Help with lowpassfilter on my subs

peelbone

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Hi!
I finaly got my two subs deliverd home to me.
Here is a measurement picture of my system without the subs.

My question is: What kind of lowpassfilter should i use on my subs and at what Hz?

Thanks.
56476
 

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Depending on how your sub's integrate in your room, I would try out 60 or 70hz and experiment with lowpass at 1,5 and 2,0.
 

peelbone

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Thanks for the reply!!

I meant what filter typ for the lowpassfilter? Like Butterworth, Linkwitz riley kind of filters.
My Funk subs have powerful dsp =).
 

Omid

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Thanks for the reply!!

I meant what filter typ for the lowpassfilter? Like Butterworth, Linkwitz riley kind of filters.
My Funk subs have powerful dsp =).

I also have subs with DSP. I've totally turned off their DSP and crossover. I let AL handle that.
AL doesn't use the classical 1st, 2nd etc order crossover slopes. You could even have asymmetry in your crossover (steep slope on your mains, gentle slope on your subs) without worrying about summing issues that a normal crossover would have. AL will use DSP to flatten the response.
 

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Before i migrated to AL, I used nothing but LR filters, 4th order if possible. For subs I used 2nd order, because of room problems.
 
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peelbone

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I also have subs with DSP. I've totally turned off their DSP and crossover. I let AL handle that.
AL doesn't use the classical 1st, 2nd etc order crossover slopes. You could even have asymmetry in your crossover (steep slope on your mains, gentle slope on your subs) without worrying about summing issues that a normal crossover would have. AL will use DSP to flatten the response.

My subs are connected through y-cable between my pre and amp so i realy want to use a lpf on my subs.
My subs play up to 200 hz.
 

Omid

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My subs are connected through y-cable between my pre and amp so i realy want to use a lpf on my subs.
My subs play up to 200 hz.

It sounds like you’re not using a multichannel DAC then. Is that correct?

To get the real benefits of Audiolense, you would feed 1stereo channel from the DAC to your preamp for the mains and another channel (mono or stereo) to the subs. The volume control would need to be done by the DAC or further upstream.

Without a multichannel DAC, you’d choose a crossover no differently than you used to before Audiolense, based on your room, sub placement and quality of low frequencies of your mains vs subs.
 

kevinzoe

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Peelbone,

Before you tackle the crossover between the subs and mains, I'd suggest you first time alignment everything because how a sound source drives a room is dependent on its location. Find and settle on your mains locations first. Then focus on the subs. Because you are using a 2 channel DAC you are limiting yourself in ways that a multi-channel DAC would not. With a 2 channel DAC here are some strategies that I would consider:

(A) Use the subs own delay dial to time align the left sub with the left main. Due to the subs inherent group delay you will need to place the sub closer to your listening position than the mains are and then experiment with the delay settings on the sub. Instead of just relying on your ears for time alignment, you might want to use Audiolense (AL) - focusing on the left channel for example, unplug the right main and right sub from your preamp so that they are off, then plug your left sub into the right preamp output. Run a 2 channel sweep and note the left and right channel delay values. If the subs delay value is greater than the mains then you have to reduce the subs delay amount and if you get to 0 delay on the sub setting and its AL delay value is still greater than the main, then you will have to move the sub closer to the mic. When subs AL delay equals the left mains then they are time aligned. Repeat process for right channel.

(B) Do not use the subs delay but instead use physical location to time align the sub with the main. If after running a AL sweep the subs AL delay is greater than its closest main speaker (using the same trick of unplugging the right channel main+sub and plugging the left sub into the right preamp input) then keep moving the sub closer to the mic until the AL delay values for main and sub are the same or as close as you can get them for time alignment. With a multi-channel DAC you can stick the subs pretty much anywhere and AL will automatically time align them. This has the advantage of placing the subs where they drive the room the best which may be behind the mains so AL would delay the mains so the subs can catch up to them in this scenario.

Now with each sub time aligned I would then focus on the subs low pass crossover on its plate amp; do not touch the sub delay knob as you will undue all your hard work to this point. Just stick to the subs volume and crossover frequency and polarity switch if it has one. If you try to use AL to high-pass the mains then your Y-adapter is passing along the high-passed signal to the subs and they will not be playing the right frequencies they were meant to play. So run your mains without a high pass crossover or set the high pass setting really low like 5Hz so that the subs still receive their correct frequencies. Then experiment with the subs crossover settings and slopes if your sub provides different slope values. Rerun an AL sweep each time you change the subs crossover frequency (or slope) and filter the results in AL so you can see the left main and left sub together (the right channel will show the left sub) and click the button to view both channels together so you can see their overlap. Once you are happy repeat the process for the right channel.

Then connect the left and right channels to your preamp as normal with Y-adapters feeding your subs I presume. Now run AL sweep for the combined left main+left sub and right main+right sub and pick your target curve and see what is generated as a predicted response curve. Examine the Corrections curves to make sure that there is not any one peak much taller than any others.

Hope this helps . . .
 
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peelbone

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It sounds like you’re not using a multichannel DAC then. Is that correct?

To get the real benefits of Audiolense, you would feed 1stereo channel from the DAC to your preamp for the mains and another channel (mono or stereo) to the subs. The volume control would need to be done by the DAC or further upstream.

Without a multichannel DAC, you’d choose a crossover no differently than you used to before Audiolense, based on your room, sub placement and quality of low frequencies of your mains vs subs.

I dont think there is a multichannel dac thats up to par with my newly ordered Playback design mpd-6, there is always a compromise =)
 

peelbone

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Peelbone,

Before you tackle the crossover between the subs and mains, I'd suggest you first time alignment everything because how a sound source drives a room is dependent on its location. Find and settle on your mains locations first. Then focus on the subs. Because you are using a 2 channel DAC you are limiting yourself in ways that a multi-channel DAC would not. With a 2 channel DAC here are some strategies that I would consider:

(A) Use the subs own delay dial to time align the left sub with the left main. Due to the subs inherent group delay you will need to place the sub closer to your listening position than the mains are and then experiment with the delay settings on the sub. Instead of just relying on your ears for time alignment, you might want to use Audiolense (AL) - focusing on the left channel for example, unplug the right main and right sub from your preamp so that they are off, then plug your left sub into the right preamp output. Run a 2 channel sweep and note the left and right channel delay values. If the subs delay value is greater than the mains then you have to reduce the subs delay amount and if you get to 0 delay on the sub setting and its AL delay value is still greater than the main, then you will have to move the sub closer to the mic. When subs AL delay equals the left mains then they are time aligned. Repeat process for right channel.

(B) Do not use the subs delay but instead use physical location to time align the sub with the main. If after running a AL sweep the subs AL delay is greater than its closest main speaker (using the same trick of unplugging the right channel main+sub and plugging the left sub into the right preamp input) then keep moving the sub closer to the mic until the AL delay values for main and sub are the same or as close as you can get them for time alignment. With a multi-channel DAC you can stick the subs pretty much anywhere and AL will automatically time align them. This has the advantage of placing the subs where they drive the room the best which may be behind the mains so AL would delay the mains so the subs can catch up to them in this scenario.

Now with each sub time aligned I would then focus on the subs low pass crossover on its plate amp; do not touch the sub delay knob as you will undue all your hard work to this point. Just stick to the subs volume and crossover frequency and polarity switch if it has one. If you try to use AL to high-pass the mains then your Y-adapter is passing along the high-passed signal to the subs and they will not be playing the right frequencies they were meant to play. So run your mains without a high pass crossover or set the high pass setting really low like 5Hz so that the subs still receive their correct frequencies. Then experiment with the subs crossover settings and slopes if your sub provides different slope values. Rerun an AL sweep each time you change the subs crossover frequency (or slope) and filter the results in AL so you can see the left main and left sub together (the right channel will show the left sub) and click the button to view both channels together so you can see their overlap. Once you are happy repeat the process for the right channel.

Then connect the left and right channels to your preamp as normal with Y-adapters feeding your subs I presume. Now run AL sweep for the combined left main+left sub and right main+right sub and pick your target curve and see what is generated as a predicted response curve. Examine the Corrections curves to make sure that there is not any one peak much taller than any others.

Hope this helps . . .

This was very helpful Kevinzoe !!!

My subs got total latency of 0.466 milliseconds wich means about 16 cm and i have them setup exatly 16 cm closer to my mains and have a delay of 0 set on the subs.
Now its time to measure this =)

TY TY TY
 

peelbone

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This was very helpful Kevinzoe !!!

My subs got total latency of 0.466 milliseconds wich means about 16 cm and i have them setup exatly 16 cm closer to my mains and have a delay of 0 set on the subs.
Now its time to measure this =)

TY TY TY

This was harder than i thought...
I now got the right sub connected to left output on the preamp and the preamp right signal to the right mains speaker.
Ive made alot of measurements and trying to set the frequencydiffrently and get all sorts of results everything from mains being 2 ms slow to sub being 6 ms slow.
This was harder than i thought...
 

kevinzoe

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Peelbone,
Are you saying that your measurement readings are inconsistent? Sometimes I have to close down the software then fire it up again and then it reads more consistent . . . if this is your issue.

If you are getting consistent readings then move the sub towards the listening position (and further away from its closest main) so that its measured delay value is the same as its closest main. I wouldn't hold my breath on a manufacturer telling me their sub is 0.466ms latency when subs typically have a group delay of up to 10ms.

How can we help?
 

peelbone

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Peelbone,
Are you saying that your measurement readings are inconsistent? Sometimes I have to close down the software then fire it up again and then it reads more consistent . . . if this is your issue.

If you are getting consistent readings then move the sub towards the listening position (and further away from its closest main) so that its measured delay value is the same as its closest main. I wouldn't hold my breath on a manufacturer telling me their sub is 0.466ms latency when subs typically have a group delay of up to 10ms.

How can we help?
Yes that was very inconsistent *=)
 

peelbone

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Peelbone,
Are you saying that your measurement readings are inconsistent? Sometimes I have to close down the software then fire it up again and then it reads more consistent . . . if this is your issue.

If you are getting consistent readings then move the sub towards the listening position (and further away from its closest main) so that its measured delay value is the same as its closest main. I wouldn't hold my breath on a manufacturer telling me their sub is 0.466ms latency when subs typically have a group delay of up to 10ms.

How can we help?

Here is a link to the dsp in my Funk subs:

https://alldsp-oem.com/product/1800b-signature/

Input-to-output latencyFIR disabled, unity gain466µs

=)
 
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