Miller Audio

Miller Audio LLC

ST-70 Auto Bias Module w/LED Extension (bias 0.40V / 400mV for EL34)



The Automatic Bias Module (ABM) is made by Auto Amp in Croatia. We use a modified module, made for Miller Audio LLC, to fit the Dyna-70 Ultimate Upgrade PCB, maintaining the factory warranty for the module.  The module comes with the bias preset and tested to ensure proper operation.  We recommend following our detailed installation instructions for the Dyna-70 Ultimate Upgrade Assembly Manual, v1.0.

While our Auto Bias Modules were designed for use with the Dyna-70 Ultimate Upgrade Kit, they can be used with other ST-70 driver upgrade PCB’s. Contact us for details prior to ordering, we can help ensure you get the right components needed for successful integration.

CAUTION: Exercise care in handling and installing the bias module. It is important to avoid generation of static electricity and ground your body when around static sensitive components and assemblies. Handle the module like a vinyl record, around the edges, trying not to touch any of the board components. The Module comes packaged in an electro-static protective packaging; always keep the module in this package until ready to install. Make sure that you always touch metal (a work bench or the ST-70 amplifier chassis) to stay grounded. Use ground straps on your body (shoes and wrists) to ensure you drain all static electricity away from yourself before handling the module to install it.  Digi-Key and Mouser Electronics sell anti-static grounding items for electronic assembly.  Anti-Static items are inexpensive and a worthy item to have around your work bench.

NOTE: Bias modules have no user serviceable components. Tampering with the module in any manner will void the warranty.  Improper handling and exposing the module to static electricity will also void the warranty.


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