Vintage style 1974 Head Build with Push Pull Extra Gain Stage
Posted: Mon 03/11/24 2:26 am
Here's my second 18watt build based on a vintage model 1974.
When you pull the Normal Channel's volume control it cascades the Normal Channel into the Tremolo Channel via a DPDT switch to kick things up a notch. The DPDT switch basically adjusts the input impedance on V3's input grid for the Tremolo Channel from about 33K to about 500K and adds a 1M resistor between the output of the Normal Volume and the input grid of the Tremolo Channel. Thing kicks ass when cascaded and has such a beautiful clean tone too. I really like how a 10uF for V3's cathode bypass cap sounds when I'm in cascade mode, so I may add a second push pull pot to switch between the 47uf and the 10uF down the road.
Was able to source a Radiospares EL84 output transformer and I had a custom power transformer built by Pacific in Anaheim with the original 300v-0-300v secondary.
180ohm cathode resistor bypassed with a 220uF cap. Sounded best to me. We're biased at about 14W on some N.O.S. Mullard EL84's.
Preamp tubes are all N.O.S. Mullard 12AX7 and the Rectifier is an Amperex EZ81.
Electrical grade Paxoline board material milled on an EZTrak equipped Bridgeport. This material sounds great with every vintage style build I've used it with so far.
Made the Perspex front and rear panels as well as the cabinet logo on Adobe illustrator and had them UV printed and painted them with a vintage metallic gold mix.
Really stoked on the mini box cab. Makes it really easy to transport like a compact model 2061.
When you pull the Normal Channel's volume control it cascades the Normal Channel into the Tremolo Channel via a DPDT switch to kick things up a notch. The DPDT switch basically adjusts the input impedance on V3's input grid for the Tremolo Channel from about 33K to about 500K and adds a 1M resistor between the output of the Normal Volume and the input grid of the Tremolo Channel. Thing kicks ass when cascaded and has such a beautiful clean tone too. I really like how a 10uF for V3's cathode bypass cap sounds when I'm in cascade mode, so I may add a second push pull pot to switch between the 47uf and the 10uF down the road.
Was able to source a Radiospares EL84 output transformer and I had a custom power transformer built by Pacific in Anaheim with the original 300v-0-300v secondary.
180ohm cathode resistor bypassed with a 220uF cap. Sounded best to me. We're biased at about 14W on some N.O.S. Mullard EL84's.
Preamp tubes are all N.O.S. Mullard 12AX7 and the Rectifier is an Amperex EZ81.
Electrical grade Paxoline board material milled on an EZTrak equipped Bridgeport. This material sounds great with every vintage style build I've used it with so far.
Made the Perspex front and rear panels as well as the cabinet logo on Adobe illustrator and had them UV printed and painted them with a vintage metallic gold mix.
Really stoked on the mini box cab. Makes it really easy to transport like a compact model 2061.