[HAM] Vedr. Re: Speakers and frequencies .. what's it all about

Thu Dec 27 16:44:56 CST 2007

Hello and by all my respect greetings to you all!
Sorry to interrupt, but this is a great place to ask
questions about Hammonds and Leslies. Mine is working
well for timebeeing. But time will come when service
is needed. This is a good place to turn to.
Sorry if I mess up the english. I'll just try my best.
Greetings from Norway.

--- goffmac747 at aol.com skrev:

> 
>  I'm curious though if the bass rotor design of a
> normal leslie will effectively "rotate" lower bass
> frequencies and not just affect the higher bass
> frequencies...
> 
> 
>  
> 
> 
>  
> 
> -----Original Message-----
> From: benjamin <benjaminmassy at hotmail.com>
> To: kziss at ozemail.com.au; hammond at zeni.net
> Cc: benjaminmassy at hotmail.com
> Sent: Fri, 28 Dec 2007 3:47 am
> Subject: [HAM] Speakers and frequencies .. what's it
> all about
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hello Kon , 
> 
> Very nice  to find somebody who respects good
> music-reproduction within our 
> fysical limits of hearing . Me to, I am leaving the
> scene if it is to loud and 
> the risk of eardamage is to high . 
> 
> Now about your your Bi amped 925  project : 
> 
> First of all the passive 12 db slope is a problem to
> make with coils and caps 
> between the amp output and the speakers , why ,
> because the coils and caps you 
> need are loosing a lot of power since they will have
> to pass high currents and 
> these components do have an internal resistor that
> you will have to take in 
> account . plus for 12 db slope you need a lot of
> coils and caps .... in short : 
> to much for what the results will be . Also it will
> put a difficult load on your 
> amps since part of it is capacitive load and the
> other part is an inductive load 
> combined with the speaker impedance , it could give
> unpredictable results in 
> some cases..even burning out your amp by oscilation
> and if it is supersonic 
> oscilation you will not even notice it unless you
> have attached an osciloscope 
> to see what happens; in short  an amp is build for a
> certain application and a 
> certain load that is matched to it ; 
> 
> second point : the gain by doubling the power output
> is only 3 dB louder 
> theoretically , practically there will be no
> noticable gain here if you take 
> into account the losses you will have by the passive
> components between speakers 
> and amp 
> 
> third point ; do you know why speakersystems are
> split up in active systems ?  
> mainly because of  to avoid DISTORTION  , the
> distortion that you get is the 
> mixing product of different frequencies  and is
> called intermodulation 
> distortion , I give you an example:  if you have two
> frequencies entering an amp  
> like 100 HZ and 2000 HZ  ; since no     amp is
> completely linear in 
> amplification there will be produced mix frequencies
> and they will be the 2000 
> Hz minus 100 Hz  thus 1900 Hz and also the 2000 Hz
> plus the 100 Hz thus 2100 Hz  
> so your amp will produce at the speaker  not only
> 100 and 2000 Hz but also 
> 1900Hz and 2100 Hz  plus the harmonics from these
> frequencies .. if you have 
> only harmonical distortion  you have not a big
> problem since the harmonics are 
> sounding ok  ( every octave is the double from the
> one that sounds lower so 
> harmonic distortion is not a bad thing that it will
> give you an ugly sound) , 
> but the Intermodulation products  from the
> intermodulation distorti!
>  on    , These are very bad in the ear ! unless you
> like that sound , but most 
> people don't like it ; 
> so to avoid these bad distortions , music systems
> are split up in active 
> frequency splitted amps and speakersystems ... that
> is the whole secret . 
> If you are going to distroy this principle you will
> always have a bad or worse 
> reproduction then the original and in this case
> practically no gain , or 
> marginally in sound production .. 
> the distortion  is mostly in the end or power 
> amplification  , it is rarely in 
> a preamp since preamps have to deal with low power
> low voltage signals , but in 
> the high voltage , high current portion of the final
> amps , there is what you 
> get from distortion due to non linear behaviour of
> the circuits ; 
> 
> If your friend wants to make it sound louder then
> let him buy a second 925  
> instead of spoiling his system that he owns now . or
> buy a tuneable active 
> preamp splitsystem that is used in caraudio and put
> more powerful amps in the 
> 925 , but DON'T try to filter after the amp.. this
> is the wrong way of doing ; 
> 
> I give you here some calculations and a bit of
> insight about speakerfiltering on 
> this link 
>
http://64.233.183.104/search?q=cache:lx2-F3scZOIJ:www.bcae1.com/passxovr.htm+passive+crossover+filter+calculation&hl=nl&ct=clnk&cd=1&gl=be
> 
> So dear friend Kon , I am sorry for my bad English ,
> but I tried to explain you 
> and some other non technical people what it all is
> about . 
> Hope it helps you and some other people .. 
> 
> all the best from Belgiums  Benjamin  ( and yes 16
> Hz is a revelation to feel in 
> the belly and to let it blow away your pants )  
> :-))
> 
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>  
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