Specifications, measurements, plots and all that

[alexclaber]

[quote name='Pixel Pirate' post='461929' date='Apr 14 2009, 11:28 AM']Alex, could you explain how the vintage has a higher frequency for the F6 value as opposed to its F3? Am i missing something???

Cheers [/quote]

Typo! Should be 59 and 51Hz. Well spotted!

Alex

[Protium]

[quote name='alexclaber' post='461771' date='Apr 14 2009, 08:10 AM']I posted this a few pages back

That's reality - doesn't seem very impressive compared to everyone else's pie in the sky figures does it?

What exactly are you going to do with the specs?

Alex[/quote]

Just fancied a look at some truthful values and it gives a useful comparison between your cabs. Beats trying to figure the difference between a "high quality 6x10 or 2x15" and a "quality 2x12 or 3x10".

What sort of specs do you reckon the Schroeder cabs have? 102dB "pie in the sky" or not?

[alexclaber]

[quote name='Protium' post='462389' date='Apr 14 2009, 07:04 PM']What sort of specs do you reckon the Schroeder cabs have? 102dB "pie in the sky" or not?[/quote]

The Schroeder 15+ is claimed to be 104dB but is actually ~98dB. The 1212L is claimed to be 103dB but is actually ~101dB. The max SPL for either of those current models is about 6dB lower than the Compact in the case of the 15+ and 3dB lower in the case of the 1212L, due to much lower excursion limited power handling.

What do you make of the truthful values I listed a few posts up?

Alex

[escholl]

[quote name='alexclaber' post='461588' date='Apr 13 2009, 09:30 PM']Again, what space conditions? To what degree of tolerance -10, -6, -3dB? I've seen a measured plot for a 410XLT which shows that it's response is only +/-2dB within an octave at max yet they claim +/-2dB to higher and lower frequencies than their cab manages even -10dB.[/quote]

perhaps they used some very generous octave or half-octave smoothing?

[quote name='alexclaber' post='462425' date='Apr 14 2009, 07:42 PM']What do you make of the truthful values I listed a few posts up?[/quote]

seem normal enough to me, i learned a long time ago not to buy cabs based off the specs anyways. half the manufacturers (and that's being kind) haven't got a clue really, and acoustics is one of those things which is so specific and finicky that the specs tend to be a bit meaningless anyways. i find your system to be quite helpful really, as it's an easier way to compare your cabs to the mainstream -- of course, i take it at face value that your comparisons are accurate

congrats on your new forum by the way

[Protium]

[quote name='alexclaber' post='462425' date='Apr 14 2009, 07:42 PM']The Schroeder 15+ is claimed to be 104dB but is actually ~98dB. The 1212L is claimed to be 103dB but is actually ~101dB. The max SPL for either of those current models is about 6dB lower than the Compact in the case of the 15+ and 3dB lower in the case of the 1212L, due to much lower excursion limited power handling.

What do you make of the truthful values I listed a few posts up?

Alex[/quote]

In the Compact you mentioned using the Kappalite 3015LF, Xmax = 9.6mm (and interestingly a useable frequency range of only 40Hz-1.5kHz)
Comparing with the Deltalite 2512 in the Schroder 1212L cabs, Xmax = 4.9mm. But as there are two of these drivers what does this mean in terms of excursion-limited power handling?

[alexclaber]

[quote name='Protium' post='465407' date='Apr 17 2009, 07:22 PM']In the Compact you mentioned using the Kappalite 3015LF, Xmax = 9.6mm (and interestingly a useable frequency range of only 40Hz-1.5kHz)
Comparing with the Deltalite 2512 in the Schroder 1212L cabs, Xmax = 4.9mm. But as there are two of these drivers what does this mean in terms of excursion-limited power handling?[/quote]

I'm using the 3015 in the Compact, Xmax=5.9mm and extended upper frequency response. The Schroeder 1212L cab no longer uses the Deltalite II 2512, it uses the Celestion BN12-300S, Xmax=2.5mm. Excursion limited output is basically dependant on your total cone area x excursion, so the older Schroeder 1212L cabs can match the Compact for this, whilst the newer ones have only half this volume displacement.

Alex

[Protium]

[quote name='alexclaber' post='465976' date='Apr 18 2009, 10:57 AM']I'm using the 3015 in the Compact, Xmax=5.9mm and extended upper frequency response. The Schroeder 1212L cab no longer uses the Deltalite II 2512, it uses the Celestion BN12-300S, Xmax=2.5mm. Excursion limited output is basically dependant on your total cone area x excursion, so the older Schroeder 1212L cabs can match the Compact for this, whilst the newer ones have only half this volume displacement.

Alex[/quote]

Useful info thanks.
Was going by my 1210L, unaware they had changed the drivers in newer models

[stevie]

[quote name='alexclaber' post='465976' date='Apr 18 2009, 10:57 AM']I'm using the 3015 in the Compact, Xmax=5.9mm and extended upper frequency response. The Schroeder 1212L cab no longer uses the Deltalite II 2512, it uses the Celestion BN12-300S, Xmax=2.5mm. Excursion limited output is basically dependant on your total cone area x excursion, so the older Schroeder 1212L cabs can match the Compact for this, whilst the newer ones have only half this volume displacement.[/quote]
When comparing specs for drivers from different manufacturers you really should make sure they are measured in the same way. The Celestion xmax is the voice coil overhang, a figure that is quoted by every other speaker maker except Eminence. Eminence uses a method that can give a figure up to twice this.

[escholl]

[quote name='stevie' post='466378' date='Apr 18 2009, 09:11 PM']When comparing specs for drivers from different manufacturers you really should make sure they are measured in the same way. The Celestion xmax is the voice coil overhang, a figure that is quoted by every other speaker maker except Eminence. Eminence uses a method that can give a figure up to twice this.[/quote]

how do eminence measure then?

[alexclaber]

[quote name='stevie' post='466378' date='Apr 18 2009, 09:11 PM']When comparing specs for drivers from different manufacturers you really should make sure they are measured in the same way. The Celestion xmax is the voice coil overhang, a figure that is quoted by every other speaker maker except Eminence. Eminence uses a method that can give a figure up to twice this.[/quote]

Manufacturers are generally switching over to the Klippel analysis method of measuring Xmax as the point where 10% THD is reached. This takes account of both voice coil overhang related distortion and suspension non-linearities. If Celestion are as far behind with their testing methods as they are with their neo speaker designs I wouldn't be at all surprised to see them using the old arithmetic method. I would be extremely surprised to see the Celestion neos come out as showing twice as much Xmax using the Klippel as the (coil length - gap height)/2 method!

Alex

[stevie]

[quote name='escholl' post='466437' date='Apr 18 2009, 11:43 PM']how do eminence measure then?[/quote]
Their xmax measurements are based on how far the coil can travel before the speaker reaches 10 percent distortion. It’s a perfectly valid method, but it will always give a higher result than the voice coil overhang, which is why it is favoured by marketing departments.

You calculate the voice overhang by taking the voice coil length, subtracting the height of the gap and then dividing the result by 2.

Eminence provide an explanation here: [url="http://www.eminence.com/resources/data.asp"]http://www.eminence.com/resources/data.asp[/url]
B&C has a good explanation of the different methods of quoting xmax. Go to their website at: [url="http://www.bcspeakers.com"]http://www.bcspeakers.com[/url]. Click on Products at the top and look under Excursion Limits.

[escholl]

[quote name='stevie' post='466655' date='Apr 19 2009, 12:08 PM']Their xmax measurements are based on how far the coil can travel before the speaker reaches 10 percent distortion. It’s a perfectly valid method, but it will always give a higher result than the voice coil overhang, which is why it is favoured by marketing departments.

You calculate the voice overhang by taking the voice coil length, subtracting the height of the gap and then dividing the result by 2.

Eminence provide an explanation here: [url="http://www.eminence.com/resources/data.asp"]http://www.eminence.com/resources/data.asp[/url]
B&C has a good explanation of the different methods of quoting xmax. Go to their website at: [url="http://www.bcspeakers.com"]http://www.bcspeakers.com[/url]. Click on Products at the top and look under Excursion Limits.[/quote]

see, to me, that Klippel method makes a lot more sense, as does BC's method of obtaining their parameter Xvar. Both of these analyses take into account the actual performance of the speaker.

on it's own, voice coil overhang is meaningless, other than to tell you what i would assume is roughly how far the driver can move within a the fairly stable area of the magnetic field. it doesn't take anything else into account though in the actual performance of the speaker itself. unless i've missed something?

[alexclaber]

Interesting that B&C don't even mention the arithmetic method! I like their use of Xvar as well. My view is that with live bass guitar the Klippel Xmax method makes a lot more sense than arithmetic - 10% distortion is going to be very hard to notice on a bass in a mix. Also I believe Xlim is very important (though Xvar is probably even more useful though rarely quoted) - when you push a bass rig hard you are guaranteed to be frequently running past Xmax (maybe not with the Big One but with just about every other cab at least!) and so you want Xlim to be much higher than Xmax so you can get plenty of output without risk of damage. Furthermore if Xvar is quite high then you'll keep getting nice sounding though progressively more compressed output well beyond Xmax.

Alex

[stevie]

[quote name='escholl' post='467135' date='Apr 20 2009, 12:40 AM']see, to me, that Klippel method makes a lot more sense, as does BC's method of obtaining their parameter Xvar. Both of these analyses take into account the actual performance of the speaker.

on it's own, voice coil overhang is meaningless, other than to tell you what i would assume is roughly how far the driver can move within a the fairly stable area of the magnetic field. it doesn't take anything else into account though in the actual performance of the speaker itself. unless i've missed something?[/quote]
I do agree with you that xmax @ 10 percent is a more meaningful spec, but it has been the subject to some controversy because it has been misused, especially in the car audio sector where xmax has become a unique selling proposition.

However, don’t underestimate the value of voice coil overhang. It is useful because it tells you exactly when the coil starts to leave the gap. It’s an accepted, commonly available specification and it is also relatively easy to check and virtually impossible to fudge. System designers continue to use voice coil overhang because they can find the distortion information they need by measuring (across the driver’s entire bandwidth rather than at the single frequency measured by Klippel).

[stevie]

[quote name='alexclaber' post='467315' date='Apr 20 2009, 11:21 AM']Interesting that B&C don't even mention the arithmetic method![/quote]
They include the information in every datasheet.
[quote name='alexclaber' post='467315' date='Apr 20 2009, 11:21 AM']Also I believe Xlim is very important (though Xvar is probably even more useful though rarely quoted) - when you push a bass rig hard you are guaranteed to be frequently running past Xmax (maybe not with the Big One but with just about every other cab at least!) and so you want Xlim to be much higher than Xmax so you can get plenty of output without risk of damage.[/quote]
I'd be happy if there were one single definition of xmax that everyone could agree on and stick to - preferably one that cannot be manipulated. But the industry has been trying to find one for decades and hasn't succeeded. This plethora of xmaxes in spec sheets doesn't help anybody except the marketeers who are happy to pick the biggest number and run with it.
Xlim certainly gives you a good idea of how much abuse a speaker will take. I note that the Eminence 3015 in the Compact has the same Xlim as the Beta 15.

[alexclaber]

[quote name='stevie' post='467585' date='Apr 20 2009, 04:09 PM']I'd be happy if there were one single definition of xmax that everyone could agree on and stick to - preferably one that cannot be manipulated.[/quote]

I don't believe its entirely a marketing game. For instance, the change in response when the voice coil starts to leave the gap will be much more drastic in a speaker with a shorter gap height than that with a longer gap. Also there are hi-fi speakers out there where the suspension goes non-linear well before the motor does. And what about underhung or split gap topologies?

[quote name='stevie' post='467585' date='Apr 20 2009, 04:09 PM']Xlim certainly gives you a good idea of how much abuse a speaker will take. I note that the Eminence 3015 in the Compact has the same Xlim as the Beta 15. [/quote]

When Xlim is almost double Xmax it's certainly more than enough - if response was linear you'd have to put four times as much power in to get it there which above the tuning frequency is more power than almost any bass amp can manage.

Something that has thus dawned on me is that Qes must rise substantially once you go beyond Xmax, which explains why having a high excursion speaker can not only make your tone less boomy through lower distortion also through the response staying more tightly damped and the transients more precise.

Alex

[escholl]

[quote name='alexclaber' post='467685' date='Apr 20 2009, 05:55 PM']And what about underhung or split gap topologies?[/quote]

i was about to ask the same, you beat me to it ^_^

[alexclaber]

Just taken some measurements of a couple of Big Ones this morning. This plot is the first vintageised Big One (should be identical response to standard Big One), orange line on-axis, purple line 45 deg off-axis. Ignore the stuff below 100Hz, it's a short chirp in non-ideal conditions so I certainly wouldn't believe that the cabs are flat to 20Hz! However the rest should be a pretty good representation.

Alex

[escholl]

nice off axis response

is there a reason for the dip at 2k and peak at 5k?

[alexclaber]

It's just what that midrange speaker does - pistonic output drops gradually above 1kHz and then the cone break-up modes kick in. Fortunately that's a rather nice sound and those break-up modes and the phase plug are what gives it superior off-axis response to every other midrange driver I've looked at.

Alex

[escholl]

[quote name='alexclaber' post='523944' date='Jun 25 2009, 05:59 PM']It's just what that midrange speaker does - pistonic output drops gradually above 1kHz and then the cone break-up modes kick in. Fortunately that's a rather nice sound and those break-up modes and the phase plug are what gives it superior off-axis response to every other midrange driver I've looked at.

Alex[/quote]

yea, no don't get me wrong, it looks really good. i just didn't know if that was a design feature, or if that was the driver characteristics. i'd love to try one someday -- the off axis performance is very impressive

what midrange driver did you end up going with, if you don't mind my asking?

[alexclaber]

Just had an idea about the specs. Rather than have one sensitivity figure, one LF roll-off point and one power handling figure, how about this?

An average midrange sensitivity figure, a thermal power handling figure, and a max continuous midrange SPL figure.
Plus a low frequency sensitivity figure, an excursion limited power handling figure, a max LF SPL figure and -3, -6 and -10dB figures. The excursion limited power handling figure is the lowest power handling in the lows with <10% THD (measured at that point before the port starts to help out) and the max LF SPL is taken at that frequency. So this is a worst case scenanario - at lower and higher frequencies within the bass region the max power and max SPL are higher.

This fits well with the fact that, for instance, the Midget is just as loud as the Compact but the Compact goes lower, whilst the Big Baby isn't as sensitive as the Compact but handles a bit more power and reaches lower, thus similar LF ability.

So, for the Compact:

Midrange sensitivity: 100dB
Continuous thermal power handling: 450W
Max continuous midrange SPL: 126.5dB
LF sensitivity: 98dB
Minimum LF power handling @ <10% THD: 410W
Max LF SPL: 122.5dB
-3dB @ 63.5Hz, -6dB @ 51Hz, -10dB @ 42Hz

And for the Midget:
Midrange sensitivity: 100dB
Continuous thermal power handling: 400W
Max continuous midrange SPL: 126dB
LF sensitivity: 96.5dB
Minimum LF power handling @ <10% THD: 355W
Max LF SPL: 118.8dB
-3dB @ 78Hz, -6dB @ 59Hz, -10dB @ 46Hz

Whilst for the Big Baby:
Midrange sensitivity: 95dB
Continuous thermal power handling: 500W
Max continuous midrange SPL: 122dB
LF sensitivity: 94.5dB
Minimum LF power handling @ <10% THD: 480W
Max LF SPL: 121dB
-3dB @ 47Hz, -6dB @ 41Hz, -10dB @ 36Hz

And finally for the Big One:
Midrange sensitivity: 100dB
Continuous thermal power handling: 500W
Max continuous midrange SPL: 127dB
LF sensitivity: 97dB
Minimum LF power handling @ <10% THD: 780W
Max LF SPL: 125.5dB
-3dB @ 48.5Hz, -6dB @ 41.5Hz, -10dB @ 35.5Hz

Note that the quoted power handling ratings are RMS, as are the calculated max SPLs, so peak power is 41% higher and peak SPL is ~1.5dB higher than these average values.

Burst midrange SPL will be at least 6dB higher than continuous. Much greater LF SPL can be coaxed from these boxes but THD will increase.

Alex

Edited August 17, 2009 by alexclaber

[Captain Rumble]

Most comprehensive specs I have ever seen for cabinets being sold to Joe Public, along with Alex's desciptions of how they compare to other cabinets I already have a mental picture of what these cabinets sound like and am convinced I need to investigate futher. I would definately be asking other manufacturers for similar information befor making a buying choice and who knows if enough people ask ?. Any more than this and I for one would probably stop reading. At the end of the day its how it sounds to the individual on the day that will sell a cabinet not the specs and most of us are only reading the specs because we havent got our hands on the cab itself so if I can just have a complete set of all your cabinetes Alex to try in all possible configurations by tomorrow Reality bites

John

[Stylon Pilson]

[quote name='alexclaber' post='560879' date='Aug 5 2009, 08:42 AM']This fits well with the fact that, for instance, the Midget is just as loud as the Compact but goes lower[/quote]

Is this right? I thought that the Compact was louder than the Midget, AND goes lower?

S.P.

[alexclaber]

[quote name='Stylon Pilson' post='571946' date='Aug 17 2009, 07:14 PM']Is this right? I thought that the Compact was louder than the Midget, AND goes lower?[/quote]

No, my brain was broken. The Midget is as loud as the Compact but the Compact goes lower. Or to put it another way the Compact is louder in the lows, because once you throw some EQ into the mix they both go as low as each other but the Midget needs more power to do so and runs out of excursion sooner.

Alex