Sweet Honey Overdrive Clipping Question

[lars-musik]

Dear Forum,
I am in the process of building a Sweet Honey Overdrive for a friend who has very fine ears and often enjoyed different clipping diodes and their corresponding compression behaviour.

Now I have this Overdrive on my workbench and thought it would be a good idea do offer some options in the hard – and softclipping department.  So I stuck two on-off-on DPDTs on the circuit for soft clipping I tried: two back-to-back red LEDs (as in the original, Fv about 1.6V) OR two UV-LEDs (Fv about 3.9V) OR none at all.

The different was not detectable to my ears. Then I tried gemaniums instead of the UV LEDs and got some sputtery and gated decay. So the soft clipping seems not the right spot for modifications in that circuit.

Then I went to the hard-clipping section and tried 1N4001 as per stock configuration (I hadn't any 1N4007 as in the "real" one) OR LEDs  OR off. And this is what really puzzles me:

I can't hear ANY difference between no hard clipping at all and the diodes switched in.
Then I connected my oscilloscope and there also I see no difference between the two clipping states.

(By the way: At approx. 7% of the drive pot rotation the clipping seems already to be at its maximum. Maybe that circuit would be better of with a smaller or reverse log pot. Will try that later)



Here are my questions (I hope somebody is willing to answer):
- Is this possible? Is this circuit designed in a way, that signal in the place of the clipping diodes never reaches the clipping threshold?
- Shouldn't clipping thresholds of 1.6V vs 3.9V in the soft clipping configuration make any audible difference?
- Why do the germanium diodes in the soft clipping gate the signal?
- Is my test setting plausible? 1500 Hz at 300mVpp (I tried to gather the signal strength of my Rickenbacker copy and thought this might be close)

Thanks!

Here's the schematic I am working with:

[Kipper4]

For reference Lars which diagram where you working from please.

[amz-fx]

The low E string on a guitar is about 82 Hz and the high E string is around 330 Hz.  You test signal should probably fall in that range. I typically use 200 Hz.

Best regards, Jack

[blackieNYC]

+1, also - what p-p voltages are those later images?  If that 300mv is the same scale as the rest of the pics, you haven't reached clipping.

[lars-musik]

For reference Lars which diagram where you working from please.

Hey Rich, there's the schematic attached to the first post. Isn't it available to you?


Gesendet von meinem Lenovo K33a48 mit Tapatalk

[anotherjim]

Try removing that "focus" control path. It's sending negative feedback to the clipping amp and cleaning it up somewhat, I suspect.

[Kipper4]

Sorry Lars I couldn't see it last night. Yours is the same as the one I found online.
I really like this one. It's an always on.

If you take away the focus path isnt all thats left, just a tube screamer?

I like the soft clipping.

[lars-musik]

Thanks for your input guys. I did some more experimenting and found that the LED in the second opamp feedback loop does most of the clipping in the circuit. When this one is taken out it makes a nice difference.

Try removing that "focus" control path.

I am not sure if I'd like the circuit with no tone control at all. But I may try it just for completeness sake.

I really like this one. It's an always on.
I like the soft clipping.

I just can't understand why Bearfoot and EQD designed it so that there is a hard clipping section that doesn't seem to have any impact?
I am pretty sure I didn't make a mistake because Diptrace kindly compares the layout to the schematic and Kipper just confirmed that one.


Now one final question: Is it possible that in that special circuit the opamp type makes all the difference? I have no OP275 at hand but thought that a NE5532 should do the job just fine.... Right?

[Kipper4]

Hum Dunno I always use the OP275

[karbomusic]

Not familiar with this circuit but I see small differences in the bottom two images. The point I'm heading to is I tend to also look for changes in FFT readout of harmonics when playing with small differences in diode configs. I assume you are looking for more difference here regardless but just wanted to mention. You might also try a triangle wave in addition to a sine as that will help distinguish small differences better on the scope.

[samhay]

I would only expect to see the hard clipping diodes come into play when the focus control is at one end - can't read the numbering to see which way is ccw.
This will also be rather frequency dependent - have you run this at a number of signal frequencies?

[lars-musik]

This will also be rather frequency dependent - have you run this at a number of signal frequencies?

The point I'm heading to is I tend to also look for changes in FFT readout of harmonics when playing with small differences in diode configs. .... You might also try a triangle wave in addition to a sine as that will help distinguish small differences better on the scope.

I tried to convince a colleague whom I know to have NI Multisim at work to run this for me... But obviously he doesn't owe me enough, so no luck (SPICE always eluded me). So unfortunately no multiband analysis. But it seems that my grasp of clipping thresholds was to simplistic...
However, I will give some other frequencies and a triangle wave a go next time.

[samhay]

For what it's worth, an LTSpice sim shows that D1 and D2 do something if the input signal is at least ~50 mV peak-to-peak. This is when the drive and focus pots are at max resistance (500k and 50k, respectively).

It has an interesting frequency response - quite scooped under these conditions.

For anyone who wants to play along at home, here is the LTSpice .asc file:
(I used 2x 1N4148 for each LED and 1N4148 in place of the 1N400x).

Code Select Expand


Version 4
SHEET 1 1836 1408
WIRE -368 -256 -704 -256
WIRE -240 -256 -368 -256
WIRE -704 -192 -704 -256
WIRE -688 -192 -704 -192
WIRE -608 -192 -624 -192
WIRE -512 -192 -544 -192
WIRE -368 -144 -368 -256
WIRE 16 -128 0 -128
WIRE 96 -128 80 -128
WIRE 176 -128 160 -128
WIRE -704 -112 -704 -192
WIRE -688 -112 -704 -112
WIRE -608 -112 -624 -112
WIRE -512 -112 -512 -192
WIRE -512 -112 -544 -112
WIRE -944 -32 -976 -32
WIRE -832 -32 -864 -32
WIRE -816 -32 -832 -32
WIRE -704 -32 -704 -112
WIRE -704 -32 -736 -32
WIRE -688 -32 -704 -32
WIRE -512 -32 -512 -112
WIRE -512 -32 -528 -32
WIRE -368 -32 -368 -64
WIRE -240 -32 -240 -256
WIRE -112 -16 -144 -16
WIRE 0 -16 0 -128
WIRE 0 -16 -32 -16
WIRE 16 -16 0 -16
WIRE 128 -16 96 -16
WIRE 176 -16 176 -128
WIRE 176 -16 128 -16
WIRE -976 0 -976 -32
WIRE -832 0 -832 -32
WIRE -144 16 -144 -16
WIRE -368 80 -368 48
WIRE -240 80 -240 48
WIRE 0 80 0 -16
WIRE 32 80 0 80
WIRE 128 80 128 -16
WIRE 128 80 96 80
WIRE 288 80 240 80
WIRE 400 80 352 80
WIRE -976 96 -976 64
WIRE -832 96 -832 64
WIRE -704 96 -704 -32
WIRE -672 96 -704 96
WIRE -576 96 -608 96
WIRE -512 96 -512 -32
WIRE -512 96 -576 96
WIRE -144 112 -144 80
WIRE 0 176 0 80
WIRE 32 176 0 176
WIRE -704 192 -704 96
WIRE -672 192 -704 192
WIRE 128 192 128 80
WIRE 128 192 96 192
WIRE 176 192 128 192
WIRE 240 192 240 80
WIRE 272 192 240 192
WIRE 400 192 400 80
WIRE 400 192 352 192
WIRE 480 192 400 192
WIRE -576 208 -576 96
WIRE -576 208 -608 208
WIRE -560 208 -576 208
WIRE -480 208 -496 208
WIRE -368 208 -368 144
WIRE -368 208 -400 208
WIRE -336 208 -368 208
WIRE -240 208 -240 144
WIRE -240 208 -256 208
WIRE -208 208 -240 208
WIRE -16 208 -144 208
WIRE 32 208 -16 208
WIRE -1056 224 -1088 224
WIRE -976 224 -1056 224
WIRE -928 224 -976 224
WIRE -816 224 -864 224
WIRE -784 224 -816 224
WIRE -672 224 -704 224
WIRE 400 224 400 192
WIRE -816 256 -816 224
WIRE -240 256 -240 208
WIRE -976 272 -976 224
WIRE -368 272 -368 208
WIRE -368 272 -464 272
WIRE -16 288 -16 208
WIRE -464 304 -464 272
WIRE -368 304 -368 272
WIRE -1056 320 -1056 304
WIRE 400 336 400 304
WIRE -816 352 -816 336
WIRE -976 384 -976 352
WIRE -16 384 -16 368
WIRE -464 400 -464 368
WIRE -416 400 -464 400
WIRE -368 400 -368 368
WIRE -368 400 -416 400
WIRE -240 400 -240 320
WIRE -416 416 -416 400
WIRE -1104 496 -1136 496
WIRE -944 496 -960 496
WIRE -864 496 -944 496
WIRE -800 496 -864 496
WIRE -1136 512 -1136 496
WIRE -944 528 -944 496
WIRE -416 528 -416 496
WIRE -944 624 -944 608
WIRE -864 624 -944 624
WIRE -816 624 -864 624
WIRE -944 640 -944 624
WIRE -864 640 -864 624
WIRE -1136 736 -1136 592
WIRE -944 736 -944 720
WIRE -944 736 -1136 736
WIRE -864 736 -864 704
WIRE -864 736 -944 736
WIRE -1136 768 -1136 736
FLAG -1056 320 0
FLAG -1088 224 IN
IOPIN -1088 224 In
FLAG -800 496 V+
FLAG -1136 768 0
FLAG 480 192 OUT
IOPIN 480 192 Out
FLAG -816 624 Vb
FLAG 400 336 0
FLAG -864 560 0
FLAG -640 176 V+
FLAG -640 240 0
FLAG -816 352 Vb
FLAG -976 384 0
FLAG -976 96 0
FLAG -832 96 0
FLAG -240 400 0
FLAG -16 384 Vb
FLAG 64 160 V+
FLAG 64 224 0
FLAG -144 112 0
FLAG -416 528 0
SYMBOL voltage -1136 496 R0
WINDOW 0 -21 56 Left 2
WINDOW 3 12 57 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 9
SYMBOL voltage -1056 208 R0
WINDOW 0 -5 58 Left 2
WINDOW 3 -77 154 Invisible 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value SINE(0 {A} {F} 5m 0 0 20)
SYMATTR Value2 AC 1 0
SYMBOL EuropeanPolcap -880 640 R0
SYMATTR InstName C2
SYMATTR Value 22µ
SYMBOL EuropeanResistor -960 512 R0
SYMATTR InstName R1
SYMATTR Value 47k
SYMBOL EuropeanResistor -960 624 R0
SYMATTR InstName R2
SYMATTR Value 47k
SYMBOL EuropeanResistor 384 208 R0
SYMATTR InstName R14
SYMATTR Value 50k
SYMBOL EuropeanResistor -944 480 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 51
SYMBOL EuropeanPolcap -880 496 R0
SYMATTR InstName C11
SYMATTR Value 100µ
SYMBOL EuropeanResistor 368 176 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R24
SYMATTR Value 47k
SYMBOL EuropeanCap -864 208 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 47n
SYMBOL schottky -1104 512 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D2
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL EuropeanResistor -992 368 M180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R25
SYMATTR Value 1Meg
SYMBOL EuropeanResistor -800 208 M90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R23
SYMATTR Value 6.8k
SYMBOL EuropeanResistor -240 192 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL EuropeanResistor -800 352 R180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R9
SYMATTR Value 300k
SYMBOL EuropeanCap -608 80 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value 100p
SYMBOL EuropeanResistor -704 -48 M90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 3.3k
SYMBOL EuropeanResistor -624 -48 M90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R6
SYMATTR Value {DRIVE}
SYMBOL EuropeanResistor -832 -48 M90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 1k
SYMBOL EuropeanResistor -960 -48 M90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R8
SYMATTR Value 5.6k
SYMBOL EuropeanPolcap -992 0 R0
SYMATTR InstName C5
SYMATTR Value 22µ
SYMBOL EuropeanCap -816 64 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 4 Left 2
SYMATTR InstName C6
SYMATTR Value 220n
SYMBOL EuropeanCap -352 144 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 4 Left 2
SYMATTR InstName C7
SYMATTR Value 22n
SYMBOL EuropeanResistor -352 -48 M0
SYMATTR InstName R10
SYMATTR Value {FOCUS}
SYMBOL EuropeanCap -224 144 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 4 Left 2
SYMATTR InstName C8
SYMATTR Value 4.7n
SYMBOL EuropeanResistor -224 -48 M0
SYMATTR InstName R11
SYMATTR Value 150k
SYMBOL EuropeanCap -224 320 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 4 Left 2
SYMATTR InstName C9
SYMATTR Value 22n
SYMBOL EuropeanCap -208 224 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C10
SYMATTR Value 22n
SYMBOL EuropeanResistor 0 384 R180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R12
SYMATTR Value 1Meg
SYMBOL EuropeanPolcap -560 224 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C1
SYMATTR Value 1µ
SYMBOL EuropeanPolcap 176 176 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C3
SYMATTR Value 1µ
SYMBOL EuropeanCap 288 96 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C12
SYMATTR Value 4.7n
SYMBOL EuropeanCap 96 64 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C14
SYMATTR Value 100p
SYMBOL EuropeanResistor 112 -32 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 5.6k
SYMBOL EuropeanPolcap -160 16 R0
SYMATTR InstName C15
SYMATTR Value 22µ
SYMBOL EuropeanResistor -128 -32 M90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 2.6k
SYMBOL diode 16 -112 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 96 -112 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D3
SYMATTR Value 1N4148
SYMBOL diode -688 -176 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D4
SYMATTR Value 1N4148
SYMBOL diode -608 -176 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL diode -544 -96 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D6
SYMATTR Value 1N4148
SYMBOL diode -624 -96 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D7
SYMATTR Value 1N4148
SYMBOL EuropeanResistor -496 192 M90
WINDOW 0 2 53 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R16
SYMATTR Value 2.2k
SYMBOL Opamps/LT1001 -640 144 R0
SYMATTR InstName U2
SYMBOL Opamps/LT1001 64 128 R0
SYMATTR InstName U4
SYMBOL diode -480 368 M180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D8
SYMATTR Value 1N4148
SYMBOL diode -384 304 R0
SYMATTR InstName D9
SYMATTR Value 1N4148
SYMBOL EuropeanResistor -400 512 R180
WINDOW 0 31 76 Left 2
WINDOW 3 31 40 Left 2
SYMATTR InstName R17
SYMATTR Value {SW}
SYMBOL EuropeanResistor -352 -160 M0
SYMATTR InstName R18
SYMATTR Value 13.7k
TEXT -1184 -248 Left 2 !.tran 5 20m 0 1m\n;.ac oct 10 1 100000\n.param A = 0.1\n.param F = 440\n.param DRIVE = 500k\n.param FOCUS = 50k\n.step param SW list 1, 100Meg



[lars-musik]

here is the LTSpice .asc file:
(I used 2x 1N4148 for each LED and 1N4148 in place of the 1N400x).

Gosh! Did you just enter the schematic and run the simulations? Are you so fast with this stuff?

Thanks a lot for that information.

[samhay]

Yes - the only real time it takes is that to re-draw the schematic.
Happy to help.

[anotherjim]

I didn't mean permanently remove the  focus. But any clipping effects are reduced by that path. So if you want to see exactly what the diodes can do, you need to remove it, since that control only has a min-max range -  it don't go to "off".