Alembic F-2B preamp | moosapotamus Alembic F-2B preamp. Posted on May 6, I would like to build my own Alembic F-2B, connects to B+ on the preamp schematic. The low voltage (shown as 5.6, 6.3 or 12V on the PSU schematic) connects to the vacuum tube pins 4 & 5. That is not shown on the preamp schematic, but you can see it in the PCB layout. Finally, Alembic F2b preamp – FrogPedals Class A vacuum Tube preamp based on the Fender Dual Showman preamplifier section which inspired the Alembic F2b preamp. It is high quality 1 board with 2 ounce copper traces (double the normal printed circuit boards) with Gold plated solder pads. Preamps - Alembic's Online Store Alembic preamps are made to the same exacting quality standards as our stringed instruments. The classic stereo F-2B remains largely unchanged after 30 years of continuous production. Our F-1X is the mono version of our classic F-2B with some extra features like direct output and a built-in effects loop. F-1X Tube Preamp: Alembic F-1X preamp | TalkBass This question is for alembic f-1x owners and others familiar with this pre. What do you set the preamp's volume at? I wanted to know if I should adjust the volume knob on the Alembic or level on the power amp. Since there's no gain knob or light on the alembic, I don't know at what point the preamp is getiing an optimium gain level from my bass. Alembic F-2B preamp (DIY) | Watersish The Alembic F-2B preamp is often referred as the secret ingredient of David Gilmour's tone. But it was originally meant for improving Roger's bass rig. It's a straight up copy of preamp section of a Fender Dual Showman, which is a copy of the basic circuit found in a RCA Receiving Tube Manual from 1948!