Subwoofer integration with integrated amplifier (no DSP)

[firestart3r]

Hello all,

Newbie here...
I would like to add a subwoofer to my stereo system to have a bit more punch when listening to movies. My question is concerning subwoofer integration with my integrated amplifier.

I was thinking to try a subwoofer "the easy way" without buying a miniDSP flex + microphone... to try and see if I like the sound in my room.
Also, my other objective is to diminish the costs of making this "sound experiment".

For that, I was looking at my bookshelf speakers spinorama to try to determine at what crossover frequency to set on the subwoofer.
My understanding is that looking at the speakers slope, I could calculate a "starting point" for the subwoofer's low pass filter crossover frequency ? Is that a good approach ?

If yes, can you guys tell me how to calculate the slope on the PSB P5 ? Im a bit confused...

Is it a -14 db / -21db slope ? -7 db / -22.5 db slope ?
100hz = +1 db
80hz = +1 db
50hz = -6 db
40hz = -13 db
25 hz = -28.5 db
20hz = -34 db

What slope should I look for when shopping for subwoofers for the speaker to "naturally" match the speaker's slope ? Is it possible to find the slope of the subwoofer without taking measurements ? Maybe the manufacturer can give me that information or I could use a spinorama data for the sub if I find it online ?

How can I integrate the subwoofer when they have a fixed 12db or 24 db/octave slope ? Is it really bad if they don't match perfectly ?
If it's not too bad and I manage to get the slopes of the two devices (speakers and sub), how can I calculate the best crossover frequency for the low pass filter?

So many questions...

Thank you for your help

 

[Lednek]

I have recently been trying the same thing with my SMSL A0200, putting off the minidsp flex. My speakers are JBL stage A130 with dual outlaw audio M8 subwoofers. The biggest challenge I found was the slope of most subwoofer low pass filters are not steep enough to integrate seamlessly without a high pass filter to the speakers.(-12db/octave) I initially spent hours with REW/Minidsp UMIK-1 measuring in room response, without an acceptable result. Eventually I plugged the ports on the A130's using peices cut from a pool noodle and some aquarium filter foam. This substantially decrease the bass response from the speakers, leaving more room for the Sub to do its thing. With the ports sealed(not airtight, see photo) I set the low-pass to 40 hz and turned the volume up until It sounded good. I haven't measured it yet as set up, but it sounds much much better with the ports plugged. Bass sounds well controlled where before it was boomy as hell. I think the measurements will reflect this as well. I'll have to check it out over the weekend.

 

[DVDdoug]

when listening to movies.

The stereo downmix does not include the "point one" LFE (low frequency effects) channel. You'll get the "regular bass" from the other channels but you need an AVR (or some kind of surround decoder/processor) to get the LFE.

An AVR also includes a full-crossover so you can optionally high-pass the main speakers and route the regular bass to the sub where it will be mixed with the LFE when watching movies with surround sound.

 

[ernestcarl]

How can I integrate the subwoofer when they have a fixed 12db or 24 db/octave slope ? Is it really bad if they don't match perfectly ?
If it's not too bad and I manage to get the slopes of the two devices (speakers and sub), how can I calculate the best crossover frequency for the low pass filter?

You can simulate and visualize how the speakers and sub will sum using REW and a measurement mic even without any DSP in the chain -- though getting a "flat" response would be harder to achieve.

REW Alignment Tool

 

[No. 5]

Hello all,

Newbie here...
I would like to add a subwoofer to my stereo system to have a bit more punch when listening to movies. My question is concerning subwoofer integration with my integrated amplifier.

I was thinking to try a subwoofer "the easy way" without buying a miniDSP flex + microphone... to try and see if I like the sound in my room.
Also, my other objective is to diminish the costs of making this "sound experiment".

For that, I was looking at my bookshelf speakers spinorama to try to determine at what crossover frequency to set on the subwoofer.
My understanding is that looking at the speakers slope, I could calculate a "starting point" for the subwoofer's low pass filter crossover frequency ? Is that a good approach ?

If yes, can you guys tell me how to calculate the slope on the PSB P5 ? Im a bit confused...

Is it a -14 db / -21db slope ? -7 db / -22.5 db slope ?
100hz = +1 db
80hz = +1 db
50hz = -6 db
40hz = -13 db
25 hz = -28.5 db
20hz = -34 db

What slope should I look for when shopping for subwoofers for the speaker to "naturally" match the speaker's slope ? Is it possible to find the slope of the subwoofer without taking measurements ? Maybe the manufacturer can give me that information or I could use a spinorama data for the sub if I find it online ?

How can I integrate the subwoofer when they have a fixed 12db or 24 db/octave slope ? Is it really bad if they don't match perfectly ?
If it's not too bad and I manage to get the slopes of the two devices (speakers and sub), how can I calculate the best crossover frequency for the low pass filter?

So many questions...

Thank you for your help

Personally, I would do this with a microphone. The reason being the room your speakers are in has its own transfer function and it will completely change the slope of your speakers and subwoofer, so trying to calculate the acoustic result without knowing that transfer function could easily lead to undesired results.

Now when I say "microphone", I don't mean that you need a UMIK-1, a free mobile app or the set-up mic from an AVR will do just fine for what you want to do. I have compared this app on my Pixel 7 Pro and this app on my iPad Mini to one of my calibrated measurement microphones with good results after a few minor settings changes.

@Lednek made a good suggestion to plug the ports in your PSB's, you may make integration with your sub easier and help reduce distortion from them.

 

[firestart3r]

Wow thank you so much for your advice guys!

I guess the best thing to do is to get a calibrated mic and use REW on my computer to see the response I get so I can change and tweak the response.

First, I thought of measuring the bookshelf speakers on their own, deduct some kind of crossover frequency from the FR, add the subwoofer, measure again and see what changed.

To add to that, I was looking at subwoofers with a 3 band EQ functionality (ex. SVS, Arendal, etc.) so I could use it to fix the "bass problems" I see in REW.
For example, to tame down the big "peaks" I see in the response. Does that make sense ?

Concerning the LFE channel:
@DVDdoug do you think movies would still be more enjoyable using the sub, even if it would'nt get the LFE channel ?
Does the basic stereo L/R channel signals carry lower frequencies ? Lower than 100hz ? 50 hz ? 25hz ?
I guess it depends on every movie... but in general what would you say?

What about music? I guess this issue doesn't really apply to music because it's usually recorded in stereo ?

I'm asking because I quite like my setup for now. I find it's simple, low number of equipement/cables and sounds pretty good.
TV with Netflix/Spotify app ---> optical cable --> integrated amplifier with DAC --> speakers

Thanks again!