Re: Speaker sensitivity and fs in multiples.

[EMAIL PROTECTED] (Dick Pierce) wrote in message news:<[EMAIL PROTECTED]>...
> [EMAIL PROTECTED] (Svante) wrote in message news:<[EMAIL PROTECTED]>...
> > "Rusty Boudreaux" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> > > "Svante" <[EMAIL PROTECTED]> wrote in message
> > > news:[EMAIL PROTECTED]
> > > > [EMAIL PROTECTED] (Dick Pierce) wrote in message
>  news:<[EMAIL PROTECTED]>...
> > > > > Stager <[EMAIL PROTECTED]> wrote in message
>  news:<[EMAIL PROTECTED]>...
> > > > > > How does using speakers in arrays affect their sensitivity
>  and
> > > > > > total resonant frequency?
> > > > > >
> > > > > > For example, say I have four 8 ohm mids, each individually
> > > > > > rated at 90 dB sensitivity (at 1 meter, 1 watt).
> > > > > >
> > > > > > If I do a series-parallel array, I know I'll still be at 8
>  ohms,
> > > > > > but how will the sensitivity change from the original
>  individual
> > > > > > 90 dB.
> > > > >
> > > > > In a series parallel array of the kind you're talking about,
> > > > > for a given voltqge across the array, the total power in the
> > > > > array is the same, since the impedance is the same, but each
> > > > > driver dissipates 1/4 of the total power, leading to the same
> > > > > sensitivity as a single driver.
> > > >
> > > > Sorry, Dick, I think you are wrong here. The efficiency is
> > > actually
> 
> Sorry, Mr. Svante, you can't read what I wrote and you chose
> to omit the crucial piece of text that I EXPLICITLY wrote.
> 
> > > Nope, Mr. Pierce is quite correct and you are wrong.
> > 
> > Nopenope... :-)
> >  
> > > Since the impedance is the same and the drive level is the same
> > > the total output is the same.
> > 
> > Nope
> > 
> > > Please explain how four drivers at one quater 'X' watts can be
> > > anything other than the same as a single driver driven at 'X'
> > > watts.
> > 
> > There is an efficiency gain on the acoustic side, due to the
> > interaction between the drivers. 
> 
> You apparently did not read or chose to ignore what I wrote
> in my original replay. I said the following, QUITE clearly:
> 
>   "Ignoring acoustic effects, and just concentrating on the
>   electrical properties, you essentially examine what the 
>   total impedance of the array is, and then examine how it 
>   is divided amongst the drivers."
> 
> Do you see how I EXPLICITLY chose to NOT talk about the acoustical
> effects? The reason being is precisely BECAUSE of the complex
> depednecny on frequency.
> Now, within the context that I had writtenm as I have just reiterated,
> would you care to show where my error was?

I think your error is to assume that ignoring acoustic effects, you
can still calculate sensitivity. For some reason you to not include
the next paragraph where you wrote:

----quote

So, in general, you can say that n drivers in parallel will have
n times the sensitivity of one, while n in series will have 1/n
the sensivitity. 

----End quote

Given that you ignore acoustical effects, this is correct, but
misleading since acoustical effects are so important.

Could you please enlighten us regarding your view on the sensitivity
for low frequencies for the 2x2 array, and for higher frequencies
straight in front of the same 2x2 array? Including acoustic effects
and assuming free field conditions.

>From what I have seen in this group you have provided many good
insights, and I beleive that you would say the same thing as I do,
regarding this. I think your input could help this thread to "settle".

> > The total electric input power to the
> > speakers will be the same in the 2x2 series/parallel connection, but
> > the acoustic output power will be quadrupled, due to this acoustic
> > coupling, see my other posts in this thread. I know, it seems terribly
> > wrong, but is not. It is acoustics... :-)