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 ----- Original Message ----- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx> To: <rollei_list@xxxxxxxxxxxxx> Sent: Wednesday, February 16, 2005 12:30 PM Subject: [rollei_list] Re: Completely OT- Loudspeaker info > > > -----Original Message----- > From: "A. Lal" <alal@xxxxxxxxxxxxx> > Sent: Feb 15, 2005 10:18 PM > To: rollei_list@xxxxxxxxxxxxx > Subject: [rollei_list] Re: Completely OT- Loudspeaker info > > > Jerry, a bare ribbon would in fact behave like a dipole. However, in > many designs material is put on othe back side to try to damp out > resonances. > > There have been ribbon speakers that used an impedance tube at the back > of the ribbon similar to the method used by RCA for directional > microphones. For a ribbon speaker an absorptive box probably would do. The > path length around the ribbon structure is what controlls the minimum > frequency it can radiate with any efficiency. This is different from > damping of resonances. What is needed if both sides of the speaker are to > be open to the air is a large enough baffle so that the path around it is > longer than a half wave at the minimum frequency of interest. > It seems to me that what the "dipole" speaker people are doing is an old > trick of exciting the reverberant field with the back radiation. > > > > -- > Richard Knoppow > dickburk@xxxxxxxxxxxxx > Los Angeles, CA, USA >