Subwoofer connections, why single RCA/Jack input and output feed?

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

Joined
Dec 28, 2021
Messages
19
Location
UK
Have you actually measured the response with the sub out-of-phase?
Many prefer that position because it creates a dip at the cross-over frequency, so deep bass is not masked by low-mids/high bass.
no! :) but I'd expect any passive crossover to exhibit varying phase shifts as the frequency changes ... so for me it's back to "if it sounds good ..."

The .1 in x.1 means there's only one sub signal,
Correct and the generally accepted way to change an x.1 system into x.2 is to add a second sub ... nothing about the signals differing for sub 1, sub 2, etc.

Now I don't get why he wants to connect it to the patchbay...
Usually it's because you have a patchbay ... :)
 
Joined
Dec 28, 2021
Messages
19
Location
UK
And then what?
I'm not sure what you mean .... or whether a simple answer even exists. Factually, passive crossovers are simple RLC networks and as such will always introduce phase shifts which will differ as a function of frequency. This, coupled with the characteristics of the drivers, the cabinets used, amount of wadding, etc., etc., all contribute to how a loudspeaker "sounds" which could be why personal likes and dislikes are such a strong factor in loudspeaker choice.

... so for me it's back to "if it sounds good ..." :D
 

abbey road d enfer

Well-known member
Staff member
GDIY Supporter
Moderator
Joined
Jan 22, 2008
Messages
14,766
Location
Marcelland
I'm not sure what you mean .... or whether a simple answer even exists. Factually, passive crossovers are simple RLC networks and as such will always introduce phase shifts which will differ as a function of frequency.
It's not unique to passive x-overs; all analog x-overs produce phase-shift.
But phase-shift, on its own, is not audible, it's only when in combination with another version of the same signal that possible audible effects may occur, and in any case, it's the frequency response effects that are audible.
So it's quite certain that the combination of electronic phase-shift due to low-passing the subs and high-passing the monitors, and phase-shift due to distance between the sub(s) and speakers result in frequency response distortion that is audible.
 

canidoit

Well-known member
Joined
Apr 6, 2009
Messages
1,051
Location
Australia
Theoretically there's no stereo information below about 100Hz, thus none at sub-bass frequencies which are typically accepted as being below 60Hz, primarily because LF isn't terribly directional so with this in mind, it shouldn't matter whether the left or right channel or a sum of both is used.
If you record an instrument in a wide stereo mic'ing setup on the left mic, doesn't the bass frequencies only record prominently on the left side. When you play it back, doesn't the bass frequencies of that recording play back more on the left side of your monitors? The issue I have is that if I only feed the sub the right channel, I would not be getting an accurate representation of the bass unless I sum it into mono when feeding the sub??

left mic .......................................................... right mic
[instrument]
 

abbey road d enfer

Well-known member
Staff member
GDIY Supporter
Moderator
Joined
Jan 22, 2008
Messages
14,766
Location
Marcelland
If you record an instrument in a wide stereo mic'ing setup on the left mic, doesn't the bass frequencies only record prominently on the left side. When you play it back, doesn't the bass frequencies of that recording play back more on the left side of your monitors? The issue I have is that if I only feed the sub the right channel, I would not be getting an accurate representation of the bass unless I sum it into mono when feeding the sub??

left mic .......................................................... right mic
[instrument]
You don't listen. We don't suggest you feed a left or right signal to your subwoofer. You habve two options: either you manage to summ teh L and R signals in a way that does not compromize stereo separation, or you use the method recommended by Mackie.
 

canidoit

Well-known member
Joined
Apr 6, 2009
Messages
1,051
Location
Australia
The terms are confusing a bit. Left and right rca into DA out? Do you mean you have a DAC that has Left and Right rca outputs?
Then it's mentioned there is only one output from patchbay? Confusing.
Yes, the only output I have remaining is RCA on my DAC.
I only have one XLR patch remaining in my XLR Patchbay to use in my setup.
Are you saying you're trying to sum the left and right unbalanced outputs from the DAC to a balanced input on the patchbay, and then from the patchbay to a side of a stereo balanced attenuator? For a second it sounded like you could just use 2 unbalanced to balanced cables to feed your stereo attenuator then go to the sub in stereo but I got lost in the construction techniques and couldn't picture what the setup is.
Actually you are right, I could probably ditch the patchbay route and just go unbalanced to balanced with two cables from
DAC > Volume attenuator > Sub
I may have overthought this setup trying to include the patchbay as I thought maybe I need the flexibility to feed the sub some other signal.
Thinking about it, it will probably be one of those patch in the patchbay that never gets changed :/
 
Last edited:

canidoit

Well-known member
Joined
Apr 6, 2009
Messages
1,051
Location
Australia
Actually, now I remember why I wanted to include the sub in the patchbay, so that I have the option to patch a send signal from my DAW interface so that I can send a customised signal. I wanted the ability to control what frequencies get sent to the sub so that I can control the crossover from my DAW.
 

radardoug

Well-known member
Joined
Oct 10, 2009
Messages
1,140
Location
North New Zealand
So instead of trying to create an accurate monitor system, you just want to play around with the thumpy thing. Why didn't you say so up front?
Most of us would be trying to create an accurate monitor system so your mixes came out good. But if thats not your aim, it would have been nice to know at the start of the thread.
I'm out.
 
Joined
Dec 28, 2021
Messages
19
Location
UK
If you record an instrument in a wide stereo mic'ing setup on the left mic, doesn't the bass frequencies only record prominently on the left side. When you play it back, doesn't the bass frequencies of that recording play back more on the left side of your monitors? The issue I have is that if I only feed the sub the right channel, I would not be getting an accurate representation of the bass unless I sum it into mono when feeding the sub??

left mic .......................................................... right mic
[instrument]
OK, I did say it shouldn't matter whether you derive a feed from L, R or a mono sum but in my defence, I also said there should be no stereo detail below about 100Hz ... it somewhat depends on the production so the best solution to cover a wacky mix which might pan a ton of bass all the way off to one side is a mono (summed L + R) feed to the sub and FYI, that's my preferred approach.

I'll just add that if you really mic'd up an instrument with a "stereo" pair of mics - let's say a piano because that would have an appropriately massive frequency range - then no matter where the mic (or mics) were positioned, LF would be picked up by both mics even if they were positioned to give the illusion of the piano being off to one side of the stereo image. Remember that directional information is derived from mid to high frequencies because the human ear struggles to tell where true LF rumbles come from. If you used a single mic and panned it over to the left in the production, then I agree all frequencies could only appear in the left channel, provided there were no other open mics in that area ... this is why my preferred approach uses an L + R mono sum to feed a sub.
 

canidoit

Well-known member
Joined
Apr 6, 2009
Messages
1,051
Location
Australia
So instead of trying to create an accurate monitor system, you just want to play around with the thumpy thing. Why didn't you say so up front?
Most of us would be trying to create an accurate monitor system so your mixes came out good. But if thats not your aim, it would have been nice to know at the start of the thread.
I'm out.
No, accurate and flexibility is what I am trying to create by having the sub patched to a patchbay.

I have multiple speakers, which have different frequency characteristics, like the Ns10m is known for midrange and lack of bass, whilst my Dynaudio speakers reach a much lower frequency. With my different speakers, they require different crossover points from my subwoofer. So my plan was to set the sub at its highest crossover and control the crossover from the DAW by way of filter plugin.

Patching the sub up would allow me to have the option to feed it direct from my Stereo out of my DAC or receive a feed from a send output in my DAW (which will have a custom frequency signal sent to suit the speakers). This setup would add control of the crossover and volume to the sub and also mute the sub when I need to by giving it zero signal feed from the send output in my DAW.

Hopefully that clarifies it better :)
 

Latest posts

Top