How Deep Must the Bass Be?

[Bugal1998]

I'm interested in people's opinions about how low the lowest frequency a subwoofer/woofer can produce with "acceptably low" distortion should be.

I'm interested only in the lowest frequency that can be heard, not just felt, regardless of how high the spl level needs to be for that to happen.

I'm at my PC and now have time for a proper response....

This is an interesting question, and I don't believe there is an objectively right or wrong answer.

I would refer you to the research on Low Frequency Hearing Thresholds for Different Age Groups. You will find measurements--such as the graphic embedded below--from research conducted over different time periods, and there's a convergence of data that demonstrates audibility down to somewhere between 2-3hz; in no case was the required SPL in excess of 123db.

Audibility is not the same as having musical tonality which, as the article points out, ceases at around 20hz. I have daily access to a system capable of reproducing audible output down to at least 6hz, and I can confirm the sensations described in the research: Tonality gives way to pressure somewhere around 20hz, with the sensation of pressure continuing down to +/-10hz, and individual puffs or cycles that you can basically count out below 10hz. The purpose built room doesn't rattle during these tests, but that's probably not the norm.

Here's where we're at, so far...

Option 1:
If you only care about tonality, 20hz is probably your answer. If you care about theoretical audibility, the sky is pretty much the limit with 2-3hz and 123db of output. But what good is theoretical audibility without content?

Option 2:
If you only listen to acoustic music and don't care about organ music, 25hz is probably fine. If you listen to non-acoustic music, solid 20hz performance is superior, and 16hz covers organ notes. I think the organ notes are neat, and they're the passages likely to elicit goosebumps and a request to 'play that again'.

If you play rap, electronic music, bass heavy music, or use the system for home theater, there is some content down to around 6-8hz. Do you care? No right or wrong answer here, just a personal decision.

Industry professionals also don't agree on how much extension is needed; for example, during a home theater seminar, one industry representative argued that 25hz is sufficient extension, while another said getting down into the infrasonic was transformative. I'm no help here, because I agree with both of them some of the time.

You asked for opinions on extension and output, and I shared mine in post numbers 126 and 225. All things being equal, wild excesses are not necessary, more is generally better, but not if that means sacrificing other aspects of playback system performance.

I did not define above "acceptably low distortion" or "loud"-please give your own opinions on what values those should be.

"How loud" is referenced in the posts linked above, but impossible to answer in the form of subwoofer output since room size, distance to MLP, room gain (or lack thereof), etc. call come into play. Therefore I referenced in room SPL (at the MLP). For distortion there are, again, no concrete answers; but here are a few thoughts.

Option 1:
Reference the CEA-2010A or newer CEA-2010B criteria which you can access here.

Option 2:
Ensure that the harmonics of the fundamental at your maximum desired output across the subwoofer's bandwidth never exceed the threshold of audibility for their respective frequencies based on the SPL frequency audibility chart above. This would likely require your own testing.

Option 3:
Trust that the higher frequency content in the source material will almost assuredly mask distortion in any competent subwoofer that isn't being pushed beyond it's limit. If you don't hear audible distortion, don't worry about it. If you do hear distortion, buy a second/third/fourth sub, or buy a higher performance sub.

Keep in mind that multiple subs are beneficial for smoothing in-room response as well. And as stated in prior posts, none of this answers the subwoofer output question, because it will depend on how a given sub performs in each room.

I am interested in people's opinions as to whether the spl level of the lowest frequency that can be heard needs to be so high to sound "loud" that it will cause hearing damage.

I don't believe anyone truly knows the answer to this question (I certainly don't), but I referenced a study in post #223:
Effect of infrasound on cochlear damage from exposure to a 4-kHz octave band of noise.

Yes, this was a study conducted on Chinchillas, not people, but don't count on volunteers for a human study anytime soon.

Here are the key points/findings from the study for for consideration (Disclaimer, I don't have expertise in the field and welcome experts to provide insight and clarification as needed):

In the animals exposed to the 4-kHz [Octave Band of Noise] at 108 dB SPL, there were larger functional losses and much greater hair-cell loss in the cochlea that was simultaneously exposed to infrasound. [bold mine] We hypothesize that the presence of infrasound during this intense 4-kHz OBN exposure increased cochlear damage because infrasound caused more intermixing of cochlear fluids through the damaged reticular lamina than that which occurred during the intense 4-kHz OBN exposure alone.

The presence of infrasound during a 4-kHz OBN exposure at 86 dB SPL did not increase hair-cell loss and functional losses. We hypothesize that the combined exposure did not increase structural damage or functional losses because the reticular lamina is rarely injured during moderate-level, 4-kHz OBN exposures.

I don't know if Chinchilla ear anatomy fully replicates the acoustic amplification of the human ear canal for frequencies between 1 and 5khz, but if it doesn't, we might not take comfort in the lack of damage with the 4khz 86db test since--based on an excellent post by Floyd Toole (and linked by @NTK)--humans can have permanent hearing loss induced by SPLs as low as 75db at 4khz. If humans are susceptible to damage above 75db at 4khz, then is it possible that humans could also experience increased functional loss at relatively low SPLs compared to Chinchilla's in the presence of infrasonic acoustic energy? I don't know. I will note that the study's authors did not attempt to correlate the Chinchilla spl exposures to human exposures, other than to say:

The combination of intense infrasound and intense noise can be found in a number of workplaces such as large ships, submarines, offshore oil and gas platforms and around large combustion sources (e.g., Leventhall, 2006; Alves-Pereira and Castelo Branco, 2006). This combination may also occur in non-workplace settings such as automobiles, airplanes and concerts. The present findings suggest that exposure to intense noise plus infrasound produces more damage to the OC than an intense noise alone. [bold mine]

If human hearing loss can occur based on noise alone above 75db, then there is nothing in the article to suggest that infrasonics could not have a deleterious effect at those relatively low levels. In my unprofessional opinion, caution is warranted.

What spl level at 20Hz is the threshold for causing hearing damage if listened to continuously?

I have no idea.

 

[Bugal1998]

Do you have interests and preferences (genre and music) on the tracks of my "Audio Sampler/Reference Playlist" consists of 60 tracks (introduction here, summary ref. here and here)?

Thanks for asking (I know you offered previously as well)... I've listened to some of your reference tracks previously, and this is a good nudge to keep working through your curated list.

I'm always most interested in learning which tracks my fellow listeners come back to again and again and again; those tracks/albums that are a special combination of great music with great sonics.

 

[Chromatischism]

After years of experience in my own systems, I'll tell you that you are trying to separate two things which cannot be separated.

The short answer is that you want as much clean output as possible into the teens of Hz. Let's just say 12 Hz is a good F3. The reason is twofold. 1) an F3 of 12 Hz implies a strong sub which means more output in the important 20-30 Hz range, so 2) You get all of the visceral effects that makeup the experience that is bass. It doesn't have to cause audible rattling of the house and the items in it. The physical vibrations from the lower frequencies are part of the same phenomenon of air pressure waves that you hear with your ears from the higher frequencies. It's a spectrum in which its parts manifest differently to our senses, but are combined together and experienced simultaneously. Without the lowest frequencies, some music lacks weight and power. Try listening to Blade Runner by Hans Zimmer with subs that roll off below 25 Hz, then come over and listen to my system. The experience just isn't the same.

 

[dualazmak]

Thanks for asking (I know you offered previously as well)... I've listened to some of your reference tracks previously, and this is a good nudge to keep working through your curated list.

Thank you for your kind response. I will PM you soon.

 

[Philbo King]

Supposedly JDS Labs "left the SINAD race", but to me there are specs that are good enough (I quoted them above) and then I look at feature sets and usability foremost. I love the fact the JDS Labs Atom 3 allows me to switch between headphones and speakers with a single button push, while always remembering the volume levels. Prevents one entirely from fiddling with the volume level as you switch output devices, which is awesome to me.

My issue with headphones is stage, not linearity and certainly not lack of bass (because we can establish via measurements it is all there).

For my own very personal experience, I don't like to "feel" bass. To me the experience is unpleasant. And living in earthquake friendly California not too far from the St Andreas faultline, it can be downright alarming. I kid you not: two weeks ago we had a slow, rumbly 4.6-ish earthquake, and I was thinking "is this some a--hole neighbor that bought a new sub?"... I don't need shaky floors in my life.

PS: By my seat of the pants feeI think it came at a 2Hz or so frequency. Doesn't get bassier than that.

PS2: I just also recalled - a friend of mine set up his theater system (quite high endish, McIntosh stuff all over it) and his personal reference is Arnold's "End of Days" which has an early scene with a jackhammer being used on the street, I think. He was screaming "Yeah, this FEELS like you're there, right?", and I nodded, but also thought "god give me some earplugs, and who wants a live jackhammer in their listening room?". There sometimes is something like too much authenticity to stuff. There are things I'd rather not hear live...

I tend to agree. I've never been too happy at a concert having my liver jump a half inch whenever the kick drum hit, sitting 100 feet away. It's just not at all pleasant or enjoyable. I vote with my feet by leaving immediately.

 

[computer-audiophile]

I have 8 Ino audio profundus Y passive 12" ported subwoofers (6 in the front, 2 in the back), 16Hz -1dB.
The analog crossover filter for the subwoofers is Ino audio, CR80s (30dB/octave, 78Hz).
The top-speaker for above 80Hz is Ino audio i64s and one i32s as center.
The front top-speakers is driven by two Sybarite audio No1200 monoblocks (2x1400 watt @ 8 ohm)
The subwoofers are driven by a 4-channel VTV PASCAL L-PRO2S (4x400 watt @ 8 ohm)
A Denon AVR-X3600H receiver for HT and as pre-amp.
Oppo and Panasonic BD and UHD players.
Denon DP59-L turntable with a Audio technica AT-OC9/III cartridge and Holographic audio RIAA Two phonostage.
Room treatment by Ingvar Ohman professional acoustician and the guy behind Ino audio. I'm VERY pleased with the room, the sound is amazing and the bass is awesome (the RT60 between 30-200Hz is between 0,4-0,25s).

Thanks for the photo. I'm glad I asked for a picture! That's quite an unusual setup. The speakers look like they're set up like musicians on a stage. In practice, you could hold concerts for speakers with this arrangement. In terms of layout and appearance, it reminds me of the classic Acousmonium* by Pierre Boulez, but that's another story.

Your turntable looks impressive as well. I recognize it as a high-end Denon model.

* Briefly explained: The Acousmonium is a special speaker orchestra used in electroacoustic music and was developed by Pierre Boulez in the 1970s.

 

[Purité Audio]

I tend to agree. I've never been too happy at a concert having my liver jump a half inch whenever the kick drum hit, sitting 100 feet away. It's just not at all pleasant or enjoyable. I vote with my feet by leaving immediately.

I like that and have tried unsuccessfully ( so far) to recreate it at home , I really just do not understand not liking bass.
I believe that being able reproduce full-range bass with no overhang is probably the single largest improvement in home audio.
I remember so clearly reading numerous posters having to return or sell their new speakers because their increased extension excited the room and back then there was literally nothing nothing that could be done about it except vainly attempting to shuffle the speakers backwards and forwards.
Keith

 

[Waxx]

32-foot stops can play 16 Hz at the fundamental, though it depends on the stop design as to how much fundamental. An open diapason's fundamental is strong compared to the harmonics, but some testing shows that even removing the fundamental doesn't change the perception of the sound. By strong I mean 10-20 dB stronger than the next highest harmonic, not necessarily stronger than the sum of the upper harmonics. A closed 32-foot diapason (which is more like a flute) would only be audible in the harmonics, but I doubt there are many of those (just as there are only two organs with 64-foot pipes, and those absolutely depend on the harmonics to be heard at all). The amount of air that would be needed to make it felt would unmanageable, though it can certainly be simulated with electronics. As with a tuba, we overestimate the importance of the nominal fundamental frequency in producing the characteristic sound. But see my note below about acoustic performance requiring the effects of the space in which it is performed to sound natural and desirable.

For example, there is one well-known modernist tuba solo work that includes a 16-Hz "pitch." This is the double-pedal of a contrabass tuba in C (which is the standard orchestral tuba in American orchestras). It cannot be produced using a buzz by anyone I've ever heard, and most performers simulate it with flutter-tonguing. There's no way that includes even the slightest measurable fundamental, given that it's a series of thumps at 16 Hz, and not a continuous oscillating vibration.

I have two standard tests for low-frequency response. One is the bass drum hit in the opening of the third movement of Gustave Holst's First Suite for Military Band, as performed by the Cleveland Symphonic Winds on a Telarc recording made in the late 70's. I have it on vinyl and later bought it on CD to get the full effect of that one drum strike. Telarc was showing off with the way they recorded the bass drum, particularly when they reissued it on CD by my recollection, and it had a reputation for damaging speakers. In my case, it was the recording that first shredded the rotted foam surround on my Advent NLA's, at least the first time that happened maybe ten years after I bought them (I've replaced the surrounds several times on those speakers).

The other is also an old recording from the 70's--the Merlin the Magician track from Rick Wakeman's King Arthur and the Knights of the Round Table. The Moog solos (there are two) go low. I'm not sure quite how low, but lower and louder than most acoustic instruments that sustain recognizable tone and pitch.

I own several dozen recordings of tuba performance, and none of them test the bass response of a system as much as those two recordings, and certainly not the recordings of the Kraft Encounters II that includes that 16-Hz double-pedal.

Prokofiev 5th? Where? Zarathustra starts with a 32-foot diapason organ stop drone that most people, even when performed live with a large organ, hear only as its harmonics. But the lowest note in the Prok 5 that I recall is the low E in the tuba at the start of the slow movement, barely over an octave below the bass clef. Even I can play that. The Prok 7 has a low C#, and Holst's Planets goes down about that far. Other examples down to the bottom of the 1.5 octaves below the bass clef are not that uncommon. Some band works, including a Percy Grainger piece that I just performed (Children's March), has pedal Bb (~28 Hz), which you won't hear unless the band's tuba player on the low part has professional training. (I don't, but I was playing the upper part, thank God). There is very little fundamental in the sound of the pedal range of a tuba, no matter what tuba players think. The contrabassoon goes about down to a nominal 28 Hz with a good player, but with even less contribution from the fundamental. Low F the octave below the bass clef is within the reliable range of most amateurs, though if you want it loud, don't expect it to have a lot of fundamental in the spectra.

But Koyaanisqatsi is in a class by itself for the demand it makes on the two tuba players. Warren Deck and Sam Pilafian (RIP) played on the original recording, and that level of world-class performer is what that music demands. Still, it didn't go below the 28-Hz pedal Bb and, still, the sound is dominated by overtones.

As I mentioned elsewhere, I helped a buddy set up his new 7.2 system that uses a large (and expensive) Marantz DVR and all Revel speakers, including the subs. (Performa-class Revels, and the subs have 12" drivers and kilowatt amps.) After we balanced the system using Audessey (however that is spelled), it didn't play that Wakeman Moog solo noticeably more impressively than my system at home with Revel F12's (no subs) and a large amp. That material was made for vinyl LP's so it probably didn't go below about 30 Hz. Those subs are capable of much lower, but the music we listened to doesn't ask for it. (I didn't have my REW stuff with me, so I couldn't check the subs for how well they cancelled room modes. But the system and room sounded very good.)

But there is one question only hinted at so far, and that is: How much of the performance space's room resonances do we want to hear in orchestral performance? Sometimes, that low rumble is what contributes to the characteristic sound of a concert hall, and it's good when a recording captures that ambience in addition to what the instruments produce. Yes, sometimes what contributes to the rumble is the air handlers and the outside traffic, but in my house at least, the air handler hums along at 120 Hz. I like rock music that is recorded dry to maintain good clarity, but classical composers didn't write their works for outdoor performances.

I've heard systems with big subwoofers set up the way Sean Olive's inexperienced test subjects seem to prefer (referring to the graph upthread), and for me those systems sound boomy and unnatural. My reference is live performance. I want accurate bass, but I'm not one to start cheering when it is emphasized unnaturally.

Rick "much ado about nothing" Denney

Your observations are largely the same as mine, that is why i got rid of my huge 22Hz tuned subwoofers and got a smaller (sealed) ones that only go to 31Hz (F3). That does the job for me, even with very low organ, tuba or synth sounds. But 40 or 45Hz as F3 is to high, then i'm missing some parts of that music. And i do realise that it will never be exact as in the concert hall or studio where this was recorded, i've seen enough classical concerts, and helped with recording some (as assistant) to know the difference. But that does not mean i want to get as close as possible, even if that includes big subwoofers.

 

[Frank Dernie]

Yep, gotta hear those panels buzzing and rattling 3 blocks away or your not really doin it. LOL

Frank, I consider you our resident expert on the whole vinyl engineering thing and I'd like your input on something.
I always felt the audio community went backwards with their love of low compliance MC cartridges, their required high mass arms,
and all the rest. What's your thoughts on the issue?

It is just a question of matching in principle but detail differences in parts can lead to peaks and troughs in the cartridge output.

One big problem with the whole “record player as a vibration transducer” is that the damping is not in the right place for optimal performance of the transducer. Also important things like cantilever design - how stiff and is the contact point of the stylus concentric with the cantilever so torsional losses aren’t introduced etc. - were never mentioned in the enthusiast sphere.

There are so many ways any design can be non-optimal and modern LP playing kit tends not to mention any of them but go on and on about stuff that doesn’t have much importance is it ignorance or marketing?

As with all engineering the devil is in the detail and whilst some concepts may be inherently superior to others a detail design oversight can render the potential superiority moot.

I had good sounding record players both using low and high compliance types though I do tend to agree with you that the whole low compliance MC thing was backwards and more marketing and profit lead than good engineering.
It allowed small volume high priced cartridges to become fashionable when a Shure V15 MR was as close to perfect as anybody needed.

IMHO.

 

[gnarly]

Hey folks, a request...
when describing the low end response of your sub(s) / system, please include at what max SPL....(Z-weighted)
Cause saying flat to 10Hz for example, is pretty much meaningless on its own.

Ime/imo, best spec if you have it, is max flat SPL across the spectrum, that stays flat down to the low spec corner (f-3 works)...again Z-weighted.
Or if you have a house curve in play, max SPL across the spectrum that maintains the house curve down to low spec corner.

 

[Bugal1998]

I was thinking of driving about an hour to where there is an Organ with a 16Hz pipe and listening to it but then it occurred to me that if I did hear the 16Hz pipe and it sounded "musical" to me, how would I know if it was the 16Hz I was enjoying or one of the harmonics? Same problem I guess listening to a speaker or headphone-again, how do I know it I am enjoying the fundamental or a harmonic? If I'm only hearing, say, the harmonics, then I don't really need a speaker to reproduce the fundamental, just the harmonics.

Doing something to attenuate out of existence the harmonics and leave only the fundamental is beyond anything I'm setup to do.

This problem seems to suffer from its own circle of confusion. Any opinions on this?

1) You can ask around to see if anyone has the ouput/extension/filtering capabilites in your vicinity that would let you experience various configurations. Look for other enthusiasts, a studio with a high-performance playback system, etc.
2) Invest in the equipment to do the test yourself. This option allows you to live with and experiment with different configurations and source material at your leisure. Used and resellable gear would minimize risk and costs.
3) Make a decision based on the available research and subjective feedback of other listeners.

There's no magic solution; the options above are what we've all had to navigate. And I personally don’t believe headphones can answer the question for you.

One other consideration that I haven't seen mentioned (but could have easily missed) is the type of flooring the listener and system will be on. Rigid basement concrete can yield tighter sounding bass when well implemented, but with less tactile feedback; this increases the SPL requirements to experience infrasound. A suspended floor (especially suspended wood floors) add a tactile sensation to all bass, including infrasound, which, in my experience, reduces the SPL requirements.

Overall I prefer bass on a rigid concrete floor where the room isn't shaking and resonating, others have the opposite preference. At times I wish I could switch back and forth.

Bass shakers are another option to consider; there's no audible experience but the tactile sensation is delivered.

 

[Bugal1998]

Hey folks, a request...
when describing the low end response of your sub(s) / system, please include at what max SPL....(Z-weighted)
Cause saying flat to 10Hz for example, is pretty much meaningless on its own.

Ime/imo, best spec if you have it, is max flat SPL across the spectrum, that stays flat down to the low spec corner (f-3 works)...again Z-weighted.
Or if you have a house curve in play, max SPL across the spectrum that maintains the house curve down to low spec corner.

Post EQ, 6-7hz at at least 117db with the room curve. Suspect 120-123db would be within reach as the speakers and amps had more headroom, but I felt no need to keep going.

System is SPL limited at the lowest extension; from 25hz and up subwoofer output capability is greater than 140db.

 

[Robbo99999]

LoL... Some of those enthusiasts are mellower and calmer than the average peeps here.

I know, it's just I think you can't really judge the quality of music and a playback system when you're under the influences of substances - eg a bit drunk or weed or whatever, I think it alters your perceptions too much.

 

[Robbo99999]

Do you have a list?

I've already made my contribution to the thread, I think 20Hz+ is best to aim for a sub, I'm thinking there's not much point to below 20Hz. I could only hear a 19Hz test tone very faintly in closed back well extended bass headphones, and that was very faint (could hardly hear it), so I think 20Hz+ for subs.

EDIT: for my 2.1 channel music & TV system I've got an SVS SB1000 Pro sub that gives me (at my loudest listening level setting) at 3.8meters 96dB at about 24Hz and 94dB at 20Hz, with it basically being flat down to 24Hz, whilst 1kHz would be at 88dB - this is all for sine sweeps. I'll include pic as with second thought it's easier to include pic:

I think that's enough low end extension for me. I don't really feel the bass though, I tend to mostly just hear it, but I'm probably not listening loud enough, albeit it's been ages since I've listened as loud as that highest setting I pictured there. I can sometimes feel the bass though when I move my listening position closer (1.5m) rather than the 3.8m I normally use; I've got seperate roomEQ settings for 1.5m & 3.8m. For me I think 20Hz+ is fine for subs, albeit I've not experienced subs capable of good 16Hz response.

 

[pablolie]

I know, it's just I think you can't really judge the quality of music and a playback system when you're under the influences of substances - eg a bit drunk or weed or whatever, I think it alters your perceptions too much.

You'd b surprised how much judicious sativa "high" actually relaxes you and allows you to completely focus, both in a sensory and even in a thinking way. It can sharpen your senses and your thinking. Indica, on the other hand, not so much - at least for me it just makes me lazy and sleepy, which is why I never use it (unless I want to knock myself out and avoid insomnia).

 

[Robbo99999]

You'd b surprised how much judicious sativa "high" actually relaxes you and allows you to completely focus, both in a sensory and even in a thinking way. It can sharpen your senses and your thinking. Indica, on the other hand, not so much - at least for me it just makes me lazy and sleepy, which is why I never use it (unless I want to knock myself out and avoid insomnia).

I guess people can use these things in different ways, but I think they all ultimately alter your perceptions, which is why I think it's quite important to be sober and in a natural unstressed mood if trying to critically judge things like EQ settings or different playback systems / headphones, etc. I know from drinking beer/wine that it can make you enjoy & like the sound of the music more, so I know in my own experience not to make judgements or do "critical listening" when a bit drunk for instance.

 

[rdenney]

I'm looking at REW sweeps, unweighted, to determine how low my speakers will go. Here's an example of my equalized Revel F12 speakers:

Looking at that graph, I don't think I'm lying by saying the speakers are functionally flat to 40 Hz and the -3 dB point is about 32 Hz. Of course, the room may be reinforcing those. There is an obvious null at 72 Hz, and where there is a null there must be resonances, too. I would expect subs to lift this curve down to maybe 25 Hz, and below that I don't care. The target curve rolls off down there mostly to minimize over-amplification and distortion. At this level, distortion was quite decent, certainly better than 3% in that range (and better than 1% everywhere else except for a narrow band around the woofer/mid crossover). A-weighted SPL at this level, playing, say, pink noise would be around 90 dB, which is very loud for continuous pink noise.

The Revel F12's have two 8" woofers, plus a 5" mid and Revel's usual tweeter in its wide-dispersion wave guide.

Here is a much older display from a good RTA app on my phone. Accuracy is questionable in the low range, and, of course, a 1/3-octave RTA display isn't going to show what REW shows.

The levels here are much lower, of course, but note that the SPL on the A-weighted scale is just under 70, which is more than 10 dB higher than any one band in the display. The speakers are Advent NLA's from 1977, which I bought new and still use in one of my systems, but for this they were in the same room as above. Of course, they have 10" (nominal) woofers. Notwithstanding the peak at 63 Hz, I would call this flat to down into the 30's. This system was also equalized, though the equalizer was an old SAE parametric equalizer with only three bands, so there wasn't much correction going on. The equalizer for the current system is a Yamaha YDP2006, which is an excellent DSP-based parametric equalizer.

So, given the current ubiquity of REW, I don't think it's the case that most people are using A-weighted SPL meters to determine how loudly their speakers are playing down low.

Rick "REW won't tolerate maximum system output" Denney

 

[gnarly]

Post EQ, 6-7hz at at least 117db with the room curve. Suspect 120-123db would be within reach as the speakers and amps had more headroom, but I felt no need to keep going.

System is SPL limited at the lowest extension; from 25hz and up subwoofer output capability is greater than 140db.

Thanks for replying ! Btw, your post #321 was great.

May i ask what subs you have?
And also what you think room gain might be at 6-7Hz...

I try to evaluate low freq SPL potential with piston excursion calculators, like this one. https://www.baudline.com/erik/bass/xmaxer.html
It's meant for direct sealed radiators. (i've found it also predicts vented SPL pretty well, by adding +6dB at any given excursion, per its notes)

I have eight 18" drivers, that I often consider converting all to sealed, to experience such deep lows, like 6-7Hz bass.)
When I run the calculator for all eight together, and despite their huge 19mm xmax, it gives about 105dB peak SPL.

That over the top amount of subbage, and only 105dB output, makes the numbers I see people post about their low end flat extension ....
well.....seem pretty impossible.

And I've learned displacement has to increase 4x for each octave decrease to maintain equal SPL.
Which is staggering to consider imo. If starting at 100Hz, ...then 50, 25, 12.5, to 6.25 Hz...would need a 4^4th power increase in displacement to maintain equal SPL at 6.25Hz. .....that's 256X the displacement needed at 100Hz. !!!

It's hard for me not to think all the low end extension folks talk about, is only for low level drive signals, and can't really support anything remotely close to equal output with the main speaker.

Am I missing something?

 

[pablolie]

I guess people can use these things in different ways, but I think they all ultimately alter your perceptions, which is why I think it's quite important to be sober and in a natural unstressed mood if trying to critically judge things like EQ settings or different playback systems / headphones, etc. I know from drinking beer/wine that it can make you enjoy & like the sound of the music more, so I know in my own experience not to make judgements or do "critical listening" when a bit drunk for instance.

Drinking is sloppy stuff. Totally different experience, but requires experience.

I wouldn't drive or ride my motorcycle or operate heavy machinery or sawing tools with sativa, of course, but for writing and focus on intellectual exercises it really can be a booster... if done judiciously. And we're all different in the way we process stuff.

 

[pablolie]

...

Am I missing something?

Your point is making total sense to me. That's one of the reasons I believe a good headphone setup is a very useful guide with this stuff. The transition to include a room environment is not trivial, as we can see by following this interesting topic.