NICE! I always get this and the discoverer confused, does your Explorer have 6V6 tubes or 6BM8s? If this is the mdoel with trem and 6V6es you have essentially a tweed fender tremolux. There are some slight voicing differences and I think the phase inverter may be a different split load type (maybe a paraphrase versus the fender cathodyne), the outbut transformer is a little smaller on these, but its a tremolux.... unless I am mixed up about my gibby models again and the output tubes are not 6V6es. In which case its a purely original Gibson circuit, but one of the couple really good Gibson originals from the 60s (Gibson really ruined their amp line in the 60s)

It used the 6V6 tubes. That's cool though, didn't know that. Thanks for the information!

yeah, that amp is in the tweed harvard, tremolux, vibrolux, and brownface Princeton/deluxe camp, very similar to all those related fender circuits.... it should be a kick ass small rock amp. You should have it serviced, most old gibsons from are ready for new electrolytics and the pots need cleaning. You may want to change the speaker out as the original may no longer be up to the wattage when you crank her (though the old Jensen SHOULD sound wonderful while you are frying it). These amps are a little less thumpy/flubby and are a little gainier andmidrangier than the equivalent fender circuits I referenced, good for rock, bad for country. Its the difference between a 5f1 tweed bassman and marshall jtm45 tonally

Finally had this thing serviced after being knocked over at a show, and you were right. Needed some work, but now the dang thing absolutely sings. Very bright if the tone knob is up above 3, but the breakup is wonderful. Real heavy tube tone, almost as broken up as running direct into a console and maxing that out. The original 10" speaker is in pretty good shape, and the two are a perfect pair in my opinion. This ought to be nice for tracking some leads.

actually, the GA14 titan and GA6 lancer are pretty much a hybrid of the 5D3 and 5E3 fender deluxe circuits. The 14 has a 10" (I owned one fof years, just sold it recently) and the Lancer was always a 12" that originally came in a wide-panel fender style box with non-tweed covering and octal preamp tubes like a 5C3 deluxe and then turned into a tweed amp that looked just like your Explorer but the guts are very much in the 5E3 deluxe cap with only a few component differences. The GA18 is not really that deluxey, probably less so than Gibson's GA20 and GA40 amps. Cool amp you've got though. I mean all small 50s combos sound pretty similar, man. But circuit-wise I think the GA18 is one of Gibson's LEAST deluxey amps. The GA18T with trem if I recall correctly is very much a tremolux circuit.... if your has trem then, that's the amp it shares topology with. If not its more like a Harvard.