Loundsberry Nigel Touch Overdrive  [traced]

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gigelmargel
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Post by gigelmargel »

Bside2234 wrote: 15 Jun 2021, 05:58
gigelmargel wrote: 15 Jun 2021, 05:04 Looking again at the photos, it seems to me that 390 ohms resistors could be 3.9K. I know that in a LPB-1 the stock value is 390 ohms, but with 3.9K I think that it sound more than an overdrive.
100% positive the resistor off the emitter of Q2 is 390Ω. I have some good pics of it and it is for sure Orange-White-Brown-Gold.
Have you measured the drains biasing voltages, Bside2234?

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Bside2234
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Post by Bside2234 »

gigelmargel wrote: 15 Jun 2021, 13:49
Bside2234 wrote: 15 Jun 2021, 05:58
gigelmargel wrote: 15 Jun 2021, 05:04 Looking again at the photos, it seems to me that 390 ohms resistors could be 3.9K. I know that in a LPB-1 the stock value is 390 ohms, but with 3.9K I think that it sound more than an overdrive.
100% positive the resistor off the emitter of Q2 is 390Ω. I have some good pics of it and it is for sure Orange-White-Brown-Gold.
Have you measured the drains biasing voltages, Bside2234?
No. It wasn't my pedal and I don't have it anymore so I can't be of any help there.

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gigelmargel
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Post by gigelmargel »

OK...thank you Bside2234!

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Manfred
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Post by Manfred »

i ran simulations for the first stage with the J201 and the second stage with the 2N3904, each by itself.
J201 stage:
Gain = 2 .
Start rounding of the positive half wave at about 780 Millivolts peak to peak.
2N3904 stage with emitter resistance = 390 Ohms:
Gain = 17.6 .
Start rounding of the positive half-wave at about 90 Millivolts peak to peak.
2N3904 stage with emitter resistor = 3.9 Kiloohms:
Gain = 2.2 .
Start rounding of the positive half-wave at about 320 Millivolts peak to peak.
I also recognize the value of the emitter resistor in the photo as 390 Ohms.
Perhaps the series connection of R1 and R4 at the input should be replaced by a 2.2 Megohm resistor with the wiper connected to the gate of Q1.
This way you would have a "sensitive potentiometer" to adapt to the output voltage of the pickup.

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Post by gigelmargel »

I replaced both J201 with 2SK170 and sounds the same (I have only a few J201) in terms of gain, clarity and sensitivity. I kept the gain control as I described above.

It's an amazing overdrive! Thank you all!

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Post by Manfred »

gigelmargel wrote: 16 Jun 2021, 21:17 I replaced both J201 with 2SK170 and sounds the same (I have only a few J201) in terms of gain, clarity and sensitivity. I kept the gain control as I described above.

It's an amazing overdrive! Thank you all!
I think Loundsberry will choose the J201.
I wonder if the J201 stages are designed to not clip over a wide input voltage range, or if they will distort and add to the overall overdrive tone.
Did you achieve the tone from the demo video in Youtube with your clone.
What drain voltage values did you set with the potentiometers?

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Post by gigelmargel »

I set the drains at 4.5 V.

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Post by Manfred »

I bought a Loundsberry Nigel Touch overdrive, but returned it because I did not get the tone I wanted.
It only works well with a tube amp, with a solid state and a modeling amp it sounded rather awful to my ears.
I took the opportunity and opened it, because I wanted to change the battery anyway, as the LED was glowing dimly.
I was amazed that the circuit is now built on a circuit board.
But it was not because of the battery but reason is the series resistor of 100 kiloohm to the LED, yes it is true.
No idea why Loundberry does this, maybe to have a glow lamp effect suitable for its vintage imprint.
Also new is that the clipping diodes are now both germanium types, which are obviously matched.
I made some measurements, traced the circuit and drew the schematic.
LoundsberryNigelTouch-OD_Layout.jpg
Nigel Touch OD Clipping Diodes.jpg
NigelTouchOverdriveSchematic.JPG

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Post by Manfred »

Now that I was back on the topic, I found an error in the circuit diagram, the LED series resistor was connected to the negative terminal of the battery instead of the positive potential.
Below the corrected schematic. I also made a strip layout a long time ago.

NigelTouchDriveStripLayout.jpg
NigelTouchDriveComponetsSide.pdf
(153.78 KiB) Downloaded 81 times
NigelTouchDriveSolderSide.pdf
(60.71 KiB) Downloaded 92 times
Edit:
NigelTouchDriveComponentSideEnlarged.pdf
(223.44 KiB) Downloaded 54 times
Edit Ge Germanium Clipping diodes replaced by 1N60P Schottkys
NigelTouchDriveCorrected2.jpg
Last edited by Manfred on 04 Dec 2022, 00:20, edited 2 times in total.

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Ben N
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Post by Ben N »

I don't understand the point of having a JFET driving the volume control/output. Surely that device isn't really being driven much after the clippers (or am I wrong about that?), and doesn't have the low Z-out that a BJT would. Can anyone explain that to me?

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Post by Manfred »

A BJT stage would have an input resistance less than or equal 50 kiloohms depending on the circuit structur and values, this would put more stress on the clipper section.
The JFET stage has an output resistance of 6.8 kilohms and in a corresponding BJT emitter circuit would have about half that.

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Post by Ben N »

Stress? How? The single stage Electra types go straight from clippers to output. Is there a real sonic/electrical benefit, other than level recovery, to the last stage? Not trying to be difficult, just to comprehend.

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Post by Manfred »

Ben N wrote: 01 Dec 2022, 12:20 Stress? How? The single stage Electra types go straight from clippers to output. Is there a real sonic/electrical benefit, other than level recovery, to the last stage? Not trying to be difficult, just to comprehend.
Sorry, that's what you get for writing in the middle of the night. I meant load not stress. :slap:

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Post by x-tn »

Manfred wrote: 09 Sep 2021, 12:53 ...Also new is that the clipping diodes are now both germanium types, which are obviously matched.
Those are 1N60P schottky diodes.

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Post by Manfred »

x-tn wrote: 03 Dec 2022, 19:43
Manfred wrote: 09 Sep 2021, 12:53 ...Also new is that the clipping diodes are now both germanium types, which are obviously matched.
Those are 1N60P schottky diodes.
I have both in my stock 1N60 germaniums and 1N60P Schottkys, so I was able to record the P/N junction curves from both.
You are right, compared to the recording of the diodes I made original pedal, these are 1N60P Schottkys.
I edited the last schematic and the vero layout above.
1N60P Schottky 1N60 Germanium Comparation.jpg

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