Monarch

Chuck D. Bones

Well-known member
Here it is, the famous (infamous?) Monarch. Now that I have it working, I'm really liking this pedal. It's a great dirty boost that cleans up pretty well. Good control ranges.

Like many EQD pedals, this one requires mods to make it work right. The starting point is this schematic from Effects Layouts. Effects Layouts (Tangerine), Pedal Parts (Orange King) and Stewmac offer, or have offered Monarch kits. They all match the schematic below, except for one resistor value (R6). It's a simple design. 1st stage is basically a SHO. Next comes a James tone stack, followed by a gain control. After that we have a mu-amp, a source-follower and finally a mild low-pass filter.

EQD Monarch (Tangerine) sch.png

How does this thing even work?
Major design flaw #1: no DC bias path for Q2's gate. Easily fixed by jumpering C9, Removing R11 and replacing C10 with a 10K resistor. The 10K resistor is a "gate stopper" that prevents RF oscillations.

Major design flaw #2: no DC bias path for Q4's gate. Easily fixed by replacing C12 with a 10K resistor. Again, the 10K gate stopper prevents RF oscillations.

With those changes the circuit works great. But why stop there?

FET Substitutions
Q1 is a MOSFET in the original circuit. Depending on whose schematic you're looking at, R6 is either 33Ω or 330Ω (see schematic above). The difference is about 8dB gain. MOSFETs and JFETs have the same transfer function (relationship between input and output), but JFETs are quieter and have more gain at these currents. I breadboarded it both ways and they sounded the same. I ended up going with a JFET. The biasing is slightly different, as you can see in my schematic. I selected a value for R6 that put Q1's drain voltage at 5V for maximum headroom. Different JFETs may require different resistor values. R6 ended up being large enough that it reduces the 1st stage gain, so I added bypass cap C19. That took the gain up to around 32dB, same as the MOSFET with R6 = 33Ω. I put a 470Ω resistor (R18) in series with C19 to bring the gain down to 24dB. Both settings sound good, so I added a switch to my breadboard that allows me to switch Q1's gain from 24dB to 32dB by shorting out R18. The lower gain setting (switch open) provides more headroom in the 1st stage if you want to play clean. The higher setting has a little more bite. You could go with the switch or hard-wire it for either gain.

There is nothing magic about the 2N5457 and since I don't have any, I tried PF5102 and MPF4393. Both work, but the PF5102 has slightly higher gain in this circuit so I went with that one. Other JFETs will also work. NB: not all 2N5457s will work in this circuit because their Vp range is so large. Whatever JFET you use, we want one with Vp no larger than 2V or we start losing too much headroom.

We set the drain current in the 2nd stage by selecting Q3 and/or adjusting R14. I went with 560Ω on my breadboard, although 1K works well too. I found that setting the current in the 2nd stage between 1mA & 2mA gives good results. An easy way to measure the 2nd stage drain current is to measure the voltage across R14 and divide by R14's resistance. On my breadboard, that voltage is 637mV. 637mV / 562Ω = 1.13mA.

Q4 does not need to be a JFET, a BJT works the same, sounds the same, has slightly more headroom and doesn't need a gate stopper resistor. I used a 2N5089. Just about any NPN will work, I even tried germanium and that worked too! But seriously, don't waste a germanium transistor here. It's just an emitter-follower, you won't get any extra mojo.

As always, mind the pinout when subbing transistors.
Monarch cb mod v1.4.png

Tone Controls
They work pretty well. I have no idea how well their sound matches an Orange amp. The component values in the Monarch's tone stack deviate from the Orange amp somewhat. If you want the sound and feel of a Monarch, leave the values as-is. Otherwise, experiment! You can use Duncan's Tone Stack Calculator to see what happens when you changes the R's & C's. B1M pots may work better for BASS & TREBLE if you prefer settings at the top end of their ranges.

Level Control
At full boogie, this pedal makes well over 3.5Vp-p at the output jack. EQD put in a B-taper LEVEL pot. An A-taper is more appropriate in my opinion. Even with an A100K, unity is pretty low - between 8:00 and 9:00.

Presence Control
I added a PRESENCE control after Q4 to allow me to reign in the higher-order harmonics generated in the 2nd stage when the GAIN is set high. See my schematic above for the details. When PRESENCE is dimed, it is slightly brighter than a stock Monarch. At 4:00 it's about the same as the Monarch and it gets gradually darker as you turn it down. You could make PRESENCE an internal trimpot if you like. C16 & R17 don't do anything within the range of human hearing, so they're gone in my circuit.

Other Mods
Some of the capacitor values are a bit silly. C3 is 68nF in the Orange amp. 100nF has the same freq response as 470nF, so use whatever you have. C14 can be as low as 100nF and have the same freq response. I used 220nF for both.
I picked a value for C19 that provides strong bass response, even in the higher-gain mode. If you want less bass in the higher-gain mode, reduce C19.
C13 controls the bass response in the 2nd stage and dominates the pedal's overall bass response. Reduce C13 to tighten the bass and increase it to fatten the bass.

One more thought... That BALLS switch could be a stomp switch! We could add a pot to set how much gain boost we get when we hit the switch. Something like this:
Monarch cb mod v1.5.png

At this point, I think I've made enough changes that I can make like JHS and claim this design as my own.
 
Last edited:

chongmagic

Well-known member
Here it is, the famous (infamous?) Monarch. Now that I have it working, I'm really liking this pedal. It's a great dirty boost that cleans up pretty well. Good control ranges.

Like many EQD pedals, this one requires mods to make it work right. The starting point is this schematic from Effects Layouts. Effects Layouts (Tangerine), Pedal Parts (Orange King) and Stewmac offer, or have offered Monarch kits. They all match the schematic below, except for one resistor value (R6). It's a simple design. 1st stage is basically a SHO. Next comes a James tone stack, followed by a gain control. After that we have a mu-amp, a source-follower and finally a mild low-pass filter.

View attachment 8686

How does this thing even work?
Major design flaw #1: no DC bias path for Q2's gate. Easily fixed by jumpering C9, Removing R11 and replacing C10 with a 10K resistor. The 10K resistor is a "gate stopper" that prevents RF oscillations.

Major design flaw #2: no DC bias path for Q4's gate. Easily fixed by replacing C12 with a 10K resistor. Again, the 10K gate stopper prevents RF oscillations.

With those changes the circuit works great. But why stop there?

FET Substitutions
Q1 is a MOSFET in the original circuit. Depending on whose schematic you're looking at, R6 is either 33Ω or 330Ω (see schematic above). The difference is about 8dB gain. MOSFETs and JFETs have the same transfer function (relationship between input and output), but JFETs are quieter and have more gain at these currents. I breadboarded it both ways and they sounded the same. I ended up going with a JFET. The biasing is slightly different, as you can see in my schematic. I selected a value for R6 that put Q1's drain voltage at 5V for maximum headroom. Different JFETs may require different resistor values. R6 ended up being large enough that it reduces the 1st stage gain, so I added bypass cap C19. That took the gain up to around 32dB, same as the MOSFET with R6 = 33Ω. I put a 470Ω resistor (R18) in series with C19 to bring the gain down to 24dB. Both settings sound good, so I added a switch to my breadboard that allows me to switch Q1's gain from 24dB to 32dB by shorting out R18. The lower gain setting (switch open) provides more headroom in the 1st stage if you want to play clean. The higher setting has a little more bite. You could go with the switch or hard-wire it for either gain.

There is nothing magic about the 2N5457 and since I don't have any, I tried PF5102 and MPF4393. Both work, but the PF5102 has slightly higher gain in this circuit so I went with that one. Other JFETs will also work. NB: not all 2N5457s will work in this circuit because their Vp range is so large. Whatever JFET you use, we want one with Vp no larger than 2V or we start losing too much headroom.

We set the drain current in the 2nd stage by selecting Q2 and/or adjusting R14. I went with 560Ω on my breadboard, although 1K works well too. I found that setting the current in the 2nd stage between 1mA & 2mA gives good results. An easy way to measure the 2nd stage drain current is to measure the voltage across R14 and divide by R14's resistance. On my breadboard, that voltage is 637mV. 637mV / 562Ω = 1.13mA.

Q4 does not need to be a JFET, a BJT works the same, sounds the same, has slightly more headroom and doesn't need a gate stopper resistor. I used a 2N5089. Just about any NPN will work, I even tried germanium and that worked too! But seriously, don't waste a germanium transistor here. It's just an emitter-follower, you won't get any extra mojo.

As always, mind the pinout when subbing transistors.
View attachment 8690

Tone Controls
They work pretty well. I have no idea how well their sound matches an Orange amp. The component values in the Monarch's tone stack deviate from the Orange amp somewhat. If you want the sound and feel of a Monarch, leave the values as-is. Otherwise, experiment! You can use Duncan's Tone Stack Calculator to see what happens when you changes the R's & C's. B1M pots may work better for BASS & TREBLE if you prefer settings at the top end of their ranges.

Level Control
At full boogie, this pedal makes well over 3.5Vp-p at the output jack. EQD put in a B-taper LEVEL pot. An A-taper is more appropriate in my opinion. Even with an A100K, unity is pretty low - between 8:00 and 9:00.

Presence Control
I added a PRESENCE control after Q4 to allow me to reign in the higher-order harmonics generated in the 2nd stage when the GAIN is set high. See my schematic above for the details. When PRESENCE is dimed, it is slightly brighter than a stock Monarch. At 4:00 it's about the same as the Monarch and it gets gradually darker as you turn it down. You could make PRESENCE an internal trimpot if you like. C16 & R17 don't do anything within the range of human hearing, so they're gone in my circuit.

Other Mods
Some of the capacitor values are a bit silly. C3 is 68nF in the Orange amp. 100nF has the same freq response as 470nF, so use whatever you have. C14 can be as low as 100nF and have the same freq response. I used 220nF for both.
I picked a value for C19 that provides strong bass response, even in the higher-gain mode. If you want less bass in the higher-gain mode, reduce C19.
C13 controls the bass response in the 2nd stage and dominates the pedal's overall bass response. Reduce C13 to tighten the bass and increase it to fatten the bass.

One more thought... That BALLS switch could be a stomp switch! We could add a pot to set how much gain boost we get when we hit the switch. Something like this:
View attachment 8689

At this point, I think I've made enough changes that I can make like JHS and claim this design as my own.
I remember us working on this circuit together Chuck. Once it worked it was great. I think EQD just throws stuff together sometimes with no idea if it is correct or not.
 

BurntFingers

Well-known member
If you made the 100k between the Bass and treble (r9) controls into a vr, would that work as a mids shift control?
 

Chuck D. Bones

Well-known member
Not really. It moves the crossover point a little bit, not enough to be useful. On the Orange Super Bass amp, R8 is a 100K MID pot. It doesn't do much unless TREBLE is dimed. If you want to move the BASS or TREBLE ranges, you have to mess with the caps.

Try these things with Duncan's Tone Stack Calculator and you'll see what I mean.
 

Chuck D. Bones

Well-known member
Chassis machining complete. Tayda "Glowing Orange," you need sunglasses to look at this thing.

Viceroy drilled enclosure - outside 02.jpg

Took a wire cup to the insides so the switches, jacks & pots will make metal-to-metal contact. I have to chase the threads because they get paint everywhere.

Viceroy drilled enclosure - inside.jpg
 

BPFuzz

Active member
Thanks for this! When I was first starting out last year, Stewmac had the official board kits for some of EQD's stuff. I almost grabbed a Monarch but went with the White Light. Then they all sold out before I grabbed any others.
 

Chuck D. Bones

Well-known member
Labels & better LED colors pending. Controls are:
(top row) LEVEL - PRESENCE - GAIN
(bottom row) BASS - TREBLE - JUICE
left switch is ENGAGE, right switch is JUICE
I renamed the boost control to a more family-friendly "JUICE."
Setting shown are for pretty heavy overdrive.

Viceroy - front 02.jpg

Viceroy - innards 02.jpg

I'm not nearly as A-R about wire routing as some folks here, but it freakin' works!

Beautiful tones from this thing. Between the JUICE & GAIN controls, it goes smoothly from clean to breakup. Lots of volume available for overdriving an amp. BASS, TREBLE & PRESENCE provide good EQ sculpting. Wonderful as a treble booster. So far, I'm happy with how the tone controls are tuned.

This is a keeper.

Here's the latest schematic. I used different JFETs (same part number) and did not have to adjust the bias.
Monarch cb mod v1.5a sch.png
 

mdc

Well-known member
I'd love to see the vero layout if you happened to draw one out in DIYLC.
Also, I hope you used EQD-spec blindness inducing clear LEDs for the sake of tradition.
 

Chuck D. Bones

Well-known member
I use VeroRoute to lay out my Vero boards. Board is 17 x 17. 14 cuts, 2 links.
1st pic is the assembly diagram. See schematic above for part values. C1 is MLCC. C11, C13, C18 are tantalum. C18 is aluminum. All other caps are film (I used silver-mica for C8, but film is also acceptable). If you plan on running this on 18V, make sure C18 is rated for 25V or higher. All resistors are metal film; I used carbon film for R20 and the LED resistors, but MF is ok too.

2nd pic is the actual cut board, viewed from the solder side.

Viceroy v1.5a assy dwg.png

Orange Viceroy bare board v1.5a (bottom view).png

Pots are:
JUICE - C1K
TREBLE, BASS & GAIN - A1M
PRESENCE - C100K
LEVEL - A100K

Outboard connections:
PRESENCE1 to LEVEL3
LEVEL2 to OUT
TREBLE2 to GAIN3
JUICE2 to JUICE sw1
JUICE sw2 to GND
LEVEL1 to GND
LED1+ and LED2+ to LED anodes
LED cathodes to stomp switches
 

mdc

Well-known member
Thanks so much! Any particular reason for the MLCC/tantalum caps or was it for spacing/layout reasons?
 

Chuck D. Bones

Well-known member
Thanks so much! Any particular reason for the MLCC/tantalum caps or was it for spacing/layout reasons?
MLCC had the right footprint for C1, I have a bunch and they are superior to disk ceramics. I prefer to use tantalum over aluminum in the audio path because tantalum is more transparent and much less leaky. But aluminum will fit and will work.

Also, vero-route looks very cool. Having all the connections traced seems super handy.

I really like using VeroRoute. It keeps track of the connections. It's easy to use and so far the only downside, if you can call it that, is sometimes I have to get "creative" with the parts to get the lead spacing the way I want. I didn't have to do it here, but somethimes I have to place a film cap where I know an electrolytic will go because the electrolytic's lead spacing is 0.1" and I want the leads to span 0.3".
 
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