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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
"HIgh voltage supply with mosfet regulation"
Posted By DanGu on 12/17/2014
Hi. I've got two power transformers rated 720VCT @ 260mA which I'd like to use for a bench high voltage supply to use for amp testing. I'm bored to build always the power supply searching for random t...

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".25 (1/4) watt Project"
Posted By Jazz5dad on 12/16/2014
Request a little help here, may have been addressed somewhere but don’t see where. I want to design and build a .25 watt tube amp with volume and master only without sacrificing tone. I already built ...

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"Wanted: fuses 400+ V"
Posted By Henrik Lidbjrk on 12/16/2014
I want a fuse for the B+ line (after rectifier) in my 6V6 Plexi build, but can only find fuses rated 250V. I need circa 400 V. Maybe 500 V is the next step after 250?

Preferably 250-500 mA or there...

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"Where to solder the 50V bias wire?"
Posted By Henrik Lidbjrk on 12/16/2014
I'm building a Mark Huss 6V6 Plexi, and in his schematic there is no separate bias wire from the OT, so he connects one of the HT secondaries to the bias circuit through a 220kΩ 3W resistor.


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"Soft-start (standby) switch -- before or after rectifier?"
Posted By Henrik Lidbjrk on 12/16/2014
I'm about to solder a "soft start" switch, as Merlin has outlined on his Valve Wizard site ( [link] This is in place of a standby switch and has (in my case) a 68 k...

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Site News

2014-10-21: Be sure to check out our discussion forum using the link on the left..

2014-10-20: 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...
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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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