2-Channel Subwoofer Integration

[Delija]

Flat (in room) is not good - FR needs to follow some house / Harman target curve.

 

[JoeESP9]

Oh really! Says who and what's the reasoning? And what does it have to do with subwoofers?

I will admit I use a gentle roll off of ~4dB/Octave above 8KHz. It's something I learned off when I first started trying to get flatter in room response back in the late 1970's.

Flat to 20KHz has always sounded overly bright to me. Flat to 20Hz is another thing altogether.

 

[rbbert]

Not sure which of the 4 links you're referring to. The (Rhonda Wilson) Meridian one is by far the most comprehensive, an overview of 45 papers.


That's why I stated earlier "mono" <40-50hz is fine. Most listening/living rooms cannot support lateralization that low. But 80-90Hz is way too high...for uncorrelated bass material/modern classical etc. All the caveats apply. Btw, the last reference above by Rhonda is to a PSR type system. Definitely no mono bass.

I think most of the discussion here has focused on whether to run the main speakers with no high-pass filter or not, then secondarily whether to run multiple subs vs. one, then on whether to feed the sub(s) a mono or stereo signal. Some of the “replies” are therefore not truly replies but rather comments on different situations.

I would guess (because there is no way to be sure) that those posters whose main speakers have good in-room response below 40 Hz and don’t wish to use a high-pass filter can still get good spatial imaging feeding any number of subs a mono signal.

Over the past 40+ years I have used many combinations in 2-channel systems; passive high-pass with active low-pass, active high and low pass, only active low-pass (no high-pass), with 1, 2 or 3 subs (haven’t yet tried 4). My opinion is that none is better in all situations, much depends on the room and the main speakers.

 

[a.wayne]

Oh really! Says who and what's the reasoning? And what does it have to do with subwoofers?

I will admit I use a gentle roll off of ~4dB/Octave above 8KHz. It's something I learned off when I first started trying to get flatter in room response back in the late 1970's.

Flat to 20KHz has always sounded overly bright to me. Flat to 20Hz is another thing altogether.

Flat anechoic response to 20khz doesn't Sound bright at all , there must be other factors leading to you making this subjective observation , mostly i would suspect your measuring system is not accurate in FR and you may not be listening to a flat FR ..

There are other distortion factors involved too that would could lead to your observation and not all totally up to a flat FR response..



Regards

 

[a.wayne]

This thread is making me pay more attention to this site.

I've been running dual DIY 12" TL subs for more than 20 years. When I started with the dual subs there wasn't anywhere/anyone to discuss the entire subwoofer thing. Consequently I've learned mostly by trial error and measurements what actually sounds best to me.

Since the later 1970's I've used measurements to set up and adjust my system for flatter in room response. Since the middle 1990's I've had a dedicated acoustically treated room. Way back then (1970's), I used an LP with test tones a Rat Shack SPL meter and a 12 band linear equalizer. Nowadays I use REW, a calibrated mic and a laptop to measure my in room response. A 12 band DSP is then used to adjust the sound. Once this is done the DSP is set and forgotten.

I use an electronic crossover to feed main and sub amps. My subs are placed asymmetrically and run in stereo.

Some of the things I've learned through trial and error are:

In a symmetrical room asymmetrically placed subs work better and need less "correction".

Subs run in stereo sound better than in mono. This is so even with LP's which typically have all frequencies below 100Hz in mono.

Once a room has been set up to sound flat different sources do not need different settings.

Bass that's flat to the lower 20Hz area can cause some weird vibrations you never knew were there.

Foundation bass brings more of the room/hall sound and helps with the soundstage.

Removing low bass from the mains allows them to play louder clearer and requires less power to do so.

The one universal truth about subs I've learned is, just about every speaker including so called "full range" speakers will benefit from the addition of a subwoofer (two is better). The only real exceptions are usually relatively expensive and more often than not include their own powered subwoofers or sub towers.

As for the original question:
The only way to be sure a sub(s) is set up properly is to use measurements. As to whether the results are satisfactory to you is for you to decide.

IME the flatter my in room response the closer my stereo sounds to live and the better it sounds to me. What it boils down to, is when I come home from hearing live unamplified (orchestral) music I'm not disappointed when I play some music.

Congratulations i have never heard a stereo system ever at any cost or size to even come close
to a real symphony Orchestra ..



Regards

 

[JoeESP9]

Congratulations i have never heard a stereo system ever at any cost or size to even come close
to a real symphony Orchestra ..

Regards

Neither have I.

I said, "I'm not disappointed when I return home from the Kimmel Center and play some music".

There have been two times when I felt/heard a very good facsimile of a full orchestra. One occasion was Infinity IRS-V's driven by Levinson. The other was Apogee Grands driven by Krell.

I heard a Levinson HQD system that was just as close at lower volume levels. Those Quad's, even when using two pair just can't play loud enough.

 

[JoeESP9]

Flat anechoic response to 20khz doesn't Sound bright at all , there must be other factors leading to you making this subjective observation , mostly i would suspect your measuring system is not accurate in FR and you may not be listening to a flat FR ..

There are other distortion factors involved too that would could lead to your observation and not all totally up to a flat FR response..



Regards

That would apply only if my listening space was an anechoic chamber. It isn't.

Listen to a system that's ruler flat in a room. Then roll off the high end slightly and listen.

I discovered flat to 20KHz didn't sound good or right in previous rooms or my current purpose built and acoustically treated room.

What one uses as a reference is of primary importance. My references are The Philadelphia Orchestra at The Kimmel Center and The Wannamaker Organ in Gimbals in center city Philadelphia.

My previous reference for orchestral music was The Philadelphia Academy Of Music.

IME: The better my system sounds when reproducing un-amplified orchestral music the better it does everything else.

Lets get back on the subject of the thread.

Flat to 20Hz is good.

 

[Delija]

Lets get back on the subject of the thread.

Flat to 20Hz is good.

We were already on the subject - I was talking about (sub)bass FR region.

And no, flat to 20Hz is not good.
It's too lean.

FR should look something like this.

 

[a.wayne]

That would apply only if my listening space was an anechoic chamber. It isn't.

Listen to a system that's ruler flat in a room. Then roll off the high end slightly and listen.

I discovered flat to 20KHz didn't sound good or right in previous rooms or my current purpose built and acoustically treated room.

What one uses as a reference is of primary importance. My references are The Philadelphia Orchestra at The Kimmel Center and The Wannamaker Organ in Gimbals in center city Philadelphia.

My previous reference for orchestral music was The Philadelphia Academy Of Music.

IME: The better my system sounds when reproducing un-amplified orchestral music the better it does everything else.

Lets get back on the subject of the thread.

Flat to 20Hz is good.

How were you achieving flat to 20Khz ..?

 

[chops]

Adding multiple subs ( We all can agree 2 min is best ) solves one issue and crates another not all speakers benefit from adding subs , but one may prefer what subs bring to the table in body , tone and power not present in recordings but add to the overall Pleasure of listening for that individual, this is totally different from systems designed to be used as 4 towers setups .

Systems designed to be used as 4 towers tend to have their bass towers matched to the mains which are capable of a proper spectral balance for such powerful woofers ..

Adding 5 subs to a simple 1” dome 4 inch midrange setup will not have a proper balance spectrally or dynamically it cant , there is no way for the small mid/twt assembly to match the dynamic Power of the added subs, in this situation subs are setup subpar for balance , this is when we get into the ridiculous 30 hz xover points ( poor hand off ) or diminished gain situation until sale ensue ..!


1. A properly designed and balanced loudspeaker will not benefit from additional subs , this doesnt mean someone wont prefer them with subs , but on well recorded non fictional music it will not sound balanced and exhibit poor timbre and attack ..

2. Properly designed 4 towers with multiple subs will have the appropriate mid/twt design to take advantage so should not lose attack, timbre or speed on music material , this is IMO the ultimate way to design a SOTA system no one box will best this arrangement when done correctly ..



Regards

1. Again, wrong. It is NOT just the speakers that are at play here. The ROOM has to be considered part of the system and why the subs are required. I don't know how many times I have to say this in order for it to sink in.

2. Agree

 

[chops]

With the comments and questions that keep coming up from a select few here, it's quite obvious that those of us who are in the "know", anything we say falls on deaf ears... Deaf in more ways than one.

 

[JoeESP9]

@Delija: You may call flat to 20Hz "lean". I doubt if many others would.

Please note, flat to 20Hz does not mean that's the lowest frequency my system can produce.

I wonder how many systems are flat to 20Hz. Only those who measure their in room response can be certain.

Were I really concerned about the sub 20Hz area I'd be looking at something like the Eminent Technology Rotary subwoofer. It has measurable response to 1Hz.

 

[AJ Soundfield]

I have used many combinations in 2-channel systems; passive high-pass with active low-pass, active high and low pass, only active low-pass (no high-pass), with 1, 2 or 3 subs (haven’t yet tried 4). My opinion is that none is better in all situations, much depends on the room and the main speakers.

Yep.

 

[AJ Soundfield]

That would apply only if my listening space was an anechoic chamber. It isn't.
Listen to a system that's ruler flat in a room.

This has to be the most confused topic on audio forums. A "flat" anechoic measurement on axis is a single point in the direct output of a (typical, monopole) loudspeaker, which radiates effectively forward at HF and omni at LF. Specifically because the chamber is anechoic (like open space), the capture is effectively only the direct on axis output. A well designed speaker will be both flat on axis and "flat"/smooth off axis. The off axis can be measured separately as well.
An in room/closed space measurement is not anechoic. One can do a "quasi" anechoic measurement near the speaker by gating/ignoring the closed space reflections, but this is not the same as a listening seat "in room" measurement. That type of measurement is a sound power/single point capture of the cumulative sum of the speakers all on/off axis radiated frequency responses. Totally different from an anechoic measurement. A anechoic "flat" typical forward radiating speaker cannot measure both flat anechoic (no space) and flat in room (closed space). An anechoic "flat" speaker placed in typical listening room measured at listening seat 9' or so away, will have a downward sloping response from low to high frequency, due to the omni>forward radiating characteristics of the speaker and the absorption of the air/room reflective surfaces, objects, etc.
For this type of measurement to be remotely "flat", a massive amount of HF power would have to be added. If this same EQd speaker is then remeasured anechoically, it wouldn't be "flat", it would have a highly tilted upward response from LF>HF.
So an anechoic "flat" speaker is not perceived as bright to anyones ears, with normal hearing, in room. A massively EQd to "flat at LP" certainly would, but only a very uninformed person would do that...and not have any clue about the difference.

cheers,

AJ

 

[a.wayne]

1. Again, wrong. It is NOT just the speakers that are at play here. The ROOM has to be considered part of the system and why the subs are required. I don't know how many times I have to say this in order for it to sink in.

2. Agree

Wrong or disagree, my point can be easily proven beyond just being Subjective, a properly designed full range loudspeaker doesn't need added subs to tune the room, regardless of your subjective preference ..!


Maybe that will sink in too ...!

 

[a.wayne]

With the comments and questions that keep coming up from a select few here, it's quite obvious that those of us who are in the "know", anything we say falls on deaf ears... Deaf in more ways than one.

So you are in the know, would love to see your work any links ..?

 

[Delija]

@Delija: You may call flat to 20Hz "lean". I doubt if many others would.

Please note, flat to 20Hz does not mean that's the lowest frequency my system can produce.

I wonder how many systems are flat to 20Hz. Only those who measure their in room response can be certain.

Were I really concerned about the sub 20Hz area I'd be looking at something like the Eminent Technology Rotary subwoofer. It has measurable response to 1Hz.

I do measure

 

[chops]

Wrong or disagree, my point can be easily proven beyond just being Subjective, a properly designed full range loudspeaker doesn't need added subs to tune the room, regardless of your subjective preference ..!


Maybe that will sink in too ...!

You obviously can't or don't want to grasp the concept, so there's literally no point continuing this with you.

 

[chops]

Flat (in room) is not good - FR needs to follow some house / Harman target curve.

LOL. Also terribly wrong.

 

[Delija]

I strongly disagree.