jlossint

My experience is that Vb is sensitive and actually detrimental to a good bass response. Try an arbitrary horn design in "Hornresp" simulation program and you can easily see what impact Vb has on the bass response and how. A Vb of 64 liters for a 50 Hz horn seems to me to be grossly over sized, 30-40 liters seems more correct. Actually, if I recall correctly, PWK stated that the khorn should have a Vb of about 37 liters. The throat area is of great importance in the upper end of the frequency response of the horn together with a rapid horn expansion in the beginning of the horns first 10-12 inches. //Peter

Thank you for your reply. It was called and is still known as the "70/80 horn". 70/80 are the front dimensions in centimeters. It is a multiflare design that shall work down to about 65- 70 Hz. The driver was a 12" german design that is no longer available. The back-chamber was designed to work with this driver and is much too large when using drivers manufactured today. Peter Akemark

The horn in your picture is not an EV design. It was published in Sweden 1975 in a paper called Radio & Television. The design was originally done by me. The picture shows a hungarian replica.

Thank you all for your contributions to my question. Using steep filter certainly will solve some problems, but the delay will still be there between the bass, midrange and tweeter and this will produce unwanted lobing effects to the sound. I know this because I have done experiments with it. In a two-way horn system, very much like a Belle Klipsch. The bass unit was working up to about 800 Hz and from there it used a Pioneer horn, the PD/PH-50, which worked from 800 to about 20 kHz. There was a clear difference when moving the Pioneer horn backwards, compensating for the different path lengths. In the usual setup, like a Belle K, and using pink noise as sound. The sound image from one loudspeaker was like coming from to distinct sources, the lower part and the upper part. Moving the Pioneer horn backwards the sound suddenly appered like one source, impossible to say that itcame from as specific part of the loudspeaker. The effect it had on the sound can most easily be described as reduced "harshness" to the music. Also the stereo image was much improved. This harshness is also described as "horn sound". I should also add that the x-over was the most simple, a first order, but it should be possible with any higher order Riley-Linkwitz x-over networks. My question still remains, is there any experiments with lattice-networks or similar to compensate for the timing difference ?

Is there any time-delay circuit delaying the signal from the K-77 relative to the signals from the K-55/K-400 horn. Also is there any delay circuitry introduced compensating the signals between the K-55/K-400 horn and the bass horn. It is likely to affect any lobing and therefore the image. Any information about this topic?

Yes, your right you will be measuring the back emf voltage, generated by the magnetic field and the voice-coil moving through it. But, since the driver is mounted in the closed back-chamber of the horn, this back emf voltage will show, by its mere existance, any leaking of air. There will always be some and it will most likly be air leaking through the center spider and via the voice coil as well as through the cone material. Sorry, if I were unclear in my description. Best regards

It was stated by PWK that the back chamber should be air tight. This "tightness" should have a time constant of several seconds. If I remember right the procedure for checking this 1/ open a hole into the back chamber. 2/ Next apply a dc voltage to the driver, which will offset the cone ( i.e move it). 3/ Close the hole in 1/ 4/ Remove the dc voltage and instantly measure the dc voltage over the voice coil and measure the time it takes before the voltage is zero. (There will be voltage since the cone/voice coil is now moving towrd its resting position. Take my word, if the chamber/box is properly air tight makes a difference and this is actually valid for any type of loudspeaker.

My hat off for you, magnificent work. I hope they will bring joy for many years. Would like to know what they sounds like when the time comes.

I am refering to the picture at http://www.onthenod.com/LaBelle.gif. I did not mean the nice Acad drawings done by Rob. Sorry if I stirred up some feelings about this. By the way, what driver is intende to be used in your design Rob (formica)? And since you have Acad drawings, what is the volume of the "dog-house", I'm thinking of putting the numbers into a horn simulation program!

Well Marvel, My intentions were only to clarify where that particular drawing is comming from. Wether it is used or not is not the question. That model uses a 12" driver and not a 15" like the "Belle" does. So the difference is obvius. Also there are errors in the given dimensions in that particular picture.

Hi there, Just saw the drawings you have. These are not any "Belle" copies. They are a design I did in 1974 called 70/80-horn. It was published in a swedish paper at that time. Swedish, since I am a native Swede living in Stockholm at the time. The drawings are actually unautorized copies done by a danish guy. I have done this horn and a few other, all published. Peter Akemark

Thank you for your answer. No it was not from Bolt, Beranek. I remember that Paul W Klipsch stated some minimal dimensions for a room where two corner horns were used. Not the ratios of the sides. This is what I am asking. Peter Akemark

Didn't Paul W Klipsch write a paper on room dimensions. According to my memory it should have been some 40 years ago. What did he state in this paper, some minimal dimensions, or what?