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Welcome to AX84® the base camp for tube (valve) electronics hobbyists.

AX84 exists to provide:

1) A great environment to learn about music-related electronics in general. AX84 is a place where those with experience are interested in helping diligent beginners who are willing to do their homework.

2) A place where those with more experience can field their ideas to peers and get useful feedback.

3) An environment that respects the past, but is not enslaved by it. INNOVATION IS GOOD (and it didn't die in the 1950s.) There are new things under the sun every day. Move the ball forward!

Our HUGE discussion area is under 'Discussion Forum' to your left.

We are hard at work improving the site- check back often!

Recent Forum Threads
"5f1 OT noise"
Posted By Mcilfilm on 09/16/2014
Finished a 5f1 build. Pretty much the standard circuit, point to point on turret strips. The only difference is the that the I made is kinda small so the power caps/resistors are on the pt side of the...

Discuss this entry
"Light bulb limiter"
Posted By Darren Porter on 09/16/2014
OK, forgive my possibly stupid question, but...

I really should build a light bulb limiter. So far I have been pretty lucky with my builds and their initial start-ups and fuse-blowing has not been ...

Discuss this entry
"fixed to cathode switch in PR clone"
Posted By cameron nicklaus on 09/16/2014
I'm about to get started on this one and I thought I'd put the switch in, I'm wondering if there's a way to keep the bias trem working in cathode bias mode. any thoughts?
seems to me that the cathod...

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"I NEED an NOS 12ax7"
Posted By GeoMan on 09/15/2014
So here's my situation. My buddy gave me a really old Supro 8 to look at and see if I could fix up. Since he was waiting to come up with the spare change for the parts I had it in a closet in my spa...

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"Biasing for a KT88"
Posted By Asa Patterson on 09/14/2014
I decided to install the variable cathode bias mod for the P1Ex so I could use a KT88 for the output tube. I'm getting 410v on the plate and the PaMax for the KT88 seems to be 42W. (The tube bias calc...

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Site News

2012-2-25: Winter is almost over. What's on your workbench?

2011-10-10: Some good discussions about LTSpice in the forums again, as well as suggestions on what all to do to a P1-eXtreme.

2011-10-10: What all can you do with a P1-extreme? check the forum

2011-10-7: Don't forget to like us on Facebook!

2011-08-11: Posted some Single-Ended Lead clips in the Classic Amp Projects->SEL section. Hundreds built but now we've got clips. Check out the archived projects section for more clips.

2010-10-22: Be sure to check out our discussion forum using the link on the left..

2009-07-01: The Treasure Fleet is on the way to Rio De La Hacha with a fortune in gold!

We're looking for media clips of recent builds... please stop by the forum and respond to the thread.

2008-10-4: Archived Projects section is functional again.

2008-9-18: RSS Feeds for the forum have been up for a while, but not advertised...
* Active Threads
* New Threads
* Recent Posts

2008-6-26: Want to participate in our discussion forums? You are welcome to read and lurk as you like. If you think you'd like to post with regularity, please sign up for an account.

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