07-16-2021 Post does not mapped to Knowledge Tree Romy the Cat Boston, MA Posts 10,156 Joined on 05-28-2004 Post #: 1 Post ID: 26193 Reply to: 26193 ULF: where is the borderline....? You have a nice very much full-range, preferably multichannel, playback system, and you like what it does. Now, disconnect your very lowest channel. Disconnect it and get use to this sound. Then put the lowest channel back to rotation. You got better sound all together. However, admit to yourself that “something” got worse. How do you deal with it? "I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

07-16-2021 Post does not mapped to Knowledge Tree Paul S San Diego, California, USA Posts 2,657 Joined on 10-12-2006 Post #: 2 Post ID: 26196 Reply to: 26193 ULF Issues, or ??? Romy, is this a trick question? You are the only person I know of with time aligned, true IB ULF channels using 4 Aurasound sub-woofers, so who's going to answer your question?  The first thought that came to my mind was how some "Big Music" composers let some musical lines be "carried on the ULF", like the ULF is buoying it along. I have observed that not having proper ULF slights this effect. But I don't have effective ULF in the first place to know what problems it causes. I know that one "needs" a balance of HF and LF; but you also have the spectacular RAAL ribbons...? One thing is to be sure perceived problems do not inhere in the recording. Of course, "phase" is always an issue at ULF... Best regards, Paul S

07-17-2021 Post does not mapped to Knowledge Tree Paul S San Diego, California, USA Posts 2,657 Joined on 10-12-2006 Post #: 3 Post ID: 26199 Reply to: 26196 DSP ULF? I forget if you started out by setting the phase and level(s) of your ULF with DSP to begin with. Not to cave in to herd mentality, but it might be "worth it" to rent a DSP/D (servo) amp(s) combo to play with. If nothing else, that amp has to modulate something like 2 1/2 pounds per channel (driver mms), not to mention dealing with the back EMF from something like 60 lbs. of magnets! Paul S

07-23-2021 Post does not mapped to Knowledge Tree rowuk Germany Posts 454 Joined on 07-05-2012 Post #: 4 Post ID: 26209 Reply to: 26193 ULF in any reasonable living space is subject to the Schröder frequency of that room The frequency where your room turns into a pressure chamber changes the way that we perceive bass. This is how we get "bass" in a too small space like an automobile. When removing the ULF channel, all of the music is transmitted in a natural way for our ears to process. Adding the ULF channel back usually shows the hard knee of the switch between radiation and pressurization. Wavelengths too long for the space fold back. How I deal with it? Open doors, windows etc until I get used to it again. Whenever I feel blue, I start breathing again.

08-02-2021 Post does not mapped to Knowledge Tree noviygera Chicago, IL Posts 177 Joined on 06-12-2009 Post #: 5 Post ID: 26225 Reply to: 26193 Level I would try reducing the level of lowest channel or only play left or right side (if stereo ULF). Then run your experiment again.