Is a high pass filter necessary for my setup?

[Wayne Highwood]

if running the mains full range i'd probably plug the ports for better phase integration over the overlap; ports tend to give a lot of phase shift and makes phase alignment between sub and main almost impossible to achieve over the range

This is the other side of the "to plug or not to plug" and worth consideration.

 

[singular]

You will not get better feelings from hearing infrasonic or ultrasonic in music content.

 

[Wayne Highwood]

There is no need for infrasonic in apartment architecture.

You do not need infrasonic for music.

The HP filter is already included in bass-reflex system - look at the first impedance peak.

Output drops, sure, but below port resonance where the driver and port decouple that wont check excessive cone motion.

This is a bit of an edge case, with the OP seeking maximum volume and extension from his Polks. I'm with the others here, would high pass the Polks and let subs do the deep digging.

 

[gnarly]

My goal is maximum SPL with the smoothest bass possible across multiple listening positions and potentially extend the LF extension to infrasonics.

Those are conflicting goals. Maximum (clean) SPL almost always favors high-passing the main speakers, as the first place their response weakens is their bottom end. Smoothest bass across multiple positions almost always favors more LF sources.

Personally, I always choose maximum SPL....just sounds cleaner and more real/exciting to me.

 

[girtab]

Room gain and acoustics may let you believe in 25 Hz extension, but ...
Erin's review and measurements state extension to 40 Hz.
The data also shows a sudden rise in distortion of 20 dB below 40 Hz.

You said, you want to maximize SPL and reach down into infrasonics?
Which sub(s) do you have, that would possibly be able to handle that?
Anyway, with the above goals, your only option is to high pass your speakers at around 40 Hz and let at least a pair of beefy subs handle the lows.
PEQ filters alone will likely not cut it for your goals, you really need to follow some of @OCA excellent advice and use more serious DSP to extract all their potential within your room constraints.

EDIT, posted the following before seeing your newer post...
And, why are you so sold on RME, if i.e. a much cheaper Topping DM7 8 channel DAC is very close in measurements, read inaudible, on skimming available data?

Numbers are often deceiving,

Room gain and acoustics may let you believe in 25 Hz extension, but ...
Erin's review and measurements state extension to 40 Hz.
The data also shows a sudden rise in distortion of 20 dB below 40 Hz.

You said, you want to maximize SPL and reach down into infrasonics?
Which sub(s) do you have, that would possibly be able to handle that?
Anyway, with the above goals, your only option is to high pass your speakers at around 40 Hz and let at least a pair of beefy subs handle the lows.
PEQ filters alone will likely not cut it for your goals, you really need to follow some of @OCA excellent advice and use more serious DSP to extract all their potential within your room constraints.

EDIT, posted the following before seeing your newer post...
And, why are you so sold on RME, if i.e. a much cheaper Topping DM7 8 channel DAC is very close in measurements, read inaudible, on skimming available data?

they do extend to 25hz cleanly, they dont output JBL M2 type of bass but theyre still very impressive and i cant hear an ounce of distortion. Also, they extend this low due to wall proximity and room reinforcement, though i do agree that a high pass may still be a good option for them for sub integration thats why im inclined to get the 4 channel rme

 

[girtab]

From what you say I gather that you use a spdif optical out from your tv to your dac and use polk r700, multiple subs and want a clean deep bass all around the room. My first thought would be: avr. A dac, crossover, manual eq and spdif would just seem unnessary complications, to me at least. What is your thinking behind going that route?

Avrs are wayy to overpriced due to the licenses which i wouldnt use

 

[girtab]

@girtab, it looks to me like the tuning frequency on your Polks is around 34 Hz. You mentioned desiring infrasonic extension, which implies that you want to play program material with strong infrasonic content. Woofer excursion shoots up rapidly below the port tuning frequency, so imo that is likely to be a limiting factor.

If you have the capability of plugging the port, thereby converting the enclosure into a sealed box, ime that's one way to get away not using a protective highpass filter in the main speakers' signal path. Otherwise, I think your speakers' tuning frequency is high enough that a protective highpass filter makes sense for loud playback of program material with strong infrasonic content.

Makes sense, i also agree that a high pass filter is probably required at some point in the frequency range just to protect the speakers

 

[girtab]

if running the mains full range i'd probably plug the ports for better phase integration over the overlap; ports tend to give a lot of phase shift and makes phase alignment between sub and main almost impossible to achieve over the range

A high pass filter would also help with phase overlap right? I cant really plug the polk r700s port

 

[girtab]

There is no need for infrasonic in apartment architecture.

You do not need infrasonic for music.

The HP filter is already included in bass-reflex system - look at the first impedance peak.

Thank you for telling me what i dont need

 

[girtab]

Output drops, sure, but below port resonance where the driver and port decouple that wont check excessive cone motion.

This is a bit of an edge case, with the OP seeking maximum volume and extension from his Polks. I'm with the others here, would high pass the Polks and let subs do the deep digging.

Im not necessarily saying i want to use the polks bass extension to the max - i merely asked which situation would fit my needs more, just saying . So i appreciate your input on this and will take it into consideration

 

[girtab]

Those are conflicting goals. Maximum (clean) SPL almost always favors high-passing the main speakers, as the first place their response weakens is their bottom end. Smoothest bass across multiple positions almost always favors more LF sources.

Personally, I always choose maximum SPL....just sounds cleaner and more real/exciting to me.

So maybe i should high pass at lower frequencies like 40hz to still make use of multiple LF sources in the above frequencies while keeping deep bass distortions to a minimum? That seems like the best of both worlds right?

 

[singular]

I agree with others,

You can try to plug the port, and add HP filter from around 25-40Hz.
You can adjust the level of damping by using different plugs.

It depence how the original Group Delay looks, if it is peaky or not.
Adding HP to peaky GD end up in much worse phase and subbas perception, slowering the bass rhythm to unacceptable.

Plugging can make it acceptable again.

You can try 1st or 2nd order HP.
Also Allpass could work.

Ideal GD is linear with all added and natural filters ( amplifier low end ).
Try it and you will see.

 

[markstein]

Hello everyone, I'm deciding between an RME ADI-2 DAC (€~1k) and ADI-2/4 Pro (€~2.5k). The 2/4 would let me properly high-pass the mains (big floorstanders) and low-pass the subs, while the cheaper DAC would mean running the mains full-range and only low-passing the subs.

My goal is maximum SPL with the smoothest bass possible across multiple listening positions and potentially extend the LF extension to infrasonics. My mains also reach flat down to 25hz in my room with no EQ. (Though I do cut a huge low Q room mode at 50hz by i think -14db because of wall proximity)

Is it generally better to:

1. Run mains full-range + low-pass subs, using multiple bass sources to help excite room modes more evenly, or
2. High-pass mains + low-pass subs, sacrificing some distributed bass sources for crossover control?

I can't audition both setups, so I'm trying to decide which hardware makes more sense. Obviously I'm also more inclined to get the Adi-2 DAC as the 2/4 is more targeted towards professionals and has features/inputs which I wouldn't use.

Any response would be greatly appreciated!

IMO and IME the RME ADI units are no good choice for a mains and subs setup, definitely not suitable as flexible x-over/ loudspeaker management system.

A miniDSP unit would be much better suited

 

[girtab]

IMO and IME the RME ADI units are no good choice for a mains and subs setup, definitely not suitable as flexible x-over/ loudspeaker management system.

A miniDSP unit would be much better suited

I did consider a flex balanced but i dont trust chinese retailers anymore, if it means i have less crossover control but in exchange 50 years of reliability and service then so be it you know?

 

[girtab]

I agree with others,

You can try to plug the port, and add HP filter from around 25-40Hz.
You can adjust the level of damping by using different plugs.

It depence how the original Group Delay looks, if it is peaky or not.
Adding HP to peaky GD end up in much worse phase and subbas perception, slowering the bass rhythm to unacceptable.

Plugging can make it acceptable again.

You can try 1st or 2nd order HP.
Also Allpass could work.

Ideal GD is linear with all added and natural filters ( amplifier low end ).
Try it and you will see.

I am unable to discern any differences in the time domain, im mainly looking for smooth FR and maximum output volume

 

[Flaesh]

My mains also reach flat down to 25hz in my room with no EQ

Have you tried 20 or 10 hertz at full volume? Or what's the frequency range of the content you're listening to? And what amplitude do you need?

Same driver in box, black - sealed, gray - ported:

 

[singular]

I am unable to discern any differences in the time domain, im mainly looking for smooth FR and maximum output volume

So you do not want good sound.

 

[girtab]

Have you tried 20 or 10 hertz at full volume? Or what's the frequency range of the content you're listening to? And what amplitude do you need?

after 24-23 hz and below theres a big roll off and you dont feel the bass hit your chest as much. 10hz is basically inaudible at the listener position which is to be expected for under 10 inch woofers. With some very specific music content that has a kind of rumble or special LF effects (downward LF sweep) I find that they lack a tiny bit for my taste. I also don't need the absolute volume to be increased by that much I would just find it nice if it did (as long as FR is perfectly smooth).

 

[girtab]

So you do not want good sound.

I want it to sound good, not sound good on paper. I am convinced most people can't discern group delays from ports as long as you don't create cancellations from poor phase alignment

 

[markstein]

I did consider a flex balanced but i dont trust chinese retailers anymore, if it means i have less crossover control but in exchange 50 years of reliability and service then so be it you know?

I had a minidsp SHD, bought in their webshop and directly imported from Hong Kong to Germany. There was an issue with the PSU and minidsp immediately sent a replacement PSU. I have nothing to complain.

As you see in my signature I own a ADI-2 Pro Fs R as well. The ADI units have only very limited PEQ capability (number of PEQ, max Q, max cut, frequency resolution), not sufficient for bass EQ, and no flexible high/low pass filters. Also no capability to set delays. They are simply not designed to be used as loudspeaker controllers.

A miniDSP SHD or Flex would offer you all the basic functionality you require at a relatively reasonable cost. If course without detailed level displays, without loudness, without bass/treble control...