Vol control with tap - Printable Version

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+--- Thread: Vol control with tap (/showthread.php?tid=21793)

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Vol control with tap - Eric - 11-07-2020

Hello All.
I have a Firestone Model R-1661,
http://www.nostalgiaair.org/pagesbymodel/273/M0006273.pdf

The radio plays after restoration with the exception of the volume control ( #41A 250k ohm) which has some bad spots in it and I would like to replace it but the control has a Tap. Also the value of the pot is 500k so someone must have replaced it at one time.
Can I omit the tap?
Is there anyway to know the value of the tap or is it standard?
Is there a workaround I have a 250k pot I can use but it does not have a tap. 

Thanks Eric

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RE: Vol control with tap - OZ4 - 11-07-2020

Eric
The tap on the vol pot is for slight equalization of the audio at low volume.  It rolls off the high frequencies a little at low volume.

On the old stereo receivers it could be switch in or out. It was called "loudness contour". 

Using a volume pot without it if you don't like the sound you could add a cap of similar value at the high side  and change it's value to suit your tastes. You may not even notice any difference unless you are listening for it.

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RE: Vol control with tap - radiorich - 11-08-2020

Hello Eric,
I would Give Mark at https://www.oldradioparts.net/
He repairs controls he has lots of them .

Sincerely rich

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RE: Vol control with tap - David - 11-08-2020

My late father in laws Zenith with a tap on the volume control that had been replaced in the past. After a recap and a few resistors replaced the radio played fine. The repair shop placed10 turns of wire from what would be the the tap feed around the in coming signal to the control. The repair was made in the time frame of 1968-1975.

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RE: Vol control with tap - Eric - 11-08-2020

So I played around with it and put in a 250k pot I had and left the tap lead off and it played fine but I also needed a switch for power so I looked in my box of stuff and came up 500k w/switch and put that in just to see what would happen and it actually played better than with the 250k pot.

 I have bought from Mark Oppat before but I also don't know the value of the tap. Is standard value?

Thanks 
Eric

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RE: Vol control with tap - radiorich - 11-08-2020

Hello eric,
Sure thing .

Sincerely Rich

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