Some people think no high pass is better. Are they wrong?
If your mains can play loud and deep without audible distortion, then you can use them full-range to have more bass sources distributed in your room, which will smooth out room modes.
But if playback is limited by bass distortion from your Mains, then high-passing them is naturally beneficial.
Depends upon what you are pairing up. One advantage of a sub and monitors is you unload the low end from the smaller monitors allowing them more power available above the crossover point. I say in general they are wrong. You have control over meshing the crossover rather than hoping for a lucky fit between sub and mains.
Also, no two ways about the convenience of one set of connections vs having to have multiple outputs from your preamp.
Even though I essentially agree with the points given by
@staticV3 and
@Blumlein 88, I would like to recommend you to objectively measure and see/observe the responses of your own subwoofer(s) (SWs) and woofers (WOs) around the possible crossover (XO) Fq for optimization of XO-Fq, filter slopes, relative gains, polarity, time-alignment,
etc.
Just for example, let's think/simulate about a typical case as follows.
Providing that, in your home audio environment, you would have HiFi class L&R SWs well capable (in spec-wise) 16 Hz to 120 Hz, and you also have HiFi class 30 cm WOs in nice cabinet well capable (in spec-wise) 35 Hz to 500 Hz, how can you decide the optimal (best) XO Fq, filter slopes, polarities, gains, relative delay (time-alignment),
etc. for your SWs and WOs?
My simple suggestion for your first step is to prepare two 8-sine-wave rectangular tone-burst signals of about -15 dB gain, one is 40 Hz, another one is 90 Hz.
Using typical measurement microphone set at your listening position, you would first record
SWs-only sound of 40 Hz tone-burst and 90 Hz tone-burst by using suitable audio-interface connected to your PC or Mac in 96 kHz 24 bit PCM format; no low-pass (LP) (high-cut) filter should be used.
Next, you would record
WOs-only sound of 40 Hz tone-burst and 90 Hz tone-burst, with no high-pass (HP) (low-cut) filter at all.
Then, you would record
SWs+WOs (singing together) sound of 40 Hz tone-burst and 90 Hz tone-burst, with no LP nor HP filter at all.
Such recorded three PCM tracks should be loaded to
e.g. Adobe Audition (ver.3.0.1 in my case) for 3D time-gain-Fq color spectrum analysis which gives visual representation of sound energy distribution in 3D (time-gain-Fq) space; you can see/observe tightness of the tone-burst air sound, yes, it represents "transient behavior" of your SWs and WOs as well as SWs+WOs for 40 Hz and 90 Hz tone-burst. Of course, you can see/observe the actual air sound wave shapes given by SWs, WOs and SWs+WOs.
Generally speaking, HiFi 30 cm WOs in excellent cabinet driven by high-damping-factor amp has better transient behavior than any SWs around 50 Hz - 120 Hz zone, and the Adobe Audition 3D color spectrum will give you visual observation/confirmation for selection of rather lower XO Fq, say XO at around 55 Hz, in this example case.
Now you can easily understand what would/should be the subsequent tests and measurements.
You may now apply LP filter for SWs,
e.g. -24 dB/Oct Linkwitz-Riley (LR) at 60 Hz, HP filter for WOs
e.g. -24 dB LR at 50 Hz, and record the room air sound of SWs-only, WOs-only, SWs+WOs, analyze them by Adobe Audition's wave spectrum and 3D-color spectrum. The wave-shape spectrum will give you visual info on phase continuity (for time-alignment), 3D-color spectrum will give you transient behaviors/characteristics (tightness/compactness of low-Fq sound energy distribution).
In this way, you can semi-objectively optimize (or best tune) XO-Fq, filter slopes, polarity, relative gains, time-alignment,
etc. between your own specific SWs and WOs in your own acoustic environment. (Of course, final decision should be done by subjective listening to various tracks of your preferred music!)
If you would be interested in such approach, you can find some example cases of spectrum analyses using Adobe Audition 3.0.1 on my project thread as follows;
- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495,
#497,
#503,
#507