Yes, that’s what I thought he said. But if you have two subs placed symmetrically and you’re in the middle, how can they be out of phase with each other?
He also mentions the axial modes, but these have their ups and downs so that’s back to the original problem. It's not really you I’m questioning 😉
He also mentions the axial modes, but these have their ups and downs so that’s back to the original problem. It's not really you I’m questioning 😉
I have a 3 way placed on top of subs. I would but the ports sideways and have the woofers facing towards you. Ports into the corners.
Rob 🙂
Rob 🙂
And he forgot tangential modes in the family of room annoyance...
As far as i understand it the sub are not out of phase, the issue come from width mode with the first one null being right in the midlle of the room's width where sweetspot is located. As such there is a freq response 'hole' ( notch) in there.
The thing i wonder is how low or high in freq it does occur?
Yes it's the 37% rule (wrt axial mode) for sweetspot location for control room design.
That said, i think what C.Tatz implemented is nothing more than a scaled down version of Welti/Devandier approach of multisub:
https://audioroundtable.com/misc/Welti_Multisub.pdf
So i think the way system is discribed in video as 'stereo sub' is misleading.
If the issue come from boundary coupling in corners why not boundary couple with the front wall? From Audiothings's sketch it seems the sweetspot is already located at a less problematic location.
Audiothings, client don't want non environnment room?
That said, i think what C.Tatz implemented is nothing more than a scaled down version of Welti/Devandier approach of multisub:
https://audioroundtable.com/misc/Welti_Multisub.pdf
So i think the way system is discribed in video as 'stereo sub' is misleading.
If the issue come from boundary coupling in corners why not boundary couple with the front wall? From Audiothings's sketch it seems the sweetspot is already located at a less problematic location.
Audiothings, client don't want non environnment room?
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@audiothings,
If you consider a compact subwwofer but providing infra-bass extension, the Ripole design could be a possible solution.
Here's mine - a 2x12" model of 400x400x440mm size, nonetheless able to reach 16Hz without any boxy sound :
Doing so, you could use more compact 3-ways monitiors placed at the suitable height and position, and place the Ripole sub under the mixing console, on the floor.
But it's me, OK ?
T
If you consider a compact subwwofer but providing infra-bass extension, the Ripole design could be a possible solution.
Here's mine - a 2x12" model of 400x400x440mm size, nonetheless able to reach 16Hz without any boxy sound :
Doing so, you could use more compact 3-ways monitiors placed at the suitable height and position, and place the Ripole sub under the mixing console, on the floor.
But it's me, OK ?
T
Not par for a driver with a Vas of 462L and Fs of 18.4Hz, unless you plan Fb (frequency of box tuning) to be well above Fs.
For studio use, you want to hear what is going on down to 20 Hz (or below), so Fb should be that low.
Somewhere around 230L plus would be getting into the ballpark.
The port(s) should be on the same side as the driver for maximum placement flexibility, and should be in the range of 1/3" the Sd of the woofer.
As tight of a vertical alignment of the drivers is preferable.
What Carl stated in the video was the subs become out of phase with each other at the room's first and third axial nulls, not that you reverse polarity of a sub.
You simply do not want your primary mixing spot in located in an axial null.
The subwoofers are omnidirectional below 100Hz. Placing them at 2" from the wall eliminates a source of cancellation.
And you want the phase of the subs and mains to match closely through the crossover region, the circled area:
Getting the crossover and EQ alignment right is the biggest challenge, but you should be able to do as well with the QSC PLD4.2's filters, if you have a pair of the amps.
If you don't already have a pair, get a second- it will be probably will be less expensive than good components for a pair of 3-way passive crossovers.
I'd suggest tuning outdoors, save the presets, duplicate them and use it as a starting point for fine tuning in the room.
Personally, I think a +6dB low end boost as Carl shows is a bit much for mixing, but may be good for client playback.
Good to have a "flat" preset, and a few "house curves" to fit the level and genre.
Art
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Looking at the graphics in post#17, one thing that gives me some concern is that the 3-way top is sitting at an angle on the top of the sub cabinet. The tweeter is on the bottom, and it will be right above a large flat surface (the top of the sub cabinet). It is best to not have a reflecting/diffracting surface so close to the tweeter.
j.
j.
