Gary D Olson
Skilled Tightwad
Is it a good plan to use the C70's "Invert" output to feed a powered subwoofer? The sub (Velodyne F-series) does feature a built-in crossover.
C70 & Subwoofers
- Thread starter Gary D Olson
- Start date
Gary D Olson
Skilled Tightwad
Negative. No Invert switch. I plan on trying it over the weekend. I believe its intended purpose was easing the load on the power amp when simultaneously playing a second pair of speakers. What results are you getting? Have you tried this with the M70?
The inverted pre-outs have two intended purposes. The most simple purpose, which can be used even with just one amp and one pair of speakers, is to invert one of the channels as it passes through the amp, and then fix it again by inverting the speaker wires on that same channel. That means content that is the same on both channels (usually Bass) will hit the opposite voltage rails of the amp (positive and negative) instead of the same voltage rail as it passes through the amp.
The other purpose is to be able to bridge amps. This works great for amps that don't have a built-in ability to be bridged, and works on pretty much any amplifier that has a common ground.
If your subwoofer and your mains overlap in terms of frequency response, and they are out of phase with each other, they could potentially cancel out each other's bass. Most subwoofers either have an invert switch or even better, an adjustable phase knob, to be able to solve this problem. In the absence of this switch or knob, the inverted pre-outs on the yamaha could be used to invert the polarity of your sub relative to your mains. I have to say though, for a sub to not have this built-in... doesn't reflect well on the subwoofer.
Gary D Olson
Skilled Tightwad
What if the positive and negative terminals on the power amp are connected to the negative and positive terminals on the back of both speakers? Doesn't this reverse phase? If so, this would match phase with the output from inverted output, eh?
Yes it would, but having both speakers wired normal vs. having both speakers wired inverted is essentially the exact same. All that matters is that they are both wired the same. If you are talking about swapping the wires on your speakers vs. swapping the preamp output cables over to the inverted preamp outputs in order to fix a phase issue with your sub, you could go with whatever you feel is easiest.
Gary D Olson
Skilled Tightwad
I'm a bit confused. Would it fix the phase issue if positive & negative were switched through the normal output but wired normally through the inverted output?
On each channel (left or right), you can either use the inverted pre-out with the speaker wired normal or use the normal pre-out with the speaker wired in reverse to invert the phase/polarity. You could do it one way on one channel, and the other way on the other channel if you really wanted. If you used both the inverted pre-out, and wired the speaker in reverse on the same channel, it will return the phase/polarity of that channel to normal.
Regardless of which way you choose to do it per channel, you need the resulting output from both of your speakers to be either normal or inverted. If one is normal and the other inverted, they will cancel out each others bass, similar to the issue you are trying to fix with your sub. There is also no guarantee that inverting the phase/polarity of your main speakers will actually fix the issue with your sub, but it's certainly worth trying.
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