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#1
Posted to rec.audio.tubes
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Goodmans Audiom 80 bass speaker and crossover.
Anyone know what the LC values are for the crossover point at 750Hz
for this ancient speaker? TIA, Patrick Turner. |
#2
Posted to rec.audio.tubes
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Goodmans Audiom 80 bass speaker and crossover.
There were two models of this 15" speaker Patrick a 40 or 60 cps
John "Patrick Turner" wrote in message ... Anyone know what the LC values are for the crossover point at 750Hz for this ancient speaker? TIA, Patrick Turner. |
#3
Posted to rec.audio.tubes
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Goodmans Audiom 80 bass speaker and crossover.
Patrick Turner wrote: Anyone know what the LC values are for the crossover point at 750Hz for this ancient speaker? What kind of crossover do you have in mind ? Graham |
#4
Posted to rec.audio.tubes
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Goodmans Audiom 80 bass speaker and crossover.
http://homepages.ihug.co.nz/~allofus/tanex/80.jpg
Some info you you Patrick "Patrick Turner" wrote in message ... Anyone know what the LC values are for the crossover point at 750Hz for this ancient speaker? TIA, Patrick Turner. |
#5
Posted to rec.audio.tubes
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Goodmans Audiom 80 bass speaker and crossover.
Eeyore wrote: Patrick Turner wrote: Anyone know what the LC values are for the crossover point at 750Hz for this ancient speaker? What kind of crossover do you have in mind ? Graham The client of mine who is purchasing two 12" modern speakers in a single box to replace his original Goodmans 15" already has the crossover which he said had a bass Xover point at 750Hz. But he sent me the Goodmans booklet from about 1955 which suggests a Xover point at 950Hz, and second order, designed for 15ohms. Unfortunately the IDIOTS at Goodmans failed dismally to provide accurate information about their products in the information booklet which contains descriptions but without details of actual sensitivity, response contours, impedance plots, and crossover circuitry and whether there was any attempt to equalise impedance with say 33uF and 15 ohms strapped across the drive to make sure the terminal load R seen by the LC filter would be correctly damped without causing ill effect because of series resonance shunting without proper R load. I have measured the response of the two Peerless drivers in a large box I designed and found it to be as planned below 300Hz and flatter than the Peerless data suggests above 300Hz but with a 6dB hump at 2kHz with rapid roll off after than, indicating pretty typical modern large woofer response. This peak should be tamed with the existing LC filter supplied by Goodmans in 1955, which should have L = 3.6 mH and C = 7.9uF. Fo would be 944Hz and the 15ohms + 33uF does equalise the Peerless in series OK. My non technical client has not a clue what is actually inside the Goodmans Xover box. If I supply the speaker terminated with 33uF + 15 ohms the resulting 15 ohms Z with a dip to 13.6 ohms at 132 Hz should suit the existing X-over and give about the right response, and one which will produce more low bass than the original Goodmans, although he may have to use more amplifier power because the Peerless will have less sensitivity than the Goodmans. Patrick Turner. |
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