Compared to Peaveys 5150 a Jubilee can sound "boxy" in terms of nasal, when the mids are turned up past 6.5 or 7 because of that extremely effective tone stack. The 5150 also may sound more "pleasing" to the ear, because it has a more "creamy" overdrive/harmonics character, and a deeper fuller bass. When you turn up the bass on a Jubilee, after around 8 on the dial, a pretty noticeable low mid boost kicks in, which can also be associated with boxy. Maybe the buyer is used to play with karge amounts of bass, using the 5150's Bass AND resonance controls. To achieve the same level of bass, he might have turned up bass past 8. The buyer should make a video of both amps and give you the settings of either. Just that we can compare. Might just not be something defective, but someone not used to the sometimes finicky tone stack of the Jubilee.
Bias in these amplifiers sound best at 35mA to 42ma per tube, my opinion. The gain is fine but can be lowered if a cleaner signal is desired. I run mine about 3 or lower but use the effects loop for added overdrive/distortion. Lead Master is very high. I set mine usually 4 to 6. My Master Volume is usually about 4 but if wanting more then I turn it up. Treble is about 5 to 7 area. Mid is 4 to 6 area. Bass is about 8 to 9 area. Presence is around 5 to 7 area. The combo do not have as much bass so this is why I set them this way. Heads and closed cabinets may differ somewhat. These settings are not to dark and provide a lead edge. Brightness and adjusting towards that helps for leads. The speakers used will require adjustments for differences. If the person does not like this then another amplifier may suit their situation better. BUT this amplifier can do most anything when utilizing the effects loop with EQ, overdrive/distortion and sound processing.
Ive had 2 jube combos and a 50w head and those are the amps l regret letting go. Maybe he did you a celestial favor?
