Tight punchy and big bass

[Joffieb]

Hi All,

I want to get my bass tight punchy and big. Would you say it's a speaker issue, sub issue, room issue or all? Can it be measured and if so, what am I looking for? ETC? Spectogram?

It would be handy to be able to measure the speakers and sub first to see what it's even capable of and then get on to the room placement, treatment and eq.

My amp has a damping factor of 1000 but obvs that will only help the speakers.

Anyone have measurements of a good example?

Thanks!

 

[Lid9497]

Depends on what system you have, for example if you have dedicated subwoofer, placement is as critical as correct integration with mains, milliseconds matter with dedicated subwoofers, even 2ms can make bass sound muddy, behind and overall less impactful and punchy.

What is your current setup, room, speakers, amps...?

 

[Keith_W]

I wouldn't say that a 2ms subwoofer delay at say 50-80Hz is audible. The threshold of audibility for group delay at bass frequencies has not been well studied, about the best study we have is by Liski, Makivirta, Valimaki et all which used headphones and test signals found that the threshold exceeded 10ms at 100Hz and the threshold was already shooting up exponentially. This is from memory, I have to look at the study to remind myself. It is a commonly accepted rule of thumb that a group delay no greater than half a period of the frequency in question should be inaudible, although some people dispute this. They think the threshold should be even longer! So if the sub is XO'ed at 80Hz, one period is 12.5ms. You should aim to align your sub with a +/- 3ms tolerance to keep well within the threshold.

For "tight" and "punchy" bass, the time domain is just as important as the frequency domain. You want the SW impulse to be aligned to the main speakers, and all subsequent peaks to decay in the step response. Sometimes you may get reflections which are louder than the main impulse itself - this should be avoided.

Bass decay can be examined in the spectrogram or in more detail with RT60 Decay. If bass decays slower, it gives the impression of more plentiful bass, but when it is overdone it sounds bloated and "slow". I generally prefer faster bass decay. Slow decay can be caused by the subwoofer, e.g. if there is inadequate mechanical or electrical damping. It can also be caused by poorly designed DSP with post-ringing. But by far the most common contributor is the room. Solidly constructed rooms (think concrete bunkers) are the worst in this regard. Plasterboard rooms with large windows have a lot of bass leakage which actually helps with bass decay. But your neighbours may not appreciate it.

My REW eBook on how to take and interpret measurements has some examples of ideal step responses and spectrograms.

 

[Joffieb]

Thank you so much!!! I look forward to reading the documents.

I am attaching a set of measurements to illustrate my progress.

System:

WiiM pro-->Chord 2Qute DAC-->Rotel RC-995 Preamp-->(2 outputs)


--> Rotel RB991 Power Amp-->Harbeth P3ESR Speakers
/
RC-995--(sep outputs)
\
-->MiniDSP 2x4--> B&W ASW765 Subwoofer


My process was:

1. Find best position for speakers and sub within the confines of my room;
2. Using REW I set a LPF for the sub at 80Hz and then using the "inverse polarity null" method in MiniDSP and REW found a 0.75ms delay on the sub to render the most bass in a 60Hz to 100Hz pink noise scenario;
3, I then got REW to create files for my sub only, which I applied in the MiniDSP module;
4. This was now one option for listening; but
5 I also got REW to generate filters for the full range of the system which I applied in the WiiM Pro to try and a set of filters below 200Hz only; and
6. I measured all three options which all appear in the attached REW mdat file.
The measurements are chronological. Initial measurements were done straight from my laptop to the preamp and the later ones through the WiiM using files generated in REW.

To my ears the bass in the option with only the Sub EQ'd in MiniDSP still sounds a bit to muddled or "general" but the Sub 200Hz option in the WiiM makes the bass quite thin, clinical and cold .I'd like to find a mid point.

How does it look on paper? Thanks

 

[Keith_W]

Your subwoofer measurement does not have a timing reference. No matter, I was able to infer how much the subwoofer was delayed by lining up the impulses in the step response. This is how I did it:

These are four step responses overlaid over each other - through the Wiim and through the MiniDSP. You can see that with ALL of them, the shape of the step response is roughly the same. So we will only use one of the step responses as the basis for our comparison.

This is the subwoofer step response (blue) overlaid over the MiniDSP step response (yellow).

Measure the distance between the two peaks, then align them.

Now we can see the alignment of your subwoofer to your main speakers. Does it look aligned to you? (Hint, the start of the subwoofer impulse should occur at the same time as the start of the main speaker impulse).

 

[Keith_W]

To my ears the bass in the option with only the Sub EQ'd in MiniDSP still sounds a bit to muddled or "general" but the Sub 200Hz option in the WiiM makes the bass quite thin, clinical and cold .I'd like to find a mid point.

As for your subjective impression, i'm not surprised. Take a look at how your measurements compare to the Harman target: