To Sub Or Not To Sub, That Is The Question

DoctorWhy · Monday at 11:01 PM

Danielaruso said:
I am pushing 87db speakers that have hybrid Lattice tweeter and go from 32 Hz to 40 kHz with 6 Ohms average 3.2 Ohms minimum.

I had JL F112v with CR1 Crossover. I simply could not get the subs dialed in. I called JL audio, you would need a PHD from NASA to get these subs to dial in. I gave up and am disconnected them. Running speakers full range and things sound more clear for sure.

I am contemplating buying the Rel Carbons.

Question: Some experts say (i) Dont use subs you are adding complexity and getting in the way of the spekears (ii) add subs for soundstage and it will open up speakers with less stress. Crossover at 50hz, 60hz, no do it at 30hz with low gain. No add more gain.

To boot, there are almost no experts that actually no how to work the crossover and the JL subs. Their implied marketshare for 2 channel must be half of rel given the lack of expertise.

Experts also say "no one uses JLaudio for 2 channel its just for movies, they are too slow. Need Rel."

I am under the impression that 9/10 times the best sounding rooms at shows do not use subs. If this is incorrect would want to know. Theoretically if dealers are trying to sell their gear they would have an incentive to pull out all the stops to make the room sound as good as possible.

I am dealing with 19x11x9 foot room.

So, to sub or not to sub, that is the question.

I just read your question and skipped all the other answers. I had two JL Audio F113 subs for my Wilson Max 3 speakers. They never really helped. I've upgraded to Wilson XLF which offer much better sound at all frequencies, but cause detrimental room interactions in the bass in my 18 x 46 ft room with essentially near field seating at 11 feet from each speaker. After years of resisting, I commissioned my friend JR Boisclair of Wally Analog in Santa Rosa, CA. By distributing bass around the room with 4 bass speakers, one set to reverse phase, many of the bass resonances have been reduced, improving the clarity of the midrange and treble. It also has improved the power and depth of low bass. You cannot do any of this with one or two sub woofers. A swarm, or distributed bass array, set up by an expert is the best path to better bass.

sigbergaudio · Tuesday at 2:40 AM

Macattack said:
It’s easier to reverse the speaker cables to your one main (either the Channel you sub is on if using two or the closest to the sub of only using one.). Mute or disconnect the other main channel.

Then find the NULL at your crossover frequency. Correct your cables and you have aligned the wave front (temporal phases) of your sub and main speaker.

The NULL is easier to see on a meter for some reason than a maximum.

I use REW and its Sound pressure level function and my UMIK microphone. It’s far better than an iPhone. Adjust the phase on my JL Audio F113v2 subs one channel at a time, watching the meter on my PC.

One key is to have the microphone at the listening position. That’s where you want the two speakers (main and Sub) to meet…

That is a Barry Ober technique.

I am bit confused by this, if you have REW and Umik, why not just measure the frequency response? Then a phase/crossover issue will be easily visible as a dip in the response, no need to use the SPL meter.

Holmz · Tuesday at 3:52 AM

Macattack said:
…
The NULL is easier to see on a meter for some reason than a maximum.
….

Maybe the derivative is zero at the sum; whereas gthe null beam is a bit steeper?

Steve Rowan · Tuesday at 5:33 AM

Barry Ober is a very wise man. Lots of experiences. I had him work with my subs and mains. The CR-1 crossover system never worked well in my system. After several months of trial and error (with Barry’s Help) I sold it. The null method does work of course. Revel published a paper on integration of subs that provided much of the info on sub placement that I tried and it worked well.

Integrating subs into a two channel system can take lots of experimentation. But once completed can really make your system sing.

I would never willingly give up my JL Audio F-113 six pack. I am using full range towers in my system as well.

Hear Here · Tuesday at 5:45 AM

Steve Rowan said:
One of the first discoveries I’ve made is always use two subs for two channel. Of course you could always start with one and add the other latter. But given the choice between one super sub and two great ones I’d choose two over one. It just seems to work better with two.

One problem with two channel sub placement is many use directions and designs for home theater. For instance placing subs in corners works well with home theater, not two channel.

The next problem I very often is placing subs behind the speakers or to right or left of the main speakers. The reason many try this is to keep the subs in phase with the main loudspeakers. Which of course is very important.

Probably the worst “offense” committed when integrating subs in a two channel system is playing them too loud. Many people believe one should hear the subs. That works well for home theater where one generally enjoys the thump and explosions.
The key to two channel subs is to NOT hear them. One doesn’t want be reminded that subs are even in the room. If you can hear them then you are missing out on bass and mid bass information that’s being hidden by the subs.

Where to place them?
I’ve found that placing the subs along the sidewalls about midway into the room is a great position. Usually that means the subs will be positioned between you and the main speakers. This is generally a very neutral place in the room and the subs don’t have corners to boost their output.

When subs are placed on the sidewalls as proposed it’s relatively easy to blend them with the mains. The most difficult task is getting them in phase with the main loudspeakers so the woofers in the subs and mains aren’t working against each other. If there is less bass when the subs are playing then the subs and speakers are out of phase.

Getting the subs and mains to play together in phase usually requires an assistant. One person to sit in the listening chair and the other to to turn the phase control slowly back and forth while playing a a favorite recording. As the phase knob is turned listen to the differences in sound. I usually divide the phase knob in four quarters and listen to one quarter at a time. After you’ve decided on which quarter sounds best then slowly turn the phase knob until the subs a mains blend together. If your subs have a remote control this task can be accomplished much quicker. Shame on subwoofer makers who do not furnish a remote control.

Next adjust the volume of the subs so that they blend with the main speakers. One shouldn’t hear any boomy, loud distorted bass, or allow the subs to mask the details your main speakers already provide. Play some recording with natural bass, drums, piano, even voices that you’re very familiar with. Keep turning the volume of the subs a bit at a time so that you actually start hearing the recoding venues acoustics not your rooms. If in doubt turn them down. One can always turn them back up a bit. Try to avoid your first inclination. Which for many is, “ I want to hear lots of bass from my subs.” especially after paying a small fortune with them. I’ve done this plenty of times for sure myself.

There are lots of other tricks also that I could add but I’m tired of typing on my iPhone. So I’ll refrain unless others ask for more.

Enjoy!

Thanks for your suggestions. I have recently bought a pair of subs (REL S812s) and I'm yet to get them doing much good. Music often sounds good but occasionally there is booming / slight honking that isn't pleasant!

I cannot position them where you suggest because of the room geography - see sketch! The options for sub positions are the green squares. REL and a local dealer have suggested their choice of positions and it would be interesting to hear your opinion.

One problem is that my main speakers (Avantgarde Duo XD) already offer plenty of bass from their twin 12" drivers, so it's not more bass but better bass that I'm hoping for. The RELs offer only 2 phase options - 0 and 180 and XO from 20 to 120Hz.

I use a very low volume and about 50Hz, although the dial doesn't show any frequencies apart from the Low and High limits.

Any suggestions very welcome, as I'm currently inclined to resell the subs. Thanks

Robh3606 · Tuesday at 8:47 AM

Hear Here said:
One problem is that my main speakers (Avantgarde Duo XD) already offer plenty of bass from their twin 12" drivers, so it's not more bass but better bass that I'm hoping for. The RELs offer only 2 phase options - 0 and 180 and XO from 20 to 120Hz.

Out curiosity what's the issue? If you run a slow sine sweep do you have severe peaks and nulls at the listening position? All you need is an SPL meter to see where they are. Re run with subs at x position. Just record it to see what the actual differences are.

Rob

delm · Tuesday at 10:19 AM

I am using three JL Audio E112 subs with, usually, Quad ESL 63 mains. The mains are on an 80 Hz high pass passive filter (built into an insertable one foot interconnect). No DSP on the mains but there is DSP for the subs with miniDSP 2x4 HD (it can handle four subs). Data gathering is with REW and UMIK-2 microphone. DSP configuration is done with multi-sub optimizer software. The ESLs sound better without having to deal with lower frequencies and three subs gives me uniform bass around the room.

One of my Quad panels is out for rebuild so I have a Paradigm 120H pair on loan. The 120H sound best for me with the same concept of passive HPF for the mains and DSP for the subs.

Hear Here · Tuesday at 11:28 AM

Robh3606 said:
Out curiosity what's the issue? If you run a slow sine sweep do you have severe peaks and nulls at the listening position? All you need is an SPL meter to see where they are. Re run with subs at x position. Just record it to see what the actual differences are.

Rob

See my first paragraph above. The bass drivers in the subs seem to occasionally argue with those in the AG speakers. I've not yet run any proper measurements yet to see what's happening - a job for next week / month!

Macattack · Tuesday at 6:32 PM

sigbergaudio said:
I am bit confused by this, if you have REW and Umik, why not just measure the frequency response? Then a phase/crossover issue will be easily visible as a dip in the response, no need to use the SPL meter.

If I understand your question correctly, I think you are confusing adjusting the crossover on a sub with adjusting the temporal phase of the sub to match the Main speaker at the listening position.

I do use REW frequency sweeps to see my room response and develop an idea of where the sub(s) might be crossed as well as the volume level of the sub(s). Once that is done, I then follow the process above to ensure the wave front of the sub meets the main speaker at my ear at or around the cross over frequency. On JL Audio subs, that is done by adjusting the ‘Phase’ control.

ecwl · Tuesday at 7:41 PM

Macattack said:
If I understand your question correctly, I think you are confusing adjusting the crossover on a sub with adjusting the temporal phase of the sub to match the Main speaker at the listening position.

I do use REW frequency sweeps to see my room response and develop an idea of where the sub(s) might be crossed as well as the volume level of the sub(s). Once that is done, I then follow the process above to ensure the wave front of the sub meets the main speaker at my ear at or around the cross over frequency. On JL Audio subs, that is done by adjusting the ‘Phase’ control.

Haha. I feel old when I read what you wrote because I was thinking like sigbergaudio too.
Historically, because most of us don’t have access to REW and a calibrated microphone, we would pick a crossover frequency and cross our fingers that it’s optimum and then measure pink noise with the sub playing at 0 degrees phase with the speakers and 180 degrees phase with the speakers and whichever phase is the loudest means that is the phase setting for the crossover as the sub and speaker would be in phase at that crossover frequency.

But of course, with REW and a microphone, your way of approaching things is more optimal in terms of determining the frequency and phase of the crossover as you have many more granular data to work from to optimally set your crossover frequency and subwoofer phase.

sigbergaudio · Wednesday at 2:18 AM

Macattack said:
If I understand your question correctly, I think you are confusing adjusting the crossover on a sub with adjusting the temporal phase of the sub to match the Main speaker at the listening position.

I do use REW frequency sweeps to see my room response and develop an idea of where the sub(s) might be crossed as well as the volume level of the sub(s). Once that is done, I then follow the process above to ensure the wave front of the sub meets the main speaker at my ear at or around the cross over frequency. On JL Audio subs, that is done by adjusting the ‘Phase’ control.

You could figure out the phase adjustments (if needed) through the measurements as well, but your method works too of course!

Macattack · Wednesday at 4:38 PM

sigbergaudio said:
You could figure out the phase adjustments (if needed) through the measurements as well, but your method works too of course!

I think I know how to do that but not sure my channel specific sweeps with external timing marks enable that. You are speaking to impulse, Group delay etc data?

Robh3606 · Thursday at 1:23 PM

Macattack said:
I think I know how to do that but not sure my channel specific sweeps with external timing marks enable that. You are speaking to impulse, Group delay etc data?

Or you could do it old fashion way using sine tones and an SPL meter. Set up at the listening position and reverse the polarity on the sub. Adjust phase for the deepest null. The null is much easier to measure and much greater compared to the +3 - +6 with them in phase. Then flip polarity to put them in phase and adjust the subs level as required. In a room trying to get group delay and impulse? This may be crude in comparison but it's effective.

Rob

sigbergaudio · 2024-07-26T02:48:02-0500

Macattack said:
I think I know how to do that but not sure my channel specific sweeps with external timing marks enable that. You are speaking to impulse, Group delay etc data?

In reality the response in the low frequencies are minimum phase, which means whichever way you arrive at a given frequency response, the result is the same. If the response (amplitude) is the same, the phase will also be the same.

So what I was suggesting was that you can measure the response, and if it is not satisfactory, you could either use EQ, or use the the phase control (or both), and measure again, until you are happy with the response.

If you are already comfortable with the other approach, this might appear more complicated not less, of course.

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To Sub Or Not To Sub, That Is The Question

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