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Make switching between 12AX7 / ECC83 and 6N2P easy

thorpej

thorpej

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Hey folks... I wanted a way to make it super easy to switch between 12AX7s and 6N2Ps without having to rewire the socket, so I whipped up this little helper board that sits in between the 6.3Vac heater winding and the sockets. It uses one of those little slide switches that are used to select 120V-240V input voltages for appliances and the like. The board measures roughly 1.25" by 2.25", so it's easy to tuck away into the corner of your project.

You can get all of the design files, including Gerbers all ready to send off to your favorite PCB fabrication house, here:

https://github.com/thorpej/Electronics/tree/master/Tube_Audio/Helper_Circuits/9A_9AJ_Heater_Helper

Enjoy!
 

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The inevitable question - how do they compare sonically to their 12AX7 counterpoint? I read on Wiki that Sovtek modeled the 12AX7WA after the 6N2P of which I have a few examples.
 
I like the 6N2P and use them a lot (I have a fairly large stash of them). I'm not a big fan of using phrases like "compare sonically". I'll just note that in my experience, from a characteristics perspective, they are indistinguishable from 12AX7s, and that I've not had any issues with noise or reliability.
 
thorpej said:
I'm not a big fan of using phrases like "compare sonically"
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Pretty open-ended question, I know, but that was the sort of useful answer I was looking for. :thumbsup:
Edit: Not being facetious either...I meant the latter part of your reply. Thanks.
 
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thorpej said:
I like the 6N2P and use them a lot (I have a fairly large stash of them). I'm not a big fan of using phrases like "compare sonically". I'll just note that in my experience, from a characteristics perspective, they are indistinguishable from 12AX7s, and that I've not had any issues with noise or reliability.
Click to expand...
My son uses 6N2P's in one of his amps. They have taken some punishment and he hasn't lost one yet. I have a bag of Chinese 6N2's that are really micrphonic. There in a box marked "targets". Great for dialing in the scope on my .22.
 
Lavane said:
My son uses 6N2P's in one of his amps. They have taken some punishment and he hasn't lost one yet. I have a bag of Chinese 6N2's that are really micrphonic. There in a box marked "targets". Great for dialing in the scope on my .22.
Click to expand...

I've never used the Chinese 6N2, and have managed to avoid Chinese tubes in general (with the exception of the occasional rectifier -- I have a couple of TAD 5AR4s in-use that I've been happy with, and It *think* those are made in China, but I'm not 100% sure).

The Russian 6N2P is indeed pretty tough and do work well when vibration will be present (essentially any instrument amplifier application), especially if you can get your hands on the -EV version which is built like a tank -- perfect for a gigging amp.
 
thorpej said:
I've never used the Chinese 6N2, and have managed to avoid Chinese tubes in general (with the exception of the occasional rectifier -- I have a couple of TAD 5AR4s in-use that I've been happy with, and It *think* those are made in China, but I'm not 100% sure).

The Russian 6N2P is indeed pretty tough and do work well when vibration will be present (essentially any instrument amplifier application), especially if you can get your hands on the -EV version which is built like a tank -- perfect for a gigging amp.
Click to expand...
I've heard the chinese 5ar4 are quite good.
 
thorpej said:
I've never used the Chinese 6N2, and have managed to avoid Chinese tubes in general (with the exception of the occasional rectifier -- I have a couple of TAD 5AR4s in-use that I've been happy with, and It *think* those are made in China, but I'm not 100% sure).

The Russian 6N2P is indeed pretty tough and do work well when vibration will be present (essentially any instrument amplifier application), especially if you can get your hands on the -EV version which is built like a tank -- perfect for a gigging amp.
Click to expand...
He uses them in one of those huge Russian Red Bear amps. With several gain controls and overdrive they can be run pretty hard. He asked about rewiring the sockets for 12ax7's and I talked him out of it. That amp is a beast. I set him up with a 12"x4 speaker cab to go with it. It gets concert level loud. 300 watts if I remember right.
 
IIRC, Lampizator favours the use of 6N2P tubes in his tube mods to CD players.

I bought my small stash from a guitar amp guy.
 
Dandy said:
IIRC, Lampizator favours the use of 6N2P tubes in his tube mods to CD players.

I bought my small stash from a guitar amp guy.
Click to expand...

They have that internal shield, so I would assume they're preferable in situations where you would want to minimize crosstalk.
 
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