Is a flat extension to 20hz or less impossible to achieve in average sized rooms?

[Verdinut]

Take great care with suggesting someone with decades of recording and playback experience, not to mention a fabulous system setup beyond the reach of most mortals, doesn't have the experience of low frequency setups.

My question to you would be, in this under 20hz range, what music plays in that range? What musical content is achievable in the under 20hz range? For home theater folks that want to make things go "thud and bang" I will concede there may be content under 20hz in some situations. But for music, what's there?
If I look at what the lowest frequency that can be produced by musical instruments (look here) its inaudible in the range you are discussing.

I have no way to prove or disprove anything in this area of audio. I can use REW and I have measurement tools. But, I don't have sound equipment that even suggests it will play that far down. For me, this is an interesting, but not a practical discussion.

Bucknekked,
In the frequency table annex, the info concerning the lowest pipe organ note is inexact. A few pipe organs around the world feature 64 foot pipes with a fundamental frequency of 8 Hertz. One of them is in Salt Lake City, at the Mormon Tabernacle Temple I believe.
Also, someone always wants to beat a record. Well, there is at least one organ, we definitely have to call it huge. It has a stopped 64 foot pipe giving what is called a 128 foot stop resultant with a fundamental vibration of 4 Hertz! You can hear some of it on Youtube, but not the 4 Hz note of course, if you google 128 foot pipe organ. That kind of vibration is not musical and the instrument is really dangerous; that kind of low frequency vibration could easily demolish a building which is not solidly constructed.

 

[ATLAudio]

You are understating the difference between 20 Hz and 10 Hz, which, physically speaking, is quite large; an entire octave, 56 ft vs 112 ft wavelength. The difference between, say 17 Hz and 10 Hz will be a lot more subtle. I have experienced properly set up systems that dig down to the single digits, and the difference between those and the systems I am more familiar with, which extend to the mid teens, is subtle. While there certainly isn't any harm in having a system that can dig to the single digits, it is difficult to justify for any practical reason. It simply is not a big difference. I don't know about Mark's tests, but unless I read about his methodology, I wouldn't take them too seriously. If you want to gauge how much of a difference is commonly experienced between different low frequencies, the thing to do is a blind test, and have the participants fill out a chart that asks something like, "on a scale of 1 to 10, how much more different is this sound experience compared to the last sound?"

"You are understating the difference between 20 Hz and 10 Hz"
Where did I do this? However, I misspoke, his tests were 16hz vs single digit (IIRC) rolloffs, again audiances routinely approved of the later.

"I don't know about Mark's tests, but unless I read about his methodology, I wouldn't take them too seriously."
That's fine, but I will. I'm comfortable accepting the outcome he stated; he's spot on here, and has suitable credibility.

"While there certainly isn't any harm in having a system that can dig to the single digits, it is difficult to justify for any practical reason."
All this talk about practicality... Justify the costs? It need not be that much more expensive, although for some it might be, usually due to room size. Just remember, most of our friends not in this hobby think we are nuts for not just getting a soundbar.

 

[TLS Guy]

"My question to you would be, in this under 20hz range, what music plays in that range?"
Very little, if any.

"What musical content is achievable in the under 20hz range?"
Again, very little if any.

"For home theater folks that want to make things go "thud and bang" I will concede there may be content under 20hz in some situations."
There's plenty of content in movies which aren't just thuds and bangs below 20hz. As Seaton and others can attest, there's a very appealing fullness to bass response which you will sense in a proper ultra low frequency set up.

"But for music, what's there?"
Once again, basically ziltch

"I have no way to prove or disprove anything in this area of audio. I can use REW and I have measurement tools. But, I don't have sound equipment that even suggests it will play that far down. For me, this is an interesting, but not a practical discussion."
Only if your position comes from exclusive music listening, however, I can't possibly disagree more on any notion which suggests ultra low bass isn't practical for home theater.

Certainly for a symphony orchestra an F3 in the 20 to 25 Hz range is perfectly adequate. For organs in the home an F3 15 to 20 Hz is optimal, especially if roll off is second and not fourth order.

I was just listening to a CD of music from Hereford Cathedral this morning, and the underpinning of the 32 ft stop was totally realistic. I think more than anything what matters is the quality of the bass. Poorly damped bass, which is so common, is a real detriment to realistic reproduction.

This is what I listen to which are dual TL speakers with the lines tuned one half octaves apart, so the lines crossover acoustically in the octave between 30 and 60 Hz. The impedance curves show the lines to be optimally damped, which is confirmed by the fact they roll off second order.

So here is the frequency response with 1/24 octave smoothing.

You can see the 3 db point is 20 Hz.

This part of the program only records to 20 Hz, but the distortion part goes to 10 Hz.

The distortion has to be read by the cursor, and the distortion even at power is below 2% until 20 Hz, when it starts to rise. The drivers in the long line have an Fs of 20 Hz, so that is what you would expect. Anyhow you can see the roll off is second order being 15 db down at 10 Hz, but only about 5 db down at 16 Hz. 16.4 Hz is the lowest fundamental of a 32 ft organ rank.

So this is adequate performance for all the music in my collection.

As far as HT, this system threatens structural damage and gives you a good shaking. I just can see no point in extension to the 5 to 8 Hz range. To me that is a totally pointless pursuit.

What would be far more useful is to concentrate on improved bass quality and not just extension. That is where the true gains in improved bass performance are to be had.

That is my approach, and listeners are immediately struck by hearing really realistic reproduction in the last four octaves.

 

[William Lemmerhirt]

+atlaudio
Not everything needs to be practical or cost the least amount of money. I also agree with mark seasons research. TLSGuy, I also agree that the importance of quality can not be overlooked. Blasting a poor quality fart box will sound accordingly.


Sent from my iPhone using Tapatalk

 

[shadyJ]

+atlaudio
Not everything needs to be practical or cost the least amount of money. I also agree with mark seasons research. TLSGuy, I also agree that the importance of quality can not be overlooked. Blasting a poor quality fart box will sound accordingly.


Sent from my iPhone using Tapatalk

The word 'research' implies some kind of scientific procedure which I very much doubt was the case.

 

[lovinthehd]

The word 'research' implies some kind of scientific procedure which I very much doubt was the case.

Like you employ scientific procedure better somehow?

 

[Verdinut]

Certainly for a symphony orchestra an F3 in the 20 to 25 Hz range is perfectly adequate. For organs in the home an F3 15 to 20 Hz is optimal, especially if roll off is second and not fourth order.

I was just listening to a CD of music from Hereford Cathedral this morning, and the underpinning of the 32 ft stop was totally realistic. I think more than anything what matters is the quality of the bass. Poorly damped bass, which is so common, is a real detriment to realistic reproduction.

This is what I listen to which are dual TL speakers with the lines tuned one half octaves apart, so the lines crossover acoustically in the octave between 30 and 60 Hz. The impedance curves show the lines to be optimally damped, which is confirmed by the fact they roll off second order.

So here is the frequency response with 1/24 octave smoothing.

You can see the 3 db point is 20 Hz.

This part of the program only records to 20 Hz, but the distortion part goes to 10 Hz.

The distortion has to be read by the cursor, and the distortion even at power is below 2% until 20 Hz, when it starts to rise. The drivers in the long line have an Fs of 20 Hz, so that is what you would expect. Anyhow you can see the roll off is second order being 15 db down at 10 Hz, but only about 5 db down at 16 Hz. 16.4 Hz is the lowest fundamental of a 32 ft organ rank.

So this is adequate performance for all the music in my collection.

As far as HT, this system threatens structural damage and gives you a good shaking. I just can see no point in extension to the 5 to 8 Hz range. To me that is a totally pointless pursuit.

What would be far more useful is to concentrate on improved bass quality and not just extension. That is where the true gains in improved bass performance are to be had.

That is my approach, and listeners are immediately struck by hearing really realistic reproduction in the last four octaves.

TLS Guy,

The shown curves are really impressive. If I understand well, the low frequency rolloff on a transmission line is of a 2nd order as with a closed box, whereas it is of the 4th order with a bass reflex cabinet.

I notice that you also like pipe organ music. Maybe you already have the disc. It's the Saint-Saëns Symphony No.3 for organ. It's an SACD on the Reference Recordings label. It is pretty well recorded and the organ as well as the 32 foot stop notes are more prominent than in any other disc of the same work. It features the Kansas City Symphony under the direction of Michael Stern. I have several recordings of that work and IMO, this one is the best of them all.

In my system, I am bi-amping the 3 front speakers which are identical three-way configurations. They consist of one Airborne Air Motion Ribbon tweeter, two Peerless 830991 5¼ inch mid-bass transducers and a Dayton RSS390HF-4 subwoofer, in a 7½ cf ducted reflex tuned at 16.8 Hz. The passive crossover, which is my own design using X-Over Pro as a starting point, divides frequencies at 3600 Hz with a 3rd order Butterworth filter on the tweeter and a 2nd order Linkwitz-Riley for the mid-range drivers. DBX 223XS will eventually divide the frequencies at 190 Hz between amps.

At present, I am using a Marantz SR5010 AVR for bi-amping the front left and right channels, and a Sony 3200F for the center channel for the time being. I am planning to purchase 3 QSC RMX850a power amps for the bi-amplification of those channels, and then use the SR5010 as a preamp-processor. That would give an additional 5 to 6 dB headroom over the Marantz without bi-amplification. I also have 2 EV 7100 power amps which will be used for the surround channels in a 7 channel setup.

Before using the RSS subs, I was using Altec 416-8A woofers and which obliged me to proceed with bi-amping with the less sensitive high frequency drivers. I like the principle of by-amping and I think that your theatre system uses that configuration too.

I don't like the idea of using a series inductor on the subs with a passive filter. The only type of inductor that I would use in such a context would be the Jantzen C Coil type (A toroidal 7.5 mH coil which would have a DC resistance of only 0.1 ohm), but it would most likely add distortion at very low frequencies below 30 Hz, apart from reducing the damping factor which is already halved with a 4 ohm load.

I have a question for you: I know that, if the frequency is halved, the cone excursion is increased by a factor of four. I never found a written confirmation of this, but am I right in assuming that in such situation, the driving amplifier has to output 4 times more power? If that's the case, the 5 to 6 dB headroom with external amps is desirable.

BTW, you have quite an interesting impressive sound system!

Your comments would be welcome.

 

[shadyJ]

Like you employ scientific procedure better somehow?

If I wanted to know how much more improved a audio experience was with the inclusion of infrasonic frequencies versus the exclusion of infrasonic frequencies, I do think I could find that out in some kind of scientific manner. If you want to give me the grant money, I can get started right away.

 

[lovinthehd]

If I wanted to know how much more improved a audio experience was with the inclusion of infrasonic frequencies versus the exclusion of infrasonic frequencies, I do think I could find that out in some kind of scientific manner. If you want to give me the grant money, I can get started right away.

You probably could, I'm not doubting that. I'm just saying that "scientific" can mean many things, not whether you could be more rigorous particularly. If it came down to your experience with subs vs his he wins handily IMO.

 

[shadyJ]

You probably could, I'm not doubting that. I'm just saying that "scientific" can mean many things, not whether you could be more rigorous particularly. If it came down to your experience with subs vs his he wins handily IMO.

Scientific does not mean many things. In the context of this discussion it means knowledge derived from scientific means ie the scientific method. I'm not even saying no other types of knowledge are useful, and, having heard the differences for the same content with and without extreme deep frequencies, I know the difference is not night and day, but that is anecdotal. I would bet his methodology was something like getting a group of dudes together and running a movie scene with and without a high-pass filter, and asking them which was better. Obviously results from a test like that can not be taken seriously. I am not saying they are wrong; I am saying don't bandy about results from testing like that as proof of some kind of point. What's more is Mark is hardly an impartial party to conduct such testing, given the type of product he sells.

 

[lovinthehd]

Scientific does not mean many things. In the context of this discussion it means knowledge derived from scientific means ie the scientific method. I'm not even saying no other types of knowledge are useful, and, having heard the differences for the same content with and without extreme deep frequencies, I know the difference is not night and day, but that is anecdotal. I would bet his methodology was something like getting a group of dudes together and running a movie scene with and without a high-pass filter, and asking them which was better. Obviously results from a test like that can not be taken seriously. I am not saying they are wrong; I am saying don't bandy about results from testing like that as proof of some kind of point. What's more is Mark is hardly an impartial party to conduct such testing, given the type of product he sells.

What, did Mark piss you off like Tom V? LOL.

 

[shadyJ]

I'm arguing against the notion that infrasonic frequencies make some kind of dramatic difference. I have reviewed much of the actual published research on the subject, and I have experienced the difference myself. I don't have anything against Mark, but his comparison isn't indicative of anything except perhaps that his audience preferred unfiltered playback as opposed to filtered playback, which is just fine. It isn't rock-solid data though. Believe it or not, there is a science that encompasses this subject, it is called audiology.

 

[Bucknekked]

Many times the stuff that gets said on this forum leaves me gasping a little bit. This particular thread strikes me that it left the realm of reality some time ago and has been in need of a refocus. I thought perhaps I could take what I have learned over the course of the last 10 to 15 posts or so and without bashing any one point of view (that's really, really tempting) summarize the distilled wisdom.

How about I have a conversation with my wife about what I learned in this thread over the last 2 days?
Ok, fair enough, if you don't have a wife, pick another human with a job and a life.

AUDIOPHILE: Hey hon, I got this great idea for dropping a couple of grand on the home theater to improve it.

SPOUSE: Oh great. Will it make the music sound better? The symphony? Will my Justin Bieber sound better? How about my Robin Thicke?

AUDIOPHILE: No, no. Nothing like that. It won't improve the music at all

SPOUSE: Oh, so it will make movies more understandable? Make the dialogue track better? Improve the music and the birds chirping in the trees?

AUDIOPHILE: No, no. Nothing like that. It won't improve the dialogue or the music or the birds. Nope.

SPOUSE: Well? What will be better ?

AUDIOPHILE: The thuds in the basement will seem more real. There will be a spaciousness to noises that will really seem like more lifelike noises. Stuff you as a woman probably can't hear, but, it you concentrate really hard you will hear "stuff" maybe that sounds like just noise, but it will be cooler than it was.

SPOUSE: A couple of thousand huh? You know where the couch in the spare room is don't you?

It aint Shakespeare, but if I had a conversation about what I learned in this thread, its about how it would go.

 

[shadyJ]

AUDIOPHILE: The thuds in the basement will seem more real. There will be a spaciousness to noises that will really seem like more lifelike noises. Stuff you as a woman probably can't hear, but, it you concentrate really hard you will hear "stuff" maybe that sounds like just noise, but it will be cooler than it was.

The only correction I would offer is that low frequencies can't contribute to spaciousness. Bass sounds the same from everywhere, at least typical subwoofer frequencies, and definitely the frequencies we are discussing. Bass can be a part of a complex sound that holds spatial cues, but if you stripped all of the upper frequencies off that sounds and left only subwoofer-band bass, there wouldn't be anything that would give you an idea of where it is coming from. The things that determine spaciousness, outside of cues in the sound itself like reverberation or echoes, is the shape of the head, the shape of your ears, and the time differences in the arrival of sound at each ear, and the long wavelengths of low enough frequencies negates all of that.

 

[TLS Guy]

The only correction I would offer is that low frequencies can't contribute to spaciousness. Bass sounds the same from everywhere, at least typical subwoofer frequencies, and definitely the frequencies we are discussing. Bass can be a part of a complex sound that holds spatial cues, but if you stripped all of the upper frequencies off that sounds and left only subwoofer-band bass, there wouldn't be anything that would give you an idea of where it is coming from. The things that determine spaciousness, outside of cues in the sound itself like reverberation or echoes, is the shape of the head, the shape of your ears, and the time differences in the arrival of sound at each ear, and the long wavelengths of low enough frequencies negates all of that.

Unless you are an elephant.

 

[TLS Guy]

Many times the stuff that gets said on this forum leaves me gasping a little bit. This particular thread strikes me that it left the realm of reality some time ago and has been in need of a refocus. I thought perhaps I could take what I have learned over the course of the last 10 to 15 posts or so and without bashing any one point of view (that's really, really tempting) summarize the distilled wisdom.

How about I have a conversation with my wife about what I learned in this thread over the last 2 days?
Ok, fair enough, if you don't have a wife, pick another human with a job and a life.

AUDIOPHILE: Hey hon, I got this great idea for dropping a couple of grand on the home theater to improve it.

SPOUSE: Oh great. Will it make the music sound better? The symphony? Will my Justin Bieber sound better? How about my Robin Thicke?

AUDIOPHILE: No, no. Nothing like that. It won't improve the music at all

SPOUSE: Oh, so it will make movies more understandable? Make the dialogue track better? Improve the music and the birds chirping in the trees?

AUDIOPHILE: No, no. Nothing like that. It won't improve the dialogue or the music or the birds. Nope.

SPOUSE: Well? What will be better ?

AUDIOPHILE: The thuds in the basement will seem more real. There will be a spaciousness to noises that will really seem like more lifelike noises. Stuff you as a woman probably can't hear, but, it you concentrate really hard you will hear "stuff" maybe that sounds like just noise, but it will be cooler than it was.

SPOUSE: A couple of thousand huh? You know where the couch in the spare room is don't you?

It aint Shakespeare, but if I had a conversation about what I learned in this thread, its about how it would go.

That's very funny and you certainly have the essence of it. I don't know what it is about audio, but it seems to attract people who will believe almost anything and hold onto lunatic ideas with stubborn ferocity.

 

[lovinthehd]

I'm arguing against the notion that infrasonic frequencies make some kind of dramatic difference. I have reviewed much of the actual published research on the subject, and I have experienced the difference myself. I don't have anything against Mark, but his comparison isn't indicative of anything except perhaps that his audience preferred unfiltered playback as opposed to filtered playback, which is just fine. It isn't rock-solid data though. Believe it or not, there is a science that encompasses this subject, it is called audiology.

Who said it was rock solid data? The reference to the actual test was vague at best. I still would take Mark's work over all your audiology reading

 

[TLS Guy]

TLS Guy,

The shown curves are really impressive. If I understand well, the low frequency rolloff on a transmission line is of a 2nd order as with a closed box, whereas it is of the 4th order with a bass reflex cabinet.



I notice that you also like pipe organ music. Maybe you already have the disc. It's the Saint-Saëns Symphony No.3 for organ. It's an SACD on the Reference Recordings label. It is pretty well recorded and the organ as well as the 32 foot stop notes are more prominent than in any other disc of the same work. It features the Kansas City Symphony under the direction of Michael Stern. I have several recordings of that work and IMO, this one is the best of them all.



In my system, I am bi-amping the 3 front speakers which are identical three-way configurations. They consist of one Airborne Air Motion Ribbon tweeter, two Peerless 830991 5¼ inch mid-bass transducers and a Dayton RSS390HF-4 subwoofer, in a 7½ cf ducted reflex tuned at 16.8 Hz. The passive crossover, which is my own design using X-Over Pro as a starting point, divides frequencies at 3600 Hz with a 3rd order Butterworth filter on the tweeter and a 2nd order Linkwitz-Riley for the mid-range drivers. DBX 223XS will eventually divide the frequencies at 190 Hz between amps.



I am using a Marantz SR5010 AVR for bi-amping the front left and right channels, and a Sony 3200F for the center channel for the time being. I am planning to purchase 3 QSC RMX850a power amps for the bi-amplification of those channels, and then use the SR5010 as a preamp-processor. That would give an additional 5 to 6 dB headroom over the Marantz. I also have 2 EV 7100 power amps which will be used for the surround channels in a 7 channel setup.



Before using the RSS subs, I was using Altec 416-8A woofers and which obliged me to proceed with bi-amping with the less sensitive high frequency drivers. I like the principle of by-amping and I think that your theatre system uses that configuration too.



I don't like the idea of using a series inductor on the subs with a passive filter. The only type of inductor that I would use in such a context would be the Jantzen C Coil type (A toroidal 7.5 mH coil which would have a DC resistance of only 0.1 ohm), but it would most likely add distortion at very low frequencies below 30 Hz, apart from reducing the damping factor which is already halved with a 4 ohm load.



I have a question for you: I know that, if the frequency is halved, the cone excursion is increased by a factor of four. I never found a written confirmation of this, but am I right in assuming that in such situation, the driving amplifier has to output 4 times more power? If that's the case, the 5 to 6 dB headroom with external amps is desirable.

BTW, you have quite an interesting impressive sound system!

Your comments would be welcome.

First of all, yes a properly designed "traditional" TL does roll off second order. The so called "mass Loaded" TLs roll off fourth order. Now an undamped or under damped TL will also roll off fourth order. You know when it is right. An undamped or under damped TL will have two peaks of impedance just like a reflex QB4 ported box. The trick is to add just enough damping to suppress one peak of impedance, so that the impedance curve looks like a sealed enclosure. The trick is, and this is key, is to add just enough to suppress the second peak of impedance and not an ounce more. Then the pipe still speaks, although with less output at resonance than the undamped pipe. However this combined with the taper of the pipe combines to greatly spread the frequency of assist to the driver over usually 1.5 octaves if you do it right. The speaker is in fact a highly modified stopped organ pipe of the Gedeckt family. Although the pipe still speaks the reproduction is non resonant. All this seems hard for those not experienced in these designs to get their mind round.

In addition in a stopped pipe there is a node of air displacement at the closed end, as there must be since it is "stopped" which means closed so the air can't move. So there has to be an antinode of air displacement at the open end. In any pipe pressure and displacement are always 180 degrees out of phase. So there is an antinode of pressure at the closed end and a node of pressure at the open end. Since the driver is towards the closed end pressure is high and so cone excursion limited and controlled. The driver is placed at the right position to suppress the odd harmonics. A stopped pipe only emits odd harmonics.

This brings me to your last question, as there is no direct relationship between declining frequency and cone displacement except in infinite baffle and sealed systems. In the ported box the pressure is high at resonance and controls cone excursion like a vice. Then below tuning cone excursion goes up like a straight line and becomes rapidly ineffective.

Pipes and horns control excursion over a much wider bandwidth and do not suddenly "let go" so to speak.

Sealed systems have an F3 far above Fs and require EQ at 12 db per octave at roll off. So speaker drivers for sealed application need to be designed to have high linear excursion.

Really everything is against you with sealed enclosures except smaller enclosure volume. However for extended bass reach with decent output a vigorous brute force approach is required, which I find intellectually unsatisfying.

 

[TLS Guy]

Who said it was rock solid data? The reference to the actual test was vague at best. I still would take Mark's work over all your audiology reading

Well I wouldn't. Mark is just truly misguided about this. For any type of music listening chasing those frequencies has zero merit. I have no interest blowing out my windows to realistically reproduce an explosion!

There is just so much bunk around about subwoofers its tiresome. There probably is no device in audio right now that is more misused and also associated with erroneous concepts. If 0.1% of people using subwoofers have properly balanced bass I would be shocked.

 

[shadyJ]

Well I wouldn't. Mark is just truly misguided about this. For any type of music listening chasing those frequencies has zero merit. I have no interest blowing out my windows to realistically reproduce an explosion!

There is just so much bunk around about subwoofers its tiresome. There probably is no device in audio right now that is more misused and also associated with erroneous concepts. If 0.1% of people using subwoofers have properly balanced bass I would be shocked.

It sounds like he is talking about movie content, not music. There is some movie content that does reach that low. While I don't think the rewards are great in chasing after single digit frequencies, it is surely a lot of fun for those who care to do it, and I wouldn't begrudge anyone that. It's more a journey and not destination type of thing. But agreed that subwoofers are poorly understood, even by hardcore audio enthusiasts.