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In Reply to: Re: Speaker impeadance changes and OTL's posted by Paul Speltz on May 18, 2003 at 18:58:33:
Sorry it took so long to respond...So it appears to me that your saying that the greatest deviation (gain) in freq. response occurs when 2x the average impeandance (i.e. 4 ohms to 8). Greater deviations result in less "gain" (i.e. 4 ohms to 16, or 4 to 32, ect.). Is this correct? If so what would the gain be from 4 ohms to 6?
My interest is general now (prototype w/in 1-2 years hopefully) for an eff. audio system. Of course this is my "dream" system - but I think I finally have the very basics down on its construction (and I've gone through thousands of permutations on widely varying concepts). The basic premis is this: a line array composed of Bandor or Jordan drivers (16 per speaker) for the upper range and a bass "horn" (front loaded) aprox. between 18 Hz to 100 Hz. The amplification for each section (i.e. 4 amplifiers for stereo - no crossovers) should be as simple as possible and utilize the highest quality parts. In this instance I'm thinking of spud se OTL utilizing the 6c45p (or a derivitive, i.e. 6s45p) and an extremely high quality custom input transformer from Tribute.
Obviously this combination means very little power (target is about 1 1/2 watts) but there is the option (and mandatory for the bass section) of high impeadance speakers (series connection for the line array depending on which driver is chosen could be anywhere from 64 ohms to 256 ohms average). For this of course I want to maximize eff. and linearity if possible with a good crossover trasition around 80 to 90 Hz without utilizing crossovers so its all in that "cocktail-like mixture" of getting everything to work together, for this of course I need to get a handle on what the OTL is doing with freq. response relative to the speakers impeadance.
The bass driver is locted here: http://www.diyparadiso.com/datasheets/speaker/beyma/102nd.pdf
Of course the air load on the driver provided by the horn will shift fs and its impeadance down closer to the cutoff freq. of the horn - but the impeadance response vs. freq. will look similar (though shifted lower). Horn chamber ("snail" shape) will load into free space w/ one boundry (the floor - i.e. 1/4 gain). Visually similar to this (or the lab horn) but w/only the use of one driver per horn:
http://expert.cc.purdue.edu/~sheerin/sub.htmlBandor drivers here:
http://www.bandor.co.uk/products_frame.htm
Jordan drivers here:
http://www.ejjordan.co.uk/drive_frameset2.htm
Either of these drivers will utilize a sealed chamber only with minimal dampening (only the use of silicon borscilate to dampen freq.s above 400 Hz). (As per these manufacturers specs for line arrays.) Visually it will look similar to this:
http://www.audience-av.com/speakers.htm
Thanks again for the responses!
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Follow Ups
- Re: Speaker impeadance changes and OTL's - ScottG 14:44:19 05/30/03 (0)
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