Re: Nocturne Junior Backyard Preamp
Posted by fx-fidden on
URL: http://guitar-fx-layouts.238.s1.nabble.com/Nocturne-Junior-Barnyard-Preamp-tp50362p50374.html
Offical page https://www.thenocturnebrain.com/products/the-jr-barnyard
I'll do some speculation about the circuit.
«This FET based preamp uses a hand selected/spec'd NOS Motorola transistor».
If this pedal has just one transistor, the black one, so this pedal is not an exact copy of the preamp of the Gibson amp, but just a simple jfet boost/preamp with clipping diodes.
I could wrong, but I say that it has two transistors and in the top left part of the board there's the NOS transistor, a "metal can type", and we can see how it's completely covered by that transparent plastic to keep the secret. So if the transistors are at least two, the schematic could be close to this EH150 preamp (look just at the two first tube 6F5 and 6N7):
The Grits Gain pot is the Gain control in the EH-150 schematic 0.5M pot (500k), and it should cut the volume, too, if it's exactly the same. The Volume pot probably a Volume Master (10k? 100k?) at the and of the circuit.
«It has a Body depth switch (deep & Flat) and Bright switch [...]. it just flat out brings you into the front of mix with reedy vintage warmth and definition [...]».
This didn't say too much about those swtch, but we can see even a switch in the end of the preamp schematic to cut low end. Maybe is the Bright/Wooly switch, the one on the upper side of the pedal in the gutshot. It adds that blue cap.
The other switch swaps two caps: a big yellow and a small red caps. The value are covered. That should be a Bass/Guitar mode. It can be done replacing the original cap before the Gain pot with another bigger pot to cut less low and and allow the use of the pedal with a bass. Or change one of the bypass cap connected to the one of transistors, I assume the first one, with a larger cap, again to cut les bass. But I said the bypass caps are placed on the board and they should be electrolytic (10uF).
The Grits On/Off Switch replace the dual input. It make, probably, the same thing of the EH-150 amp: bypass the first stage, that is the gain stage, and it goes directly in the second stage, for a cleaner sound.
«a mix of imported Soviet germanium & Fairchild silicon diodes».
I see something in the top right part of the board. Placed vertically those could be a transparent diode (germanium) and a black diode (silicon like 1N400X).
We don't know how that are used, but it probably as hard clipping. Without those diodes probably when the Grit pot mode is off the pedals would sound very clean.
«I added a second channel that blends in the hotter mic channel of the EH185 to it so I could dial in more texture and finger tone for my vintage style big bobbin single coil guitars. (thats the stomp switch on the left) too boot!».
The new V2 version (with smd components) doesn't have the Grit switch, but a pot to blend the two channels. This version has just two knobs, so I assume the Gain pot is missing and just set at max.
I think the bland of the two channels could be done in a pair or different ways.
I don't know if this board has one, but an electrolytic cap as power filter it's a good idea if you have to use with a PSU.
What do you think?
URL: http://guitar-fx-layouts.238.s1.nabble.com/Nocturne-Junior-Barnyard-Preamp-tp50362p50374.html
Offical page https://www.thenocturnebrain.com/products/the-jr-barnyard
I'll do some speculation about the circuit.
«This FET based preamp uses a hand selected/spec'd NOS Motorola transistor».
If this pedal has just one transistor, the black one, so this pedal is not an exact copy of the preamp of the Gibson amp, but just a simple jfet boost/preamp with clipping diodes.
I could wrong, but I say that it has two transistors and in the top left part of the board there's the NOS transistor, a "metal can type", and we can see how it's completely covered by that transparent plastic to keep the secret. So if the transistors are at least two, the schematic could be close to this EH150 preamp (look just at the two first tube 6F5 and 6N7):
The Grits Gain pot is the Gain control in the EH-150 schematic 0.5M pot (500k), and it should cut the volume, too, if it's exactly the same. The Volume pot probably a Volume Master (10k? 100k?) at the and of the circuit.
«It has a Body depth switch (deep & Flat) and Bright switch [...]. it just flat out brings you into the front of mix with reedy vintage warmth and definition [...]».
This didn't say too much about those swtch, but we can see even a switch in the end of the preamp schematic to cut low end. Maybe is the Bright/Wooly switch, the one on the upper side of the pedal in the gutshot. It adds that blue cap.
The other switch swaps two caps: a big yellow and a small red caps. The value are covered. That should be a Bass/Guitar mode. It can be done replacing the original cap before the Gain pot with another bigger pot to cut less low and and allow the use of the pedal with a bass. Or change one of the bypass cap connected to the one of transistors, I assume the first one, with a larger cap, again to cut les bass. But I said the bypass caps are placed on the board and they should be electrolytic (10uF).
The Grits On/Off Switch replace the dual input. It make, probably, the same thing of the EH-150 amp: bypass the first stage, that is the gain stage, and it goes directly in the second stage, for a cleaner sound.
«a mix of imported Soviet germanium & Fairchild silicon diodes».
I see something in the top right part of the board. Placed vertically those could be a transparent diode (germanium) and a black diode (silicon like 1N400X).
We don't know how that are used, but it probably as hard clipping. Without those diodes probably when the Grit pot mode is off the pedals would sound very clean.
«I added a second channel that blends in the hotter mic channel of the EH185 to it so I could dial in more texture and finger tone for my vintage style big bobbin single coil guitars. (thats the stomp switch on the left) too boot!».
The new V2 version (with smd components) doesn't have the Grit switch, but a pot to blend the two channels. This version has just two knobs, so I assume the Gain pot is missing and just set at max.
I think the bland of the two channels could be done in a pair or different ways.
I don't know if this board has one, but an electrolytic cap as power filter it's a good idea if you have to use with a PSU.
What do you think?
I build pedals
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