The rare 1964 Vibrolux sounds just as nice as the brown version if set up right. They came with the Oxford alnico but sound much better with a modern speaker.I use an Eminence Red Fang Alnico with 102db rating and the amp sounds twice as loud.Only a few had the Normal/Normal typo on the faceplate.Mine is Normal/Vibrato. These have a few more watts than the brown Vibroluxes because mainly of the upgraded power transformer,the Schumacher 125P26A also used in the 64 Tremolux. This gave a little more voltage to the plates than the previous Triad 125P6A.The tremelo is the only drawback. The brown amps had the best tremelo. This uses the photoresister which is weak compared to the brown ones. If you don’t use the tremelo(vibrato) which I don’t you can disconnect the yellow wire to the intensity pot and get more gain and tone.I also change the new 12AT7 phase inverter tube back to the 12AX7 used in the brown ones which also gives more gain.You can use an RCA 5751 also.They work great. The cab is a little larger than the brown ones also.Fender should have kept making these amps and added reverb to this instead of going to the 2-12 Pro Reverb in 1965.What an amp that would have been. 30+ watts through a 12″ speaker such as the C12N Jensen.!!