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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
"Suggestions for Switching EL84/6P1P"
Posted By Tim Hall on 06/24/2016
I have an PP pair EL84, cathode bias amp that I'd like to be able to drop in 6P1P's (I have a dozen or so of these I've never used). I'd need to switch the bias resistor, control grid, and the anode c...

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"Log or Linear pots for James stack?"
Posted By Paul Fawcett on 06/24/2016
Does anyone out there have direct experience comparing log and linear pots in a James-style tone-stack in a musical instrument amplifier? I had assumed linear, based in part on analogy to a Baxandall...

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"V4A Gain. Measurement vs Calculation"
Posted By skimy on 06/23/2016
I've already put the preamp stage on a prototype board to check this block (so the Tone controls and the Output stage are NOT connected yet).

All the voltage measurements on the circuit, DC and...

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"Other uses for valve diodes?"
Posted By Alva Goldbook on 06/22/2016
Other than rectification and perhaps a compression circuit of some sort, can anyone think of any other uses for valve diodes? ...

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"FX loop question"
Posted By ColinD on 06/21/2016
Referring to this schematic: [link]

On page 4 there is a schematic for an optional FX loop. The loop schem adds R40, a 1M resistor between the...

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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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