distortion, or even damage the amplifier. Older analog amplifiers were usually capable of driving 4 ohm loads, or two parallel 8 ohm speaker sets. New "digital amps" have switching power supplies and outputs which do not have the high current, low impedance capabilities of the older analog amps... so you most often see amplifiers today rated for 6-8 ohm loads. When presented with a lower impedance load (for example, 2 sets of 8 ohm speakers in parallel), the amplifier safety circuit may shut down or disconnect the load to prevent damage to itself. Older analog amps were often capable of driving low impedance loads with ease, due to the nature of their design (and the massive high current stepdown power transformers & full wave line voltage bridge rectifiers used in the power supply).. But, they were bulky, heavy, and not as efficient as modern switch-mode power supplies, and the digital switching type output amplifier itself (class D or above). My old MacIntosh MC2300 amp can drive 16, 8, 4, or 2 ohm loads with ease... sounds great even today, but does weigh over 100 lbs. If your amplifier output is rated for 4 ohms, then it could not only drive a pair of 8 ohm speakers in parallel, but had twice the power output at 4 ohms than it would at 8 (in theory). I.E., if your amp is rated at 100W at 8 ohms, but can safely drive 4 ohm loads, then in theory the amp can produce 200W. So, your 6 ohm rated amp output is better than 8 ohms, because it can produce more current (power) in theory. But, you would need speakers rated at 6 ohms to take advantage of that. Another reason to want lower output impedance in your amp output is for something called damping factor. The lower the impedance, the higher the damping factor. It's complicated, but basically high damping allows the amp to control unwanted speaker cone movement better, especially a woofer which has a lot of mass and therefor inertia. High damping factor helps reduce speaker overshoot and ringing, which are forms of distortion. SO, you can safely use 8 ohm speakers on your receiver/amp with 6 ohm output impedance (and that is a MIN rating, not max)... but you should NOT use 4 ohm speakers on a 6 ohm rated amp. Most amps these days have overcurrent and other safety circuits built in, but you could possibly still damage the amp or speakers under certain circumstances. Anyway, lower amplifier output impedance is usually a good thing, so just make sure your speaker are the same NOMINAL impedance or HIGHER and you should be fine.
Sorry, there was a problem. Please try again later.Yes. This amp will drive your 8-ohm speakers fine. 6 ohm is more difficult to drive than 8 ohms. 4 ohms is even more difficult to drive. The lower the number, the tougher it is for an amp to drive.
Sorry, there was a problem. Please try again later.