Is there any safe way to double up speakers on my AV receiver?
Dynamic (voice coil + diaphragm [cone]) type loudspeakers of any size are a significantly complex load, especially at low frequencies, near their mechanical resonance frequencies. A primary function of a well designed baffle in some classic designs like a bass reflex enclosure (ported Helmholz resonator), or an acoustic suspension enclosure is to flatten the natural free air cone resonance peak of the speaker by loading it to a larger volume of air mechanically than it can encounter by itself. But the most efficient mechanical enclosure, the folded horn (like the classic Klipschorn) is only
I can’t see all your SR7000 specs on the Marantz site, but I do see that it talks about “capability for control of a second zone” which might be what you want. If you can still locate the manual, I’d read up on how that feature is intended to be used. As for hooking up a second set of 8 ohm speakers on each channel with an existing set of 8 ohm speakers, what you create is a nominal 4 ohm load for each channel. Ohm’s law says that twice the current will be wanted by the speakers for equivalent loudness in each zone (assuming linear and equal efficiency for your different speaker sets, which is probably slightly different in practice). Your amp is supposed to deliver 100 watts of power for each of its 5 channels into 8 ohm loads, but it may have enough internal resistance in each channel’s amplifier to deliver something substantially less into 4 ohm loads (or there maybe internal current protection circuits that are tripped more regul
Hook them up in parallel. A series hookup gives you a 16 ohm load into which, your amp will never develop full power, and which will present weird enough reactances that you will probably notice degraded sound. If you’re interested, back in 1961, Popular Electronics published an article on “The Sweet Sixteen,” which was a home brew speaker system, designed around 16 inexpensive 8 ohm small speakers, internally wired series/parallel (series to create 4 banks of drivers at 64 ohms each, then the 4 banks paralleled to bring the total array impedance back down to 16 ohms). It was a hugely popular home hifi project, and my Dad and I built several versions of it, that sounded pretty good for the day and the 10 watt tube amps we used. What made the series/parallel wiring necessary was the need to match the impedance of all those driver elements to the 8 or 16 ohm outputs of tube amps popular back in those days. But what made
Hook them up in parallel. A series hookup gives you a 16 ohm load into which, your amp will never develop full power, and which will present weird enough reactances that you will probably notice degraded sound. I agree about paralleling them, but.. Assuming linearity, it doesn’t make any difference if you chose series or parallel. The first limit you will hit (the first significant non-linearity, if you like) is the maximum output voltage of the amplifier. Serial is worse because it will require increased output voltage. The problem with paralleling them is that you may be asking the amplifier to supply either more current or more power than it is able to. In the worst case this could cause a failure, but it is far more likely that the amplifier will switch into some kind of over-current or over-temperature protection mode. It might turn off for a few minutes, it might just sound really distorted, or you might not even notice. One more note about this.. Protection modes are a safety fe
