Aux feed subs?

Re: Aux feed subs?

That's what I do with our X32 and link the mono bus to the stereo bus. But it still has a variable send for each channel that I use and adjust depending on the signal I'm receiving. Any particular reason you turn the subs down on the DSP vs the master aux/or mono bus send on the desk?

second thoughts... I need more sleep.
 
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Re: Aux feed subs?

It's not that the phase is changing with amplitude, it's that the crossover is changing to a place where the phase is NOT aligned. It's rarely possible to align the phase 3 octaves wide.

I guess we could get into an argument over aligning phase and how some apparent phase shift seen in measurements are really down to alignment of the measuring system etc. etc., but we would probably get lost and the topic at hand wouldn't benefit at all.
My suggestion however is that in a aux-fed sub application, the phase alignment is, or should be a moot point because one would not be running the same signal thru' the two systems, thus one would not have any immediate issues related to the alignment at crossover frequency, whether electronic or acoustic. In the event that alignment is needed to tighten up the response for any particular instrument, thaty can be done individually for each of the instruments in question, and we are seldom talking more than two, the bass and the kick, that needs to be tightened by proper alignment.
 
Re: Aux feed subs?

Regarding phase shift, and subs.
I have not read the thread for a while. I have been percolatin'.

It seems to me that the matter at hand is being looked at from the wrong end of the telescope.
I think that no matter how you go about getting a *haystack* low end on the kick drum, there is going to be phase shift.
EG, if you have a perfectly flat PA, both frequency and phase. Then you are going to have to boost a lot of LF on the kick strip to get that haystack. This is going to induce phase shift.
And to my way of thinking, no matter where you do get your boost from, it is going to bring phase shift into the equation. So, if you separate the crossover frequencies, and then boost the sub output, this is still going to induce relative phase shift. So, no matter where the gain comes from, if it is not naturally there in the signal when it reaches the board, there is going to be phase shift.

Alternatively. If you are using a lot of HPF on the input strips on the board, there is also going to be a lot of phase shift going on.

BUT, if you are using subs on an separate send, and most of your mix is not going to the subs. And if because of this, you are not using very much HPF on the board, and running your strips flatter because of this, then you will be inducing lest phase shift overall into the mix.

So, to my way of thinking at the moment, aux fed subs will not correct any phase shift in the low end, nor will they eliminate any in instruments going to the subs.
But, there will be overall much less phase shift in the mix/system.

Regards, Jack

second thoughts... I need more sleep.
Either that or you've been eating too much meat.
 
My suggestion however is that in a aux-fed sub application, the phase alignment is, or should be a moot point because one would not be running the same signal thru' the two systems, thus one would not have any immediate issues related to the alignment at crossover frequency, whether electronic or acoustic. In the event that alignment is needed to tighten up the response for any particular instrument, thaty can be done individually for each of the instruments in question, and we are seldom talking more than two, the bass and the kick, that needs to be tightened by proper alignment.

Then you are doing it wrong. Just because you send one input to the aux subs, doesn't mean you cut it out of the mains. Everything, unless a super special FX goes to the mains.
 
Re: Aux feed subs?

I guess we could get into an argument over aligning phase and how some apparent phase shift seen in measurements are really down to alignment of the measuring system etc. etc., but we would probably get lost and the topic at hand wouldn't benefit at all.
My suggestion however is that in a aux-fed sub application, the phase alignment is, or should be a moot point because one would not be running the same signal thru' the two systems, thus one would not have any immediate issues related to the alignment at crossover frequency, whether electronic or acoustic. In the event that alignment is needed to tighten up the response for any particular instrument, thaty can be done individually for each of the instruments in question, and we are seldom talking more than two, the bass and the kick, that needs to be tightened by proper alignment.

Wrong....

First, the phase shift caused by any misalignment in the measurement rig is irrelevant because you don't change the reference delay between measurements. You are only concerned with relative phase of one to the other.

Second, the transfer function may not be accurate when using subs on an aux, but if you are aligning the subs to mains you will benefit with addition for the instruments that are being sent to both.

I send a lot more than kick and bass.
 
Re: Aux feed subs?

We aren't concerned here about phase shift. We are concerned about the phase angle of the subs and the phase angle of the mains being the same. If they both shift together but are still the same, it is good.


Regarding phase shift, and subs.
I have not read the thread for a while. I have been percolatin'.

It seems to me that the matter at hand is being looked at from the wrong end of the telescope.
I think that no matter how you go about getting a *haystack* low end on the kick drum, there is going to be phase shift.
EG, if you have a perfectly flat PA, both frequency and phase. Then you are going to have to boost a lot of LF on the kick strip to get that haystack. This is going to induce phase shift.
And to my way of thinking, no matter where you do get your boost from, it is going to bring phase shift into the equation. So, if you separate the crossover frequencies, and then boost the sub output, this is still going to induce relative phase shift. So, no matter where the gain comes from, if it is not naturally there in the signal when it reaches the board, there is going to be phase shift.

Alternatively. If you are using a lot of HPF on the input strips on the board, there is also going to be a lot of phase shift going on.

BUT, if you are using subs on an separate send, and most of your mix is not going to the subs. And if because of this, you are not using very much HPF on the board, and running your strips flatter because of this, then you will be inducing lest phase shift overall into the mix.

So, to my way of thinking at the moment, aux fed subs will not correct any phase shift in the low end, nor will they eliminate any in instruments going to the subs.
But, there will be overall much less phase shift in the mix/system.

Regards, Jack


Either that or you've been eating too much meat.
 
Re: Aux feed subs?

So now that we know what we know, consider for a moment that it may not matter that much if the subs are aligned to the mains at all. If the subs are right next to the mains, it makes a big improvement. If the subs are no where near the mains the improvement will only really be where the mic is located when you align them. If that's the case, then maybe you are over thinking it. I'm not directing this at anyone in particular.
 
Re: Aux feed subs?

So now that we know what we know, consider for a moment that it may not matter that much if the subs are aligned to the mains at all. If the subs are right next to the mains, it makes a big improvement. If the subs are no where near the mains the improvement will only really be where the mic is located when you align them. If that's the case, then maybe you are over thinking it. I'm not directing this at anyone in particular.

This may partially explain why I usually prefer L/R sub deployment in most settings rather than a center cluster.
 
Re: Aux feed subs?

Wrong....

First, the phase shift caused by any misalignment in the measurement rig is irrelevant because you don't change the reference delay between measurements. You are only concerned with relative phase of one to the other.

Second, the transfer function may not be accurate when using subs on an aux, but if you are aligning the subs to mains you will benefit with addition for the instruments that are being sent to both.

I send a lot more than kick and bass.

You're probably totally right, my thinking is that most stuff you put into the subs you put in at a level that gives you a consistent response through the x-over frequency, thus maintaining acoustic/electrical x-over frequency correlation. The stuff that you haystack into the subs would be stuff that has a little signal around crossover frequency, so the main thing would be to make sure you have good alignment in time between the higher frequency content and the fundamentals that goes into the subs, like getting the snap and boom from the kick aligned for the right impact.
 
Re: Aux feed subs?

What does the word 'haystack' mean in the audio world?
It is a "hump" in the response-typically in the sub region. And usually around 60ish Hz. The highpass will provide the slope on the low freq side-and the slope on the HF side is sliding down to the full range response. Since in many cases the sub level is much louder than the full range response-when you look at a measurement you will see they "haystack' on the low freq. It looks like a pile of hay.
 
Re: Aux feed subs?

It is a "hump" in the response-typically in the sub region. And usually around 60ish Hz. The highpass will provide the slope on the low freq side-and the slope on the HF side is sliding down to the full range response. Since in many cases the sub level is much louder than the full range response-when you look at a measurement you will see they "haystack' on the low freq. It looks like a pile of hay.
Ah, ok...

Anyone knows of a swedish/scandinavian word for this term?
 
Re: Aux feed subs?

Ah, ok...

Anyone knows of a swedish/scandinavian word for this term?

Høysåte, høystakk, höbalar, höstack. ;)~;-)~:wink:
In norwegian I think we just call it "hump", maybe "puckel" in Swedish

Interesting sidestep that has developed, but what is the responce to my original question?

Wasn't that answered on page one? :D~:-D~:grin:
 
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Re: Aux feed subs?

That would be it :)

I want to nominate the word "Puckel" to be the new international term for this response feature.

And John C. makes a good point, I tend to notice the separation of bands when subs are not spaced closely with the tops, or when performers are far away from the speakers-Elton John at Caesar's would be a very recent example for me. The sound quality was very nice, just sitting about 6' in front of SL had it sounding a bit disjointed.

Best regards,

John
 
Re: Aux feed subs?

Looks like that after talking to some folks outside of the forums, I have come to a simple conclusion: I'm spoiled.

I often forget that when I use AUX subs, they are an extension of an already full range system. The L/R system is already capable of response down to 30-40hz, so when I add my subs in, the alignments seem to stand, as I align my subs well beyond their bandpass. So, my apologies for the confusion. My AUX subs are primarily an effect. :)




Evan
 
Re: Aux feed subs?

Looks like that after talking to some folks outside of the forums, I have come to a simple conclusion: I'm spoiled.

I often forget that when I use AUX subs, they are an extension of an already full range system. The L/R system is already capable of response down to 30-40hz, so when I add my subs in, the alignments seem to stand, as I align my subs well beyond their bandpass. So, my apologies for the confusion. My AUX subs are primarily an effect. :)




Evan
And this is where I'd need some clarification/education...

It seems like the pro's primary use of aux feed subs is for fx and the rest of the system is always(?) full range. If this is the case then you usually don't separate the mudd-offenders from the low end register other than not feeding the fx-sub with them.

If so, how do you overcome the issue of low end rumble from open mics and like as the channel strip highpass would be insufficient for this type of situation?

In my case I'm using the sub as a primary sub (remember I'm JV ;-) so one of my initial question remains. If you use the sub as I do in a 2.1 configuration, how would I then normally handle FoH fx/processing that in normal case would go to the main bus but now instead is split into 2.1 path (or should I even care)?

Oh, btw. If I were to say that I want to put a haystack on my subs then the men with tight white jackets using straps would probably come and give me some nicely colored pills ;-). Puckel sounds like a resonable word to use.
 
Re: Aux feed subs?

Looks like that after talking to some folks outside of the forums, I have come to a simple conclusion: I'm spoiled.

I often forget that when I use AUX subs, they are an extension of an already full range system. The L/R system is already capable of response down to 30-40hz, so when I add my subs in, the alignments seem to stand, as I align my subs well beyond their bandpass. So, my apologies for the confusion. My AUX subs are primarily an effect. :)




Evan
I am with you-I prefer to have the full range systems as full range as possible. that way you are not "knocking out" any of the low freq of say guitars/vocals etc.

Then the subs are used to get the added depth for kick/bass/synth/effects etc.

If you actually "crossover" between the subs and the full range cabinets-some signals will sound a bit "weak".

Yes the sub drive is quite a bit louder than the low end of the full range signal-so you aren't getting any "addition" in level by running the full range down low (on the instruments going to the subs)-but the other signals not going to the subs are more "full" sounding.

But that is what I like to do-others have different opinions.