Other Amps

Hammond/Vox hybrid amp


Between the weeks of smoke and now heat wave, it seemed a good time to spend in my workshop - conveniently the coolest area in my house - with a good project.

Powdog sourced a Hammond AO-44 chassis for me, and with technical help from various people more knowledgeable than me came up with a schematic using a Vox style EF86 pentode preamp to push the ECL86 power section (ECL86s are essentially a half a 12AX7 and a slightly lower powered EL84 in one tube).

Added a triode/pentode switch for the EF86, and a boost switch (selectable cathode bypass cap) and now it's a raw, rude, raunchy rock and roll machine!


How does it compare to Thomas Vox 6BQ5 designs?


interesting power tube choice..i see it put's out about 2.8-4w...

what are the benefits, aside from uniqueness..(and fun)?



DC, the Thomas Vox tube amps have a dual triode preamp with the tone controls between the gain stages. This uses the 60s Vox AC15 EF86 pentode preamp with a single, hot gain stage and tone controls after it. The few TV tube amps I've tried sounded great, just different than this. This is more aggressive and hot if that makes sense.

Neatone, no benefits, except that the power section is already built, and I already had it, thanks to Powdog. There are a few other Hammond chasses that use EL84s which are better for full Vox conversions. I've got an AO-50 I plan to convert into an AC15 before too long.


Thanks for explaining. You know way more than me -- still I thought the TV tube models, when tweaked were nice amps This is different ...,more of a screamin demon


DC, the TV tube amps ARE really great. They've got an interesting voice that's basically a Californian interpretation of an English accent - it sounds British but there's still a hint of California in there.

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