File Size: Kb Number of Views: After downloading, the file may take a moment to open in the browser. Fender – Bassman 5f6a -Schematic Thumbnail. The Bassman 5F6-A preamp contains two voltage amplifiers, one for the bright inputs and one for the Fender Bassman 5F6-A schematic of first two stages. 5F6A Amp Kit Item Code: 5f6a_c_kt We provide a layout and a schematic (on the Technical Details tab), but we do not include step by step assembly.

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A higher resistor value will dim the LED.

The normal channel lacks the pF bright bypass capacitor. Remove the two wires that run from the top of the grid leak resistors to the power tube grids or stopper resistors. This will make several modifications much easier since you won’t have to pull the board to access schematjc wire. Here is the tone stack response dB gain versus frequency in hertz with the middle control at percent rotation. If you would like to cut even more highs than the pF cap, you can go all the way up to a.

You could also disconnect the 15k and 56k bias resistors and 8uF capacitor from their shared eyelet or turret to isolate them from the under-board wire. Zchematic can also combine the Raw Switch with the Raw Control pot schemstic mod below so you can fine tune the tone you get with this switch.


Fender Bassman 5F6-A Circuit Analysis

Cap C19 blocks the upper triode’s The unmodified channel gets a new 1. The 5F6A’s bright cap is very small at pF pico Farad. Adding the resistor eliminated scheatic pop for my amp. The extra gain from removing the lossy tone stack was enough to cause a downstream gain stage to freak out.

Keep your tubes in their sweet spot.

Dropping a half of a volt would be perfect to get the standard 6. The bias pot wired as a variable resistor and 27k resistor replace the 56k resistor above.

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You tap high voltage AC from the rectifier AC input and create an adjustable bias circuit. I was surprised by how much of a signal boost I got with this switch engaged, even with all three tone controls at max. We can round to the standard resistor size of ohms. V1’s extra caps and resistors can get a little crowded on the circuit board so it’s a good idea to raise the hot cathode resistors higher off the circuit board than the coupling caps to aid cooling and minimize heat transfer from the resistors to the caps.

Notes on the tweed Bassman schematic.

Reducing their value will “raise the floor” and tighten up the clean and especially the overdrive tone. You should always ensure the Standby Switch is in the standby position before powering up the amp. All three tone stack capacitors act as coupling caps to keep V2B’s high cathode voltage from flowing downstream. At max volume there 5f6x no difference between the Normal and Bright channels so voicing schemqtic channel differently is a useful mod.


He opened it up, removed it, and then let me do my thing.

Heater current in amps: The pulsing negative DC is filtered by the two 25uF filter caps and 15k resistor. If you are building a head cab consider installing an Eminence 6 inch 20 watt hemp coned H speaker. When the switch is closed the diodes’ low voltage drop bypasses current around the tube rectifier.

The Phase Inverter Bass Response calculator shows that the hefty 0. I like this very late tone tweak because it schemxtic well with an early tone control or stack.

List of Mods

If you find you run out of room and need to get a hotter bias then 5fa the value of the resistor. The diodes are cheap insurance and I install them in all my amps.

Tags bassman guitar amp fender Musical instrument. Instead of connecting the center terminal to ground as shown, connecting it to a cathode biased amp’s cathode resistor will elevate the center tap and reduce hum.

By clicking the submit button on the order form, the buyer is certifying his or her compliance with this agreement and guarantee. Ground switch is deleted3-Prong power cord, balanced 6.