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Hoffman Amps Forum image Author Topic: Using an 8 ohm OT in a 5F1 build Question.  (Read 1976 times)

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Offline xochipelli

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Using an 8 ohm OT in a 5F1 build Question.
« on: February 13, 2024, 05:15:01 am »
I'm building a 5F1 Champ using a Mercury Magnetics 8 ohm Champ OT since all my speaker cabs are 8 ohms.  I'm trying to figure out if there are any changes to the original 5F1 circuit that i need to make being that the original circuit was designed for a 4 ohm output. Any insight would be greatly appreciated.

Offline sluckey

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Re: Using an 8 ohm OT in a 5F1 build Question.
« Reply #1 on: February 13, 2024, 05:41:11 am »
You may want to replace the 22K NFB resistor with a 33K or 47K. This is not really necessary though. So, experiment and let your ears decide which you prefer.

It's popular to use a switch for different resistor values or use a pot for variable NFB.

A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline xochipelli

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Re: Using an 8 ohm OT in a 5F1 build Question.
« Reply #2 on: February 14, 2024, 06:08:21 am »
Thanks Sluckey. I was planning on adding an NFB switch so i'll just play around with different rated resistors.

 


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