Ron’s New System

[Ron Resnick]

Thank you, Ron. It sounds like you found the devices effective in your old system but now your system is different so I presume the devices are off and you no longer use them. Is that correct?

basically correct

I still have two of them on in the breakfast nook because that breakfast nook acoustically is unhelpful and it probably accumulates bass.

I have no doubt the AVAAs have efficacy. Pro audio products actually have to work, otherwise people don't buy them.

 

[Atmasphere]

PSI AVAAs have efficacy, Ralph. It is a pro audio product -- not a baffle us with bul%sh*t / I cannot tell you how it works / secret proprietary quantum woo-woo technology high-end audio product at 5X the price.

I know how they work as I had the idea of an active bass trap myself. Using subs to kill standing waves is far more effective nor is doing so woo-woo

I've worked with pro audio gear all my adult life as I've had a studio that long too.

Dr Floyd Toole developed the Distributed Bass Array concept which is what we're talking about to kill standing waves. Standing waves can manifest as a bass null or a bass peak ('room mode' as you put it). A peak is when the standing wave reinforces the existing bass note; a null is when it cancels.

Your speakers have rear-firing information and that information has bass energy which is not in phase with the front output after bouncing off the wall behind the speakers. That makes them less prone to standing wave problems (which occur in any room with regular dimensions and even some that don't) but does not eliminate the problem. It does make it a bit easier to deal with.

 

[Holmz]

I know how they work as I had the idea of an active bass trap myself. Using subs to kill standing waves is far more effective nor is doing so woo-woo

I've worked with pro audio gear all my adult life as I've had a studio that long too.

Dr Floyd Toole developed the Distributed Bass Array concept which is what we're talking about to kill standing waves. Standing waves can manifest as a bass null or a bass peak ('room mode' as you put it). A peak is when the standing wave reinforces the existing bass note; a null is when it cancels.

Your speakers have rear-firing information and that information has bass energy which is not in phase with the front output after bouncing off the wall behind the speakers. That makes them less prone to standing wave problems (which occur in any room with regular dimensions and even some that don't) but does not eliminate the problem. It does make it a bit easier to deal with.

I’m not sure that that is 100% Ralph.

Ideally one kills waves passively, and then tries to kill what is remaining actively.
(which may be more “at the same time” than a sequential set of steps.)

Just adding more subs may fill in nulls, but of one wants transient response, then they want to remove energy from the room and not add it.
But the only way to decrease the decay time, is to remove the energy.

 

[Atmasphere]

I’m not sure that that is 100% Ralph.

Ideally one kills waves passively, and then tries to kill what is remaining actively.
(which may be more “at the same time” than a sequential set of steps.)

Just adding more subs may fill in nulls, but of one wants transient response, then they want to remove energy from the room and not add it.
But the only way to decrease the decay time, is to remove the energy.

Actually its the other way 'round when it comes to bass. Subs will do about 95% of what needs to be done; traps and DSP can do the remaining 5%. This is because if there is a cancellation (null), no amount of amplifier power can overcome the bass null it since its being cancelled.

The problem usually isn't a bass boom (easy if it is) but a bass cancellation. For traps to really deal with that they must move about the room as the wavelength of the bass note changes; obviously impractical.

By adding subs the goal is not more bass. Its to break up standing waves and that does not take a lot of energy. Standing waves can be (as in Ron's earlier case) responsible for quite a lot of energy in the room; by using subs to break up the standing wave that bass energy peak is vastly reduced or gone entirely.

One other thing that makes this possible: at 80Hz the wavelength is 14 feet. The ear needs the entire waveform to pass by it to detect that a note is there and a few more to winnow out what note it actually is. By that time (in all but the largest rooms) the bass note has bounced all over the room a few times; its 100% reverberant. That means that decay time and time alignment are not important for this to work and a mono bass signal can be used (the main speakers will reproduce harmonics, allowing the listener to locate the bass instrument in the sound stage), so long as the subs are not allowed to go too high. In most rooms, practically speaking, this is about 80Hz. Most of the standing wave problems occur at a lower frequency so this is usually no worries.