Keith_W
Master Contributor
You didn't show any measurements, so there is nothing to say?
5.23ms delay is not unusual for subwoofers. In fact it's pretty normal.
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Does dual sub matter if both subs have equal dips/peaks in REW room sim?
- Thread starter Geertidow
- Start date
You didn't show any measurements, so there is nothing to say?
5.23ms delay is not unusual for subwoofers. In fact it's pretty normal.
Why does 5.23ms sound like a lot to you?
boxerfan88
Major Contributor
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For your reference, my KH310 almost right up to the front wall with one third party sub in the middle yielded 6ms mains delay (determined via REW step response sighted/manual estimation). My XO is 100Hz.
Yours is probably correct.
- Thread Starter
- #24
Thanks, I thought it was lot since the speakers are close to the sub.
I'll post some measurements soon.
The delay is caused by latency in the amplifier / DSP processing of the sub, not just physical distance.
It's not uncommon that two subs don't achieve a more even reposponse than one. In those cases, you can place the subs tight together for more output and lower distortion. Stacking is seldom beneficial unless you cross very low.
Keith_W
Master Contributor
The delay is also caused by the inherent group delay of subwoofers. A lot of beginners think that subwoofers have constant group delay - i.e. that the "5.23 ms" delay applies to all bass frequencies. If 50Hz is 5.23ms delayed, then 20Hz must also be 5.23ms delayed. This is not true. Let me show you something.
Take an actual subwoofer measurement (blue) and create a bandpass crossover (green) to match it. Here, I have a 5th order Butterworth XO with corner frequencies of 20Hz and 80Hz. You can see that its roll-off almost matches the subwoofer. So this will be our simulation sub.
And this is the group delay of the simulation vs. the real sub. The vertical scale is in milliseconds. You can see that the minimum-phase nature of the simulation is already causing the group delay to rise at low frequencies, never mind all the physical problems of subwoofers (driver inertia, ports, etc) that contribute to group delay.
Take an actual subwoofer measurement (blue) and create a bandpass crossover (green) to match it. Here, I have a 5th order Butterworth XO with corner frequencies of 20Hz and 80Hz. You can see that its roll-off almost matches the subwoofer. So this will be our simulation sub.
And this is the group delay of the simulation vs. the real sub. The vertical scale is in milliseconds. You can see that the minimum-phase nature of the simulation is already causing the group delay to rise at low frequencies, never mind all the physical problems of subwoofers (driver inertia, ports, etc) that contribute to group delay.
- Thread Starter
- #29
Is the XO then the best place to set your delay time? It seems then that all delay are wrong so have to choosing an optimal value.
The tuning / crossover design / high pass / what have you of the subwoofer is very likely implemented in the digital domain via DSP, so there really is no such a thing as "no processing" in a modern subwoofer or active speaker.
Keith_W
Master Contributor
Um, I can't think of any other way to set delays apart from the XO?
Keith_W
Master Contributor
Would you be able to link me to that post? I have to admit it's not clear to me what you are referring to.
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I dunno about all modern subwoofers, but SVS certainly relies heavily on DSP for all their subwoofers AFAIK. There will certainly be an additional delay due to DSP regardless of whether or not any additional processing is enabled via the app.
Philbo King
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5mSec at 20 Hz is a 36° phase shift; not really audibly apparent. (1/20Hz -> 50mSec per cycle; 5mS/50mS=36°/360°)
At higher freqs it is proportionally more degrees (e.g., 72° at 40 Hz).
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I will go out on a limb and say that a subwoofer without DSP isn't modern.
- Thread Starter
- #37
What you do is:
1. Set speaker closest to the sub as L (or R) and the sub as R (or L).
2. Run a single sweep with DIRAC and immediately apply a filter after one measurement on MLP.
3. Look at the delay DIRAC applies to the speaker.
So far that has worked really well in my setup. Checking the delay with other methods yields almost exactly the same results.
I just wonder if this also works for multiple subs.
- Thread Starter
- #38
I have had a very, very lucky streak. Today the couches arrived and after placing them, the 2nd subwoofer I have (but thought I'd had to sell because it is huge and self made) fits behind the couch in a diagonal line with the other subwoofer. I'm listening in the middle of that diagonal.
The effect is quite sensational!
But a lot of measuring has yet to be done, but the effect on the music is phenominal.
The effect is quite sensational!
But a lot of measuring has yet to be done, but the effect on the music is phenominal.
- Thread Starter
- #39
This however brings out an additional question.
Downstairs I have a Wiim Amp Pro with a subwoofer out. The sound so far is really excellent on my current setup.
I could 'downgrade' my setup (Wiim Pro + MiniDSP flex + Hypex nCore 252MP) using the Wiim Amp Pro (much more simple). But then I would have to set the sub delay as one for both subs (different subs on different locations). But, since I cross over at 80 Hz, is that really relevant (to time allign both subwoofers invidiually to the mains)?
Whenever I start reading I get confused by the physics. If the effect is really small, I might give it a try.
Downstairs I have a Wiim Amp Pro with a subwoofer out. The sound so far is really excellent on my current setup.
I could 'downgrade' my setup (Wiim Pro + MiniDSP flex + Hypex nCore 252MP) using the Wiim Amp Pro (much more simple). But then I would have to set the sub delay as one for both subs (different subs on different locations). But, since I cross over at 80 Hz, is that really relevant (to time allign both subwoofers invidiually to the mains)?
Whenever I start reading I get confused by the physics. If the effect is really small, I might give it a try.
Keith_W
Master Contributor
If you have two subwoofers on one DAC channel, you lose the ability to control them individually. This means they can't be time or phase aligned individually - not ideal. Each subwoofer should be on its own DAC channel.
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