tube amps
SOHA
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all panels (front, top, bottom, rear, side) by Frontpanelexpress.com |
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case tied directly to signal ground and via ground loop braker to mains earth 65VA 2x18V potted toroidal transformer + Dynalo PSU as buffer psu 30VA 2x15V toroidal transfomer for SOHA main board Alps RK27 50k "blue velvet" volume potentiometer Neutrik NC J6FI-S locking headphone jack |
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ε12 muting delay and offset protection from AMB labs class-A hybrid buffers (jfet input stage, bjt push-pull output stage) set to 50mA, design by courtesy of AMB Elna Silmic-II electrolytic capacitors, Toshiba 2sk30a JFETs for cascoded ccs Mundorf MCapZN caps (tin foil + polypropylene film) as coupling caps tube: JJ ECC82 at 0.85mA (alternatively I recommend GE 5963 at 0.7mA or Electroharmonix 12AU7/ECC82 at 1.0mA) |
EHHA (prototype)
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adjustable gain of 6, 9 and 12 set via a rotary switch
dedicated AKG K1000 jack |
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heaters wired in series and powered by a separate transformer and a TREAD psu set at 12.6V
board powered by a 65VA potted and shielded toroidal Avel-Lindberg transformer and a β22 psu at ± 30V ε12 muting delay and offset protection |
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6GM8 tubes |
Millett Hybrid MAX
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MH-max project page
acrylic frontpanel made by Frontpanelexpress.com |
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BJT version Panasonic FM / FC electrolytic caps, Wima film caps Alps RK27 "blue velvet" volume pot black painted acrylic rear panel Neutrick RCA input jacks built Dec 2007 |
Millett Hybrid (head-fi revised), tubes pcb mounted
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| front |  |
800x600 125 kB |
by Frontpanelexpress.com |
| front, above |  |
800x600 108 kB |
aluminum front and acrylic top by Frontpanelexpress.com |
| bias adjust |  |
800x600 132 kB |
holes straight above trimpots for direct adjustment with a screwdriver, air wired 2mm laboratory jacks for external bias measurement, easy tube rolling and adjusting |
| board |  |
800x600 148 kB |
Elna Silmic + Panasonic ECQ-P polypropylene film caps in the signal path, Panasonic FM + Wima MKP caps for power rail bypassing, discrete diamond buffers |
| rear |  |
800x600 109 kB |
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| dayglow |  |
800x600 113 kB |
3500mcd ultrabright LEDs |
| nightglow |  |
800x600 93 kB |
3500mcd ultrabright LEDs |
Pete Millet hp (original designer)
Millett Hybrid (head-fi revised), maxed out
| view | preview | comments |
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| front |  |
aluminum front and acrylic top by Frontpanelexpress.com |
| rear |  |
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| top |  |
holes straight above trimpots for direct adjustment with a screwdriver, air wired 2mm laboratory jacks for external bias measurement, easy tube rolling and adjusting, ventilation holes |
| top |  |
ultrabright blue LEDs |
Pete Millet hp (original designer)