Aion FX L5 Build Questions…

[greatmagnet]

Hey so I don’t see any other forums out there where people are having conversations with @aion about his amazing PCBs, so I hope this is a good place to post questions. I could ask directly but why not share the love?

QUESTION 1:
What is the deal with the component on the parts list that is labeled as “RPD” and why is it given a RANGE of values…”1M to 2M2”? What exactly IS an RPD, and why is the exact value unimportant? In people’s build pics it seems to always be a different base color than the other resistors so I’m not sure if that implies it also may NOT be metal film but something else?

QUESTION 2:
So I’m actually gonna be mounting this in a rack enclosure, and as such I would love to be able to substitute 3PDT toggle switches instead of stomp switches. So what “unctionality of 3PDT toggle am I going to need for the “bypass” and the “channel” switches respectively? “on-off” and “on-on”? Something else?

Would love to have some knowledge on all if the above, and THANKS in advance!!!

[szukalski]

RPD is a pull-down resistor (Resistor Pull Down) to allow the coupling capacitor to  discharge if the input isn't grounded in the off state. Sometimes you get popping when switching, and this can help. If you don't have it then no problem.

Putting it into a rack just means using a toggle switch instead of a foot-switch like you mentioned. You want on-on. In and out are always going through the switch. One throw just connects them together, this is bypass. The other throw routes them through your effect.

[greatmagnet]

THANY You @szukalski !!!

So, just to be really clear (this is new territory for me)...

• The pull-down resistor can be any ol' metal film 1/4 watt I have laying around, as long as it falls within that value range?
  BOTH 3PDT toggles—the left side one for bypass, AND the right side one for channel—should be of the on/on variety?

Thanks again...really excited by this build!

[szukalski]

The resistor just needs to resist in that range. 3PDT are both on-on.

I would read the warning in the build docs.. if you're not experienced in building then leave this until you are. There is a higher chance of something going wrong, which will need troubleshooting and you may end up with a bunch of money stuck into a build which isn't working. Get a half-dozen overdrives under your belt and then give it a go.

[greatmagnet]

I've been doing this for a couple of years actually...this is just my first Aion build: I've been doing stuff from PedalPCB.com up to this point. There's just a scant few things unique to this build that I'm unfamiliar with, and of course it being a true preamp and two-channel, the component count is a bit higher than I'm used to.

[gordo]

Kevin is good people and his stuff is always stellar.  The L5 is a great project.  The only thing you need to pay attention to is your AC power supply.  I've had good luck using the 9vAC supply from a Yamaha pedal and an AC output from a Voodoo Labs Pedal Power AC.

[greatmagnet]

Yeah he’s been directly helpful with me more than once already!
One more question: is it REALLY okay that the output jack ONLY has the positive wire connected to it? There’s no ground wire connection shown in the build docs. I’ve never seen such a thing before…

[Invertiguy]

Yeah he’s been directly helpful with me more than once already!
One more question: is it REALLY okay that the output jack ONLY has the positive wire connected to it? There’s no ground wire connection shown in the build docs. I’ve never seen such a thing before…

It's usually fine in the case of a die-cast enclosure as long as you make sure the jack is contacting bare metal, the idea is that the circuit only gets grounded to the enclosure at a single point in order to prevent ground loops. It may or may not work in a rack mount unit depending on how conductive your front panel is. If you're worried about it just tie the grounds together, you probably won't hurt anything.

[greatmagnet]

That’s about what I figured was the safe bet thanks!

[Evilfartman]

Sorry to hijack the thread with a noob question, but is it possible to wire the aion boards directly to a switch without using the daughter board? I get the feeling this is a stupid question but I might as well ask

[mauman]

Sorry to hijack the thread with a noob question, but is it possible to wire the aion boards directly to a switch without using the daughter board?

In general, yes.  For some boards, Aion sells a "legacy" version that was designed for 1590B enclosure and doesn't have the daughter board.  You have to dig on Kevin's website but they're there.  For PCBs with daughter boards, you'll need to see what else is on the daughter besides foot switch connections - typically there's an LED current limiting resistor, some power protection/filtering, sometimes other stuff.  You can make a vero or perfboard with these items on it if you need the functionality without the daughter board.  The advantage to that is you can tuck a vero underneath the main PCB and save the space around the foot switch.   

[Evilfartman]

Sorry to hijack the thread with a noob question, but is it possible to wire the aion boards directly to a switch without using the daughter board?

In general, yes.  For some boards, Aion sells a "legacy" version that was designed for 1590B enclosure and doesn't have the daughter board.  You have to dig on Kevin's website but they're there.  For PCBs with daughter boards, you'll need to see what else is on the daughter besides foot switch connections - typically there's an LED current limiting resistor, some power protection/filtering, sometimes other stuff.  You can make a vero or perfboard with these items on it if you need the functionality without the daughter board.  The advantage to that is you can tuck a vero underneath the main PCB and save the space around the foot switch.

Fair enough, thanks for asking. I haven't yet got my head around vero but I'll take a look at the legacy boards