I got a couple of HM-3's and these are spec-ed for 1:20 and/or 1:40 ratio having the secondary loaded with 47K.
For 1:20 the primary impedance is 47000/(20*20)= 117,5 Ohm and this is in line with the recommended cart loading of 10x the internal impedance. Up till now all makes sense.
Why would Hashimoto recommend such a wide cartridge internal impedance from 7-40 for the 1:20 ratio?
For 1:20 the primary impedance is 47000/(20*20)= 117,5 Ohm and this is in line with the recommended cart loading of 10x the internal impedance. Up till now all makes sense.
Why would Hashimoto recommend such a wide cartridge internal impedance from 7-40 for the 1:20 ratio?
You have calculated the reflected secondary impedance right . But there is also series primary winding resistance in series to it. The impedence cartridge sees is sum of the reflected and winding impedences.
The actual amplification factor (not 20) is the attenuation created by the volatge division between the total primary impedence and the primary reflected impdence. But the cartridge impedence also attenuates the signal somewhat. 7-40 cartridge impedence may well be the range where attnuation is less noticible.
I dont know if it helps your quaestion
The actual amplification factor (not 20) is the attenuation created by the volatge division between the total primary impedence and the primary reflected impdence. But the cartridge impedence also attenuates the signal somewhat. 7-40 cartridge impedence may well be the range where attnuation is less noticible.
I dont know if it helps your quaestion
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