Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

tone control
#1

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.

-Keith
#2

OK. Nobody will ever know.
#3

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.

--
Ron Ramirez
Ferdinand IN
#4

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?

-Keith
#5

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.

--
Ron Ramirez
Ferdinand IN
#6

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.

-Keith




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
HiFi (Chifi) tube amp build - but my own design.
It's the other forum. I'm also in DIY, but mostly read there. Honestly, I kinda jumped into this without much thought to...TV MAN — 10:43 AM
Philco 71 Code 125
Hello,  I am in need of a schematic for this radio. Mine has the three separate circular tube shields and a shadow me...dconant — 08:06 AM
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM

[-]
Who's Online
There are currently 4539 online users. [Complete List]
» 1 Member(s) | 4538 Guest(s)
Avatar

>