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Bonzo

SOLD! JWN (Jim Nicholls) Tube Power Amplifier

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I have a classic, almost cult like, tube amplifier built by Jim Nicholls. My friend had this built in, at least it was completed, in July, 2014. After paying over $1800 for it, he never used it. You would have to know my friend to understand. I had a technician friend of mine bring it up an his Variac, slowly, and check the voltages. It came up just fine and everything works as it should. I have played it for about an hour through my test speakers and it sounds great. I’m going to try it with the Forte’ II’s later. Power tubes are GE black plate 6BG6’s with exposed grid, basically a 6L6. Driver and phase inverters are the plentiful and cheap 6SN7. It uses two 5U4 GB rectifiers, hence the large power transformer. This is basically a highly modified Magnavox pull. I do have some correspondence paperwork between Jim and my friend Richard I will include. It gives some unique insight on the building process including the installation of a stand-by switch. Even though it was built over four years ago, it ie essentially new. It probably needs a bit of breaking in I would think. One nice feature is he installed a detachable power cord. I would like $750 for it plus shipping via FedEx ground. I will try to post some pictures, thanks!

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Here’s another, I will post more later, thanks!

122F62B7-EC00-447C-B15D-2A9A674CF4A3.jpeg

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It’s called a “Beam-Pentode” that was originally used in TV Horizontal applications. 

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Really cool amplifier.  I dig that Beam Pentode doo hickey.

 

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I haven’t spent a lot of time with it but it is very revealing. When I hooked it up to the Forte II’s I noticed some blow type noise through the left speaker. After swapping some tubes and other troubleshooting, I found the balance control on my Sansui integrated, using it as a pre-amp, needs a bit of cleaning. I will hopefully get to cleaning it later. 

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Finished the Deoxit gig on the Sansui and it helped. I’m still getting some unwanted noise however. I’m going to hold off selling it for awhile until I get a fresh batch of tubes in it. A friend of mine has a “bazillion” tubes and I’m sure I can talk him out of some. 

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It’s still too noisy for my liking. I’m going to have a technician I know check it out before I go further with it. 

 

Sorry I posted this before checking it out more thoroughly. 

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Swapped in a strong trio of 6SN7’s and swapped pre-amps and she’s working and sounding great. Looks like the main issues were the pre-amp and the 6SN7 in the center which is the front end. The amp itself is fine. As far as I can tell, it’s good to go. Thanks!

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