[rollei_list] Re: Completely OT- Loudspeaker info a pop up question

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Wed, 16 Feb 2005 17:04:40 -0800

----- Original Message ----- 
From: "Ruben" <ruben@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, February 16, 2005 4:16 AM
Subject: [rollei_list] Re: Completely OT- Loudspeaker info a 
pop up question

>I see that you are talking loudspeakers and I have a couple 
>of questions
> 1. On an amplifier it is often statet to use only 8 ohm 
> speakers - I I have
> a speaker unit and it mesures 8 ohm when an Ohm meter is 
> attached to the + -
> I guess it is ok - but what if there are more thant one 
> speaker ?  or my
> speaker set is only 4 Ohm - can you just put a resitant 4 
> ohm on the wire
> and everything is cool ???
> 2. I have several boxes with speaker units, from jbl, 
> cervin vega, pearless,
> b&o, kef and b&w - I would like to built new cabinets and 
> could use a guide
> to both "spliting filters" - cabinet acoustics etc. Can 
> you recommend books
> on do it your self high end speakers ??
> thanks and sorry for jumping into your thread
> Ruben

   The impedance of a loudspeaker is not its DC resistance 
and can not be measured with an ohm meter.
   Some of the drivers you have were intended to be used in 
specific systems. Its possible to use them in a home built 
box but for an optimum box you have to make a lot of 
measurements on them. Small low frequency speakers such as 
those used by KEF, B&O, and B&W are intended to be used in 
rather small boxes of the sort I mentioned earlier where the 
box stiffness becomes part of the restoring force of the 
speaker. Cerwin-Vega built mainly high power speakers for 
sound re-inforcement or musical instrument use. JBL has made 
an enormous number of models over the years some of which 
are specific to JBL systems and some of which are general 
purpose speakers. I am not familiar with Pearless.
   I am enough out of touch with audio that I don't know of 
a book currently in print that covers crossover networks but 
most of the older books on audio did. Simple networks work 
fine. I may be able to give you specific help off list.

Richard Knoppow
Los Angeles, CA, USA

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