tone control - Printable Version
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tone control - ipwizard - 10-19-2011
I'm rebuilding the tone control of my 71 (p/n 4757) and I notice that it has a.02 cap in it. Would it be ok to use a .033 cap? It's the closest thing I have in stock.
Re: tone control - codefox1 - 10-20-2011
OK. Nobody will ever know.
Re: tone control - Ron Ramirez - 10-20-2011
Actually, you can probably get by with it...but be prepared for all bass and no highs at all. The sound may be rather muddy with a .033. An .022 would be a better choice, really.
Re: tone control - ipwizard - 10-20-2011
Ok Ron, Ill heed your warning and come up with a .02 cap for the tone control.
Off Topic a bit:
I read somewhere where you changed the tone curcuit of your 71 making it sound much better. Do you have instructions for this? Is it an easy thing to do without having to rewire a bunch of stuff?
Re: tone control - Ron Ramirez - 10-20-2011
It is easy, but it will modify your radio so that it no longer has the original volume and tone circuitry.
You will need a 1 or 2 meg. volume control, and it must have a bass compensation tap. One pulled from a 41-280 will work quite nicely. You will also need the tone control potentiometer from the same 41-280 or similar.
You will remove the old two-position tone switch and replace it with the 6 megohm tone control potentiometer. The original volume control gets replaced by the 41-280 volume control.
Connect a 68K resistor from the volume control tap to the low end of the tone control potentiometer, and a .0047 uF cap from the low end of the tone control potentiometer to ground.
Connect the center (wiper arm) terminal of the tone control potentiometer to ground.
Now connect a .0068 uF cap from the high side of the tone control potentiometer to the plate of the "det. amplifier" tube, a 44.
You can see the actual circuitry by looking at a 41-280 schematic, although the values of the added resistor and two caps are different from those shown in the 41-280 schematic.
This hot-rod circuit will make your 71 sound like a big console radio - but, as I said, it isn't original!
I did this to my "Super" 71 because it was a rust bucket to begin with, a chassis that some people might have just tossed out.
http://www.philcoradio.com/notebook/super71.htm
I would not do this to a good chassis, but that's just the way I am. I prefer to keep the good stuff original; but I am not opposed to experimenting on junk sets.
Re: tone control - ipwizard - 10-20-2011
Thanks Ron. Yeah I'm like you I like to keep things a original as possible. I wasn't sure how much had to be changed. If I end up having to switch out the OSC curcuit ill probably do the tone "upgrade" also but I hope I dont have to do that.