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EL84 Amp - another possibility

This design is the best amp in my collection. Of course we all think our own design sounds the best BUT it is truely stunning. I called it the "Baby Huey".

Bas Horneman has kindly hosted the schematics on his site.

The Amp Schematic:
http://basaudio.net/schematics/pp/ppel84_baby_huey.gif

The power supply Schematic
http://basaudio.net/schematics/pp/p...by_huey_psu.gif

Recent Mods:
1)The EL84 CCS Cathode bypasses are now 1000uF/25V Blackgate NX in place of the 4700uF/470uF/1uF networks shown.
2)10 Ohm + 220nF zobel added across the 4 Ohm secondary tap (the tap I use)
3) 47 Ohm series resitors in the the HV feeds to Left and Right Channels dropped to 4R7
4) Note that there is a very small amout of global feedback and local balanced shunt feedback set by the 15K which connects across the 2 47K resistors off the EL84 Anodes.

IF - 2 Ohms Output Impedance is acceptable to you THEN ditch the global feedback altogether by removing that 12K global fedback resistor and increase that 15K to 27K - THIS is how I run my amp (I tried 33K but thought it a bit much)

IF 2 Ohms Output Impedance is not acceptable then leave the global feedback as is but increase the 15K to 20K. This was the best option with global feedback intact for an Output Impedance of just over 1 Ohm.

B.T.W. This whole design grew aout of an ECL86 (6GW8) circuit by Yves Monmagnon.
here
http://www.diyaudio.com/forums/attachment.php?s=&postid=552739&stamp=1105777406

The ECL86 version I built and subsequently sold was also seriously stunning.

Cheers,
Ian

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