Lowering of the efficiency may not be a problem when it comes to matching to the midrange speakers. In fact mass can be added to both lower bass resonance and match the efficiency of the bass to mids. If the increased Q is an issue you can increase the cabinet size.
speakers that go below 20hz
- Thread starter Graeme Lamb
- Start date
cooky1257
pfm Member
This may prove a bit of an eye-opener.
The two traces are for JBL 15" bass drivers 2235-includes a mass ring to lower fs the other 2234 without.
These drivers were used in most JBL studio monitors from the 70's through to the late 90's.
Of special note is the output, excursion and power handling limitations at extreme lf.
You can't beat the laws of physics but even from these graphs you could claim they go down to 15hz but it would be a pretty meaningless one..
The two traces are for JBL 15" bass drivers 2235-includes a mass ring to lower fs the other 2234 without.
These drivers were used in most JBL studio monitors from the 70's through to the late 90's.
Of special note is the output, excursion and power handling limitations at extreme lf.
You can't beat the laws of physics but even from these graphs you could claim they go down to 15hz but it would be a pretty meaningless one..
As muz said above, I added a Danley tapped horn sub to my Tannoys earlier this year. It has really been a nice addition; after several months of listening, the thing I would want to emphasize from that review I posted is that the sub helped to give a kind of relaxed, easy character to the system. The sense of dynamics and scale is terrific.
In fact, I listen to this system at much lower volumes than any other I have owned. Maybe it's just that I'm getting older, but I don't think so; there's just no feeling of needing to turn the thing up louder since everything feels fully lively and dynamic even at low volumes.
In fact, I listen to this system at much lower volumes than any other I have owned. Maybe it's just that I'm getting older, but I don't think so; there's just no feeling of needing to turn the thing up louder since everything feels fully lively and dynamic even at low volumes.
I feel there is a need for sub 20hz bass in a lot of music.
Basement Jaxx has sub 20hz bass in it. And Photek has plenty, just to name a couple.
I used to have a pair of PMC IB1's that extended down to 25hz. Even these could not play the bass drops on Basement Jaxx's Rooty. Only when connecting up the Rel Q201e(17hz @ -6db) that i had and cranking it up could you feel/hear the full depth of the bass notes.
I like to play music at live levels where possible as i feel that music is as much about feeling the sound as hearing it, therefore very deep bass is important to me.
Basement Jaxx has sub 20hz bass in it. And Photek has plenty, just to name a couple.
I used to have a pair of PMC IB1's that extended down to 25hz. Even these could not play the bass drops on Basement Jaxx's Rooty. Only when connecting up the Rel Q201e(17hz @ -6db) that i had and cranking it up could you feel/hear the full depth of the bass notes.
I like to play music at live levels where possible as i feel that music is as much about feeling the sound as hearing it, therefore very deep bass is important to me.
demotivated
pfm Member
That is exactly what wide bandwidth and headroom give you
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ChristianThomas
Registered User
I would be surprised if ANY speaker goes below 20Hz, and if it does, whether it is above the threshold of hearing. KEF may have achieved it with the 105s, to some extent. For many years they were the only people who knew how to design the low end frequency response to get the maximum extension for a given efficiency.
It is not just the Fs that counts (though this does in a TL) but the Fo - once it's in the cabinet. Getting this below 40Hz, let alone 30Hz, is far from easy.
Dedicated drivers (as also mentioned above) such as the XLSs from Peerless may have stunning xMaxes/xMechs (it's about an inch each way) but even these I doubt would make it to 20Hz. I could work it out, but my memory from working with them is that it's nowhere near.
Then you have the amazing power requirements needed for equalisation down this low. Starting with anything normal the exponential nature means you quickly run into kilowatt requirements. Since the nominal roll off of a sealed box is 12dB/Octave, or a quarter of the output level each time you go down an octave, there is a lot of ground to make up. If one assumes an initial bandwidth of 40Hz (not easy to achieve in itself) then to bring 20Hz up to flat (remember we are going below 20Hz) would need 15dB of correction. With a doubling of power every 3dB, this is five lots of those, or 2^5, or 32x. So if you are starting with a 100W amp the requirement is now 3.2kW. Even from 70W you are still looking at more than 2kW. And that's on each side, not just from one subwoofer!
I can therefore say with some confidence that, Bingo or not, neither the Isobariks nor the Keltics with their lighter bass unit, get anywhere near flat to 20Hz. As can easily be seen even a Climax Solo is underpowered and as for doing it with a 250, puhlease.
What we do have in our favour, however, are the boundaries of our rooms which, with each reflection double the level because the driver is radiating into half the space each time rather than omnidirectionally. But this is also true in a church or a concert hall. (Note that the wavelength at these frequencies is 30m or so, meaning that most things look quite small to them. So, to have the same sense of power you do need to put that power into the room.
In many ways this should be obvious to anyone who has been to Downside Abbey or heard other large organs. There is simply no speaker that I have heard that gets anywhere close.
Best, CT
It is not just the Fs that counts (though this does in a TL) but the Fo - once it's in the cabinet. Getting this below 40Hz, let alone 30Hz, is far from easy.
Dedicated drivers (as also mentioned above) such as the XLSs from Peerless may have stunning xMaxes/xMechs (it's about an inch each way) but even these I doubt would make it to 20Hz. I could work it out, but my memory from working with them is that it's nowhere near.
Then you have the amazing power requirements needed for equalisation down this low. Starting with anything normal the exponential nature means you quickly run into kilowatt requirements. Since the nominal roll off of a sealed box is 12dB/Octave, or a quarter of the output level each time you go down an octave, there is a lot of ground to make up. If one assumes an initial bandwidth of 40Hz (not easy to achieve in itself) then to bring 20Hz up to flat (remember we are going below 20Hz) would need 15dB of correction. With a doubling of power every 3dB, this is five lots of those, or 2^5, or 32x. So if you are starting with a 100W amp the requirement is now 3.2kW. Even from 70W you are still looking at more than 2kW. And that's on each side, not just from one subwoofer!
I can therefore say with some confidence that, Bingo or not, neither the Isobariks nor the Keltics with their lighter bass unit, get anywhere near flat to 20Hz. As can easily be seen even a Climax Solo is underpowered and as for doing it with a 250, puhlease.
What we do have in our favour, however, are the boundaries of our rooms which, with each reflection double the level because the driver is radiating into half the space each time rather than omnidirectionally. But this is also true in a church or a concert hall. (Note that the wavelength at these frequencies is 30m or so, meaning that most things look quite small to them. So, to have the same sense of power you do need to put that power into the room.
In many ways this should be obvious to anyone who has been to Downside Abbey or heard other large organs. There is simply no speaker that I have heard that gets anywhere close.
Best, CT
James
Lord of the Erg\o/s
There is a slight flaw in this argument. Most 100W systems are run at a fraction of their rated power. For the most part, and in an average sized room at sensible listening volumes with averagely sensitive loudspeakers, 2-5W is plenty loud.
So, if EQ is applied to flatten the loudspeaker response down to 20Hz, you wouldn't need more that 60-200W at the same listening levels. Of course, the headroom is much more constrained, but it's very much achievable within the limits of competently designed amplifiers.
Yes, room gain is a wonderful thing and is one very important reason why a flat response below 20Hz in domestic loudspeakers is not necessary.
I've been to a few concerts where I'm pretty sure some infrasonics were going on. It's simply a question of shifting air.
James
YNWOAN
100% Analogue
ChristianThomas
Registered User
While taking your point, I think there is a slight flaw in the slight flaw you point out. In short, it is that that power is needed, sometimes. If one is going to get to use the postulated 40Hz bandwidth speakers we now have properly, then all of that 100W will be needed. So, if we are going to have a comparably capable sub to extend the response flat to 20Hz then, if one is not going to introduce new restrictions, my figures have to be correct.
Infra bass at concerts makes this point too. How many drivers and what total area with what excursion do you think you were listening to? Sure as hell wasn't a pair of B139s with 6mm of linear excursion.
Also, it is worth bearing in mind the audible thresholds too. Your 5W plus 200 would, I guess, not get above them.
It's a little confusing Christian, because you seem to want to generalize about "ANY speaker" but then derive your restrictions from power measurements based on a sealed box design. Since other designs can be far more efficient, your generalization shouldn't extend to any speaker.
Mine will (within the confines of my listening room). The Danley sub I use was independently measured at 99 dB at 1w/m at 20 Hz, and it will take one Kw. I haven't heard the Downside Abbey organ, but I have heard several large ones including the Ruffatti organ in Davies Hall in San Francisco. My sub will generate significantly more infrasonic effect than anything I experienced there (not that having it do so is realistic or pleasant, but it will do it if you push it a little).
Mine will (within the confines of my listening room). The Danley sub I use was independently measured at 99 dB at 1w/m at 20 Hz, and it will take one Kw. I haven't heard the Downside Abbey organ, but I have heard several large ones including the Ruffatti organ in Davies Hall in San Francisco. My sub will generate significantly more infrasonic effect than anything I experienced there (not that having it do so is realistic or pleasant, but it will do it if you push it a little).
ChristianThomas
Registered User
That would be the thing to do. You're lucky to have a 12" - I have used the 10" ones only (though in a pair on one sub) and the practicality is that you can't do all you dream about when you look at the tools you have in front of you. You may just manage 30Hz from them - and you have the advantage of knowing the limits which an average punter won't - but my experience is they will flap and hit the end stops. Or, at least, if you wanted to market them, you'd feel safer higher up.
I had a way of adjusting the LF -3dB point with pots. I can't remember whether that was easy to do as it was three years ago or more when I did it. I may have picked a Q that allowed it to be done easily on a ganged pair or it may lend itself to this anyway.
I would be very interested in seeing how far down you can comfortably get.
ChristianThomas
Registered User
I did think about designs other than sealed box as I wrote this and decided it was a fair and good starting point to go with sealed box as the model. TLs in particular. For ported design the roll off is much sharper but it doesn't greatly affect the needs of the sub. And on the transmission lines one doesn't get all one might at first expect. One might think that you could get double the output from a transmission line, but this isn't the case. It's really a lift of 3dB at the quarter wavelength, but that is on a Q that is markedly lower than it would be with the same driver in a box. Probably somewhere around 0.3 or 0.35, which is quite a loss already. But, in fact, my general model was just any speaker of average efficiency across the spectrum that was 3dB down at 40Hz, irrespective of how we got there.
Your sub sounds like it's closer than most. I'd have to think about it properly to see whether I believe the figures really do work out correctly, but at first glance they appear to be about right. 99dB should be about 16W for a 87dB/W system so a kilowatt seems about right to supplement that to 20Hz. Though my guess must be that excursion is the limit here rather than power.
Still, it doesn't appear to confound my off-the-cuff generalisations for the power requirements.
James
Lord of the Erg\o/s
Likewise. Don't hold your breath though; things have been moving very slowly lately due to other priorities. But this will be experimented with in due course. I might even make it switchable.
James
ChristianThomas
Registered User
I thought this was a joke when I clicked on the fan. But apparently it isn't.
I bet, when one thinks about it, it doesn't really go that close to DC. But maybe a Rolls Royce Trent engine could manage it. Two of those in your living room for bandwidth free reproduction?
demotivated
pfm Member
DC is a breeze in 1 direction, so it will do DC. It will be interesting to see what sort of windage noises you get from it, and how reliable the moving vanes are. It's been around a while and people aren't rushing to buy it. I'd rather have a Servodrive contrabass if they were still making them. I'm guessing the motor sources dried up.
You can certainly get flat to 26Hz with the original low Q Peerless XLS [-3dB 23Hz] in a big box and a 25Hz port for a few hundred quid a pair:
http://farm4.static.flickr.com/3349/4632028934_2a2cffb563_z.jpg
a bit cheaper than a $12000 fan..
http://www.danleysoundlabs.com/images/Matterhorn Finished.jpg
You can certainly get flat to 26Hz with the original low Q Peerless XLS [-3dB 23Hz] in a big box and a 25Hz port for a few hundred quid a pair:
http://farm4.static.flickr.com/3349/4632028934_2a2cffb563_z.jpg
a bit cheaper than a $12000 fan..
http://www.danleysoundlabs.com/images/Matterhorn Finished.jpg
stackowax
pfm Member
Here's a link to a public broadcasting show on "infrasounds" in which there is some (very brief) footage of the TRW-17 in action (not playing music however).
http://www.pbs.org/kcet/wiredscience/video/143-sounds_of_silence.html
FWIW, Eminent Technology is a pretty well-known (and small) manufacturer of high end audio products in the US with a reputation of the products being "good values" in the context of high end audio. I suppose their most well-known product is the LFT8 planar speaker which goes for around $1900.
I wouldn't pay $12,000 for a subwoofer even if I could afford to. But I'm reasonably sure there is some rational reason for the high price (if high end audio prices can ever be said to be "rational").
http://www.pbs.org/kcet/wiredscience/video/143-sounds_of_silence.html
FWIW, Eminent Technology is a pretty well-known (and small) manufacturer of high end audio products in the US with a reputation of the products being "good values" in the context of high end audio. I suppose their most well-known product is the LFT8 planar speaker which goes for around $1900.
I wouldn't pay $12,000 for a subwoofer even if I could afford to. But I'm reasonably sure there is some rational reason for the high price (if high end audio prices can ever be said to be "rational").
I agree to a large degree, this is certainly true of own implementation - they get down to about 35Hz.. just:
The graph is both sides driven measured from my listening seat. From a subjective perspective they can do a bottom E fairly convincingly but drop very rapidly indeed below there. I've tried running sine waves from 20Hz in 1Hz increments and I can only start to hear some fundamental above 35Hz.
The speakers are in a rigid sealed (to a degree at least) box of about 75L. I understand that say Autographs can get the same driver down a lot further, but obviously we are talking something absolutely huge and remarkably expensive here.
I agree completely. It's all about shifting air without any strain or effort, and IMO that takes a big driver. The only thing I'd argue is I'd like some real energy down to 35-40Hz or so, a bass / bass guitar guitar bottom E is 41.5Hz, and to my mind the music suffers if a speaker is only capable of delivering harmonics there (e.g. my Klipsch Heresys which are out of the game at about 50-55Hz). It's easy to argue there is a lot below 40Hz too, a kick drum effectively rises rapidly from a 0Hz thwack, as indeed does a nice big bass amp etc, i.e. you pluck / hit the string and there is a hefty subsonic thud as the speaker reacts that constitutes much of the leading edge of the note, the sound of the string and speaker rapidly accelerating to pitch, think big Ampeg horn cab. I'd file that as nice to have out of a home stereo rather than essential, but the bottom E is part of the music, we needs that!
Tony.
Apologies for resurecting and old thread but I've been searching for some measurements of vintage drivers to compare against the measured response achieved by the new cabinets for my K10A's. The cabinets are rectangular GRF's upscaled for the size and parameters of the drivers.
I would agree that a large driver is needed for effortless low bass and some horn loading certainly helps.
The graph below shows the response at the listening position with no eq applied. The slight lift at 1.7kHz has now been flattened by reversing the polarity of the HF.
Having heard lots of different drivers and cabinet configurations over the years, I have always felt that low bass produced by large diameter short throw drivers is far more natural and realistic than that produced by smaller diameter long throw drivers. There appears to be more to it than just moving air. The way the air is moved seems to have a significant infuence on the quality of the reproduced sound. It is particuarly noticable on the lower notes of piano music.
JemHayward
pfm Member
Does anyone remember Graham Holliman and infra bass?