From: pshoward@ix.netcom.com (Paul Howard )

To: bass@mcfeeley.cc.utexas.edu

Subject: Re: Ribbon smoothing

The following is a quote from Clearview engineering that may explain 
the "smoothing" concerns some have. 

"About Ribbons (Reading this paragraph is optional--may cause minor 
neurosis) Or more specifically, YOUR dipolar ribbon transducer. The 
Carver ribbons all by themselves do not have a suitably flat frequency 
response for high fidelity audio reproduction. The passive equalization 
built into your speakers can and does counteract this problem. There
are several reasons for the ribbons' inherent inability to reproduce 
all frequencies at the same level. The ribbons emit radiation from both 
front and rear, and the rear being out of phase, some of the front 
radiation is cancelled. This effect is most prevalent at low
frequencies where the long wavelengths can find their way around the 
panel. Thus a boost in the drive level to the ribbon near its lower 
cutoff frequency, (which is also near the panel's cutoff frequency} is 
desireable. There are other equally important nasty response
variations caused by the physical dimensions of the ribbon transducer 
which must be dealt with. By now a prudent person must seriously wonder 
whether all the necessary tweaking is worth the effort. A quick listen 
to the wonderful transparent openness and ability of these loudspeakers 
to fool the brain into believing there is a live event in front of it 
will quickly dispel this thought. Try finding another speaker that 
sounds nearly the same whether you are standing or sitting. The reason 
for this characteristic, as well as the accurate imaging you have 
experienced, is the tall thin wave launch, tightly contained in the
vertical dimension, covering a wider frequency range than almost any 
other type of acoustic transducer. IF you can find these 
characteristics in another speaker, try finding it at three
times the price or less. The existence of the aforementioned frequency 
response anomalies is why efficient biamped, direct connection of the 
drivers to the amplifier is not feasable unless sophisticated
equalization circuitry is placed in the signal chain ahead of the 
amplifiers. Clearview Engineering is the only company capable of 
providing this function. The use of the CXR- series crossover you have 
purchased allows higher transient peak sound pressure levels,
lower intermodulation distortion, and the use of smaller power 
amplifiers than needed in normal passive bi-wired (now you can call it 
bi-wierd) mode or singly amplified mode. Another characteristic of this 
system is that the power amplifiers will now "see" a very constant 
impedance over their operating range. The ribbon impedance varies very 
slightly around their 3.6 ohm (48") or 4.6 ohm (60") nominal 
resistance."

Anyone care to cook up an electronic alternative?