Disconnect the woofer


If I was to unhook the wires to the woofer of my (non-biwireable) 3 way speakers, would the crossover parts that make up the low pass to the woofer still be using up energy from my amp, or is there no energy loss since the circuit is not completed?

I am thinknig of active bi-amping the woofers with another amp and letting the mid/tweeter run off my orignial amp.
koestner
>If I was to unhook the wires to the woofer of my (non-biwireable) 3 way speakers, would the crossover parts that make up the low pass to the woofer still be using up energy from my amp, or is there no energy loss since the circuit is not completed?

You don't want to do that because you're going to loose baffle step compensation, the high frequency roll-off needed to sum-flat and any notch filters present.

Energy used is also the wrong way of looking at it.

Passive bi-amplification would be more appropriately called active bi-wiring because the same signal is being fed to each amplifier which is in turn limited by the peak voltage of the summed signals.

An amplifier good for 100W into 8 Ohms will swing 40V peak positive and negative, thus allowing for a 20V peak signal into each of the high and low pass filters of a 2-way or 25W per for 50W total with sine waves. I'm going to completely ignore that driver impedance is reactive and concede that's a simplification with the real numbers being more like 22V and 18V for typical 2-way cross-over frequencies for 30W and 20W for the same 50W total on sine waves.

When you split the signals before the speaker level cross-over, each amplifier sees the same input and clips at the same place it would (assuming competent amplifier design) with just a single amp. With two 100W amps, or even a beefy 200W amp on bass and 100W on the tweeter you're still getting only 50W total out (with a 3dB crest factor; 25W with a 6dB crest factor, etc).

That's not interesting.

You can come up with all sorts of pseudo-science about not having the DC resistance of coils in the picture, although their tenths of an Ohm are inconsequential against the 5+ Ohm DC resistance of an 8 Ohm driver's voice coil.

To get performance gains you need to split the signals before getting to your power amplifiers and scrap the speaker level cross-overs. Typically that's done with active circuits although passive line level implementations are also possible.

That needs to be at least as good as the transfer function provided by your passive cross-overs which includes compensation for baffle step, rising response, driver resonances, differences in the acoustic centers, etc.

Obviously none of that is present in an off-the-shelf unit or even a programmable one just set for cross-over points and slopes.

You're not going to duplicate that without measurement capabilities and filter design knowledge; so if you want to bi-amp for performance you need to buy speakers with an outboard line level cross-over or build a proven design that works that way.
All that's why I replaced my modded Dahlquist DQ-LP1, with a modded TacT RCS 2.2X, after 23 years. It was Linkwitz's writings, in the early eighties, that got me started bi-amping at home. I'd been doing it for years before that, in live venues, but his articles inspired listening room experimentation, and the first LS3/5A's that I built.
Sorry to get back so late. The speakers are Mag 20.1 and I disconnected the woofer by not hooking the wire from the crossover to the woofer inputs on the panels. I am using open baffle subs for 110 Hz and lower and it sounds great. I split the signal from my preamp. One leg to my amp and then to the Mags and the other to a Velodyne SMS1 and then to another amp where the output signal has low pass of 110 Hz at an 18 db/oct filter. This is what Magnepan recommends as a frequency and slope if I choose to bi-amp. As to why I did this, is because the Mag woofer is the worst part of the speaker. The mids and highs are glorious, but the woofer is not very dynamic and need tons of power. WTH, who needs that? This is just an experiment though, but I must admit, it does sound good. Thanks for all the feedback.
The 20.1 crossover is jumpered, and as long as you are removing the LF signal from the input, via an active x-over(with jumpers removed); you shouldn't have any issues. I'm, using a modded TacT 2.2X to actively bi-amp my Maggies, with tubes above 250Hz/SS below w/a 10th order slope and transmission line woofers. Open baffled woofs would(of course) be accurate/fast enough to seamlessly blend with planars also, if driven with amp that can control them, and avoid excessive overhang(amp and woofer have to trace the signal faithfully). An interesting balancing act.
Koestner -- Since the Maggies are designed for both bi-wiring and bi-amping, and you are using their passive crossover to feed the mid/high frequency section, why didn't you just disconnect the low frequency section by removing the jumper from the low frequency crossover input?

Rodman99999: The 20.1 crossover is jumpered, and as long as you are removing the LF signal from the input, via an active x-over(with jumpers removed); you shouldn't have any issues.

It sounds like he is not doing that. He is supplying a full-range signal to the Maggies, which goes through the speaker's passive crossover to the high frequency panels. And he's using an electronic (active) equalizer to provide a low-pass function for the signal which is applied to the separate open baffle subs. I suppose that's within reason, if not ideal.

Regards,
-- Al