Soldano SLO100: analisi e modifiche
Inviato: 13/12/2008, 15:19
Ciao ragazzi,
riporto in questo forum i miei interventi sul thread di sloclone, così che qui fra noi si contribuisca più facilmente allo sviluppo di modifiche ed all'analisi del circuito.
Lo schema di riferimento è quello ufficiale di SloClone ovviamente.
Everything is interacting, but I'll start with some parts:
R2: grid stopper of the first gain stage: with miller effect of gain stage 1, avoids to amplify radio signals. Low pass filter @ 19.4 kHz. Lowering this resistor you'll have a more open sounding amp.
R3: cathode resistor: sets the working point of the gain stage, its gain and bias. With R4 and C1 you can choose gain, voice and eq shape of the first gain stage. Lowering you'll have more gain, a spike in low-mids, and higher cutoff point of Rk-Ck bypass gain, different saturation.
R4: plate resistor: sets the gain of the stage, its load line, and tone. Lowering you have less gain and a more open sound. This is one of the main point of the amp. You have to choose the right resistor (maybe 1W metal film) to reduce noise and have a good tone.
C1: with R3 and R4 chooses the frequency at which you want unbypassed to bypassed cathode gain (you know unbypassed gain is lower). Lowering you have a bright effect on sound, and less saturation (because the low-mids are less amplified). Something like a shelving effect.
C2: this cap is doing a hipass filter with a parallel of two series (R5+VR1)//(R10+VR2).
If you are on the clean channel you have (R5+VR1)//[(R6+R10)+(R7//VR2)]. Well, It's always about 500k load.
So you have a 14.46Hz hipass filter.
You can lower this value to something around 4n7 (67.7Hz). In this coupling stage I like cutting between 70 to 150Hz on higain stages. This removes fuzziness on top end.
C3: with R5 and VR1 sets the voice of the lead. MArshall has a 338Hz hipass here, with a 1/3 attenuation with pot on 10. Soldano uses a 144Hz hipass with a 1/2 attenuation with pot on 10. this makes the amp more rouchy and singing on leads. Lowering you have a brighter lead.
R5 and VR1: you can choose lower values in order to reduce noise (higher values of resistors keep more noise), and scaling C2 and C3 to the needed value. Too much values lowers the gain, so you'll need to recalculate the divider.
C6 (the one on VR1): is a hipass filter from tip to ground. With VR1 on half, the pin to gnd is 1/10 of VR1 value, so the hipass is @ 1.59 kHz.
R8: grid stopper of the second gain stage: with miller effect of gain stage 2, low pass filter @ 3.5 kHz. Lowering this resistor you'll have a more open sounding amp, but you have to take care of R5 too, and you can't lower this too value much.
R9: cathode resistor: sets the working point of the gain stage, its gain and bias. With R9 and C4 you can choose gain, voice and eq shape of the second gain stage. Lowering you'll have more gain, a spike in low-mids, and higher cutoff point of Rk-Ck bypass gain, different saturation. It's important to set this value so it saturates in a nice way with the previous stage.
C4: with R11 and R9 chooses the frequency at which you want unbypassed to bypassed cathode gain. Lowering you have a bright effect on sound, and less saturation (because the low-mids are less amplified). Something like a shelving effect.
R11: plate resistor: sets the gain of the stage, its load line, and tone. Lowering you have less gain and a more open sound. This is one of the main point of the amp. You have to choose the right resistor (maybe 1W metal film) to reduce noise and have a good tone. Again, is important to change this value looking at the previous stage too.
This gain stage is the one that has one of the highest swing on its output. You must have care of its supply.
C6: with R12 and R13 sets the voice of the second stage of the lead. Less important of the first stage bypass, but still evident. You have to cut what's below 70 to 150Hz here too. 2n2 is a good choice.
R12 and R13: this sets the swing to the third gain stage. If you want to keep the same dividing rate, you have to scale them as R12 is half of R13 (is a 1/3 attenuation, aka the output is 2/3 of the input). Lowering them too much you'll have a gain loss of the 2nd gain stage, and you'll have to change their values.
R14: cold stage cathode resistor: here you can change the harmonic content of the OD. Standard value, 39k, is a bit too Hard Rock oriented. 33k is just better to my taste, but I prefer lower values (eg 10-15k) to increase harmonics and saturation. With such low values you have to scale down the previous voltage divider (R12 + R13) to something like 470k + 470k, otherwise this stage and the next two stages (V3) will distort too much and you'll have a fuzzy sound.
Keep in mind that everything has to clip with the other stages in the same way, if you want to improve dynamics.
You can choose to have no cold stage, and use a 1k5 bypassed by 1uF, but you have to drop the signal before this stage (eg R12 120k and R13 33k) and also after the stage (otherwise V3 will distort too much).
You can play with values, but first times remember to keep the total amount of gain quite similar stage to stage.
R19: plate resistor of the cold stage. Play with R19 and R14 to keep the gain of the stage as 100k 39k, but with different sounds (eg R19 33k and R14 10k).
C9: plate resistor's bypass cap: just a rolloff of harshness. Cuts off highs. The right value changes due to how the previous stages makes the amp clip. I prefer not more than 470p, otherwise the stage loose punch.
C10: coupling cap: sets the low cut point with the parallel R18//R20, so R18 only. 22nF is the right value.
R20: just to keep the C10 grounded while you play on clean/crunch. 2M2 just not to change the R18 value when paralleled.
R18: load resistor for lead channel, part of the divider for clean/crunch channel. If you change this value, you'll have to rescale the clean channel. Keep this value.
R21: grid stopper of the 4th gain stage: with miller effect of gain stage, low pass filter @ 8.6 kHz. Lowering this resistor you'll have a more open sounding amp, but can became fuzzy. Raising the value you have a more focused amp, but with less harmonics.
riporto in questo forum i miei interventi sul thread di sloclone, così che qui fra noi si contribuisca più facilmente allo sviluppo di modifiche ed all'analisi del circuito.
Lo schema di riferimento è quello ufficiale di SloClone ovviamente.
Everything is interacting, but I'll start with some parts:
R2: grid stopper of the first gain stage: with miller effect of gain stage 1, avoids to amplify radio signals. Low pass filter @ 19.4 kHz. Lowering this resistor you'll have a more open sounding amp.
R3: cathode resistor: sets the working point of the gain stage, its gain and bias. With R4 and C1 you can choose gain, voice and eq shape of the first gain stage. Lowering you'll have more gain, a spike in low-mids, and higher cutoff point of Rk-Ck bypass gain, different saturation.
R4: plate resistor: sets the gain of the stage, its load line, and tone. Lowering you have less gain and a more open sound. This is one of the main point of the amp. You have to choose the right resistor (maybe 1W metal film) to reduce noise and have a good tone.
C1: with R3 and R4 chooses the frequency at which you want unbypassed to bypassed cathode gain (you know unbypassed gain is lower). Lowering you have a bright effect on sound, and less saturation (because the low-mids are less amplified). Something like a shelving effect.
C2: this cap is doing a hipass filter with a parallel of two series (R5+VR1)//(R10+VR2).
If you are on the clean channel you have (R5+VR1)//[(R6+R10)+(R7//VR2)]. Well, It's always about 500k load.
So you have a 14.46Hz hipass filter.
You can lower this value to something around 4n7 (67.7Hz). In this coupling stage I like cutting between 70 to 150Hz on higain stages. This removes fuzziness on top end.
C3: with R5 and VR1 sets the voice of the lead. MArshall has a 338Hz hipass here, with a 1/3 attenuation with pot on 10. Soldano uses a 144Hz hipass with a 1/2 attenuation with pot on 10. this makes the amp more rouchy and singing on leads. Lowering you have a brighter lead.
R5 and VR1: you can choose lower values in order to reduce noise (higher values of resistors keep more noise), and scaling C2 and C3 to the needed value. Too much values lowers the gain, so you'll need to recalculate the divider.
C6 (the one on VR1): is a hipass filter from tip to ground. With VR1 on half, the pin to gnd is 1/10 of VR1 value, so the hipass is @ 1.59 kHz.
R8: grid stopper of the second gain stage: with miller effect of gain stage 2, low pass filter @ 3.5 kHz. Lowering this resistor you'll have a more open sounding amp, but you have to take care of R5 too, and you can't lower this too value much.
R9: cathode resistor: sets the working point of the gain stage, its gain and bias. With R9 and C4 you can choose gain, voice and eq shape of the second gain stage. Lowering you'll have more gain, a spike in low-mids, and higher cutoff point of Rk-Ck bypass gain, different saturation. It's important to set this value so it saturates in a nice way with the previous stage.
C4: with R11 and R9 chooses the frequency at which you want unbypassed to bypassed cathode gain. Lowering you have a bright effect on sound, and less saturation (because the low-mids are less amplified). Something like a shelving effect.
R11: plate resistor: sets the gain of the stage, its load line, and tone. Lowering you have less gain and a more open sound. This is one of the main point of the amp. You have to choose the right resistor (maybe 1W metal film) to reduce noise and have a good tone. Again, is important to change this value looking at the previous stage too.
This gain stage is the one that has one of the highest swing on its output. You must have care of its supply.
C6: with R12 and R13 sets the voice of the second stage of the lead. Less important of the first stage bypass, but still evident. You have to cut what's below 70 to 150Hz here too. 2n2 is a good choice.
R12 and R13: this sets the swing to the third gain stage. If you want to keep the same dividing rate, you have to scale them as R12 is half of R13 (is a 1/3 attenuation, aka the output is 2/3 of the input). Lowering them too much you'll have a gain loss of the 2nd gain stage, and you'll have to change their values.
R14: cold stage cathode resistor: here you can change the harmonic content of the OD. Standard value, 39k, is a bit too Hard Rock oriented. 33k is just better to my taste, but I prefer lower values (eg 10-15k) to increase harmonics and saturation. With such low values you have to scale down the previous voltage divider (R12 + R13) to something like 470k + 470k, otherwise this stage and the next two stages (V3) will distort too much and you'll have a fuzzy sound.
Keep in mind that everything has to clip with the other stages in the same way, if you want to improve dynamics.
You can choose to have no cold stage, and use a 1k5 bypassed by 1uF, but you have to drop the signal before this stage (eg R12 120k and R13 33k) and also after the stage (otherwise V3 will distort too much).
You can play with values, but first times remember to keep the total amount of gain quite similar stage to stage.
R19: plate resistor of the cold stage. Play with R19 and R14 to keep the gain of the stage as 100k 39k, but with different sounds (eg R19 33k and R14 10k).
C9: plate resistor's bypass cap: just a rolloff of harshness. Cuts off highs. The right value changes due to how the previous stages makes the amp clip. I prefer not more than 470p, otherwise the stage loose punch.
C10: coupling cap: sets the low cut point with the parallel R18//R20, so R18 only. 22nF is the right value.
R20: just to keep the C10 grounded while you play on clean/crunch. 2M2 just not to change the R18 value when paralleled.
R18: load resistor for lead channel, part of the divider for clean/crunch channel. If you change this value, you'll have to rescale the clean channel. Keep this value.
R21: grid stopper of the 4th gain stage: with miller effect of gain stage, low pass filter @ 8.6 kHz. Lowering this resistor you'll have a more open sounding amp, but can became fuzzy. Raising the value you have a more focused amp, but with less harmonics.
