Subs - out through Aux or let he crossover handle it

[bradneal]

I have just picked up a couple of 800W powered Yamaha subs, and it was suggested that I run them through an Aux so that I can control which channel gets the big lows, and which are protected from unwanted low freq's.


So, this being the first time that I have worked with subs, what is standard protocol? Loop them through the mains and let the crossover handle the task, or take control and run them via one of my aux's?

Thanks,
Brad

[daver2]

Brad,

We originally looped ours through the mains but did not like what we heard.

We then shifted to running them from an AUX and problem solved.

Dave

[Brad Weber]

Do the subs and/or the mains have the requisite high and low pass filtering? Whether aux fed or fed from the same output as the mains and whether addressed by internal passive filters or an external crossover, you still need to get lows to the subs and highs to the mains rather than either trying to reproduce a full range signal.

If you can tell use the specific models of your mains and the subs as well as whether you have a crossover or speaker processor then that would help in offering more directly applicable responses.

[bradneal]

The subs are Yamaha MSR800W's and the mains are Yamaha C115V's

Thanks,
Brad

[SamG269]

You have the LS9. It would be best to use it post-aux. We have a Presonus SL and Im using a aux fed sub for our bass guitar and a lil piano and a lil guitar(no drum mics yet ). Sounds great! You would want it post aux that way it gets adjusted with the fader.

[SamG269]

Haha. Just read your other post. I see you have a SL as well. Great mixer. Do it post aux. You have to go into system and change it for whatever aux your going to use. Then turn up the fader. I do unity. And turn up the aux for whichever channel you want fed to the sub... Make sure your fader is up on the channel you want to use as well. And turn down the main fader so you only hear the sub.

[bradneal]

Originally Posted by SamG269

You have the LS9. It would be best to use it post-aux. We have a Presonus SL and Im using a aux fed sub for our bass guitar and a lil piano and a lil guitar(no drum mics yet ). Sounds great! You would want it post aux that way it gets adjusted with the fader.

Hi Sam,
Actually, the LS-9 is what I use at church. This is my personal gear, and I too use a PreSonus 24. So with 10 Aux's, I have plenty of real estate to experiment.

[bradneal]

Originally Posted by SamG269

Haha. Just read your other post. I see you have a SL as well. Great mixer. Do it post aux. You have to go into system and change it for whatever aux your going to use. Then turn up the fader. I do unity. And turn up the aux for whichever channel you want fed to the sub... Make sure your fader is up on the channel you want to use as well. And turn down the main fader so you only hear the sub.

Yea, I learned that the hard way a couple of weeks ago. I was playing some mp3 stuff in between sets and when I brought the mains down, the subs kept thumping, so I switched them to post.

I have only had the SL for about 4 weeks, so I am still in major learning mode. Quite a different approach as compared to the LS-9. But man, for 3 grand, that's a lot of desk! I didn't think I'd miss the motorized faders, but I really do, and would have gladly paid another thousand bucks to get them. My only other complaint so far is only having access to 2 effects.

[SamG269]

Yeah, sadly I haven't experienced the Ls-9. But I have played a bit with a PM1D and that is a huge difference. We got the small SL to get my feet wet with digital. Im very happy with the difference. I agree the motorized faders and having only 2 effects is a big con. But for the price? Guess its a trade off. I dont think there are many "tricks" to the board. Its very straight forward. I do like the presets that you can load. Although I usually tweak them to my liking.

[Brad Weber]

Originally Posted by bradneal

The subs are Yamaha MSR800W's and the mains are Yamaha C115V's

The MSR800W has an integrated low pass filter for the signal going to the subwoofer that is adjustable from 80-100Hz as well as a 100Hz high pass filtered 'pass through'. The C115Vs have no filtering or processing, thus the 'normal' setup would be the main outputs of the mixer to the subs and the high pass outputs of the subs to the mains amplifier inputs.

In an aux fed arrangement the aux out goes to the subs, which could then use the internal low pass in the MRX800Ws, and the console main outputs go to the mains amplifier. However, you're going to want to be able to high pass the mains. While you have a Fat Channel on each aux, I don't think there is a good way to get a high pass filter via the Fat Channel processing.

Aux fed subs can be very useful but are not without some compromises. For example, if you vary the aux or main level you vary the level of the high passed or low passed band, which in turn can actually change the acoustic crossover frequency. Even if you have the both the low and high pass filters set for 100Hz, if the low pass level is raised in level compared to the high pass signal then the resulting acoustical crossover is moves up in frequency. Conversely reduce the low pass signal relative to the high pass signal level and the acoustic crossover point moves down in frequency.

[waynehoskins]

Originally Posted by Brad Weber

Aux fed subs can be very useful but are not without some compromises. For example, if you vary the aux or main level you vary the level of the high passed or low passed band, which in turn can actually change the acoustic crossover frequency. Even if you have the both the low and high pass filters set for 100Hz, if the low pass level is raised in level compared to the high pass signal then the resulting acoustical crossover is moves up in frequency. Conversely reduce the low pass signal relative to the high pass signal level and the acoustic crossover point moves down in frequency.

I have a similar but different problem, if you can really call it a problem at all, using an 03D in LCR mode. The Main fader is only LR; the 03D does C through one of its buses, and its master is on another layer. I'm using this on a musical, so most of the show (ie, vocals) is panned Center, so it's not practical or useful to grab the main faders and push them up or pull them down. I knew this going into the first LCR show I did on the 03D so it's not a problem, just a peculiarity or inconvenience.

I generally prefer to not use aux-fed subs. I understand the benefit in some cases, and I don't mind it, but many times it seems like a band-aid solution that could be better addressed with channel high-pass filters and better system processing. Les and I did a system design back in '02 (which never got built) that used matrix-fed subs on a GL4K. With that arrangement, both main-fed and aux-fed subs were possible with only a little bit of console rerouting. Best of both worlds. Wish we could have seen it built; it's still a good design today.

[Tim Padrick]

Originally Posted by Brad Weber

..... if you vary the aux or main level you vary the level of the high passed or low passed band, which in turn can actually change the acoustic crossover frequency. Even if you have the both the low and high pass filters set for 100Hz, if the low pass level is raised in level compared to the high pass signal then the resulting acoustical crossover is moves up in frequency. Conversely reduce the low pass signal relative to the high pass signal level and the acoustic crossover point moves down in frequency.

While this is true, the results are still often far
superior to that of using a shelving LF boost/cut to try to get what you want, as these controls have very gentle slopes and have some effect as high as 1K, so they can add a lot of mud, or remove a lot of needed body.