Free Space Alignment.

Dedicated to those large boxes at one end of the room
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Cressy Snr
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#1 Free Space Alignment.

Post by Cressy Snr »

Does anyone have any idea why manufacturers design highly expensive speakers that have a free space alignment.
It seems like an odd thing to do.
Last edited by Cressy Snr on Sat Feb 11, 2017 5:34 pm, edited 2 times in total.
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Scottmoose
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#2 Re: Free Space Alignment-Why?

Post by Scottmoose »

Hopefully none are free space or only a giraffe or brontosaurus is likely to get much benefit. ;) Half-space perhaps.

It depends on whom in particular, as reasons will vary. FWIW though:

-Drive units are measured (or should be) by their manufacturer / developer on IEC baffles in an anechoic chamber since in engineering terms it's important to know exactly what they're doing without external influences.

-Many (not all) loudspeakers are designed assuming 1/2 space conditions for similar reasons on the basis that all rooms are different so trying to design a speaker assuming 1/4 or 1/8 space conditions usually contains about as many caveats as using 1/2 space. Exact position of the enclosures (and their size & shape) within the room, the construction materials of the room itself, its proportions & furnishings along with the exact listening position[s] all affect behaviour to the point that you're on a hiding to nothing trying to account for it all. While you can make a reasonable stab at negating some of these with an omni or quasi-omni speaker, like every other speaker they have their own issues to contend with and will not give consistently repeatable results in every room or room position. The absolute flooder type gets about as close as you can with that approach, but there's a limit even then to what can be done, and not everybody cares for the often diffuse results. Same can be said for dipoles and nearfield arrays: they can go some distance to eliminating room effects, but they're not panaceas and have their own balances of advantages / disadvantages.
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Cressy Snr
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#3 Re: Free Space Alignment.

Post by Cressy Snr »

Cheers Scott,
I appreciate the difficulty of trying to account for every room and listening condition. In fact it is impossible.
I just wonder if the mainstream hi-fi speaker manufacturer is assuming a listener who will be willing to play around with positioning until they get their speaker to not boom in their room. To me it will lead to inevitable domestic conflict unless the listener has a separate room in which to put their gear.

In the 50s, 60s and early to mid 70s speakers were wide baffled and against walls or in corners, so that even the biggest, such as Leak 2075s remained relatively unobtrusive. The smaller stuff was designed for bookshelf mounting. I never saw a speaker anywhere but next to a wall or in amongst books, until I became aware of the Spendor BC1 around 1975. The only stuff I remember from the 80s that could be stuck on bookshelves were the Environmental Sound models and the Videoton Minimax II. 'Orrible stands were fast becoming de rigeur by then and the wall-placed speaker was almost extinct except for the Linn Sara, Kan and Naim SBL, but they had other problems, due to the fact that they, to a man, sounded like someone dragging their nails along a blackboard, whilst dancing around in a bag of spanners. :lol: :lol:
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#4 Re: Free Space Alignment.

Post by Scottmoose »

Possibly. It also doesn't help that some go for a maximally flat (or a QB3) bass alignment for vented boxes, which is probably responsible for triggering more room modes than anything else, but does give 'impressive' quantities of output.

I suspect a lot of manufacturers do tend to take that sort of view (mass-market appeal), plus many have to consider the North American market where rooms are typically larger, and speakers often pulled further out into the space than many of us in the UK (and Japan is a notable example also) are able to do. As a result, less immediate room gain from boundary loading, and the flatter the LF alignment needs to be. Another factor has been the shift toward narrow baffle speakers -smaller units, often needing more help from the box than big woofers. On the other hand, a lot of those big woofers didn't necessarily go very low, since efficiency was the object rather than extension.

That they did (do). Over-reliance on boundary gain and positioning can be as bad as under-reliance. Just to make life difficult. ;)
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