- Nov 19, 2012
- Reaction score
This is 6657 that I use to own. Really regret letting this go. Note the thick Vox front panel strip.Nice amp!...And it has the RS potted military PT!.. @Ned B . She's had some changes but it's in good shape for an amp from around April 1966. It looks like someone did a little re-voicing for the individual channels. Some of the changes I noticed are:
The cathode cap for V1 has been replaced.
Someone added a bypass cap (can't make out the value) for the 270K summing resistors for channels 1 & 2.
The preamp coupling capacitors for channels 3 & 4 have been changed to what looks like 0.1uF instead of the usual 0.022uF.
The cathode follower 100K resistor has been replaced.
The preamp filter cap has been replaced with a dual section cap. Original would have been a 16uF/450Vdc. Also someone added an addition 10K/1w B+ voltage dropping resistor at this filter cap.
The bias circuit has been updated with a slider trim pot and at least one bias cap has been changed at one point.
An additional 32uF/450Vdc filter cap was add.
Looks like the diodes & 0.05uF/1000Vdc cap for the rectifier circuit changed at some point. They look like IR diodes but typically around this time frame they were using metal cased Mullards.
The On/Off switch has been replaced.
Not sure why the OT has R/S 207-330 written on it...To me it looks like a Drake 1202-84 which would be period correct. Looks like someone moved the Yellow 8-ohm tap wire from the Selector to the speaker jacks....
The choke looks like a replacement.