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Drive units, facts and fashion


Torben Hedstrøm
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Catchy headline... Eh ?! ;)

Following a discussion in another thread, I came to thinking: Been playing bass for 25 years (on and off), and as I am on the prowl for one or two cabs to complete my new setup, some thoughts came up...

When I started out, 15" drive units were very very common, and the cabs were big as buildings. certain makers were beginning to put out 12" cabs for bass, but as I recall mainly for combos.

A little later on it was combinations of drive units... 115+412 was very popular, and as time passed people even begang flattering the 115+410 combination, leaeding to the 410 fashion really taking off. I remember in the mid/late 90's many fellow bass players running 2x410 in their setup. Seemed like the more drive units the better !.

Then the 210 and 212 sort of gained popularity... And after that even the 112 flavour. Looking at the second hand market today sort of reflects this change in fashion and taste. 610 and 810 cabs are selling at very very low prices, and are typically up for grabs for quite some time.

This made me think a bit... What parameters are into play here ??. I can think of the following off hand:

Fashion, plain and simple
Technical development
Supply & demand (This sort of goes with the above, as there is usually a 'sweet spot' decided by demand and research budgets)
Portability (very important factor... Just look at smartphones and laptops !)

Simplifying things alot, we are still dealing with pistons moving air... Meaning surface area is indeed a factor. You cannot defy the laws of physics here. In another thread there was a guy pointing out that more units (as a very general rule) equals more outpout pr. Watt. I think that was the philosophy back in the prime of 810 cabs... That wall of sound, nomatter what exotic detune you could think of. I decided to make a very simple chart (very very simple, but usefull)...

[sharedmedia=core:attachments:155621]

So from the calculations we see, that for instance 1x15" is only a little more than 2x10" which roughly equals 3x7" and so on. Interestingly the 4x10 is about 150% combined area of very very popular 212 combination, and as ultralight cabs go the only weigh app. 5 kg. more as I remember.

This is the point where I need someone filling in the blanks. There many other (physical)parameters than just surface area that determines optimum performance... Voice coils for instance (length vs. diameter and more), given that a smaller unit has to work harder to output he energy in the lower register, than a larger unit. Anyone have some formulas explaining the relationship between the amount of air to be moved, compared to the stroke of a given membrane for starters ?.

Regards.

Torben

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The current crop of drivers we have available are far superior to anything we had in the 70's and 80's, unfortunately main stream manufacturers still choose to put these drivers in aesthetically rather than acoustically designed boxes. But some are catching on, hence the popularity of relatively new brands such as Barefaced or TKS who are placing these drivers in suitable boxes.

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A big difference between the 4x10 and a 2x12 is the vertical 2x12 has a far superior dispersion, meaning more people get to hear it when they're off axis.
Back in the late 80s & early 90s I had 2 15" cabs. I moved them on & got a 4x10. Now I have a 2x10 that outperforms either of those rigs in every respect.

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[quote name='Torben Hedstrøm' timestamp='1392741857' post='2372207']Anyone have some formulas explaining the relationship between the amount of air to be moved, compared to the stroke of a given membrane for starters ?.

Regards.

Torben
[/quote]

volume (of cylinder) = pi * r^2 * h

Big drivers don't have to move back'n'forth by as far in order to shift a given amount of air. It's called volume for a reason.

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[quote name='LukeFRC' timestamp='1392742635' post='2372226']
efficiency... tuning... low end response...
[/quote]

Effiency: I agree that materials today are better than 30 years ago. But you sill need to displace some serious air in the lower register. Smaller unit = more movement = Higher average speed of the membrane = Hard work for the amp (?).

Tuning: Dunno... I am not sure we know ALOT more about tuning today, compared to 30 years ago. But we may have become alot wiser on how we as humans percieve sound...

Low end response: Requires movement of air... Alot of air. On the note (no pun intended) of tuning, you do have different options. Horn loading, transmissioin line bass reflex to name some of the well known ways of emphasizing low end respnse. But none of these principles are perfect.

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[quote name='FinnDave' timestamp='1392743076' post='2372233']
I'd question your dates, I remember buying a 410 back in 1978, used it for bass exclusively for several years.
[/quote]

No rules without exceptions I guess... Still, looking at the 2 hand market it appears to me that alot of the cabs are products of their time, configurationwise. For instance you don't really see that many 2x12" configurations older than say 15 years.

A funny side note on the 2x12"... A shop here in Copenhagen developed, in start 90's, what they thought to be the ultimate cab configuration. Advocating that the 2x12" configuration was by far the best compromise all things considered (size, weight, frequency spectrum). Mind you, this was before it became evidently popular to put tweeters in the cabs. They developed the cabs, using Beyma units which they seemingly modified a bit.

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[quote name='Torben Hedstrøm' timestamp='1392765848' post='2372619']
Effiency: I agree that materials today are better than 30 years ago. But you sill need to displace some serious air in the lower register. Smaller unit = more movement = Higher average speed of the membrane = Hard work for the amp (?).

Tuning: Dunno... I am not sure we know ALOT more about tuning today, compared to 30 years ago. But we may have become alot wiser on how we as humans percieve sound...

Low end response: Requires movement of air... Alot of air. On the note (no pun intended) of tuning, you do have different options. Horn loading, transmissioin line bass reflex to name some of the well known ways of emphasizing low end respnse. But none of these principles are perfect.
[/quote] my point was more that there are a lot more variables to what a cab can produce than simply cone size and number.

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[quote name='LukeFRC' timestamp='1392796281' post='2372740']
my point was more that there are a lot more variables to what a cab can produce than simply cone size and number.
[/quote]

I do agree... And I am certainly not intending to 'know better' or arguing for the arguments sake :). Quite simply, I am trying to get wiser, and hopefully end up buying a nice cab or two (preferably the size of a matchbox, with APL and low end to spare ;) ).


Regards.

Torben

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Drivers of today are far more efficient than they were in the 90s. Whereas a larger diameter will move more air, that's only if the driver has the same spec as a smalle driver. A B&C 10" driver has a longer excursion and a better surround than the Celestion 15" driver I had. This means a 10" moves far more air than the old 15".
More movement on the driver doesn't mean harder work for the amp, it means the driver is moving more & if it's built to do this, then it's more efficient.

Now don't get me wrong, movement of air is what we hear & the more you can move, the louder you can go. But you don't need big drivers to do this & remember, driver diameter has no bearing on how much bass a cab produces, that is down to the tuning of the cab.

I don't believe 4x10s & 4x12s were designed for bass, they're more like poorly designed guitar cabs with bass drivers put in them.

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[quote name='FinnDave' timestamp='1392799264' post='2372776']
I was obviously ahead of the times! I recently sold my Ashdown 410 (not bought in 1978!) and replaced it with a Barefaced 212, there is a world of difference between them.
[/quote]

Could just be that a 1 x 212 solution (or a 2/3 x 112 maybe) is the way to go. I mean if I can have a 25 kg. 212 performing like my current 115+210 I would be more than happy.

Reason why I am being so anal about all this is, that the diversity of bass gear really sucks here. That means that I will likely buy my stuff from UK or DE. And since a bass cab is not exactly in the same league as sending a postcard, I would like to hit the bullseye on my first try :).

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I think from a buying point of view there's far more to consider than the size of driver and it's ability to shift air. The SVT is hardly cutting edge technology yet 45 years on there are plenty of people who still like it. It may have had the drivers updated several times, but from a technical POV they're still not great.

It may be better to say what sort of sound you're looking for and try for some recommendations on here.

Edited by Musky
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[quote name='Musky' timestamp='1392751895' post='2372376'] Barefaced has some useful articles on this. http://barefacedbass.com/technical-information/Volume-displacement.htm http://barefacedbass.com/technical-information/Real-world-sensitivity.htm There are also Alex's columns for BGM up there. [/quote]

Good reading indeed... And some very interesting points.

With all due respect for Barefaced (I really really like the concept and the story... Never heard their products though)... When I read their rundown on the laws of physics, and how to work around them, it strikes me that they don't really dig deep into the compromises they make in their designs. They do describe the pros and cons of, for instance, the passive radiator design... But every design short of the absolute optimum has compromises... So where do Barefaced cut corners ?.

Don't get me wrong, I am sure that their products are excellent, but they are measuring themselves against corporations with million dollar R&D budgets, and production quantities that likely lowers the price pr. unit to a level well below what Barefaced can get from their subcontractors. Ofcourse they don't have the same expenses for advertising and PR in general either (they seem to be very popular without...). But still, if you as such a small company claim to 'know better' than R&D departments with huge budgets and decades of experience, I get curious as to how and why... As stated, all designs IMHO contains compromises !.

And just to emphasize: I am in no way trying to degrade Barefaced products, or their brands... I don't have the tech knowledge nor the experience with their products to do so in any way !. I ma just trying to use common sense and logic...

Regards.

Torben

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A compromise is not always negative, ie cutting corners, but can be positive, ieabout choice. The choices a manufacturer makes will be obvious if you know the science.

Cabs in previous decades were just boxes of speakers. The good ones today are tuned to the specs of better designed drivers which produce more volume and better quality tone out of (sometimes) smaller speakers.

Your choice should be based on the tone you want. That's difficult to do at a distance so I'd start by looking at what your favourite bass players use.

My recommendations for a big, clean, full toned cab would be Bergantino, Barefaced and Aguilar.

Edited by chris_b
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[quote name='Torben Hedstrøm' timestamp='1392805588' post='2372866']
(...)

Don't get me wrong, I am sure that their products are excellent, but they are measuring themselves against corporations with million dollar R&D budgets, and production quantities that likely lowers the price pr. unit to a level well below what Barefaced can get from their subcontractors. Ofcourse they don't have the same expenses for advertising and PR in general either (they seem to be very popular without...). But still, if you as such a small company claim to 'know better' than R&D departments with huge budgets and decades of experience, I get curious as to how and why... As stated, all designs IMHO contains compromises !.

(...)
[/quote]

Sorry for this, not directly aimed at you, but what "million dollar R&D department"? I could build a 15mm thick plywood square box with no bracing or damping inside, cut four circular holes on the baffle, cover it in carpet and add plastic corners and rubber feet. The only thing i would have to be carefull is to leave enough space on the baffle to fit 4 cheap OEM 10" drivers and make sure i stick my brand's logo very visible on the metal grille. Then i would just move it for a premium and see them fly off the shelfs. Very small investment for a big profit!

Now, jokes aside and answering to your main question, i had a 2x10" + 1x15" Trace Elliot rig, it sounded immense and i allways thought nothing would sound louder but then i entered the lightweight wagon and ended with a Barefaced Super12T, it's much much louder, more defined and hi-fi and weights a small fraction of that TE rig. I also lost all the boominess i felt on stage and started to be able to use less volume on the amp but at the same time hearing my bass a lot better.

Things change and technology evolves, designing a cab has a lot of factors to take in to consideration being cone size one (but not the most important by a long shot).

Summing it up i'll never gonna get me a 810, i love my back and my tone too much for that ;)


Cheers

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According to Bill Fitzmaurice (a BC member) there are some "high volume" cab makers who don't have an R&D department at all.

They just hire in a designer, like him, who does the lot, not based on anything technical but on price.

It would be hard for someone like Alex/Barefaced to not design something better.

Edited by chris_b
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[quote name='Torben Hedstrøm' timestamp='1392805588' post='2372866'] Good reading indeed... And some very interesting points. With all due respect for Barefaced (I really really like the concept and the story... Never heard their products though)... When I read their rundown on the laws of physics, an d how to work around them, it strikes me that they don't really dig deep into the compromises they make in their designs. They do describe the pros and cons of, for instance, the passive radiator design... But every design short of the absolute optimum has compromises... So where do Barefaced cut corners ?. Don't get me wrong, I am sure that their products are excellent, but they are measuring themselves against corporations with million dollar R&D budgets, and production quantities that likely lowers the price pr. unit to a level well below what Barefaced can get from their subcontractors. Ofcourse they don't have the same expenses for advertising and PR in general either (they seem to be very popul ar without...). But still, if you as such a small company claim to 'know better' than R&D departments with huge budgets and decades of experience, I get curious as to how and why... As stated, all designs IMHO contains compromises !. And just to emphasize: I am in no way trying to degrade Barefaced products, or their brands... I don't have the tech knowledge nor the experience with their products to do so in any way !. I ma just trying to use common sense and logic... Regards. Torben [/quote] who? i know what you mean but a lot of the forward steps in bass amplification down the years have been smaller companies innovating.

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[quote name='Torben Hedstrøm' timestamp='1392805588' post='2372866']
Don't get me wrong, I am sure that their products are excellent, but they are measuring themselves against corporations with million dollar R&D budgets,
[/quote]When those comparisons are made it's the corporations with 'million dollar R&D budgets' that come up short. First off, no bass cab manufacturer spends that kind of money on R&D. For that matter, a very small percentage of their budget is devoted to R&D with respect to technical improvements. Most of it is spent on market research for what really sells cabs, which isn't how they sound. It's how they look.

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[quote name='xgsjx' timestamp='1392816203' post='2373022']
Barefaced do have a 30 day return if you're not satisfied & Alex is a member here too.
[/quote]

I saw that, and I am tempted... If claims hold true I would be thrilled !. But postage for a 30 kg. cab is something like £870 or so I hear, and that not only add significantly to the price - It is is also quite far from a 'free' trial if I return it ;)

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