Alternatives for connection to Preamp

[Nmaxy]

I have full range tower speakers, a VTF sub, and an Anthem pre/pro. It seems clear that I would use the Sub pre-out from the pre/pro for 5.1 surround sound etc. The pre/pro has extensive crossover management options and speaker setting options.

My question relates to using the subwoofer to augment 2 channel stereo listening. My goal is to run the two front tower speakers full range. Then, I'd like to augment that with the sub outputting only below a certain frequency, say 40 - 50hz, and I'd like to control that setpoint on the sub.

The Anthem has an analog bypass for the left and right pre-outs. This eliminates any conversion to digital and back, and therefore any signal processing. I would like to use this for 2 channel music. Unfortunately, if I set the left and right to analog bypass, there is not output from the sub pre-out.

My amplifiers for the front left and right have two sets of binding posts - could I use one of the extra sets to run to the high level input on the sub? I think in that situation, I have a full analog signal to the speakers and the sub, and only the sub crossover would be used to attenuate the sub. The downside is that for surround sound, I would have to change connections around. OR - is it possible to also leave the low level connection to the sub hooked up at the same time? There would be no signal to it from the pre-pro during two channel music. But it seems when I enable the sub low level output from the pre/pro, there would still be a signal from the high level speaker connection as well.

Thanks in advance for any help!

Neal

[Lwang]

It should work, since the line level and speaker level input are seperately buffered. In surround sound mode, the sub would probably electrically sum the line level and speaker level input and you could end up with a 6dB increase in the <50hz region. The only issue is that the LFE signal fed by the pre-pro to the line level input of the sub would also go through the low pass filter circuit of the subwoofer, thereby altering the LFE output, filtering out everything in the 50-120hz range.

To do it, you would first have to have it in 2ch mode, hook up the amp's speaker level output to the sub's speaker level input and calibrate by adjusting the sub's level knob and crossover freq. Then hook up the LFE/sub out from the pre-pro and adjust the level via the pre-pro's sub level. There might be regions where you get bass bumps due to the electrical summing of line level with speaker level, and if there is a phase shift in the pre-pro's crossover, you could get a decreased level or even complete suckout when a 180 deg phase shift is encountered.

[Nmaxy]

Lwang - thanks for your response. It raises some issues I hadn't thought of. To avoid 'bumps' or unintended filtering I should probably resign myself to detaching the speaker level connection when I go to surround sound movie mode. If I have to go to the sub anyway to change the crossover point to allow a fuller LFE range, I should be able to handle unplugging some speaker cable!! Thanks.

[Lwang]

I had plans to do the exact opposite with my 500w amp, feeding L&R's preamp out to the line level input, actively cross over @ 51hz and feed everthing above that to my main speaker's amp. Then feed the LFE signal into a integrated amp lying around to boost its voltage so that I could feed it to the speaker level input. Problem arises when LFE is filtered out above 51hz. I asked if the crossover could be bypassed on an individual input basis to no avail. So I just set the system up to no-sub and all LFE goes to the large speakers, but with the Meridian pre-pro, it limits LFE to -5dBFS.