subwoofer placement

[rlsound]

When stacking a group of subwoofers, let's say, 4 4645c,
Is it better to have all the ports together, or all the drivers coupled together, with the ports on the left and right of the array?

Or does it matter?

[Mr. Widget]

It doesn't make any difference.


Widget

[rlsound]

Thanks Widget!

[svollmer]

Here's a picture of my 2245's. I just stacked them this way because they would look better this way with the grills removed. But I dont think it makes a difference acoustically.

[svollmer]

Sorry! I can't get the picture oriented correctly. The subs are stacked vertically.

[rdgrimes]

You mean like this?

[rlsound]

Looks good!

My question was just wondering in where having all the drivers together ( with ports out ) would increase the level further by coupling. I guess if there was an increase, it wouldn't be much too notice.

[svollmer]

[QUOTE=rdgrimes;372148]You mean like this?

Yes, thanks!

[ivica]

[QUOTE=svollmer;372156]

You mean like this?

Yes, thanks!

Hi svollmer,

The "problem" is NOT so easy. May be attached figure can be useful.
When the distance (D) between sources has raised the 'problem' become more "visible".

regards
ivica

[svollmer]

[QUOTE=ivica;372157]

Hi svollmer,

The "problem" is NOT so easy. May be attached figure can be useful.
When the distance (D) between sources has raised the 'problem' become more "visible".

regards
ivica

Hi Ivica,

I agree that there can be driver interactions.But isn’t the severity of it dependent on frequency?My subs are crossed over at 40Hz, so the wavelengths are much larger than the distance between drivers.

I guess what I’m asking is does it make a difference at very low frequencies assuming the drivers and ports aren’t a great distance apart?

I’ve never measured the subs, but I can tell you that they are tight and smooth.Much better than what I’ve heard in most high end audio stores.

[ivica]

[QUOTE=svollmer;372158]

Hi Ivica,

I agree that there can be driver interactions.But isn’t the severity of it dependent on frequency?My subs are crossed over at 40Hz, so the wavelengths are much larger than the distance between drivers.

I guess what I’m asking is does it make a difference at very low frequencies assuming the drivers and ports aren’t a great distance apart?

I’ve never measured the subs, but I can tell you that they are tight and smooth.Much better than what I’ve heard in most high end audio stores.

Hi svollmer,

"Fortunately" You have use the drivers for very low audio frequency range, so all of the mention "problems" would not be involved.
But a kind of reflections from the floor, walls and the ceiling have to be aware of. It would be interesting if You can do the measurements, and show us the results.

Regards
Ivica

[BeDome]

[QUOTE=ivica;372159]

Hi svollmer,

"Fortunately" You have use the drivers for very low audio frequency range, so all of the mention "problems" would not be involved.
But a kind of reflections from the floor, walls and the ceiling have to be aware of. It would be interesting if You can do the measurements, and show us the results.

Regards
Ivica

Back in the day, I used dual and quad fifteen, series/parallel JBL boxes by the buttloads, just stacked. Being that there is a delay (phase difference) between drivers run in series, it can certainly make a difference in how they are positioned. I am talking about using less EQ corrections to satisfy room acoustics by placement and or orientation of the actual Low Frequency driver cabinets. Not that I could hear, but measurements of the room with pink noise and live hot mics, the difference in how the LF cabs were positioned was very noticeable, even just flipping the stack on its side.Not sure if it was more the coupling of driver and port as much as the coupling to the environment due to the delay of series drivers. I understand that 90 degrees phase difference between adjacent drivers does not sound like much to contend with, considering all the other problems with stacks of drivers, but every little bit helps and if being able to use less EQ corection by re-orienting the stacks makes the whole night go more smoothly, I'll take it.

[dezmond]

I have 4 stacked on there sides, ports by ports , woofers next to woofers.

[ivica]

[QUOTE=BeDome;372160]

Back in the day, I used dual and quad fifteen, series/parallel JBL boxes by the buttloads, just stacked. Being that there is a delay (phase difference) between drivers run in series, it can certainly make a difference in how they are positioned. I am talking about using less EQ corrections to satisfy room acoustics by placement and or orientation of the actual Low Frequency driver cabinets. Not that I could hear, but measurements of the room with pink noise and live hot mics, the difference in how the LF cabs were positioned was very noticeable, even just flipping the stack on its side.Not sure if it was more the coupling of driver and port as much as the coupling to the environment due to the delay of series drivers. I understand that 90 degrees phase difference between adjacent drivers does not sound like much to contend with, considering all the other problems with stacks of drivers, but every little bit helps and if being able to use less EQ corection by re-orienting the stacks makes the whole night go more smoothly, I'll take it.

Hi BeDome,

If we are talking about the connection of the drivers 'in series' (owing to my 'modest' knowledge) I can imagine that there are complex impedance interaction between each-other, but as the same current is 'passing through' each voice coil at the same time, I can only 'imagine' that their mutual physical position and relative to the large surface ( ceiling, floor, walls ) would be of importance.

May be interesting reading:

http://www.harman.com/EN-US/OurCompa...s/multsubs.pdf

regards

ivica