We want to do is plug into a single channel and send the high frequencies to the mains and use the HPF to mute the lower frequencies. We want to use the aux sends to send signal to our subs. However, the aux send signal is after the HPF so it does not work.
Outside of using two channels, one channel going to the main with HPF on, and another just going to the sends for the subs, is there a way to accomplish this?
I read (on Chat GPT) there is a way to send the aux signal pre-eq but cannot seem to figure out how.
Chat GPT can be fun and useful for some things, but has led you astray here.
The CQ has two send source points (tap off) points from input channels to outputs which are set per output.
You can see them in the block diagram here - https://www.allen-heath.com/content/uploads/2023/09/CQ_User_Guide_V1_2_0_iss3.pdf#page=146&zoom=310,25,26
Post-PEQ (Pre-Comp) - to retain dynamic range for monitoring
Post-Comp - to include all channel processing for routing to fill speakers and the like
Thanks Keith for the sad confirmation – both send source points are post the HPF.
Is there a way to feed a single input to two channels simultaneously, so I can send one to the mains with a HPF and the other to the sends (subs) without the HPF?
Using a separate aux only for instruments with sub-low frequencies (bass, kick, etc.) is a sensible and common practice.
However, it is not yet entirely clear to me why you need an HPF in your mains for such a channel.
If you use a PA with subwoofers, this usually uses frequency management, which only sends the corresponding sub-low frequencies to the subwoofers and the remaining frequencies (without the sub-low frequencies) to your main.
Your mains are therefore certainly already using an HPF in the PA, which also protects them from overloading due to frequencies that are too low, if that is your concern.
So an additional HPF would not improve this and could even accidentally remove fundamental tones from your bass guitar.
However, if your PA in the mains does not limit the low frequencies, it might make sense to do this generally with an EQ in the mixer - probably the GEQ.
Subs have a built-in crossover, so it is automatically filtering out all the high end and sending the signal via Aux.
I currently use a second/separate channel to send the signal to the mains and use HPF to filter out below 200hz. I suppose I could just use the EQ instead.
Because of where the HPF sits in the chain, we can’t use one channel as that would block all low end out to the sub. And the bass player wants high end to the main, but without HPF engaged it puts stain on the PA speakers.
On other channels (mics), when I filter out too much low (above 100hz), it sounds thin, so I have to do it on a per-channel basis (vs a filter on the mains).
Or am I missing something?
My bassist always used an amp but am trying to get smaller and skip the amp.
without HPF engaged it puts stain on the PA speakers.
Maybe the level of bass is just set too high for your main and too low for your subs.
But you’ve found a solution and everything is fine.
My bass player wants to use the PA as his amp.
My bassist always used an amp but am trying to get smaller and skip the amp.
So you want this change - not your bassist.
So would an alternate solution, be to run the signal to the mains, and then have the sub pull the signal from the mains, letting the speakers split the frequencies? Or vice versa?
Certainly not.
But we don’t know which PA components are involved.
Perhaps you have a mini PA with only relatively small tops and subs that reach relatively high frequencies.
If it is not a coordinated system of tops and subs that produces a balanced frequency response, then, as already mentioned, an alternative could be to limit the lower frequencies of the main PA that is overloaded by the bass.
If vocals actually sound too thin, you could possibly mix them also into the subs.
But that depends, among other things, on where the specified crossover frequencies are between the tops and subs.
… I’d rather control the frequencies on a input basis, not a blanket solution.
You don’t lose the ability to HPF cut your inputs individually if you view your tops and subs as a unit.
I understand you to mean that you run your subs up to 200 Hz and your tops still full range down to 50 Hz.
I’m not saying you have to, but please try at least once to cut your tops in this dangerous bass range and to get the missing lows of your vocals by mixing them into your sub aux.
If your subs play up to 200 Hz, that’s exactly where you’ll find the senor fundamentals of male voices.
And if that works, you could probably save yourself the second bass channel with HPF.
That sounds like a solution. I will see if it works.
One issue for me is that I also use the system - without subs - for small acoustic gigs. It’s just guitar and vocals. I have to have a different setup for both.
One solution would be to instead of turning the HPF on the speakers themselves, turn them on the mains and then run the lower end to the subs and have a different show set up for when I play acoustic with the HPF set differently on the mains.
