5e3

[Rockranger]

https://el34world.com/Hoffman/files/Hoffman_5E3.pdf
Looking to add a nfb switch to the Hoffman 5e3, if anyone has any info on this it would be appreciated. Thanks

[shooter]

there's no nfb for a switch to be added to.
surf up more fender schemo's to find how they did use nfb.
fwiw, the schematic attached has NOT been built/tested, but was stolen um borrowed from the other attached schematic

[DummyLoad]

see items circled in RED - you need to fiddle with the value of the 1500Ω NFB resistor as shown: it can be anywhere from 820Ω to 5KΩ or more - i chose 1500Ω because it made the paint chop up easier, but is also a good value to start with.   

IF you add NFB loop you may need to swap the OT primary leads if the amp squeals on initial power-up. after wiring in, use SW to check - e.g. power up with SW open - if it squeals when SW is closed, then swap OT primary leads.   



--pete

[isaac_teller]

https://robrobinette.com/5e3_Modifications.htm#Switched_Negative_Feedback

[2deaf]

I like Dummyload's version better than Robrob's because Dummyload's has about twice the open-loop gain.  If the unbypassed gain stage has 6dB less gain than the bypassed gain stage and the closed-loop gain is -6dB in both cases, then Dummyload's version takes a 6dB hit with NFB and Robrob's takes a 12dB hit. 

[PRR]

> Dummyload's version better than Robrob's

Rob's linearizes the 12AX7. This stage dominates the 2nd harmonic of the otherwise push-pull amp.

Different, not better/worse.

[2deaf]

> Dummyload's version better than Robrob's

Rob's linearizes the 12AX7. This stage dominates the 2nd harmonic of the otherwise push-pull amp.

Different, not better/worse.

Allow me to re-phrase my statement to make it a bit more difficult to quote out of context.  "I, and I alone, would prefer to use Dummyload's version rather than Robrob's . . . "

[sluckey]

Allow me to re-phrase my statement to make it a bit more difficult to quote out of context.  "I, and I alone, would prefer to use Dummyload's version rather than Robrob's . . . "

I know who "I" is. But who is "I alone"?   

[shooter]

But who is "I alone"?

think it's lyric from a '90s grunge band; "I alone love you I alone......"   

[2deaf]

think it's lyric from a '90s grunge band; "I alone love you I alone......"

You got it.  I learnt English from a car radio.

[shooter]

 

Yup, NO spelling tests !!!