JWN “Colorado Special”

[Jenkster]

This unique amp is from a friend’s collection, thought I would share.

He had this amp built in 2012 after reading an article that extolled the quality and sound of this amp built by Jim Nicholls. My friend said it was a marathon, not a sprint, getting it built. It did arrive safely but he said Jim’s packing skills were seriously lacking. The kicker, my friend said he never tried it even though he spent nearly $2K for it? This, however, was not uncommon for him not to test the gear he bought.

Tubes are a quad of 6BG6’s, three 6SN7’s and dual 5U4 rectifiers. The extra toggle on top is a standby switch. Supposedly there was an extra hole on the top so that’s what he used to fill it.

It is a nice looking build and I assume the transformers are Magnavox? I will have a friend test all the tubes and bring it up on his Variac.

Anyone have experience with Jim Nicholl’s amplifiers? Just curious if his reputation is justified? Thanks

 

[Jenkster]

I did read some reading of old threads today. Sounds like a mixed bag of opinions and issues with Mr. Nichols a few years ago. Those grid caps would be a concern for me. Would have to be used in the Man Room, always under watch, especially when the grandkids are here. I’ll bet when working properly it will sound damn good.

 

[GordonW]

Those don't look like Magnavox output transformers- unless someone has taken off the bottom end bell. Magnavox 330024 output transformers (the ones that would be about that size, and that would work with 6L6s) always came with end bells on both sides of the lamination stack.

They look like they possibly might be Sherwood transformers, from what I can see. Many Sherwoods came without the bottom bell...

Regards,
Gordon.

 

[Jenkster]

Hey Gordon,
My friend, who knows his way around tube gear, thought the same. Since that’s the opinion of both of you, I’m going with it. I know the owner would have no idea what they are, nor would I. Any clue if it would be possible to switch the power tubes for a 6L6 or variant without too much modification?

 

[opnly bafld]

I had this JWN Baldwin 6L6 amp; thought it was pretty good.

 

[Jenkster]

It does look kind of familiar. I assume you sold it? If so and, if you don’t mind me asking, why?

 

[knockbill]

9405803699300704432329
. Any clue if it would be possible to switch the power tubes for a 6L6 or variant without too much modification?

6BG6 is one of my favorite output tubes,,, dirt cheap and available!! They are actually the same specs as 6L6s, not GC,,, and have a different pin out,, and plate cap... You can rewire the amp to use 6L6s, but should sound the same...
nice amp,, enjoy it!
Here's an SE version I built...

 

[Jenkster]

Thanks for the information knockbill, I appreciate it. Awesome looking amp BTW!

 

[opnly bafld]

It does look kind of familiar. I assume you sold it? If so and, if you don’t mind me asking, why?

I think I gave it to a friend (told him he could have it; not sure if he is keeping it).
Reason? Not listening to music much anymore and have sold or gave away almost everything.

 

[Jenkster]

I wish I was your friend!