Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on August 31, 2025, 05:16:27 am

Title: What is this, a local NFB ??
Post by: kagliostro on August 31, 2025, 05:16:27 am

There is a part on this schematic that I'm not sure to understand correctly

What is the Blue Jumper on the top of the schematic ? Is it a local NFB ?

Thanks

Franco

p.s.: whole schematic here

https://el34world.com/Forum/index.php?topic=32959.0 (http://)

https://el34world.com/Forum/index.php?topic=32959.0 (https://el34world.com/Forum/index.php?topic=32959.0)

Title: Re: What Is this, a local NFB ??
Post by: Merlin on August 31, 2025, 06:11:34 am

Technically it is posisitive feedback. But it looks like V1B used to be a reverb driver, and someone has converted it into a signal path for more gain.

Title: Re: What is this, a local NFB ??
Post by: kagliostro on August 31, 2025, 08:00:18 am

Many thanks

Yes, the owner of the amp asked to the builder to mod it (unfortunately without a great success, on the thread I linked there are detailed info about)

Franco

Title: Re: What Is this, a local NFB ??
Post by: Merlin on August 31, 2025, 08:30:19 am

Link doesn't work for me :dontknow:

Title: Re: What Is this, a local NFB ??
Post by: kagliostro on August 31, 2025, 10:40:26 am

I apologize

may be something that has to do with the phone SO or I did something wrong

try this link https://el34world.com/Forum/index.php?topic=32959.0 (https://el34world.com/Forum/index.php?topic=32959.0)

The title of the thread (on this forum) is: 4x 6v6 Donor amp head - Any conversion suggestions


Franco