EF86 AC4 inspired amplifier

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EF86 AC4 inspired amplifier

Postby Thomas_H » 20 Aug 2017, 16:28

Hi,
I finished a small amp based on the AC4 build here> http://www.dougcircuits.com/neon.html
Just used one half of the 12ax7 as another preamp stage.
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The preamp stages are switched by the jacks, giving the four different configurations. Not an AC4 anymore, but still with the character of the EF86.
The cab came from an old transistor amp, I added the 10" speaker, the grill cloth and a new faceplate.
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cheers,
Thomas

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bmxguitarsbmx (20 Aug 2017, 17:33), HENK (23 Aug 2017, 11:13), karul (05 Sep 2017, 09:33)
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Re: EF86 AC4 inspired amplifier

Postby okgb » 01 Sep 2017, 14:28

looks great , Do you find yourself using the ef86 channel more than the normal 12ax7 ?
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Re: EF86 AC4 inspired amplifier

Postby Thomas_H » 04 Sep 2017, 22:41

Yes, the Ef86 channels sound better, It's not a regular ac4, the extra triode between the EF86 and the El84 gives some extra gain, so the sound is not as weak as in the original. And the all in series configuratin, with the Ef86 in front of the two triodes has a lot of gain on tap, but with that pentode sound, more compressed or full sounding.

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HENK (05 Sep 2017, 11:20)
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