Schematic/layout Disparity

[unclej]

this question is really for my continuing education. while double checking some things as i'm wiring up my champ i've noticed something curious. this is the model 5f1 that i'm working on. in the layout there are 7 wires leading to or leaving the 6v6 tube. in the schematic there are only 4 wires shown. one of the missing wires would be the ground wire comming from the 1 and 2 pin on the 6v6. the wire from pin 5 going to the .o2mfd x 600v cap and the 220k resistor shows up but doesn't take the same route. and there's one wire in the layout that goes from pin seven of the 6v6 to pin 4 of the 12ax7 and i don't see a stright jump at all on the schematic.

well hell,now i'm not sure what the question is except why the difference and where'd the other wires go on the schematic?

[JohnnyG]

two of the wires would most likelly be the heater connections. depending on the schematic it may show the pins on the tube diagram for the heater connections butthen some just assume that everybody knows tubes need heater connections lol

the other wire may well be the case connection for earthing the shell of the tube (if it has one, thats what pin 1 on my 6v6 datasheet is defined as)

hope thats all helpful. if you can point us to a schem then we can give you any more help you need

[lovekraft]

Johnny's hit it - in most tube schematics, heater wiring is assumed and not explicitly drawn out. The heater winding should be connected to pins 2 and 7 on the 6V6, and 4+5 and 9 on the 12AX7. Pin 1 is (as he said) the 6V6's shield ground.

[unclej]

thanks johnny...i'm not having any trouble wiring it so i don't really need any help....yet. the layout that i have is fine and i'm not having any trouble following it. i'm just wondering why the schematic is so much different. i guess the real question is could any of you guys that have been doing this for a while build an amp with just the schematic and if so how would you know to put in the wires that are obviously needed but don't show up in the drawing?

[lovekraft]

Heater wiring is left to the builder's discretion (his design contribution, if you will ) - some push-pull amps actually use a 12 volt heater winding , and simply run the two power tube filaments in series and using only pins 4 and 5 on the 12A_7s. The more time you spend comparing amp schematics to the real thing, the easier it is to figure this stuff out.

[JohnnyG]

woot, i was useful

like lovekraft says, the more schematics and layouts you look at the more things you know without it having to be said.

its much like ground wires. you know they all have to go to the same point but the schemaic will just have the ground symbol instead

im planningto get down to building the ax84 P1 as soon as i have the cash and thats being done alloff the schematic. im making it on turret board and have already taken the time to draw up a layout for it.

tho im almost certain i couldnt have done that a yearago

[unclej]

well, i'm gettin' there...i can't remember anything that i've enjoyed learning any more than tube amps. don't think i'd be any where near this far along if i'd have tried to learn solid state or without all you guy's direction. thanks as always.

[lovekraft]

Doing layouts always gives me fits - even if you follow all the rules and spend time keeping everything well separated and grounded, I'm never sure it's not going to go batnuts until I've got it wired up and hit the switch! Like they say, it's not just a job, it's an adventure!

[JohnnyG]

im finding that with stomp boxes i much prefer the designing that the building....but then im having to put my circuits on perfboard :S

want to get to building an amp because a) im a cheap mofo and it just gives more scope for having it looks the way you want it to

what i really need is a small slave boy to just build all the circuits i design