Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on January 19, 2013, 07:34:03 am

Title: Mosfet CF vibrato?
Post by: tubenit on January 19, 2013, 07:34:03 am

I am not knowledgable enough to know if one could use a mosfet for the CF in a 6G16 type vibrato?

Would this work using 5881 power tubes.

With respect, Tubenit

The schem & layout are here:

http://www.el34world.com/Forum/index.php?topic=13615.0 (http://www.el34world.com/Forum/index.php?topic=13615.0)

Title: Re: Mosfet CF vibrato?
Post by: sluckey on January 19, 2013, 09:38:03 am

That should work just as well as the other mosfet followers you have used. I don't think the power tubes will be an issue.

Title: Re: Mosfet CF vibrato?
Post by: Willabe on January 19, 2013, 09:43:18 am

IIRC, Tubeswell has done that in a few builds before and has posted a schemo for it here.

Said it worked well and that he liked the sound of it.


                  Brad      :icon_biggrin:    

 

Title: Re: Mosfet CF vibrato?
Post by: sluckey on January 19, 2013, 09:52:59 am

That's right. It was Tubeswell. Here's his schematic...
http://www.el34world.com/Forum/index.php?action=dlattach;topic=13211.0;attach=28400 (http://www.el34world.com/Forum/index.php?action=dlattach;topic=13211.0;attach=28400)

Title: Re: Mosfet CF vibrato?
Post by: tubenit on January 19, 2013, 10:44:31 am

Gentleman,

THANKS for taking the time to respond!  I appreciate the help and info.

Not sure how I missed Tubeswell's PR schematic?  I typically read anything he posts and he's come up with some great ideas that are somewhat innovative.  That's a cool schematic.  My guess is he ran into the same issue that I did & was also wanting to avoid having to set up another 12A_7 tube.

With respect, Tubenit

Title: Re: Mosfet CF vibrato?
Post by: Willabe on January 19, 2013, 01:39:12 pm

Quote from: tubenit on January 19, 2013, 10:44:31 am

he's come up with some great ideas that are somewhat innovative.  That's a cool schematic.  

Yep. He's a sharp one alright. I'd love to have the chance to hang out with him and some of his NZ buddies. He's a darn good guitar picker too.    :icon_biggrin:

I was blessed to have had the chance to spend 1 week in NZ and I'll tell you it is an absolutly beautiful country and the people are the best!
  

Quote from: tubenit on January 19, 2013, 10:44:31 am

My guess is he ran into the same issue that I did & was also wanting to avoid having to set up another 12A_7 tube.

Yep, I think that was it. He'll be around soon.


              Brad     :icon_biggrin:

Title: Re: Mosfet CF vibrato?
Post by: tubeswell on January 19, 2013, 02:33:21 pm

Sorry I missed this thread when you first posted Jeff. I've used the IRF820 as a source follower with several bias-vary trem circuits and they work great. I put 100-200R in series with the gate and a 12V zener from source to gate, but other than that, its just a straight sub for a triode (but without heater-cathode problems), and off course there is no impact on tube tone. Pete

Title: Re: Mosfet CF vibrato?
Post by: tubenit on January 19, 2013, 03:44:01 pm

Tubeswell,

Thanks, man!   I appreciate your info/help and innovative approaches.  And I love seeing your work and hearing the soundclips!

With respect, Tubenit