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Author Topic: Time alignment between mains and subs  (Read 1235 times)

Ryan C. Davis

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Time alignment between mains and subs
« on: April 11, 2018, 09:01:18 pm »

Someone smarter than me want to educate me on speaker time alignment?

Iíve got a pair Danley SH50ís used in a stereo config, and i just picked up 4 TH115ís Iím using in pairs as left and right subs. The amp is a danley dna20k. My sh50ís are setup on some scaffold and the Subs are on the ground about 6í in front of the mains.

When i first setup the subs i was totally underwhelmed. No deep bass. I tried inverting polarity and playing with crossover points but it still sounded really bad on the low end. Crossover point is 80Hz at 24 dB/ octave BW. After messing around with about everything under the sun I tried delaying the subs by 6í and everything came to life. I knew the time misalignment would impact the fidelity but  I really didnít think Iíd see so much interaction between the mains and subs that far below the crossover point. Iím stunned.

Maybe thereís nothing to explain but hopefully thereís something I can learn from it all.


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Ryan Davis

Tim McCulloch

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Re: Time alignment between mains and subs
« Reply #1 on: April 11, 2018, 09:59:05 pm »

Someone smarter than me want to educate me on speaker time alignment?

Iíve got a pair Danley SH50ís used in a stereo config, and i just picked up 4 TH115ís Iím using in pairs as left and right subs. The amp is a danley dna20k. My sh50ís are setup on some scaffold and the Subs are on the ground about 6í in front of the mains.

When i first setup the subs i was totally underwhelmed. No deep bass. I tried inverting polarity and playing with crossover points but it still sounded really bad on the low end. Crossover point is 80Hz at 24 dB/ octave BW. After messing around with about everything under the sun I tried delaying the subs by 6í and everything came to life. I knew the time misalignment would impact the fidelity but  I really didnít think Iíd see so much interaction between the mains and subs that far below the crossover point. Iím stunned.

Maybe thereís nothing to explain but hopefully thereís something I can learn from it all.


Sent from my iPhone using Tapatalk

Delay the SH50s, not the subs.
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Michael Lascuola

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Re: Time alignment between mains and subs
« Reply #2 on: April 12, 2018, 01:16:47 am »

I'm not sure why you'd want to delay the tops if they are behind the subs.

"I really didnít think Iíd see so much interaction between the mains and subs that far below the crossover point."

What do you mean that far below the xover point?
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Len Zenith Jr

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Re: Time alignment between mains and subs
« Reply #3 on: April 12, 2018, 02:04:25 am »

I'm not sure why you'd want to delay the tops if they are behind the subs.

The sound comes out of the tops waay before the subs. The horn path of the TH115 has to be over 7ish feet long and the phase lag on large woofers with big inducting voice coils is greater than small woofers with smaller inducting voice coils.

Counter intuitive but it is the same reason you need to delay the horn on a 2-way box and not the woofer even though the woofer is about 6" in front of the compression driver.
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Tim McCulloch

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Re: Time alignment between mains and subs
« Reply #4 on: April 12, 2018, 03:57:01 am »

I'm not sure why you'd want to delay the tops if they are behind the subs.


That's a mighty big "IF" you've got there, pal.  ;)

As Len Z points out there is path length to the horn and even if there weren't, there is still group delay from the subwoofer processing as well as group delay from the inertia of the sub transducer itself.

Now the homework question:  Ryan says his "deep bass" improved when he delayed the subs by 6ms.  I don't doubt that it sounded better to him where he was standing at the time.  Does anyone want to venture an explanation?  Hint:  it involves lots of "wheel trips".

My question for Ryan - how did the subs sound by themselves, without the tops?
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Ivan Beaver

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Re: Time alignment between mains and subs
« Reply #5 on: April 12, 2018, 07:31:56 am »

Someone smarter than me want to educate me on speaker time alignment?

Iíve got a pair Danley SH50ís used in a stereo config, and i just picked up 4 TH115ís Iím using in pairs as left and right subs. The amp is a danley dna20k. My sh50ís are setup on some scaffold and the Subs are on the ground about 6í in front of the mains.

When i first setup the subs i was totally underwhelmed. No deep bass. I tried inverting polarity and playing with crossover points but it still sounded really bad on the low end. Crossover point is 80Hz at 24 dB/ octave BW. After messing around with about everything under the sun I tried delaying the subs by 6í and everything came to life. I knew the time misalignment would impact the fidelity but  I really didnít think Iíd see so much interaction between the mains and subs that far below the crossover point. Iím stunned.

Maybe thereís nothing to explain but hopefully thereís something I can learn from it all.


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Do you have any measurements?

There are many things that can affect the sound quality/perception.

Physical placement in the room is a big one.  Room modes will easily "overpower" any loudspeaker.

Why are the subs so far in front of the mains?

Proper setup is a matter of "divide and conquer".  First of all, make SURE that all of the wiring is correct.  I often see a polarity reversal, even from people who have done it for years. 

Make sure all the processing in the amps is correct, polarities, delays etc.

It seems really strange that you delayed the subs 6ms, while they are already about 6ms ahead of the mains.

The actual HP and LP freq will affect the delay times.

The listening position in the room can be a issue, due to room modes and physical placement of the cabinets.

The best way is a deliberate course of actions, not pressing buttons and hoping for a good outcome.

Depending on the system configuration (subs on an aux for example), you may want to raise the HP of the SH50s, or lower the LP on the subs.

There are many variable that can affect the overall outcome.  Some of which you can control, others you cannot do anything about.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
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Ryan C. Davis

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Re: Time alignment between mains and subs
« Reply #6 on: April 12, 2018, 05:11:30 pm »

I'm not sure why you'd want to delay the tops if they are behind the subs.

"I really didnít think Iíd see so much interaction between the mains and subs that far below the crossover point."

What do you mean that far below the xover point?

Well I havenít done any testing with TEF yet, this was all seat of the pants. But the upper bass was decent, the lower bass-50 ish hz is what seemed so light. The reason I said this is the slope of the high pass is steep enough that I figured the top boxes would have almost no interference with the bottom boxes at 50 Hz. In my logic that interference was going to affect the upper bass way more than the deeper bass.


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Ryan Davis

Tim McCulloch

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Re: Time alignment between mains and subs
« Reply #7 on: April 12, 2018, 05:14:57 pm »

Well I havenít done any testing with TEF yet, this was all seat of the pants. But the upper bass was decent, the lower bass-50 ish hz is what seemed so light. The reason I said this is the slope of the high pass is steep enough that I figured the top boxes would have almost no interference with the bottom boxes at 50 Hz. In my logic that interference was going to affect the upper bass way more than the deeper bass.


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One would think.  Go back and check Ivan's reply.

I think there was something else at play in addition to the top/sub alignment.
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Ryan C. Davis

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Re: Time alignment between mains and subs
« Reply #8 on: April 12, 2018, 05:16:43 pm »

Do you have any measurements?

There are many things that can affect the sound quality/perception.

Physical placement in the room is a big one.  Room modes will easily "overpower" any loudspeaker.

Why are the subs so far in front of the mains?

Proper setup is a matter of "divide and conquer".  First of all, make SURE that all of the wiring is correct.  I often see a polarity reversal, even from people who have done it for years. 

Make sure all the processing in the amps is correct, polarities, delays etc.

It seems really strange that you delayed the subs 6ms, while they are already about 6ms ahead of the mains.

The actual HP and LP freq will affect the delay times.

The listening position in the room can be a issue, due to room modes and physical placement of the cabinets.

The best way is a deliberate course of actions, not pressing buttons and hoping for a good outcome.

Depending on the system configuration (subs on an aux for example), you may want to raise the HP of the SH50s, or lower the LP on the subs.

There are many variable that can affect the overall outcome.  Some of which you can control, others you cannot do anything about.

Understood, I double checked the wiring to each 115 and the polarity. And Iíd inverted the polarity of the subs in the processing - tried it both ways.

Iím pretty new to delays- you say it seems strange that I would delay the subs when they are already ahead of the mains. This doesnít make sense to me and I could use a little explanation.

If the subs are physically 6í in front of the mains (not accounting for any physics pathway or group delays) it seems to make perfect sense that Iíd want to delay the subs so their arrival time is matching the mains.


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Ryan Davis

Mac Kerr

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Re: Time alignment between mains and subs
« Reply #9 on: April 12, 2018, 05:34:35 pm »

Iím pretty new to delays- you say it seems strange that I would delay the subs when they are already ahead of the mains. This doesnít make sense to me and I could use a little explanation.

If the subs are physically 6í in front of the mains (not accounting for any physics pathway or group delays) it seems to make perfect sense that Iíd want to delay the subs so their arrival time is matching the mains.

Not accounting for any physics or group delay it would seem straightforward, unfortunately we do have to account for them. Subs in general appear to be delayed because of phase shift that occurs due to the nature of low pass filters, and horn subs have the additional "delay" of the horn path length.

Mac
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