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Total bass suck out at 40hz

So I'm a little slow, but it occured to me today to see if there were test tones recordings on Tidal of Qobuz. Yes there are. I have a radio shack SPL meter so I went to work playing them to see what I had in my room. I was shocked to find a total lack of audible bass at 40hz. At first I thought they must have made an error in the recording. Then I went to a different set of test tones and wow same thing. I never dreamed something like that would take place. I have read a lot of discussions about bass peaks and nulls and always thought it would just be slightly less in volume at the null, not completely gone. So Am I imagining this and if not what do I do to remedy it. I am apparently missing a lot of music and never knew it. I am currently listening to my freshly refinished Yamaha NS 1000m speakers(just put them in the system Wednesday after work) with a Modwright KWI 200 integrated amp and a Lumin streamer/dac. I also have stereo Rythmik  F12 subs. Thanks, Allen.
mizike
mike_in_nc
1,153 posts
 
Regarding phase, there are a several ways to adjust. Here are the two I think are best. In each one, you run ONE speaker and its associated sub at a time:

1. Put a mic at the main listening position (MLP), run a sweep, and analyze with something like REW. Move the phase control to get the smoothest frequency response (FR) around the xover frequency. This is the most direct and reliable way, in my opinion.

2. Sit at MLP, having reversed speaker leads of the main to put it out of phase. Play a tone at the exact xover frequency. Adjust phase control to give the best null at that frequency. (Remember to put the speaker back into phase when done!) This is the best way when you don't have the measurement equipment for method 1.

Any phase adjustment depends on positions of main speaker, sub, and listener. If you move anything significantly, it will change, so needs to be redone.

Hope that helps.
mizike OP
107 posts
 
I have just went through the entire range of phase adjustment, moving the nob three clicks at a time and playing test tones up to 60hz. Above 60 nothing really changes no matter what I do.I have made the mode better but it is still there, down 8/9db from 30hs and 5/6db from 50hz. (i have some loss of volume at 50hz as well, although not nearly as much) I do notice a definite gain if I move my head and/or meter forward and down towards the floor. Maybe I should just get a much shorter chair. Or consider building a platform for one or both subs. 
twoleftears's avatar
twoleftears
5,318 posts
 
Sub crawl. Put one sub exactly at your listening position. Play the 40 hz tone on continuous repeat. Get down on your hands and knees, and carefully cover the whole of the listening area--some kind of grid pattern is good so you know where you’ve been. Mark any spots where you can actually hear the tone. Hopefully there will at least two. Move the two subs to the marked positions, and return to your listening position to check result.
millercarbon's avatar
millercarbon
12,531 posts
 
I wonder how many have actually done any of the stuff they recommend. I did the sub crawl. Subs wound up right back where they were, along the walls, asymmetrically different distances from the corners. Tim did the crawl, his are in the corners, same thing. Its no big mystery. Bass is ALWAYS strongest in these locations! 

Want good bass? Put a sub near each corner. 

We now return you to your regularly scheduled missing the point comments. 
mizike OP
107 posts
 
I do not have enough cable to place subs at my listening chair. My room is very long at 38' only 14' wide. I bought a pair DL Labs sub cables here on the Gon at 12' each, also hampered by outlet locations. 
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