Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jjschessmaster on December 14, 2024, 07:46:54 pm

Title: Parallel Preamp Design Help
Post by: jjschessmaster on December 14, 2024, 07:46:54 pm
Hey all!  I have a question that might seem silly to anyone who has ever designed an amp.  I've built a bunch of kits, followed some scratch built layouts, and have made benign mods (bright switches, depth mods, etc) but have not done much more than that.

I'm looking at building a tube town ac18 (just want to try out an ef86 ultimately).  The kit is based on an 18 watt chassis so it has a spare preamp spot and a few inputs and controls open.  I figured it would be relatively easy to toss in a parallel triode like the spitfire as a channel 2.  I would like to run it parallel with individual inputs.

Where would I tie the signal path in?  I've copied the link to the ac18 schematic and spitfire.  I think I disconnect the ground off the phase inverter c9 and plug in there?  Do I need to change c9 to 10nf?

Appreciate any help as I get my feet wet into more significant mods.

https://media.tubetown.net/cms/?DIY/18Plus/TT_AC18_-engl- (https://media.tubetown.net/cms/?DIY/18Plus/TT_AC18_-engl-)

https://media.tubetown.net/cms/?DIY/18Plus/TT_Spit_F (https://media.tubetown.net/cms/?DIY/18Plus/TT_Spit_F).

Edit; tried to fix Spit F. link, failed.  :dontknow:
Title: Re: Parallel Preamp Design Help
Post by: SEL49 on December 14, 2024, 08:04:30 pm
This may give you some ideas...

https://sluckeyamps.com/dual_lite/dual_lite.htm