Beer of the Bass Posted October 11, 2012 Share Posted October 11, 2012 (edited) I've got a query for the technically inclined, to do with interpreting Xmax figures and using WinISD. I've got a cabinet using B&C drivers, and I figure that the excursion limited handling at lower frequencies is always a useful bit of information to have at hand. B&C present their figures in the format "+/-4.0mm" in their datasheets, which I'd always thought meant 4mm. I happened to notice that one online vendor quotes the Xmax of the same driver as "8mm". Have I got this wrong or is this particular vendor fudging their figures? Edited October 11, 2012 by Beer of the Bass Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted October 11, 2012 Share Posted October 11, 2012 +/-4mm is the same as 8mm peak to peak. Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted October 11, 2012 Author Share Posted October 11, 2012 (edited) Thanks Bill. Are Eminence and others who quote a single positive number using peak-to-peak then? Edit; I did a quick bit of reading - it looks like WinISD uses one way peak figures (and I guess that's the convention?), so +/-4mm would be entered as 4mm. If I'm mistaken about that, feel free to say so. Edited October 11, 2012 by Beer of the Bass Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted October 12, 2012 Share Posted October 12, 2012 Most sources quote xmax one way, Eminence among them. One would think that it would be stated as a +/- figure, but it isn't. Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted October 14, 2012 Share Posted October 14, 2012 [quote name='Beer of the Bass' timestamp='1349990178' post='1833363'] it looks like WinISD uses one way peak figures (and I guess that's the convention?), so +/-4mm would be entered as 4mm. [/quote] Yup. As I've delved further I've found all xmax's aren't created equal and behaviour beyond xmax differs between different drivers in an audible way, so I reckon take the numbers as a rough guide and use your ears. Your cab with the B&Cs sounded reaaally nice I thought! If for some mad reason you want rid of it, let me know Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted October 14, 2012 Author Share Posted October 14, 2012 [quote name='LawrenceH' timestamp='1350221923' post='1835896'] Yup. As I've delved further I've found all xmax's aren't created equal and behaviour beyond xmax differs between different drivers in an audible way, so I reckon take the numbers as a rough guide and use your ears. Your cab with the B&Cs sounded reaaally nice I thought! If for some mad reason you want rid of it, let me know [/quote] Oh no, that cab is definitely staying! It's my big ol' valve amp I might be reconsidering, so I had a fiddle around with WinISD just to remind myself of the capabilities of the cab. Trying the cab with your F1 made me wonder whether I really need to be lugging big lumps of iron around for the sound I go for, as there are clearly good sounds to be had from lighter amps. Quote Link to comment Share on other sites More sharing options...
xgsjx Posted October 14, 2012 Share Posted October 14, 2012 I'm wanting to see your cab now. Incidentally, Markbass cabs also use B&C drivers. Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted October 14, 2012 Share Posted October 14, 2012 [quote name='Beer of the Bass' timestamp='1350233963' post='1836087'] Oh no, that cab is definitely staying! It's my big ol' valve amp I might be reconsidering, so I had a fiddle around with WinISD just to remind myself of the capabilities of the cab. Trying the cab with your F1 made me wonder whether I really need to be lugging big lumps of iron around for the sound I go for, as there are clearly good sounds to be had from lighter amps. [/quote] Hah, I said it'd have to be a mad reason! You're obviously welcome to borrow the F1 if you've got any gigs coming up that'll push it a bit harder. If you think you'll take it to the limits, you've also got the know-how to build a decent HPF which would give a bit more breathing room, no? But I don't think you'd need it unless you had a really powerful amp, especially given that it's an 8 ohm cab Quote Link to comment Share on other sites More sharing options...
muttley Posted October 17, 2012 Share Posted October 17, 2012 [quote name='LawrenceH' timestamp='1350221923' post='1835896'] Yup. As I've delved further I've found all xmax's aren't created equal and behaviour beyond xmax differs between different drivers in an audible way, so I reckon take the numbers as a rough guide and use your ears. Your cab with the B&Cs sounded reaaally nice I thought! If for some mad reason you want rid of it, let me know [/quote]I In the old days the formula for Xmax was often (coil length - front plate thickness)/2, sometimes adding a fudge factor "for good measure". Nowadays, with sophisticated kit like the Klippel distortion analyser there are various ways in which it can be quoted, for example within a certain % of max Bl (motor force) or shove factor (Bl[sup]2[/sup]/Re) or % THD. Quote Link to comment Share on other sites More sharing options...
bremen Posted October 17, 2012 Share Posted October 17, 2012 (edited) I modelled a 2by10 using Eminence Beta 10A in WinISD and however big or small I made the cab, however I tuned it, the power handling dropped to 20-40W between resonance and 100Hz. Should I have doubled their stated Xmax figure, or are they really this crap? Or is WinISD very pessimistic? Edited October 17, 2012 by bremen Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted October 17, 2012 Author Share Posted October 17, 2012 [quote name='bremen' timestamp='1350462921' post='1839075'] Should I have doubled their stated Xmax figure, or are they really this crap? Or is WinISD very pessimistic? [/quote] Bill's post above suggests that Eminence Xmax figures are one way peak figures. WinISD uses the same format, so it would be entered as-is. Lots of cabinets have surprisingly low handling in the low fundamental range, but are still usable for many of us because the fundamental of our lowest notes is a small proportion of the total signal. Many drivers also have usable output beyond the quoted Xmax. Quote Link to comment Share on other sites More sharing options...
bremen Posted October 17, 2012 Share Posted October 17, 2012 [quote name='Beer of the Bass' timestamp='1350464489' post='1839102'] Bill's post above suggests that Eminence Xmax figures are one way peak figures. WinISD uses the same format, so it would be entered as-is. Lots of cabinets have surprisingly low handling in the low fundamental range, but are still usable for many of us because the fundamental of our lowest notes is a small proportion of the total signal. Many drivers also have usable output beyond the quoted Xmax. [/quote] Trace 4 by 10s use Beta 10s, am I right? Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted October 17, 2012 Share Posted October 17, 2012 [quote name='muttley' timestamp='1350459701' post='1839025'] In the old days the formula for Xmax was often (coil length - front plate thickness)/2, sometimes adding a fudge factor "for good measure". Nowadays, with sophisticated kit like the Klippel distortion analyser there are various ways in which it can be quoted, for example within a certain % of max Bl (motor force) or shove factor (Bl[sup]2[/sup]/Re) or % THD. [/quote] Trouble is we don't have access to all the data to compare different drivers, and even then it's arguable which is the 'best' method though a lot of work recently seems to have been done on linearising BL curve across the operating range. Certainly can't account for all these in the small signal-based programs used by DIY-ers to simulate loudspeaker behaviour. Ears are a much cheaper and quicker way of gauging things! [quote name='bremen' timestamp='1350466162' post='1839124'] Trace 4 by 10s use Beta 10s, am I right? [/quote] Dunno what they use nowadays but Trace certainly used to use Celestion Quote Link to comment Share on other sites More sharing options...
alexclaber Posted October 17, 2012 Share Posted October 17, 2012 [quote name='bremen' timestamp='1350462921' post='1839075']I modelled a 2by10 using Eminence Beta 10A in WinISD and however big or small I made the cab, however I tuned it, the power handling dropped to 20-40W between resonance and 100Hz. Should I have doubled their stated Xmax figure, or are they really this crap? Or is WinISD very pessimistic?[/quote] You may have had the cab tuned a bit low but the power handling at low frequencies is pretty rubbish for a lot of bass cabs. It isn't quite as disastrous as it seems because you don't hit a brick wall at that limit and the power vs loudness relationship is logarithmic. I've been putting together some sample specs so people can compare generic cabs to Barefaced ones and this is what a ported 4x10" with Beta 10s is looking like: [color=#000000]Sensitivity (@ 1m 1W half-space) = 101dB[/color] [color=#000000]Max SPL (@ 1m half-space)[/color] = 124dB [color=#000000]Core bandwidth[/color] = 50Hz - 4.5kHz [color=#000000]Extended bandwidth[/color] = 37Hz - 6kHz [color=#000000]Volume displacement[/color] = 408cc [color=#000000]Recommended amplifier power (W)[/color] = 50 - 300W [color=#000000]Nominal impedance (ohms)[/color] = 4 or 8 ohms [color=#000000]Size (cm)[/color] = 64 x 58 x 47 You can knock 3dB off the sensitivity and 6dB off the max SPL for a 2x10" (and halve the Vd, size and max recommended power). Explanation of specs here: [url="http://barefacedbass.com/technical-information/how-to-interpret-our-specs.htm"]http://barefacedbass...t-our-specs.htm[/url] Quote Link to comment Share on other sites More sharing options...
muttley Posted October 17, 2012 Share Posted October 17, 2012 [quote name='LawrenceH' timestamp='1350467187' post='1839140'] Trouble is we don't have access to all the data to compare different drivers, and even then it's arguable which is the 'best' method though a lot of work recently seems to have been done on linearising BL curve across the operating range. Certainly can't account for all these in the small signal-based programs used by DIY-ers to simulate loudspeaker behaviour. Ears are a much cheaper and quicker way of gauging things! [/quote] A pro would have the facility to build and test several different cabs and/or alignments, using instruments and ears. The best an amateur can do (and this is the approach I would take) is to ensure that the small-signal alignment is the best that can be achieved and that predicted excursion is sensible for the voltage level that's expected to go into the driver(s). Quote Link to comment Share on other sites More sharing options...
Happy Jack Posted October 17, 2012 Share Posted October 17, 2012 Am I the only person who saw this topic title and throught: [color=#800000][i][b]"So here it is, Merry Xmax, everybody's having fun[/b][/i][/color]"? Quote Link to comment Share on other sites More sharing options...
alexclaber Posted October 17, 2012 Share Posted October 17, 2012 My iphone autocorrects Xmas to Xmax... Quote Link to comment Share on other sites More sharing options...
RandomBass Posted October 18, 2012 Share Posted October 18, 2012 [quote name='Happy Jack' timestamp='1350473664' post='1839271'] Am I the only person who saw this topic title and throught: [color=#800000][i][b]"So here it is, Merry Xmax, everybody's having fun[/b][/i][/color]"? [/quote] oh great. That reminds me I will need to brush up on that song again soon. Grrrr Quote Link to comment Share on other sites More sharing options...
xgsjx Posted October 18, 2012 Share Posted October 18, 2012 [quote name='alexclaber' timestamp='1350473878' post='1839280'] My iphone autocorrects Xmas to Xmax... [/quote] Well in a couple of months you can wish us all a Merry Xmax, sss. [quote name='Happy Jack' timestamp='1350473664' post='1839271'] Am I the only person who saw this topic title and throught: [color=#800000][i][b]"So here it is, Merry Xmax, everybody's having fun[/b][/i][/color]"? [/quote] Cheers HJ, I've now got Xmax songs going through my head! Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted October 18, 2012 Share Posted October 18, 2012 [quote name='bremen' timestamp='1350462921' post='1839075'] I modelled a 2by10 using Eminence Beta 10A in WinISD and however big or small I made the cab, however I tuned it, the power handling dropped to 20-40W between resonance and 100Hz. Should I have doubled their stated Xmax figure, or are they really this crap? Or is WinISD very pessimistic? [/quote]They really are this crap. Makes you wonder why Orange uses them, and charges what they do for them. The bad news is that the Beta 10 not only isn't unusual in its lack of output capacity, it's actually better than many OEM drivers. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.