Moderators: JMPGuitars, Daviedawg, Graydon, CurtissRobin, colossal, zaphod_phil
That's great! And it also means you can do whatever you want.yello wrote: ↑Wed 09/28/22 12:05 pmCurrently I'm creating a new layout for this amp circuit, so it can be built on a turret board in a typical amp chassis, not in the original projector enclosure which is crowded and convoluted. That means I'm not recreating what I see in person in my layout, but rather translating the original schematic and original layout, into a totally new (better) layout. Its a great learning process.
I will likely mimic the layout sections of the 18w, as that worked out great when I built my ef86 Lite 2p.JMPGuitars wrote: ↑Wed 09/28/22 8:01 pmThat's great! And it also means you can do whatever you want.yello wrote: ↑Wed 09/28/22 12:05 pmCurrently I'm creating a new layout for this amp circuit, so it can be built on a turret board in a typical amp chassis, not in the original projector enclosure which is crowded and convoluted. That means I'm not recreating what I see in person in my layout, but rather translating the original schematic and original layout, into a totally new (better) layout. Its a great learning process.
I'm circling back to reviewing this tone circuit (been awhile since we discussed it). This tone control affects various changes in a preamp negative feedback loop.
Thanks, that is what my staring at the circuit and multimeter seemed to be showing, but I'm not familiar with these switches and that dotted line in a schematic, so an extra set of eyes or two is always helpful!JMPGuitars wrote: ↑Fri 09/27/24 5:38 pmIt's showing you the common terminal on each half of a 2 pole 5 position switch. The poles move together, but are isolated.
The more schematics you see, the more new things you'll see. The dotted line is a standard thing for multi-pole switches, but it gets more confusing when the poles are farther apart like that. Here's a basic 2 pole switch symbol:
And another interesting schematic/switch thing: there is a switch to select between the 8 ohm internal speaker, or the 16 ohm remote speaker cabinet output jack that lifts/moves the ground wire to accomplish the task. I don't think I've seen that before, is that common on a combo amp (as opposed to a selector switch that chooses between OT secondary wires as seen on most heads)?JMPGuitars wrote: ↑Sun 09/29/24 2:58 pmThe more schematics you see, the more new things you'll see.
The wire may be grounded, but is it a ground wire? Do your speaker terminals say + and Ground, or do they say + and -?
Ah, yes, forgot to think of it in terms of the OT. So it is muting the speaker by not completing connection with both sides of the OT secondary, is that the right way to say/think about it?JMPGuitars wrote: ↑Wed 10/02/24 1:13 pmThe wire may be grounded, but is it a ground wire? Do your speaker terminals say + and Ground, or do they say + and -?
Pretty close. It's swapping the negative speaker connection to the external speaker, which disconnects it from the internal speaker. The OT is still connected to something.