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Output Transformer Resistor

Posted: Thu Nov 10, 2022 2:34 pm
by dchapis
I've been gifted with an amp out of a Silvertone console record player. The question I have is about the output transformers and speaker. Is the 220 Ohm resistor across the right speaker terminal there so that the transformer has a load when a speaker is not attached? The impedance on the secondary is listed as 6-8 Ohms and I have a pair of 8 Ohm that I plan to use. Would I want to remove the 220 Ohm resistor since I don't plan to use the amp with just one speaker.
Sears Amp Schematic.jpg
Sears Amp Schematic.jpg (164.17 KiB) Viewed 58 times

Re: Output Transformer Resistor

Posted: Fri Nov 11, 2022 12:45 pm
by rdabbs
Yes. The resistor is there so that there is a constant load on the right channel. From the schematic it appears that the built-in speakers are only connected to the left channel. I, personally, would leave the resistor in place. If you were to connect an 8 ohm speaker to the right channel with the resistor in place, the total impedance seen would be ~7.7 ohms. However, if you are going to ALWAYS have the speaker attached to the right channel, it would be fine to remove the resistor. Hope that helps....

Re: Output Transformer Resistor

Posted: Fri Nov 11, 2022 8:51 pm
by dchapis
Thanks so much. It helps immensely.