[rollei_list] Re: jerry : refrasede Completely OT- Loudspeaker info a pop up question
- From: "Ruben" <ruben@xxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Wed, 16 Feb 2005 23:28:04 +0100
Thanks Jerry
All the speakers I have are "units" taken out of the cabinetts for one
reason or the other (not by me) all paired as in two 12" bass unit etc. and
two tweeter units but they may not come from the same set of speaker
cabinets - could be tweeters come from JBL model A and midtone speakers from
JBL model B - So it is not like I am going to ruin an exhisting set of
beutifull B&W speakers! It would be like putting my self above the allmighty
and for that there is only nemesis - SO TO GET BACK TO my initial question -
apart from the impedance thing that I need to get straitened out - can any
of you fine gentlemenn recommend a good book on building speakers ??? and
making cross over filters hov to calculate cross over filters ??? etc in
order to make some speakers that are plain nice to listen to and will not
ruin your amplifier ??? I am and will ot turn into a HI-FI use all my money
on gear freak (I spent it on lenses and cameras anyway) but I would like to
have some decent speakers in my own design - I will be trying to use two
older mono tube amplifiers so my listing preference would be more in terms
of soft and with great bokeh and not as crisp as the newest Zeiss lenses :-)
thanks Ruben
----- Original Message -----
From: "Jerry Lehrer" <jerryleh@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, February 16, 2005 10:08 PM
Subject: [rollei_list] Re: Completely OT- Loudspeaker info a pop up question
> Ruben,
>
> Hoo boy!! We gotta go BEFORE Audio 101. Impedance is NOT the
> same as pure resistance, it is frequency dependent. The LAST thing you
> want to do is put a resistor in series with a speaker.
>
> Please don't screw with the Kef or B&W speakers! They are PFG as
> they are. It takes an expert to improve them.
>
> Jerry
>
> Ruben wrote:
>
>> 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
>> >
>
>
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