Time-align dual subwoofers

JazAV

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I need to figure out how to time-align dual subwoofer. I can hear it's aligned well enough but I know it's not perfect. Using REW I can't figure out how to use timing reference or impulse response. The REW manual doesn't help either.

I need to get the subwoofers to sing together at the MLP and then I can set the global delay for the subwoofers to the furthest sub. Right? Yes I'm sure that's right (it's logical).

But how to get them perfectly aligned in the first place?
 
Have you got REW configured so that you can select all of the different channels of your system? Once you have you need to pick one of your front speakers as the timing reference and then make a full frequency range measurement for each of the speakers you want to time align in turn. The slight complication is that enabling crossovers and EQ will introduce further delays, which may be different for different speakers, so whether you want these enabled or not for the measurements will depend on how any optimisation in your AVR may run.

Once you've done this you can roughly align them by looking at the impulse response, and can do a better job if you look at the phases in the crossover region.
 
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I'm not sure the OP has a miniDSP but from a quick skim through there is still some useful info. in there, and is a good starting point for doing things based on impulse responses.
 
I do have a minidsp 2x4. Sorry, I should have put up all relevant info before I relayed my problem.

I have also skimmed through the guide and it's really good. Is there a quicker 'in a nutshell' guide that I can refer to?I will come back with a diagram of my room to help.
 
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I do have a minidsp 2x4. Sorry, I should have put up all relevant info before I relayed my problem.

I have also skimmed through the guide and it's really good. Is there a quicker 'in a nutshell' guide that I can refer to?I will come back with a diagram of my room to help.

That guide is already a simplification of a complex problem. I'd take the time to read it and follow what it says to be honest. I don't really see how a diagram of your room will help so spend the time you save by not producing that on reading :).
 
I found the minidsp easy to follow and got a reading of 9.32ms
Really? 9.32ms equates to a distance of about 10'6" Is your sub 10'6 away from your mains - which is what you should align to, or from your listening position?

Sub alignment is much more about phase than delay - although both are important. We used to build cardioid sub arrays for large PA systems to reduce on stage spill. This would use anything up to 20 subs setup in 2 lines - or with certain cabinets reversed to create a wave front. We needed to set both phase and delay correctly for this to work well. I am not talking about absolute phase, but varying it away from in-phase by about 30 degrees or so.

In home audio where you are dealing with rooms normally shorter than the wave length, delay is not going to make a huge difference. I would be looking more at the relationship between the sub and the mains, as most of the errors will occur in the crossover region.
 
Really? 9.32ms equates to a distance of about 10'6" Is your sub 10'6 away from your mains - which is what you should align to, or from your listening position?

Sub alignment is much more about phase than delay - although both are important. We used to build cardioid sub arrays for large PA systems to reduce on stage spill. This would use anything up to 20 subs setup in 2 lines - or with certain cabinets reversed to create a wave front. We needed to set both phase and delay correctly for this to work well. I am not talking about absolute phase, but varying it away from in-phase by about 30 degrees or so.

In home audio where you are dealing with rooms normally shorter than the wave length, delay is not going to make a huge difference. I would be looking more at the relationship between the sub and the mains, as most of the errors will occur in the crossover region.
Yes from main listening point to front of room
 
Really? 9.32ms equates to a distance of about 10'6" Is your sub 10'6 away from your mains - which is what you should align to, or from your listening position?

Sub alignment is much more about phase than delay - although both are important. We used to build cardioid sub arrays for large PA systems to reduce on stage spill. This would use anything up to 20 subs setup in 2 lines - or with certain cabinets reversed to create a wave front. We needed to set both phase and delay correctly for this to work well. I am not talking about absolute phase, but varying it away from in-phase by about 30 degrees or so.

In home audio where you are dealing with rooms normally shorter than the wave length, delay is not going to make a huge difference. I would be looking more at the relationship between the sub and the mains, as most of the errors will occur in the crossover region.

TWENTY subs!!!! o_O:thumbsdow

wow!
 
TWENTY subs!!!! o_O:thumbsdow

wow!
Those were the days... I don't miss loading them in or out, but a £250K hifi was always fun to play with...

With phased sub arrays it was not about power so much as coverage and controlling spill. We could make sub directional even at very low frequencies, cleaning up the audio on stage and concentrating the energy at the audience.

With 20 subs we would have been running 12 3KW line array boxes per side, plus out fills and front fills. Probably a 16 or 32 channel output digital speaker controller with multiband compressions and parametric EQ. Monitoring at multiple locations across the venue and compensating for humidity and temperature - as well as the amount of energy the audience would soak up.

Some great bands - some unexpectedly so. Sugababes - probably the tightest band I've ever worked with, McFly - genuinely talented musicians, Aled Jones - total legend, had a road manager whose sole job was to stop him shagging his support act - Hayley Westenra...

And now I manage software projects.

Still, could be worse ;)
 
Those were the days... I don't miss loading them in or out, but a £250K hifi was always fun to play with...

With phased sub arrays it was not about power so much as coverage and controlling spill. We could make sub directional even at very low frequencies, cleaning up the audio on stage and concentrating the energy at the audience.

With 20 subs we would have been running 12 3KW line array boxes per side, plus out fills and front fills. Probably a 16 or 32 channel output digital speaker controller with multiband compressions and parametric EQ. Monitoring at multiple locations across the venue and compensating for humidity and temperature - as well as the amount of energy the audience would soak up.

Some great bands - some unexpectedly so. Sugababes - probably the tightest band I've ever worked with, McFly - genuinely talented musicians, Aled Jones - total legend, had a road manager whose sole job was to stop him shagging his support act - Hayley Westenra...

And now I manage software projects.

Still, could be worse ;)

Absolutely love this story! This is brilliant! :) :) :)
 
In home audio where you are dealing with rooms normally shorter than the wave length, delay is not going to make a huge difference. I would be looking more at the relationship between the sub and the mains, as most of the errors will occur in the crossover region.

Long long is a 20hz sine wave?🤔
 
Long long is a 20hz sine wave?🤔
Guess you meant 'how long'?

The time for a single cycle is 50ms and the wavelength is about 17.2 m. Not sure which value you wanted :) .
 
Guess you meant 'how long'?

The time for a single cycle is 50ms and the wavelength is about 17.2 m. Not sure which value you wanted :) .

Sorry, yes how long. 17.2 m, I didnt know that. So in a normal living room you really wont here 20hz or are we only hearing half the wave/cycle??
 
Sorry, yes how long. 17.2 m, I didnt know that. So in a normal living room you really wont here 20hz or are we only hearing half the wave/cycle??
That the wavelength is longer than room dimensions doesn't affect whether you can hear it or not. What your ears detect is how the sound pressure varies at their position as a function of time, not how the pressure varies over the length of the room.

The significance of the wavelength compared to room dimensions is how this relates to room modes, and that what you hear is heavily influenced by boundary reflections rather than just the sound travelling directly from the sub to your ears.
 
In what way do you mean 'tight' ?

You have a very impressive CV :smashin:
We'll, I can only comment on their stage sound and musicianship rather than anything else...

My CV also includes Jools Holland, Status Quo, The Queen, Prince Charles, Joanna Lumley, Jim Davidson - on HMS Invincible moored in the middle of the Thames, Katherine Jenkins, Girls Aloud, Liberty X, Kate Rusby, Englebert Humperdinck, The Hollies, The Beach Boys, Beyonce (but only once, catering was great, her entourage are all tossers), Pretty much every arena in the UK and the pinnacle of my career, mixing and directing live video for Daniel O'Donnell...

Looking back, it was a fun 17 years but in the current climate I'm glad I'm in a more secure industry now.
 

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