One sub, two different signals

MaxCast · « **on:** 12 Apr 2006, 03:32 pm »

What happens when you feed a sub's left line input with a signal and the right line input with a different signal at the same time?

Will it blow up

mcgsxr · « **Reply #1 on:** 12 Apr 2006, 04:41 pm »

I would expect that it will produce a blend of the two signals, it should not blow up though...

I figure that, since in the write up of my sub plate amp, it states that either L or R RCA can be used alone, since both sides are combined, prior to amplification.

I would expect mud...

CJ Paul · « **Reply #2 on:** 12 Apr 2006, 04:43 pm »

Heheh. It definitely will not blow up unless you do something completely jacked. There is zero reason why you couldn't combine line level inputs from two different sources. Heck, they make stereo to mono adapters and cables. That's two different sources technically.

MaxCast · « **Reply #3 on:** 12 Apr 2006, 05:01 pm »

I didn't think it would do anything.

I use two subs through a Merchand xo (plus amp and pre) for two channel. I was hoping I could take the sub out of a receiver, split it and run it to the subs other unused input. It could be possibel the the subs would receive each signal depending on what source was playing and how it was switched.

Wonder if I could get speaker outputs to balance this way. Might be worth a try as long as I don't smoke the subs. he he he

Corbin Johnson · « **Reply #4 on:** 12 Apr 2006, 05:45 pm »

Maxcast,

This is exactly what I do with my single sub. I have output running from my surround receiver LFE output to the subs LFE input and use this for Home Theater. I also have R&L outputs running from my stereo preamp to the R&L inputs for the sub for stereo. The sub receives signals from all three when I listen to Home Theater. It works fine for me. My sub has an integrated plate amp by parts express http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-808.

Corbin

MaxCast · « **Reply #5 on:** 12 Apr 2006, 06:19 pm »

Thanks Corbin.
So you actually use all three inputs on purpose for HT.

TomS · « **Reply #6 on:** 12 Apr 2006, 06:27 pm »

I'm doing the same thing with a pair of ACI Titans. LFE goes to both subs via a y adapter for HT. Left line out goes to one of the left sub inputs, Right line output goes to one the right sub inputs. Main L/R speakers are then set to "large" in the processor. For normal stereo and anything that is directed by the process to L/R, the lo-pass in the Titan takes care of crossover needs.

Per Mike at ACI, the inputs are "summed" so all you have to do is manage the relative levels and cutoff frequency (managed by the processor for LFE).

mjosef · « **Reply #7 on:** 12 Apr 2006, 06:33 pm »

I DIY a Marchand using the XM1 modules back in the 80's and Mr Marchand recommended that I use a 100ohm resistor on the output of each channel for a summed mono output. I was using a single subwoofer in a biamp stereo set up crossing over at 70Hz.

Folsom · « **Reply #8 on:** 12 Apr 2006, 07:26 pm »

Most plate amplifiers take a stereo input and will turn it into mono.... Look into their specification for this... The same deal is that you can normally plug in just say an LFE one RCA into the right (or left if specified) when there is only "stereo RCA inputs".

What do I suspect from the combination, electronically? Mud, yup, I do suspect some mud. Well it depends on where at because even in the recording, if done well, there will be no difference between left and right in the very low frequencies. Why do I say this? Well basically a combination of any insturment playing in these frequencies will become a summed mono sound. Now if they do not combine when recording the album will not reflect what the band would sound like if they where to all be playing in one area, a stage.

Solve this? Stereo subwoofers! Well that or try to cut things off as low of frequencies as possible from your main speakers....

I actually am going to be using XM1's with some FC's, upgrade opamps.... FC 1500uf upgraded PS10 with some shorting Jantas.

I plan on stereo subwoofers but that is because I found some really well priced plate amplifiers that fit drivers I already had, I just have to make boxes. The original plan was one subwoofer for a desktop rig but that is out now iwth my FR125s speakers and Dynaudio stereo subwoofer setup, yeah I changed my mind.

MaxCast · « **Reply #9 on:** 12 Apr 2006, 08:18 pm »

Hmmmm, I wonder if I played some bass, bass drums, and tuba through my DVD player then played some flutes, sax, and violins through my CD player....would I have an orchestra???

If I played the same CD in both players would I have double the output?

just kidding.

ryno · « **Reply #10 on:** 12 Apr 2006, 10:07 pm »

Using two inputs on a sub is a great way to combine 2 channel and HT systems. The best way is with a sub that combines the L/R input with the HT input after the L/R signal goes through the subs crossover not before. This way your 2 channel pre gives a full range signal to your mains, and the sub crosses over to fill in under the mains. For HT, your processor gives a high pass signal to your mains, and a low pass to the sub, which bypasses the xover in the sub. I like this because it doesn't put a crappy xover in line with your mains for music, plus takes some strain of your mains with a xover for HT.
My REL lets you do this, I think Corbin's PE will allow this too. I may be wrong, but it looks like the titan combines signals before the xover, so both HT and music systems have to be treated the same.
Ryan