FAC control orange amps etc

[wildebelor]

So I've done some searching and haven't really had any luck with getting answers.

What capacitor in the circuit is the FAC control changing on orange amps etc?
Or am I totally off the mark? I know it's a rotary switch with usually 6 capacitors wired to it - allowing for better bass response.
But where is it placed in the circuit?

I noticed that there have been a few different pedals along the years with this control and I'm really intrigued by it.
It adds a lot of tonal options on my amps so I figured why not add it to a pedal!

Thanks in advance! 

[teemuk]

It's the coupling cap of the 2nd gain stage.

Why not Google search Orange schematics to find out yourself...

[diydave]

As teemuk said.
Just build an orange graphic clone with the FAC-control.
Adds bass to the amp... a whole lotta bass.

[Davelectro]

There were at least three different locations for the FAC control (input / after first stage / between tonestack and phase inverter).

The first Orange amps had it right at the input. Many people say those are the best sounding ones.

[R.G.]

And could you please go to a non-animated avatar?

[duck_arse]

^ it certainly is attention getting.

[wildebelor]

There were at least three different locations for the FAC control (input / after first stage / between tonestack and phase inverter).

The first Orange amps had it right at the input. Many people say those are the best sounding ones.

So the FAC on the early orange amps were switching the input capacitor?
I know a guy with an OR120 and OR80 that have an incredibly versatile FAC but I'm unsure exactly what year they are -  I know they are original however.

And sorry about the avatar guys - had to head out and pick up a friend unexpectedly last night and I ended up in a car accident!
haven't had the chance to change it to something better until now.

[Davelectro]

So the FAC on the early orange amps were switching the input capacitor?

Yes.

Take a look: http://www.orangefieldguide.com/OFG_SCHEM/GRO100_preamp.jpg

[wildebelor]

I ended up diving in anyway and it turned out perfect! I wish this was something on all distortion / fuzz / overdrive pedals!!! 

[wavley]

As teemuk said.
Just build an orange graphic clone with the FAC-control.
Adds bass to the amp... a whole lotta bass.

I tend to think of it the other way, it's taking away bass that's already there by adding series capacitance to the second/third stage coupling cap, as you make the series cap smaller the knee of the HPF gets higher in frequency.

So I've done some searching and haven't really had any luck with getting answers.

What capacitor in the circuit is the FAC control changing on orange amps etc?
Or am I totally off the mark? I know it's a rotary switch with usually 6 capacitors wired to it - allowing for better bass response.
But where is it placed in the circuit?

There's an Orange amp field guide on the internet that has all the classic Orange schematics.  But we need to think of it as a "less bass" not a "more bass" switch, at it's lowest setting it's a straight wire after the .068uF second stage coupling cap, as you turn it up it progressively adds smaller caps in series, caps in series lower the capacitance (but increase the voltage rating).  The lower capacitance = less bass at it's highest setting it's 203pF.

So the FAC on the early orange amps were switching the input capacitor?

Yes.

Take a look: http://www.orangefieldguide.com/OFG_SCHEM/GRO100_preamp.jpg

This is the only Orange model/schematic that has it as the input cap that I've ever seen.  I've never had the pleasure of playing an Orange from this early and would be curious to try one against the F.A.C. being after the second stage.

[diydave]

I tend to think of it the other way, it's taking away bass that's already there

Quite right... all those 68n coupling caps.
But because I have to turn the FAC clockwise to "uncut" the bass, it's like adding it (back). 

[Davelectro]

Note that the FAC control at the input works / is wired different than the one between second and third stages.