Pharaoh diode toggle question

[medio-core]

Hello,

Just built a Pharaoh clone on a Fuzz Dog board. Works well and I'm mostly happy. But that middle no diode clipping option is just stupid loud. I will probably never use it. If I were to use a SPDT on/on/on (replacing the on/off/on) would the middle position give me both diodes at once instead of none?

Or is there even a point in wanting the ge and si diodes simultaneously? I guess it might just sound like ge since they would squash the signal more than si anyway?

Thanks for your time!

[mth5044]

Hello!

Could you link to the schematic you're talking about?

However, to my knowledge, SPDT on/on/on aren't real. You could put in a DPDT on/on/on, but it won't be a drop in replacement, and as you say, the germanium may conduct first and the si may not do it's thing.

Perhaps trying something like this would give you a new flavor for the center position?

http://www.muzique.com/news/diode-clipping-switch/

[fuzzmax]

What if you use a two positions switch (on/on)?  You simply eleminates the middle position option.

[antonis]

To avoid big loudness step when clipping bypassed you need a switch that connects in series a resistor to account for extra voltage drop such as output signal level should be similar to clipped one..
(Big Muff tonestack bypass switch wiring is a good example..)

(perfectionists do it even for different clipping level diode pairs..) 

[j_flanders]

How about:
red LED's in the middle OFF postion (still pretty loud, but much quieter than opamp clipping)
GE in one ON position (parallel to the LEDs, so you'll only hear the GE's)
Si in the other ON position (parallel to the LEDs, so you'll only hear the Si's)

[medio-core]

Thanks for all the replies so far!

Here is a link to the specific pcb I'm using- https://shop.pedalparts.co.uk/Ramesses_Fuzz/p847124_14708980.aspx

I did mean DPDT on/on/on, not SPDT, sorry about that. As much as I like have the switch mounted directly to the board I'm totally open to going offboard to add a DPDT. I think LEDs might be a good option, great call out!

[ElectricDruid]

How about:
red LED's in the middle OFF postion (still pretty loud, but much quieter than opamp clipping)
GE in one ON position (parallel to the LEDs, so you'll only hear the GE's)
Si in the other ON position (parallel to the LEDs, so you'll only hear the Si's)

+1. Yeah, this was my thought too. Put the diodes with the biggest drop in permanently, and then use the switch to switch the others in the two 'on' positions. When they're on, the permanently-in-position set won't really do anything much.

[medio-core]

Right on, thanks everyone! Sounds like leds are a good route to go.
Is there a way to incorporate the leds in with the existing spdt on/off/on switch? I don't have an issue going to a dpdt but it can be a pain to remove switches from a pcb, trying to work smarter than I normally do so I'm open to suggestions.

[ElectricDruid]

Have you got a link to a picture of the board and/or a schematic? We could probably show you where to connect them up.

[medio-core]

I don't have an image of the board at the moment, but here is a link to the project docs and schematic-

https://shop.pedalparts.co.uk/Ramesses_Fuzz/p847124_14708980.aspx

[antonis]

You may as well connect LED pair on D3 anode/D4 cathode or on Q3 Collector (right BJT leg) or even on R17 opposite to +9V leg.. 

[medio-core]

Awesome, thanks so much! This forum seriously rules.

Seems like going on D3/D4 would give me the most space to fit the LEDs in, but R17 looks like it would work well too. Any specific benefits of doing one over the other? Just asking for my own edification and knowledge.

I'm thinking a pair of 5mm red diffused LEDs?

Has anyone else cloned the Pharaoh and made changes or tweaks you like? I lowered the input and output caps to 1uf to tighten up the bass a bit, it feels more guitar friendly and less boomy now.

[antonis]

Seems like going on D3/D4 would give me the most space to fit the LEDs in, but R17 looks like it would work well too. Any specific benefits of doing one over the other?

If you wish to permanently place LED pair on PCB, D5 cathode (or D6 anode) should be more space convenient..

No other reason for doing so, such as cross-talk inteference or stray capacitance issues prevent..
(although - ideally -  LED pair should be lied in parallel with R15 placed somewhere on "free" space above D5/D6 diodes..)

[medio-core]

I finally had a chance to sit down on work on this, I got the LED pair added. It definitely added a cool clipping option in the middle "off" position, which I prefer to the no diode option. Didn't really seem to change much in terms of the volume jump. I know from other mods I've done that LEDs have a lot of headroom, but I was still thinking it wouldnt be such a massive jump.