Fender amp red knobs9/19/2023 Never attempt to repair, modify, test, work on or touch electronic equipment unless you are trained or otherwise qualified to do so. Valves operate at high temperatures that can cause severe burns. Valves, transformers, capacitors, amplification circuits found within a guitar amplifier operate at high voltages that can cause permanent injury, disability or death. some comments on the web forums mistakenly attribute this amp to the Paul Rivera era at Fender – this is not the case, this design is dated 1988 – well after Rivera moved on to manufacture his own products. the previous owner of this amp discarded the red knobs, but installed some really cheapo looking ones in their place we ended up matching up some Fender vintage reissue black knobs, which look much better. We have more Fender MODs to be published soon. Upgrading the preamp valves will improve the tone of the amp in both ‘clean’ and ‘overdrive’, and will smooth out the spiky distortion characteristic and reduce hum/noise. The end result is still a compromise, but the changes will result in a fuller signal range and also more saturation available for a more modern ‘lead’ sound. Biasing this amp to run much hotter would be a mistake, as per the preceding paragraphs. We rebiased for 2 x 35ma Ik at B+ of 487V DC. We would suggest leaving the 3-band EQ as it is, to maintain the ‘clean’ tonality, even though the EQ is less than ideal for the ‘overdrive’ mode.įor those of you who have access to a schematic we modded the following components: R167 to 82K, C102/C105 to 0.01uF, R103 to 100K and R158 is the resistor to be changed for different bias levels, or else remove altogether if a trimpot is to be installed. This ‘balancing act’ doesn’t achieve absolute perfection, but is a definite improvement over the stock amp. We would have to completely strip out the boards anyway, so this was the perfect opportunity to implement some MODs to try and improve the ‘overdrive’ qualities plus balance up the two modes a bit better. The ‘clean’ mode level was considerably lower then the ‘overdrive’. The pots have a solid shaft with a flat section, and the original knobs naturally match this shape. The input and footswitch jacks on this model are the very brittle and easy to break PCB mounting types from the 80’s and 90’s. This customer’s amp was delivered to us with low output level, a couple of badly damaged pots, and broken jacks. The three preamp valves are not especially a problem, but the heat from the pair of output valves will to some extent end up being absorbed into the chassis and the main board. The valve sockets are mounted direct to the main board. Unfortunately for the service tech, these boards are kind of ‘back-to-front’ with the solder side of the board facing upwards, and the component side facing downwards, so they cannot be inspected without stripping out the boards. As you can see from the 2nd and 3rd photos, all components (apart from transformers) are mounted to either the large main board (PCB), or the smaller front panel board. Which leads us to serviceability issues with these amps. This is really tedious ! However, the PCB can be modified to accept a bias trimpot. So, the service tech has to change resistor values as required to achieve the desired result. The bias supply voltage is not adjustable, leading to complications when installing a fresh pair of 6L6GC output valves. This is due to the amount of shared circuitry, which is re-configured using opto-couplers. On the minus side, the ‘overdrive’ mode is not that great, and the clean/overdrive tonalities and levels really don’t match up. The ‘clean’ tonality is good, it’s just not quite the same as a ‘blackface’ Fender. On the plus side, this is a 60 watt 1×12 amp in a compact combo (although quite heavy as a result), with ‘clean’ and ‘overdrive’ modes plus reverb (solid-state driven, not valve/tube). It has a few admirers, to be sure, but the model was eventually deleted. This model caused some confusion for people who purchased one, as it sounds nothing like the traditional Fender amplifier models. The Fender Super 60 was introduced in the late 1980’s as one of the dreaded ‘red knob’ series of amps, which weren’t always favourably received.
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