Bass Phase


#1

This morning, Paul noted in his daily Post that he found it worthwhile to adjust the bass phase in his system after achieving a good sense of Huron’s strengths and weaknesses. Whenever I read advice like that from an expert listener, I check it out on my system. My experiences:

In the absence of any standard for correct bass, the key question is: what is correct bass response in any system? Although I listen almost exclusively to classical music, I find it much easier to adjust bass using rock and jazz. For example, Lyle Lovett’s “She’s Already made Up Her Mind” (Joshua Judges Ruth) which has a very deep synthesizer part; Paul Simon’s “50 Ways to Leave Your Lover” with two bass drums tuned differently; Jennifer Warnes “Rock You Gently” (The Hunter) with a deep bass part beneath a prominent less deep beat; and Christian McBride’s “Stars Fell on Alabama” (Gettin to It).

I used these tracks to determine if a change in bass phase (using a JL Audio f113 sub) improved bass in Huron. My finding was that a very slight change in phase did in fact improve bass, and thereby, everything else.

Lovett: You want the very deepest notes to appear in the mix, rather than from the sub, and all notes should be at the same volume. Too much change in phase adds an edge to Lovett’s voice, so an easy way to determine whether you need to add to, or decrease, phase is to make a slight change and then listen to the voice–if it moves forward in the mix and acquires an edge, try adjusting the phase in the other direction. Also, you have gone too far if the bass drum whack at about 3:50 is more bass thud than whack.

Simon: Adjust so each drum is clear and separated in space. Listen for the percussion instrument just to the right of Simon–it should be clear, but not prominent (another sign that you’ve gone too far)

Warnes: The track starts with a mid-bass beat; the deepest bass then joins. Again, adjust so the deepest bass is in the mix rather than from the sub and has a clear and distinct beat. Another song where, as the phase moves off the correct setting, the voice acquires an edge and the many percussion instruments are suddenly too prominent in the mix.

McBride: Bass players spend hours getting every note, from highest to lowest, to sound at the same volume. Aim for this in general (on a couple of fast passages the lowest notes are not quite so loud). The piano should be equally even on every note, well back in the mix, with absolutely no edge. There is a very soft drummer even deeper in the mix. If the drummer is prominent, you’ve again gone too far.

Note that the trick is not to get the most bass but the correct bass. Ultimate test: “Kicho” on Blue Chamber Quartet (Stockfisch SACD, reverse polarity). The string bass should be huge, in your room, and absolutely even from top to bottom, with the fundamental (the sine wave) slightly audible on the lowest notes). Amazing!


#2
jrango said In the absence of any standard for correct bass, the key question is: what is correct bass response in any system?
I know that some subs have an automated system with measuring microphones and all but I prefer to do the setting by hearing. With any rhythmic music it is possible to turn the phase correct and I keep the cut-off frequency as low as possible. After that you can get the volume which more depends on taste. I've kept the DSP correction in my pre-amp as this dampens two nasty spikes in my room profile. This I have found out by measuring and by listening to several correction profiles I have made based on that measurement with different dB dampening and Q factors.
jrango said My finding was that a very slight change in phase did in fact improve bass, and thereby, everything else.
Also in my case it was a minimal change since Huron.

With the correct setting Huron really makes the speakers sing! What a pleasure to listen to the music.


#3

Wow - I had never noticed the two bass drum tones in “50 Ways…”!
I’m not sure if it would have been obvious prior to Huron, but it is quite distinct now. Thanks for the tip!


#4

I don’t think this was related to Huron, but after looking at this thread, I checked the phase in my dual subs (JL Audio Fathom 110s) with Room EQ Wiard (REW) and they were totally out of phase with respect to each other! How does that happen, anyway?? Anyway, I dialed them back in and also synced them with my speakers and BOOM! The bass was back, baby! surprised-011_gif


#5

Bass phasing is needed and important in some speaker setups.

How did the bass change in your dual sub set up once you fixed it.

Dsp for me takes the magic out of the music but can add some clarity not there before.

In Paul’s room and his speakers he would hear changes in phase more than most do by nature bass line sources that are in mono have an additive effect in the middle where we sit

as such putting each tower out of phase to each other cancels this. Not sure but he might of heard less bass on ref recordings he knows well.


#6
Cable-guy said

I’ve kept the DSP correction in my pre-amp as this dampens two nasty spikes in my room profile. This I have found out by measuring and by listening to several correction profiles I have made based on that measurement with different dB dampening and Q factors.

Your reference to DSP in your post and looking at your system listing; aren't you losing part of the DSjr. magic by doing an additional AD/DA after, rather than before, the DSjr.?

#7

After thinking about it, I realized that the problem has to do with the fact that I switched the crossover point with my front speakers from 60 to 80 Hz. The JL subs must have been in phase at 60, along with the speakers, but slightly out of phase at 80. I had to do this so I could get rid of a dip in frequency response in the front left speaker due to room issues. I couldn’t get rid of it with placement. The subs and speakers also have a stable phase response at this frequency while the phase was a little squirrelly at 60. Bass and impact are much, much better now. Having done this several times, I think it’s important to choose a crossover point where there is stable phase for both speakers and subs to optimize. I think the technical way of looking at it is to make sure that there is normal group decay for subs and speakers, otherwise you’ll have a hard time syncing things up.


#8

I agree and when putting a setup from alt companies it’s of paramount concern

having said that our rooms effect certain causes that we need to address and this can lead to more causes. In my case it’s all one company and system but the room is not the only cause as design is part of this as well.


#9

It’s useful to have a proper mic and analyzing software like the Studio Six stuff when changing crossover frequency. One will see that sometimes rising crossover frequency means a strong dip not much below it that wasn’t present with the lower crossover point.

It saves a lot of time to do both, measuring and listening.


#10

@jrango my understanding is that the fundamental frequency is the lowest frequency of a particular note and usually the fundamental has higher amplitude than its harmonics.

Can you explain a bit more by what you mean in your comment - particularly the last part “with the fundamental(the sine wave) slightly audible on the lowest notes” that I’m having trouble understanding.

‘Note that the trick is not to get the most bass but the correct bass. Ultimate test: “Kicho” on Blue Chamber Quartet (Stockfisch SACD, reverse polarity). The string bass should be huge, in your room, and absolutely even from top to bottom, with the fundamental (the sine wave) slightly audible on the lowest notes). Amazing!’


#11

Just re. fundamental levels - the ear/brain is excellent at filling in missing fundamentals, so much so that you clearly hear a fundamental at times when it’s not present at all. e.g. https://blogs.scientificamerican.com/roots-of-unity/your-telephone-is-lying-to-you-about-sounds/ and https://en.wikipedia.org/wiki/Missing_fundamental