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Magnavox 142 - rebuild/modification thread

GordonW said:
I measured one of those transformers with a signal generator. Looks like the aux tap was about a 2 ohm tap. Would make sense... that would make the aux speaker a little less loud than the main. Or, if you wanted to wire BOTH the main and aux speaker to one tap... it would work.

Regards,
Gordon.
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I know this is an old thread but currently I am trying to sort out how I can use these two taps for running the speakers in my signature. If the output transformer has two taps than can I use the 2 ohm section for a pair of 15" Magnavox woofers and the 4 ohm section for the treble horns? Does the speaker selector switch on this amp do 4 ohm and 2 ohm simultaneously or does it see the 2ohms by paralleling the internal and external speakers? The woofers are 4 ohms but I run them to a subwoofer that highpasses them at 80hz. The rp 109horns are 12 or 16 ohms and the foster is 8 ohms. I guess I don't understand the way the speaker selector switch is using the amp and if I would be overtaxing it. Thanks for any help!
 
If you use the 2 ohm tap for the woofers, and the 4 ohm tap for the horn, it will increase the gain of the horn, relative to what it would be if you just paralleled the horn (and crossover) with the woofers.

If the horn is too loud when hooked up to the 4 ohm tap- then move it to the 2 ohm tap along with the woofers.

Regards,
Gordon.
 
Jumping in here at the end just so as to 'join' the thread and keep in my active file. GREAT info!!!

Tom D.
 
Scuzzer said:
Battradio had an interesting point about the phase shifts in the splitter in this post: http://www.audiokarma.org/forums/showpost.php?p=4186690&postcount=342. Perhaps even 0.22 caps are too high.

I made a note to check this out the next time I mess with mine but I haven't had a chance to play with it lately.
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Simple solution. Use a large enough coupling cap so that there is no low frequency phase shift. The phase shift won't be there hence it cannot cause problems.
 
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