Vd

[alexclaber]

Updated data so you can compare apples to apples. Using the modern mathematical method seems to give a slightly optimistic figure but it's closer to reality (Klippel based figure) than the pessimistic figure given by the older mathematical method.

Klippel method:

Midget = 330cc
Compact = 505cc
D.M. = 660cc
Big One = 846cc
Vintage = 1010cc

Newer mathematical method:

Midget = 340cc
Compact = 566cc
D.M. = 680cc
Big One = 915cc
Vintage = 1132cc

Newer mathematical method is: Sd x (((Hc-Hg)/2)+(Hg/4)) = Vd

where Sd equals cone area (Pi x D^2)/4, Hc equals voice coil winding length (or height but definitely not diameter) and Hg equals magnetic gap height (or length or depth depending on your perspective).

Alex

[EBS_freak]

[quote name='alexclaber' post='684022' date='Dec 14 2009, 02:20 PM']Updated data so you can compare apples to apples. Using the modern mathematical method seems to give a slightly optimistic figure but it's closer to reality (Klippel based figure) than the pessimistic figure given by the older mathematical method.

Klippel method:

Midget = 330cc
Compact = 505cc
D.M. = 660cc
Big One = 846cc
Vintage = 1010cc

Newer mathematical method:

Midget = 340cc
Compact = 566cc
D.M. = 680cc
Big One = 915cc
Vintage = 1132cc

Newer mathematical method is: Sd x (((Hc-Hg)/2)+(Hg/4)) = Vd

where Sd equals cone area (Pi x D^2)/4, Hc equals voice coil winding length (or height but definitely not diameter) and Hg equals magnetic gap height (or length or depth depending on your perspective).

Alex[/quote]

Now this is interesting. Two different values for Vd. Just shows that it's open to interpretation - how can you guarantee that manufacturers are calculating Vd in the same manner?

[alexclaber]

[quote name='EBS_freak' post='684092' date='Dec 14 2009, 03:34 PM']Now this is interesting. Two different values for Vd. Just shows that it's open to interpretation - how can you guarantee that manufacturers are calculating Vd in the same manner?[/quote]

I've already explained the different ways Vd can be calculated, please re-read my previous posts. It is easy to standardise this as if Klippel based values are not provided you can use the arithmetic explained in my last post. The alternate methods are within 10% which is a perfectly reasonable tolerance but if you want to be more precise then ask the manufacturer for the voice coil length and the gap height so you can do the sum yourself.

Alex

[EBS_freak]

[quote name='alexclaber' post='684101' date='Dec 14 2009, 03:43 PM']I've already explained the different ways Vd can be calculated, please re-read my previous posts. It is easy to standardise this as if Klippel based values are not provided you can use the arithmetic explained in my last post. The alternate methods are within 10% which is a perfectly reasonable tolerance but if you want to be more precise then ask the manufacturer for the voice coil length and the gap height so you can do the sum yourself.

Alex[/quote]

I didn't say that you hadn't explained there is more than one method to measure Vd but the fact that you now have two diffent quoted figures, means that it's just another figure that is open to a little massage around the edges. Which calculation method are other manufacturers using? Going by cab forumula, both are valid calculations for Vd. I'm not suggesting that you are massaging the BF figures but that's not to say that manufacturers wouldn't... afterall, you claim that other manufacturers are already massaging the figures that they produce now. Would a slight tweak to the Xmax figure go unnoticed in the spec? Who is to say? 10% out on all measurements is not that insignificant.

Out of the thousands of people who buy bass cabs, who is realistically going to ask the manufacturer for the required information to do the sums yourself?

Edited December 14, 2009 by EBS_freak

[JTUK]

Not me... I'll just play the cab with my gear and if it sounds great, then I am likely to be interested.

but then I'll also go on a few other parameters as well..
How well made is it, do I like the look of it...?

The only real specs I'll pay any real attention to are the are freq range and RMS figure.
I'll run my cabs conservatively anyway..

[Protium]

[quote name='JTUK' post='684136' date='Dec 14 2009, 04:23 PM']The only real specs I'll pay any real attention to are the are freq range and RMS figure.[/quote]

Both of which tell you practically nothing :facepalm:

[EBS_freak]

<taking the piss>Volume is not measured in watts. It's measured in Lux.</taking the piss>

Edit: for clarification.

Edited December 14, 2009 by EBS_freak

[Protium]

[quote name='bigfatbass' post='684402' date='Dec 14 2009, 08:09 PM']And thats why Alex is wasting time. The level of ignorance of technical matters on this forum is staggering, and from the regular repeated questions it seems most have no interest in improving their knowledge. I have seen some blazing flame wars because somebody said [/quote]

I hope this isn't aimed at my response

Edited December 14, 2009 by Protium

[EBS_freak]

[quote name='bigfatbass' post='684492' date='Dec 14 2009, 09:00 PM']Not aimed at anyone in particular, technically ignorant bass players in general.[/quote]

Vast majority then!

[Johngh]

[quote name='EBS_freak' post='684494' date='Dec 14 2009, 09:01 PM']Vast majority then![/quote]


Ain't that the truth. If I have a rig that's loud and clear enough for my needs then thats it. On my amp I want a graphic, compressor and a a few knobs to twiddle to get the tone I want and that's about it. Cab's have to be portable enough to fit in whichever car I have. At present I have a Hartke 2x10.5 and a 1x15, they are portable, and give me a lot of versatility.

[EBS_freak]

[quote name='Johngh' post='684515' date='Dec 14 2009, 09:15 PM']Ain't that the truth. If I have a rig that's loud and clear enough for my needs then thats it. On my amp I want a graphic, compressor and a a few knobs to twiddle to get the tone I want and that's about it. Cab's have to be portable enough to fit in whichever car I have. At present I have a Hartke 2x10.5 and a 1x15, they are portable, and give me a lot of versatility.[/quote]

And there's your average customer, right there.

[51m0n]

[quote name='EBS_freak' post='684414' date='Dec 14 2009, 08:12 PM']Volume is not measured in watts. It's measured in Lux.[/quote]

You are kidding aren't you???

[EBS_freak]

[quote name='51m0n' post='684543' date='Dec 14 2009, 09:31 PM']You are kidding aren't you??? [/quote]

You think?!

[Rich]

Surely volume is measured in cubic metres..?

[crez5150]

[quote name='Rich' post='684664' date='Dec 14 2009, 11:15 PM']Surely volume is measured in cubic metres..? [/quote]

I thought it was measured in those little bars you get at the bottom of the TV screen..... am I wrong?

[alexclaber]

[quote name='bigfatbass' post='684861' date='Dec 15 2009, 09:22 AM']Here is a thought. I used to have a brace of the baby EBS Neo's, but they farted out so I got an EBS Neo 212. When the babies were farting the big boy was just clearing his throat.

Same drivers though. Same Vd![/quote]

I'm guessing that to try to get the perception of sufficient bass out of a small enclosure the 112s are tuned too high and the speakers are unloading. The 212 has 50% more volume per driver so it's a very different alignment. Knock out the lows below the tuning frequency with a highpass filter and I'd expect similar performance between two 112s and one 212.

I've deliberately avoided the temptation to tune the Midget higher to make it feel more bassy - and I suspect if they were sold through shops the tuning I've chosen would actually mean none get sold because you have to boost the lows to get fatness and it's hard for people to get their head round that actually being a good thing for a tiny cab, instead they deem the cab with less apparent bottom end to be inferior. if I had £1 for every time I've heard someone compare two cabs side by side at shop/bedroom volume and make a judgement on LF performance based on such low SPL I'd definitely have a good Xmax (sic) fund. So what works best in the real real world of gigging is very different to the (un)real world of the guitar shop.*

At the moment the uninformed are going by 'RMS power' and 'freq range'. Get a load of cabs together with very similar claimed specs and the variability in max output will be HUGE. Get a load of cabs together with very similar Vd and there will be a difference but its going to be within a reasonable tolerance.

Alex

* This isn't an uncommon problem in engineering. Since the CO2 tax bands came into force manufacturers are having to skew their engine management systems to perform as well as possible on the unrealistic laboratory tests so you pay less tax but actually get worse fuel economy and performance in actual usage.