RE: Re: Amp/speaker recommendations?

["Keith Doxey" <ukha@xxxxxxx>]

Hi Tony,

I saw the bit about "last day at work". Are you setting up some
sort of
business of your own?

Re the speakers. Its the suspension of the cones that limits movement. If
the surround is stiff and hard to move then it needs more power to move it.
At the end of the day, the way you get sound is by moving a volume of air.
A
smaller speaker means that the cone needs to move forwards and backwards
more than a large cone would to move the same volume of air. This tends to
make them less efficient as there are greater losses in the cone
suspension.
They also dont last as long because the spider wires to the cone get flexed
more and they eventually break at the point of attachment.

A mate of mine had some "revolutionary" bass bins that instead of
having a
15" driver had 2 x 10" drivers. The cabinet was only slightly
smaller than a
normal 15" bass bin. It could certainly produce a decent bass thud but
there
was a serious downside. He was using a 500W amp to drive it to get the same
sound pressure level (SPL) that the 15" would have acheived with a
200W amp.
The other downside was that within 12 months the spider wires detached from
the cones due to the larger cone exertion required to move the same volume
of air.

The biggest single factor to consider when choosing your speakers is the
sensitivity usually expressed as SPL for 1W input. Remembering what I wrote
yesterday about amplifier power and that 3dB  represented a doubling or
halving of power, the sensitivity of the speakers will affect how much
power
you need.

The Fane Disco 80's I referred to have a sensitivity of 99dB/W, many HiFi
speakers are in the low 90's and some as low as 87dB/W. That is a
difference
of 12dB which in raw power terms means 2x2x2x2 (doubling for each 3dB
difference) = 16 times the power required to drive it.

To put it another way, The Low effiecency Hifi speaker driven with a 32W
amp
would only be the same volume as the 12" speaker driven with a 2W amp!

Hope that helps

Keith

www.diyha.co.uk
www.kat5.tv


> -----Original Message-----
> From: Tony Butler [mailto:tony@xxxxxxx]


> What about opening night party?  Might want to crank it up
> then - do you think
> 15w each will be enough?
> Also, looking for small speakers=>stiffer cones=>harder to
drive?
>