Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fossilshark on May 30, 2023, 10:47:39 pm

Title: Wendigo preamp completed + advice request
Post by: fossilshark on May 30, 2023, 10:47:39 pm
Hi all, with much credit going to you lovely people here on EL34world I finished the "Wendigo" preamp. It is the Ceriatone Chupacabra circuit turned into a rack mount preamp. This thing sounds absolutely killer and the options all the different settings give are endless.

As expected for a high gain preamp this boy is quite noisy at max gain. So I plan on adding a bunch of shielded cable to the controls (and the long yellow wire going to the output), the potentiometer near the transformer is going to be replaced with a fixed resistor, and I will add the resistor divider humdinger circuit to the heater line as previously recommended.

I was just wondering if anyone has any advice for my layout? The blue and black twisted pair is the heater wires and I am worried they are much too close to the output jack, maybe I should use shielded wire for the heaters?

Again I appreciate all who helped me get the circuit made up, and I appreciate any input on what I could change to make this layout better.
Title: Re: Wendigo preamp completed + advice request
Post by: kagliostro on May 31, 2023, 02:12:39 am
OMG  :bump1:

 :bravo1: :bravo1: :bravo1:

 :thumbsup: :thumbsup: :thumbsup:

 :worthy1: :worthy1: :worthy1:

Have you a layout you can share ?

THANKS

Franco




Title: Re: Wendigo preamp completed + advice request
Post by: ShoemanGB on May 31, 2023, 04:42:27 am
Fantastic job! 
Title: Re: Wendigo preamp completed + advice request
Post by: DummyLoad on May 31, 2023, 04:53:02 am
Just a suggestion - See attached.

Respectfully,

--Pete
Title: Re: Wendigo preamp completed + advice request
Post by: fossilshark on May 31, 2023, 06:58:06 am
Fantastic job! 
OMG  :bump1:

 :bravo1: :bravo1: :bravo1:

 :thumbsup: :thumbsup: :thumbsup:

 :worthy1: :worthy1: :worthy1:

Have you a layout you can share ?

THANKS

Franco

Haha thanks guys! I really wanted this one to be perfect. I will post all my documentation with some sound clips after I evict the noise gremlin.

Just a suggestion - See attached.

Respectfully,

--Pete

I was thinking this originally but I guess I was thinking too hard, the negative terminal of the caps should shield them right?

Used some PTO so I can stay home and work on this all day :icon_biggrin: I will implement some tweaks and keep yall updated.
Title: Re: Wendigo preamp completed + advice request
Post by: DummyLoad on May 31, 2023, 08:20:47 am
The negative ends of the caps are at ground potential. Not shielding per-se but not as susceptible to eddy currents produced by heater conductors.


With as much gain as you built, DC heaters would likely have been of benefit to this plan.


Respectfully,



--Pete
Title: Re: Wendigo preamp completed + advice request
Post by: fossilshark on May 31, 2023, 09:31:46 am
Just a suggestion - See attached.

Respectfully,

--Pete

Even without shielding that long output wire this seems to have worked well, thanks dummyload. I threw in the humdinger and switched the janky pot for a fixed resistor and its already leagues better. With the volume on max you can almost hear a 60/120hz but it really is negligible.

I am just chasing a very small amount of static noise from the input section now. Nothing a bit of shielded cable can't take care of I think.
Title: Re: Wendigo preamp completed + advice request
Post by: tdvt on May 31, 2023, 03:50:29 pm
Really beautiful job!
Title: Re: Wendigo preamp completed + advice request
Post by: fossilshark on May 31, 2023, 04:59:27 pm
Really beautiful job!

Thank you! I am not entirely happy with it mostly due to aesthetics but hey gotta know when to put the soldering iron down amiright?