Orange Model 80

[CJ]

here is an early 70's guitar amp, two EL34's  and a few 12AX7a's

 

[CJ]

has jumpersfor the line voltage and speaker Z,

chassis is punched for two more tubes, a different OPT would then be used,

 

[CJ]

has the lay down transformers, possibly Drake,Radio Spares, don't think it is a Partridge, otherwise it would be a gettin to be taken apart,

 

[CJ]

that pc board is mounted on rubber grommets, single strand wire is used, harnessed old schoolstyle,

 

[CJ]

can not find a Model 80 schematic,

current line voltages jack the B+ up to 530 DC sowe have red plates, sowe drop the screen voltage with 2K R in front of the choke, so screens now at 500 DC, otherwiseyou need a new pwr trans or a rewind, so we can preserve the relic natureof this by keeping the transformersstock,

but thisis close>

 

[CJ]

this is a hi-fi transformer, has UL screen taps that were cris crossed on the terminals that get glued to the wrapper, so we had some arcing as there was much voltage between the plate terminal and the opposite screen terminal, so we broke the twooutside terminals loosed and epoxied them a littlew further apart to give more isolation,

this guy goes up to 1 mega hertz, first OPT i have seen with this kind of response, closest thing was that API quad-filar job, but  it used a phase flip in order to do that, th3ere are a few peaks at about 200 K and 500 K,

150 EI core, about 48 ohms DCR on the total primary,

primary is bi-filar wound, 10.3:1 on the 16 ohm tap so about 1700:16 Z ratio,

 

[CJ]

ringing starts at about 10 K Hz.

how does this amp sounnd?  very loud for 50 watts,probably becauseof the OPTcore,

pretty clean also, no Marshall crunch until about 2 oclock on the dial.