eBay Auction Link to this '59-'61 Epiphone EA5 Emperor. Not in especially good condition but an interesting link between Epiphone and later Gibson 'Crest' models; 6-tube preamp, twin 7951s, and GZ34 rectifier ... close to 30 watts. Auction amp has replacement Realistic/Radio Shack speaker in it.
Breakdown of the schematic by function (Link To Schematic). This is a more powerful and complex version of the Gibson GA19RVT; either the tweed or Crest versions and the reasonable, if not actual, predecessor to the Gibson Crest model GA30RVT Invader except that it only has one 12" speaker. This amp is fixed bias which means making the volume fluctuate for the tremolo function has to be done by manipulating line voltage.
The EA5 audio chain: Like the Ampeg RRs that post-date it, it uses an optical coupler to connect the oscillator to the line to abate snaps and pops. Like the GA19RVT, it uses the premium 7199 for reverb drive and recovery but, unlike the RRs, it couples the reverb can with a transformer, not a capacitor (or speaker like some Guilds)
This amp has both bass and treble tone controls for both channels, a choke in the power supply to prevent the owaowaowa saggy thing that (some) people object to in choke-less 6V6 amps, and an additional gain stage v. the GA19. To get from this amp to the Gibson 'Crest' GA30RVT Invader (where did they get these names?), substitute a 6EU7 for the 7199 reverb operator and add a 0A2 tremolo voltage regulator and a 10" speaker to go with the 12" ... the only meaningful differences.
According to Gibson (from its self-congratulating webpage):
"In 1957 Gibson’s parent company, Chicago Musical Instrument, acquired Epiphone. The old line was discontinued and in 1959 a new era of tube amps were ushered in, manufactured at the Kalamazoo, Michigan facility. The Devon, Century, Zephyr and Emperor were a carry over by name only because the circuitry was actually the Gibsonette, GA20T, GA40 and GA77 respectively." [Juan's note: not exactly ... Epiphone produced two other versions of the 'Emperor', the EA4 and EA6; both were 6L6-driven like the GA77. The EA5 is 7591-driven ... like the later GA19RVTs and the GA30RVT.]
Continuing:
"The tube amps produced from 1959-61 were made in such small numbers that these early EA series have become highly sought after and very collectable. The EA5 Emperor, produced from ’59-61, the EA10 Deluxe, made from ‘59-61 and the EA12RVT Futura ‘61-67 were some of the more popular amps in the 1960’s. By 1965, Blues great Mike Bloomfield could be seen using a Futura with four 10” speakers at the Newport Folk Festival as he performed with the Paul Butterfield Blues Band. “Mr. Tambourine Man”, the iconic Byrd’s hit from 1965, was recorded using an EA14RV, more commonly known as the Epiphone Ensign. This grey vinyl 50 watt combo had two 10” speakers and was forever captured recreating Roger McGuinn’s jangling intro to this famous song penned by Bob Dylan."
Some more Epiphone v. Gibson details Here and more Gibson/Epiphone self-praise Here. I think this amp has too much in common with the later Ampeg Reverberockets not to sound like one too. This one is rare but with Gibson amps generally, rare doesn't necessarily mean pricey.
CJ
Breakdown of the schematic by function (Link To Schematic). This is a more powerful and complex version of the Gibson GA19RVT; either the tweed or Crest versions and the reasonable, if not actual, predecessor to the Gibson Crest model GA30RVT Invader except that it only has one 12" speaker. This amp is fixed bias which means making the volume fluctuate for the tremolo function has to be done by manipulating line voltage.
The EA5 audio chain: Like the Ampeg RRs that post-date it, it uses an optical coupler to connect the oscillator to the line to abate snaps and pops. Like the GA19RVT, it uses the premium 7199 for reverb drive and recovery but, unlike the RRs, it couples the reverb can with a transformer, not a capacitor (or speaker like some Guilds)
This amp has both bass and treble tone controls for both channels, a choke in the power supply to prevent the owaowaowa saggy thing that (some) people object to in choke-less 6V6 amps, and an additional gain stage v. the GA19. To get from this amp to the Gibson 'Crest' GA30RVT Invader (where did they get these names?), substitute a 6EU7 for the 7199 reverb operator and add a 0A2 tremolo voltage regulator and a 10" speaker to go with the 12" ... the only meaningful differences.
According to Gibson (from its self-congratulating webpage):
"In 1957 Gibson’s parent company, Chicago Musical Instrument, acquired Epiphone. The old line was discontinued and in 1959 a new era of tube amps were ushered in, manufactured at the Kalamazoo, Michigan facility. The Devon, Century, Zephyr and Emperor were a carry over by name only because the circuitry was actually the Gibsonette, GA20T, GA40 and GA77 respectively." [Juan's note: not exactly ... Epiphone produced two other versions of the 'Emperor', the EA4 and EA6; both were 6L6-driven like the GA77. The EA5 is 7591-driven ... like the later GA19RVTs and the GA30RVT.]
Continuing:
"The tube amps produced from 1959-61 were made in such small numbers that these early EA series have become highly sought after and very collectable. The EA5 Emperor, produced from ’59-61, the EA10 Deluxe, made from ‘59-61 and the EA12RVT Futura ‘61-67 were some of the more popular amps in the 1960’s. By 1965, Blues great Mike Bloomfield could be seen using a Futura with four 10” speakers at the Newport Folk Festival as he performed with the Paul Butterfield Blues Band. “Mr. Tambourine Man”, the iconic Byrd’s hit from 1965, was recorded using an EA14RV, more commonly known as the Epiphone Ensign. This grey vinyl 50 watt combo had two 10” speakers and was forever captured recreating Roger McGuinn’s jangling intro to this famous song penned by Bob Dylan."
Some more Epiphone v. Gibson details Here and more Gibson/Epiphone self-praise Here. I think this amp has too much in common with the later Ampeg Reverberockets not to sound like one too. This one is rare but with Gibson amps generally, rare doesn't necessarily mean pricey.
CJ
