Newcomb Pathfinder E-20 Guitar Amp Conversion Overview // Gray Bench Electronics

Hello all and welcome back to the bench. Today we'll be reviewing a tube amp conversion based on the Newcomb Pathfinder E-20. Enjoy!
Check out Uncle Doug! ‪@UncleDoug‬
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Business contact: [e-mail]
#newcombpathfinder #guitaramps #tubeamps #tubes #diytubes #electronics

[@saffronforthesoul4552]

Plus 1 for Uncle Doug shout out! Thanks for the knowledge!

[@thenonebadh]

Great Amp. UncleDoug was/is a great inspiration for me too.

[@velvetsound]

Uncle Doug taught me tube amps as well. I’ve made 7 amps now and a tube reverb. I’ve only shocked myself once @ 185V - I’ll never work on amps when tired again.

[@crochambeau]

I dig the drab institutional colors on these amps.

[@CausingLewis]

So Soothing honestly lol

[@rayackerman7872]

Great Video, I too have learned a lot from Uncle Doug, and Mr Carlson.

[@EJ_Crough]

Uncle Doug rules! So far the worst shock I’ve gotten from diy electronics/ repairs came from modding an EHX Wiggler which was one of their tube pedals. Turns out that is a tube pedal that uses a fair amount of voltage lol

[@drew2936]

Found this from your Craigslist ad. That sounds really great! I wish I had the need/extra cash for it. Thank you for the Uncle Doug recommendation. I have an amp project in waiting that I don't have all the knowledge to complete.

[@tomfinn8076]

Same here. I was curious. I'm a big vox amp guy also so this would be right up my alley. Unfortunately i dont have room in my life for another 'Voxy" amp. But sounds great.

[@nickdevriese]

Uncle Doug is the man! Great video.

[@MrCongolia]

Nice to hear some of “Hocus Pocus”👍🏼. Great sounding amp. P.s. Thanks for those Prescription Electronics germaniums. Just finished my Yardbox clone. They worked great.

[@OwenBagel-oj2qy]

Yeah!!! Love this

[@matthewf1979]

Uncle Doug, Mr Carlson’s Lab, Psionic Audio, Yeatzee Guitar….all great channels for electronics/guitar amps/vintage gear. I’d be far more invasive with modifications to the circuit. Power switch, tube changes, pot changes etc etc. It does sound really cool though, so I’d have to test drive the simple version first.

[@sushimandaddi]

Agreed! Uncle Doug is awesome, I’ve been building a good amount of pedals but I always wanted to do something like this finding an old wacky tube amp. Hopefully some day!

[@tomodonnell9882]

What cabinet are you going into?Sounds great!

[@MonosonicJukeJoint]

curious if you have any interest in converting another Newcomb pathfinder E20 to a guitar amp? i recently found this collecting dust in a shop locally and took it home

[@tomirwinbernier-ll2hm]

Cool amp, Uncle Doug Rules.. Just a couple things I noticed from looking at the schematic, did you remove the caps going into the grids and add grid stopper resistors as it doesn’t have any on the schematic? 34-68k is typical. Also, the plate resistors are pretty high and the plate voltage is a little low.. 100k is normal. You may have done so without mentioning but I don’t know. Nice job though, and still sounds great as is.

[@graybenchelec]

The caps going into V1 are necessary for the grid leak bias to work, so those had to stay. I did not add grid resistors though, no. I generally try to keep vintage amps close to original, same answer for the plate resistors.

[@tomirwinbernier-ll2hm]

@@graybenchelec Very cool, I had to look again as I didn’t even realize. The Cathode goes straight to ground. On a side note, I have quite the vintage tube collection (I’m sure you do too), and never noticed a difference between rectifier’s labeled 5Y3 or 5Y3GT, however the 6087 or 5Y3WGTB is very neat as it has an indirectly heated cathode like the 5AR4/GZ34. Try one if you haven’t yet. And thanks for the biasing info!