tonyclaret Posted March 13, 2018 Share Posted March 13, 2018 Hi, What does this actually mean? if I have one cab A at 200cm and cab B at 450cm, is cab B louder? Is it moving more air? chees Quote Link to comment Share on other sites More sharing options...
CameronJ Posted March 13, 2018 Share Posted March 13, 2018 Calling @Bill Fitzmaurice! Quote Link to comment Share on other sites More sharing options...
pete.young Posted March 13, 2018 Share Posted March 13, 2018 It's the volume of air displaced by the speaker - the area of the cone multiplied by the distance that it moves. Assuming that the dimensions you've given are speaker diameters, it's not possible to say - you need to know what Xmax is for the speaker (that's the maximum distance that the cone can move before mechanical damage starts to occur to the voice coil). Quote Link to comment Share on other sites More sharing options...
Happy Jack Posted March 13, 2018 Share Posted March 13, 2018 3 hours ago, tonyclaret said: if I have one cab A at 200cm and cab B at 450cm, is cab B louder? Is it moving more air? chees As a complete amateur in these matters, I think of it as being surface area x excursion (i.e. the amount that the cone moves to & fro). If you think of the entire speaker cone moving forwards and backwards then the volume it occupies is a cylinder and that's something you can measure. While I typed that, Pete gave the same answer. Thing is, very few manufacturers publish excursion figures, and you've got this thing called "efficiency" which incorporates the idea of not losing too much power to heat (through friction) so I never feel that I either can work out displacement properly or estimate potential volume either. What I can do, though, is a quick mental calculation when comparing cabs. Since the only variable that I know for sure is the radius of the speakers, I can do a quick & dirty comparison of, say, a 1x15 -v- 2x10. Radius squared for a 15 is 56.25; radius squared for a 10 is 25, but there are two of them so that makes 50. So if someone tells me that a 1x15 is about as loud as a 2x10 that doesn't upset me. If someone tells me that their 1x10 (that's a 25) is as loud as someone else'e 1x12 (that's a 36) then I expect them to explain how they've achieved that ... more efficient speakers, greater excursion than usual, cab filled with magic smoke, whatever. And chees has nothing to do with it. Quote Link to comment Share on other sites More sharing options...
EBS_freak Posted March 13, 2018 Share Posted March 13, 2018 2 hours ago, Happy Jack said: If someone tells me that their 1x10 (that's a 25) is as loud as someone else'e 1x12 (that's a 36) then I expect them to explain how they've achieved that ... more efficient speakers, greater excursion than usual, cab filled with magic smoke, whatever. Step 1. Convince the gullible crew on an Internet forum. Quote Link to comment Share on other sites More sharing options...
machinehead Posted March 13, 2018 Share Posted March 13, 2018 2 hours ago, Happy Jack said: What I can do, though, is a quick mental calculation when comparing cabs. Since the only variable that I know for sure is the radius of the speakers, I can do a quick & dirty comparison of, say, a 1x15 -v- 2x10. Radius squared for a 15 is 56.25; radius squared for a 10 is 25, but there are two of them so that makes 50. I'm not trying to be a smartarse here, but the area of a circle is given by Pi x R x R. So your answers will be approximately three times more area. But there are lots of other factors as you probably know well enough. Frank. Quote Link to comment Share on other sites More sharing options...
EBS_freak Posted March 13, 2018 Share Posted March 13, 2018 1 minute ago, machinehead said: I'm not trying to be a smartarse here, but the area of a circle is given by Pi x R x R. So your answers will be approximately three times more area. But there are lots of other factors as you probably know well enough. Frank. I think he was demonstrating the sort of maths that cab manufacturers use to derive their published specs. 1 Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted March 13, 2018 Share Posted March 13, 2018 (edited) 7 hours ago, tonyclaret said: Hi, What does this actually mean? if I have one cab A at 200cm and cab B at 450cm, is cab B louder? Is it moving more air? chees Cab B will be louder, by about 7.5dB. In fact, Cab B will be more than the equal of a pair of cab A. This assumes that you're actually driving both cabs to their full excursion. If their sensitivities and frequency response are similar and both are driven with the same voltage swing they'll be equally loud. What gives Cab B the ability to go louder is that it can take over twice the voltage swing, which is more than four times the power, as Cab A. Quote Assuming that the dimensions you've given are speaker diameters, it's not possible to say True, because speaker diameter is not a measurement of displacement. But displacement would not be stated as 200cm anyway. Cone area (Sd) is stated as square cm, displacement (Vd) is stated as cubic cm. As the OP specifically asked about displacement I assume that's what he means. The main issue with trying to compare displacement of different cabs is that almost every cab manufacturer won't reveal it. One can rightfully assume that those very few who do publish displacement specs don't feel the need to hide it. Edited March 13, 2018 by Bill Fitzmaurice Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted March 14, 2018 Share Posted March 14, 2018 On 13/03/2018 at 05:17, tonyclaret said: Hi, What does this actually mean? if I have one cab A at 200cm and cab B at 450cm, is cab B louder? Is it moving more air? chees I hope this hasn't been too confusing so far All of the information given so far is good but I'm not sure how easy it is to follow. I think you may have a mistake in your question, if you change it into ' if I have one cab A at 200 cubic cm and cab B at 450 cubic cm, is cab B louder? Is it moving more air' then it makes sense. Displacement is the volume of air displaced when the speaker cone moves through it's full undistorted range. In this case the answer would then be yes, it moves more air. As to how important this figure is, well it's one figure amongst many, it's important but not without all the other figures. Barefaced use it a lot in their adverts because their drive units are very good in this area and Alex Claber regularly posts in this forum so it has become a significant quality factor for many people. To be fair I don't think he has ever claimed it's the only important factor or made false claims but some of his fans have jumped upon it as being the key figure by which speakers should be judged. Over the last couple of years it has become a figure people on BC have fixated upon. I'm going to use the car analogy I'm afraid. The volume displacement of the speaker is like the capacity of the engine, it's the piston area times the stroke length. But , the cubic capacity of the engine won't tell you its power and the cubic capacity of a speaker won't tell you how loud it is. That also depends upon how efficient the speaker is, not all it's movement is converted into sound. A 2 litre engine is likely to be more powerful than a 1litre engine but you will know that isn't always true, I've just traded in my 1.6 litre VW for a more powerful 1.0 litre Vauxhall. If Vd is too low then your speaker isn't going to be able to make lot's of undistorted bass. If your goal is a small loud lightweight speaker then high excursion and therefore Vd becomes very important. If you can't displace enough air then you can't make sound above a certain volume and bass frequencies need a lot of air shifting. If I was designing a 10" high performance speaker I'd be proud if it had Vd Another factor though is efficiency. If you double the cone area and keep everything else the same then you'll get an extra 3dB for the same power. It's quite possible for example that if you took two 10" speakers with Vd of 200cm3 they might be louder at 300W than a single 10" speaker with Vd of 450 cm3.'t I couldn't tell you for sure without all of the figures. The physics of speakers isn't that hard, if you've got 'A' level science or maths you'll have no trouble, GCSE maths is enough if you are interested enough but plucking any single figure out of the air isn't going to explain much, you have to do the maths. I the end I don't think Vd is very helpful to the average bassist. Yes it's particularly important that small speakers have good excursion but in the end that won't tell you how they sound. You wouldn't buy a car without a test drive or choose the engine size without considering other factors first and I don't think you should choose a bass speaker like that either. Quote Link to comment Share on other sites More sharing options...
xgsjx Posted March 14, 2018 Share Posted March 14, 2018 23 hours ago, pete.young said: Assuming that the dimensions you've given are speaker diameters, it's not possible to say - you need to know what Xmax is for the speaker (that's the maximum distance that the cone can move before mechanical damage starts to occur to the voice coil). That would be BIG drivers! @ 79" and 178" Quote Link to comment Share on other sites More sharing options...
Happy Jack Posted March 14, 2018 Share Posted March 14, 2018 23 hours ago, machinehead said: I'm not trying to be a smartarse here, but the area of a circle is given by Pi x R x R. So your answers will be approximately three times more area. But there are lots of other factors as you probably know well enough. Frank. What I know, Frank, is that Pi is not a variable. Quote Link to comment Share on other sites More sharing options...
pete.young Posted March 14, 2018 Share Posted March 14, 2018 4 hours ago, xgsjx said: That would be BIG drivers! @ 79" and 178" Good spot - I think my brain translated it into millimetres rather than centimetres! Quote Link to comment Share on other sites More sharing options...
RandomBass Posted March 14, 2018 Share Posted March 14, 2018 6 hours ago, xgsjx said: That would be BIG drivers! @ 79" and 178" 😎 Quote Link to comment Share on other sites More sharing options...
RandomBass Posted March 14, 2018 Share Posted March 14, 2018 Now that's what I call displacement... Quote Link to comment Share on other sites More sharing options...
tonyclaret Posted March 14, 2018 Author Share Posted March 14, 2018 Ok, here are the cabs I’m comparing 👍 http://www.bassgear.co.uk/product/tks-engineering-s112/ http://www.bassgear.co.uk/product/tks-engineering-1126/ Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted March 14, 2018 Share Posted March 14, 2018 Assuming that the 237cc displacement of the first and 496cc displacement of the second does in fact refer to woofer Vd (odd they can't find anyone to translate their spec explanation into English) the second would equal two of the first in maximum output capability. I'd bet pence to pounds that the first is loaded with an Eminence Beta 12, the second with an Eminence 3012LF. Quote Link to comment Share on other sites More sharing options...
CameronJ Posted March 15, 2018 Share Posted March 15, 2018 @Bill Fitzmaurice you are indeed correct! Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted March 15, 2018 Share Posted March 15, 2018 They also will have completely different tonal characteristics. It would be nice if they posted response charts, but at least they're one of the perhaps 5% of manufacturers who provide displacement. I guess response charts will have to wait until the next century. 1 Quote Link to comment Share on other sites More sharing options...
M@23 Posted March 15, 2018 Share Posted March 15, 2018 What percentage of people actually care? Most of those that do probably shouldn't quite as much. I had TKS s112 and they sounded great and were plenty loud enough. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted March 15, 2018 Share Posted March 15, 2018 42 minutes ago, M@23 said: What percentage of people actually care? The same percentage who know what it means. 3 1 Quote Link to comment Share on other sites More sharing options...
M@23 Posted March 16, 2018 Share Posted March 16, 2018 15 hours ago, Bill Fitzmaurice said: The same percentage who know what it means. Nope. Although we know on paper brand X is technically better, the reality is that in practice it doesn't make for a more suitable product for all. Quote Link to comment Share on other sites More sharing options...
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