[sdiy] Speaker Impedance

[Metrophage]

But that would be 25% difference, I'm not sure if my meter is that
accurate... (lol, barely!)

Sounds like a good idea to measure the coils so one can be certain.
Thank you for the explanations!

CJ
--- Bob Weigel <sounddoctorin at imt.net> wrote:

> Sure.  But say you started with a 4 ohm speaker that had a 3 ohm DC 
> voice coil (potentially 25% efficient or less).  NOW....with the 
> resistor you have the equivelent of an 8 ohm speaker with 7 ohms of
> DC 
> resistance that is only making heat..no sound. So now it's half as 
> potentially efficient roughly. 
>      In other words were you to have put a speaker instead of a dead 
> impedence there (sonically speaking) then you would have an 8 ohm 
> speaker equivelent neglecting phase cancellations and so on from
> having 
> two sources now... that is the same efficiency as one speaker.   ie.
> if 
> you give the entire unit 100watts of power, you will realize the same
> 
> decibel level (ideally again) that you would get with a single
> speaker 
> with 100watts of power across it.  Follow?  BUT....you now can double
> 
> the power without blowing out the speaker.  -Bob
> 
> Metrophage wrote:
> 
> >Hi Tim,
> >Does this mean that the same applies to a speaker plus a resistor?
> Does
> >, for example, a 4 ohm resistor in series with a 4 ohm speaker equal
> an
> >8 ohm impedance for the output? I was wondering whether or not this
> was
> >the case. 
> >CJ
> >
> >--- Tim Parkhurst <tparkhurst at siliconbandwidth.com> wrote:
> >  
> >
> >>Hey Rafael,
> >>
> >>If memory serves (sometimes it does, sometimes it don't...), I
> >>believe the
> >>same tricks used with resistors will work with speakers. Ohm's Law
> >>still
> >>applies. In other words, two 16 Ohm speakers wired in parallel will
> >>give you
> >>8 Ohms. Conversely, two 16 Ohm speakers wired in series will give
> you
> >>32
> >>Ohms, and so on. 
> >>
> >>
> >>Tim (a Starbucks mocha in each hand gets me wired in parallel)
> Servo
> >>
> >>"Imagination is more important than knowledge." - Albert Einstein
> >>
> >>
> >>
> >>
> >>    
> >>
> >>>-----Original Message-----
> >>>From: Rafael_Cohen at prusec.com [mailto:Rafael_Cohen at prusec.com]
> >>>Sent: Monday, May 23, 2005 9:56 AM
> >>>To: synth-diy at dropmix.xs4all.nl
> >>>Subject: [sdiy] Speaker Impedance
> >>>
> >>>
> >>>Hey everybody,
> >>>Guess what... it's another newbie question!!
> >>>
> >>>I have some schematics requiring 8 ohm speakers, and in some of my
> >>>DIY/scavenging I come across speakers of various other impedance,
> >>>      
> >>>
> >>usually
> >>    
> >>
> >>>higher than 8ohm.  Everything from 16ohms to 45 ohms... sometimes
> >>>      
> >>>
> >>computer
> >>    
> >>
> >>>speakers or speakerphones, etc...
> >>>
> >>>My question is, what do I need to do in order to adapt the circuit
> >>>      
> >>>
> >>to
> >>    
> >>
> >>>speakers of different imedance?  Also, is there a simple way to
> >>>      
> >>>
> >>test the
> >>    
> >>
> >>>imedance of a speaker?
> >>>
> >>>Thanks again,
> >>>Rafael
> >>>
> >>>--
> >>>No virus found in this incoming message.
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> >>>Version: 7.0.322 / Virus Database: 266.11.15 - Release Date:
> >>>      
> >>>
> >>5/22/2005
> >>    
> >>
> >>-- 
> >>No virus found in this outgoing message.
> >>Checked by AVG Anti-Virus.
> >>Version: 7.0.322 / Virus Database: 266.11.15 - Release Date:
> >>5/22/2005
> >> 
> >>
> >>
> >>
> >>
> >>    
> >>
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