Time alignment of three subs

[IWC Doppel]

So, invert the FL and FR so that all look good.

Ahh okay and I guess I could do the same with the surrounds if needs be ?

 

[Praba]

It looks like you need delays on L,R,C and not on subs

 

[IWC Doppel]

Is this because the C LFE only is showing a delay of 4ms, I had assumed this was the LFE (subs) that needed delay ? the graph shown earlier was C, no LFE (LFE turned off) C LFE only (centre amp turned off)

 

[Praba]

The delay is with respect to the reference. You said the reference was L in your case. When you turn your Center amp off, it sends the output nevertheless, and all but the LFE component is ignored. The delay indicated therefore is the delay of the output from your subs with respect to the Left, and this could happen if the delay for C is wrong, or if the delay for the LFE is wrong. That is why asked you to do a sweep first, above the sub frequencies, for all the channels to make sure L,R,C,SL,SR are aligned to start with. In general, delay increases with decreasing frequencies.

 

[IWC Doppel]

I made some more sweeps looking at the LRC and looking at how the profiles changed by adding delay to the LCR, they all did similar things and improved some areas but not others

here's the right with 1ms delay and then 6ms, pure is 6Ms, buff is 1Ms (my original setting)

The same for the left 1Ms blue, 6ms green

Center blue 0 ms green 5ms

 

[Praba]

Use only delays you get from measurements. Delays affect phase. So, when you change delays, try flipping the phase to see what works. Now the graphs seem better at the crossover. The spectrogram may be now. You can try equalization after getting the timing and phase set correctly.

The plot of SPL shows only part of the story. Equalization can shape the response. But timing is a very different parameter. You should not try to correct SPL with wrong timing. The tools to correct are timing, phase, equalization. Trying to use delays to solve all problems is not correct.

 

[IWC Doppel]

Looking a the analysis I did with the LRC looking at no LFE and just LFE when playing through these channels it suggested I needed 15, 17 and 8ms respectively, but the graph looked very similar at 4Ms each, so I tried just adding 4Ms, I could try the odd numbers shown on the analysis but if In understand correctly if I put the top aligned copy as the no LFE then the aligned copy at the bottom LFE only then at the crossover point if Shows a delay of 15 ms it is suggesting that the LFE needs to be delayed by 15ms ?

 

[Praba]

SPL is averaged over time. Energy Time Curve (ETC) gives information about the energy output at various frequencies over time. ETC and SPL should be correct to give the correct tonal balance. You have three parameters to adjust to get the balance right. Trying to compensate for a wrong value of one parameter with a compensating wrong value for another parameter will at best work at a limited band of frequencies. So, no shortcuts. Set the timing with respect to the reference for every independent source. I have tri-amped L,R,C which have independent delays for the Low, Mid, and High. I have had to set the delays for each of those with respect to the reference. Likewise, the phase of every source has to be set to make sure that no source is undoing the effort of another. Then set the equalization.
You have to tell yourself to stop messing with delays so much!

 

[IWC Doppel]

Tks, I think I'll start again later today and set the timing reference from the centre which currently has no delay and follow your earlier post and see how I get on

Still confused by the increasing equal delay to just the LFE channel having an effect though !

 

[Onetrack97]

Hey, this all seems like a lot of work when you could be using a free tool to get it done.

Multi-Sub Optimizer (Andy the developer is very helpful).

I used it to integrate my three subs. It worked so well, I then added a fourth channel with my two internal “subs” from My GoldenEar speakers.

It can optimize your prime listening area to cover you and your guests.

 

[JStewart]

Hey, this all seems like a lot of work when you could be using a free tool to get it done.

Multi-Sub Optimizer (Andy the developer is very helpful).

I used it to integrate my three subs. It worked so well, I then added a fourth channel with my two internal “subs” from My GoldenEar speakers.

It can optimize your prime listening area to cover you and your guests.

Also the OP can search this site for "Alignment Tool" in REW. Much easier than tweak and re-measure to set the correct relative delays between the subs or between the group of subs and the mains if the most even response among listening all listening positions is not a goal.