The thing about the delay of the subwoofer caused by DSP is that the main speakers are receiving signal from the same DSP.
I was referring to the internal DSP of the subwoofer. You don’t just hook up a speaker amp to a subwoofer driver.
The thing about the delay of the subwoofer caused by DSP is that the main speakers are receiving signal from the same DSP.
The delay of the main speakers was less then 0.10 ms. I also found the delay of the sub confusingly long. It is not within site of the listening position but it is only a few feet back from the speakers at most. The thing about the delay of the subwoofer caused by DSP is that the main speakers are receiving signal from the same DSP. The signal for the main speakers is only being modified with a high pass filter and delay.
I still don't understand what is causing such huge delay in subwoofer. Which miniDSP device are you using? Maybe it would be more clear if you post screenshot of your config screen.
Btw, are you using high pass filter on your mains to roll off bass to make life easier for them? If that is so I think that is a good idea.
Which sub are you using? Are you setting low pass filtering on the sub or within miniDSP software?
Here is the block diagram of the SPA250DSP:
I tried varying the delay while looking at an RTA of the system but there was no noticeable change in frequency response. I suppose I should be looking at other graphs to see whether the sub is integrating into the system properly.
.. but is it possible to dial in whatever your desired crossover is, set the delay for both subs and mains to zero, and then use your measurement software to generate a step response similar to the one Mitchco posted in post #13?
Those delay measurements are not useful for the intended purpose. They are wrong, because delay depends on frequency, and can not be expressed as a single number.
Typically, the delay is longer at very low freq - caused by the system roll-off. Moving up in freq the room starts to dominate, causing quite large variations. The overall delay also depends on the low-pass filter, lower cut-off means more delay, higher order filtering means more delay.
@mitchco has showed how this can be fixed, requires Audiolense, which many people may not have.
But you can still get the integration part right. Set crossover freq and slopes, set delay on main speakers, observe that mains and bass system actually integrates into one sound source. To get it right requires measuring, and being able to understand what the measurements mean.
If I understand correctly delay measured by REW is a difference between expected initial raise of IR and the one recorded by microphone, so, when measured with fixed timing reference, it simply reflects the time delay when sweep sound from various speakers reached the mike. In that context it is usefull when distance of various speakers varies significantly. It has nothing to do with delay variation caused by frequency - this one is a "physical" delay of the whole speaker caused by the time sound takes to travel from the speaker to the mike. That figure he can enter in his SW so it makes sense to measure it.
With @mitchco setup things are different as he has 2 subs and each sub is adjacent to the main speaker so they practically act as one speaker. If @mitcho decides to move his subs say 2 meters from main speakers he would also have to adjust the delay although phase of the subs would stay correct as the sound from subs will simply have longer distance to travel and this would cause the delay.
So, in my opinion the single number delay figure compensates for the fact that sub is far away from the main and you have to set it correctly. When you have done that than you should have a situation similar as when sub is below your main so you can start playing with phase of the sub to get frequency dependent timing right.
Btw, as @TimW 's concern is about configuring delay for mains I am assuming he has already set correct volume and low pass for sub and high pass for mains resulting in the linear frequency response.
I'm using REW for measurement and the Dayton Audio SPA250DSP software for changing DSP settings. I can only set delay for the mains, not for the sub. There is probably a way to generate a step response with REW but idk how or what to look for on the graph.I didn't catch earlier what software you were using, but is it possible to dial in whatever your desired crossover is, set the delay for both subs and mains to zero, and then use your measurement software to generate a step response similar to the one Mitchco posted in post #13?
There is probably a way to generate a step response with REW but idk how or what to look for on the graph.
I messed with delay, phase, and crossover settings while looking at the RTA and this was the best summation I could get (right speaker + sub):The easy way to do this is simply to measure the system including subwoofers, look at the measurement, and enter a delay that gets you close around the crossover. Then fine tune to get the summation correct- which in practical systems means as good as possible.
So is this my step response?
I messed with delay, phase, and crossover settings while looking at the RTA and this was the best summation I could get (right speaker + sub):
View attachment 26774
The dips from 100 to 300 Hz are as small as I could make them. This is with 12 db/octave high and low pass filters at 125 Hz, sub is 180 degrees out of phase, no subsonic filter, and there is a 3.4 ms delay on the mains. Interestingly I had tried to tune the delay by ear before ever measuring the system and I had ended up with 3.3 ms of delay.
The easy way to do this is simply to measure the system including subwoofers, look at the measurement, and enter a delay that gets you close around the crossover.
Then fine tune to get the summation correct- which in practical systems means as good as possible.
I messed with delay, phase, and crossover settings while looking at the RTA and this was the best summation I could get (right speaker + sub):
View attachment 26774
The dips from 100 to 300 Hz are as small as I could make them. This is with 12 db/octave high and low pass filters at 125 Hz, sub is 180 degrees out of phase, no subsonic filter, and there is a 3.4 ms delay on the mains. Interestingly I had tried to tune the delay by ear before ever measuring the system and I had ended up with 3.3 ms of delay.
Ah I see. Well here is mine in all of its ugliness:
View attachment 26776