CtG A-6F5 custom amplifier concept (based on the Fender Tweed Bassman 5F6-A)
A-6F5 Description
The CtG A-6F5 is a slighty modified version of the classic Fender tweed 5F6-A bassman amplifier known for its unique tone and distorion qualities. Using the same packaging scheme as the FCN-51-B, the A-6F5 is the next in a series of kit / project amplifier head designs from CtG that offer afforabilty as well as flexibility.
The A-6F5 has two channels with individual volume controls. Both channels share a cathode follower driven tone stack which has treble, bass and middle controls. The presence control acts as a "variable bright switch" on both channels by modifying the frequency characteristics of the negative feedback loop.
The power amp section is designed to output 40 - 50 watts (RMS) through a fixed bias mode pair of 5881s / 6L6GCs. There is also a line out provided on the back panel.
A 12AY7 dual triode serves for both channel preamps. A 12AX7 is configured as a cathode follower tone stack driver. A second 12AX7 is used in the long tail phase inverter circuit. The power amp uses two 5881 / 6L6GC power tubes, and a 5AR4 power supply rectifier. This design packages the 40uF and 2-20uF in a FP multi-cap can in place of axial electrolytics.
A layout using a generic fiber board with dual rows of eylets is provided. A mirror image 5F6-A fiberboard could be used as well.
The power transformer is a Fender Super Reverb type. The output transformer is the universl 2/4/8 ohm output version of the Bassman OT. A back panel rotary switch allows selectable use of 2, 4, or 8 ohm speaker loads.
The chassis is a steel Hammond p/n H1441-26 painted with ASA 61 smooth grey paint. Its dimensions are 8" x 16" x 2". A black p-coat 8" x 16" x 5.2" perforated steel cage top p/n H1451-26 is also available from Hammond. Brass plates in front and back are used to facilitate grounding.
The A-6F5 has two channels with individual volume controls. Both channels share a cathode follower driven tone stack which has treble, bass and middle controls. The presence control acts as a "variable bright switch" on both channels by modifying the frequency characteristics of the negative feedback loop.
The power amp section is designed to output 40 - 50 watts (RMS) through a fixed bias mode pair of 5881s / 6L6GCs. There is also a line out provided on the back panel.
A 12AY7 dual triode serves for both channel preamps. A 12AX7 is configured as a cathode follower tone stack driver. A second 12AX7 is used in the long tail phase inverter circuit. The power amp uses two 5881 / 6L6GC power tubes, and a 5AR4 power supply rectifier. This design packages the 40uF and 2-20uF in a FP multi-cap can in place of axial electrolytics.
A layout using a generic fiber board with dual rows of eylets is provided. A mirror image 5F6-A fiberboard could be used as well.
The power transformer is a Fender Super Reverb type. The output transformer is the universl 2/4/8 ohm output version of the Bassman OT. A back panel rotary switch allows selectable use of 2, 4, or 8 ohm speaker loads.
The chassis is a steel Hammond p/n H1441-26 painted with ASA 61 smooth grey paint. Its dimensions are 8" x 16" x 2". A black p-coat 8" x 16" x 5.2" perforated steel cage top p/n H1451-26 is also available from Hammond. Brass plates in front and back are used to facilitate grounding.
A-6F5 Design Documentation
a-6f5_031810_chassis.pdf | |
File Size: | 123 kb |
File Type: |
|
|
a-6f5_bom_031810.pdf | |
File Size: | 92 kb |
File Type: |