Is a high pass filter necessary for my setup?

[girtab]

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!

 

[Keith_W]

Whether you need to high-pass your mains is a question nobody can answer without knowing more about your setup. All we know is "big floorstander", and that is nowhere near enough information to give advice. There are benefits to both "overlap" (mains full range + sub low passed) and "high passed" (mains high passed, sub low passed). Sometimes you are forced to pick one, and the usual reason is that the mains don't have enough bass extension.

More outputs is generally better if you are running subs. You have more flexibility. If you pick an interface that has only 2 DAC channels, you are stuck with two DAC channels and you have no way to independently manipulate your sub with DSP.

 

[girtab]

There are benefits to both "overlap" (mains full range + sub low passed) and "high passed" (mains high passed, sub low passed)

May I ask what the pros and cons of each approach are?

 

[kemmler3D]

More overlap means more sources in the overlapping frequencies, means more opportunities to fill in dips / nulls. Also more total bass SPL which may or may not be helpful.

Less overlap means probably running the subs for lower frequencies only, so less chance of localization and also possibly less distortion from the mains vs. running them full range.

I think the right answer depends on how you plan to EQ things. If you can do proper room correction / PEQ in your setup I think it's less consequential which way you go. If you are not using PEQ or something more advanced then I think having the hi pass will be more helpful. (in terms of achieving a successful integration.)

 

[girtab]

More overlap means more sources in the overlapping frequencies, means more opportunities to fill in dips / nulls. Also more total bass SPL which may or may not be helpful.

Less overlap means probably running the subs so lower frequencies only, so less chance of localization and also possibly less distortion from the mains running them full range.

I think the right answer depends on how you plan to EQ things. If you can do proper room correction / PEQ in your setup I think it's less consequential which way you go. If you are not using PEQ or something more advanced then I think having the hi pass will be more helpful.

Well that's the main difference between the RMEs for me, I think with the adi-2 DAC I will have a PEQ curve for the sum of the mains + subs while with the adi-2/4 pro i can not only set a crossover for both mains and subs, but also independenlty EQ the mains and the subs (as far as i know)

 

[kemmler3D]

Well that's the main difference between the RMEs for me, I think with the adi-2 DAC I will have a PEQ curve for the sum of the mains + subs while with the adi-2/4 pro i can not only set a crossover for both mains and subs, but also independenlty EQ the mains and the subs (as far as i know)

Gotcha, if you are not using a PC / DSP/ AVR with room correction in addition to the DAC I might go for the 2/4.

 

[girtab]

I could use EqualizerAPO but I use toslink from my TV which is limited to stereo so I don't think that's an option

 

[Redacted]

If your mains are 0dB at 25Hz, as you imply, you arguably don't need subs.
If you are are not getting enough SPL, you may need more watts.

 

[girtab]

If your mains are 0dB at 25Hz, as you imply, you arguably don't need subs.
If you are are not getting enough SPL, you may need more watts.

You can never have enough bass extension

My polk r700s do sound great by themselves already though no question about it

Also I have enough watts, but im just looking to maximize the SPL capability of my system with subs and maybe flatten out the LF a little once the right time comes. Right now i just need a futureproof dac like the rme 2/4 but its super expensive and im having a hard time justifying the price difference to the regular adi-2 dac

 

[Redacted]

There is no future-proof DAC. Don't waste your money.
Instead look for subs with 18" drivers and with 2kW amps, maybe build one? - you likely only need a simple filter to get the -3dB point to whatever your current system has. A more interesting and manly project, I'd say, in the unlikely event your room works well with it!

 

[girtab]

I have pretty specific needs with dacs, mainly reliability (hence why I said future proof), optical input, the ability to control volume via midi over usb, 7V output voltage so i can use my apollon amp at lowest gain, etc.. so i would need at least an rme adi-2 dac if not the 2/4

Such a sub would a cool project though, cant lie

 

[singular]

Talking about stereo...
High pass is good - you cut off what is not there, and at the same time emphasize remained subbas which wants to work elsewhere, and you want it in the room in right time to percept.

Sometimes Allpass works too.
You dont need to add what is already there.

Bassreflex systems works always the same.

I would not work with a subwoofer unit which cannot be adjusted in time (delay for main pair), cutoff freq., and whatever other filters it needs.
With a luck you can go without DSP or FIR, manually.

I doubt there is better result using subwoofer compare to main pair.
It can confuse you by using one sub in assymetric room - seems better because subbas works mono (summed)...it means less difference between stereo subbas, and inability to recognize bass localization.

When use 2 subwoofers in assymetric setup/room, you need to have exact differencial setup for everything, to get proper stereo result for whole range.

There are some old classis ways how to work with those things thru analog.

 

[marin.weigel]

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?

 

[Keith_W]

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?

There are some things that are worth extra money. Like RME's rock solid reliability and driver support many years into the future. I can virtually guarantee that in 15 years, your RME will still be working, there will be drivers for whatever OS is in common use, and RME will not abandon the product. How do I know? Because MY RME is still getting firmware updates and product support, and it is almost 15 years old AND it's a superseded model. The Topping is a bit of an unknown quantity by comparison. I am not saying that the Topping is a bad product, but they don't have quite the proven track record that RME does. IMO the Topping would be an excellent choice if the OP wanted to save some money. Nobody would criticize him for that.

 

[Marc v E]

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?

 

[Duke]

@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.

 

[YouDontHaveEnoughBass]

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

 

[kemmler3D]

I could use EqualizerAPO but I use toslink from my TV which is limited to stereo so I don't think that's an option

EQAPO can copy input channels to multiple output channels, it should be possible to implement filters for 3-4+ channels in there even if you only have stereo input.

 

[Wayne Highwood]

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

Good post. I might suggest a line level hpf in lieu of plugging the ports. That would offer a protective "rumble filter" when you're really blasting it, where merely plugging ports won't protect from super loud low freq content as well while also raising f3.

 

[singular]

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.