AMT Electronics - SS-20 [schematic]
- Ihunda
- Breadboard Brother
Bumping an old thread, any news on what type of FET's are being used?
I am have one and it sounds very good and is very dynamic, my only concern is the tone stack, I usually keep it all the way up and use my own circuit for tones.
I can take a look inside if other people are still interested!
I am have one and it sounds very good and is very dynamic, my only concern is the tone stack, I usually keep it all the way up and use my own circuit for tones.
I can take a look inside if other people are still interested!
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This is not just jfet. This is some circuit, named "jfet-tk". I will try to draw the input stage today.
Sorry for my English.
- Ice-9
- Degoop Doctor
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More than likely 2sk208 (JR) in the same topology they use in there othere valve emulating pedals (jfet + shottky diode) See the AMT S1 legend thread for examples of how the schematics go.Ihunda wrote:Bumping an old thread, any news on what type of FET's are being used?
I am have one and it sounds very good and is very dynamic, my only concern is the tone stack, I usually keep it all the way up and use my own circuit for tones.
I can take a look inside if other people are still interested!
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !
No silicon heaven ? preposterous ! Where would all the calculators go ?
No silicon heaven ? preposterous ! Where would all the calculators go ?
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- KMG
- Solder Soldier
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"1"
BAS70-04
http://www.nxp.com/documents/data_sheet ... 70_SER.pdf"
2" (True marking is 6L)
MMBF5459
http://www.fairchildsemi.com/ds/MM/MMBF5458.pdf
"3"
MMBTA42
http://www.fairchildsemi.com/ds/MM/MMBTA42.pdf
BAS70-04
http://www.nxp.com/documents/data_sheet ... 70_SER.pdf"
2" (True marking is 6L)
MMBF5459
http://www.fairchildsemi.com/ds/MM/MMBF5458.pdf
"3"
MMBTA42
http://www.fairchildsemi.com/ds/MM/MMBTA42.pdf
- bajaman
- Old Solderhand
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looks like the Peavey transtube input
be kind to all animals - especially human beings
- Ice-9
- Degoop Doctor
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Which i believe is patented ?bajaman wrote:looks like the Peavey transtube input
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !
No silicon heaven ? preposterous ! Where would all the calculators go ?
No silicon heaven ? preposterous ! Where would all the calculators go ?
- KMG
- Solder Soldier
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- Ice-9
- Degoop Doctor
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Thanks for that info, I already drew out the little circuit snippet and could see it was different anyway. I have / had a few AMT pedals and think the stuff there doing is great. Would love to see a bit more of the SS-20 ans I would expect it to follow more or less in line with the Legend series topology but with the obvious addition of the valve bits.KMG wrote:Nothing close to Peavey patent
http://milas.spb.ru/~kmg/files/literature/US5647004.pdf
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !
No silicon heaven ? preposterous ! Where would all the calculators go ?
No silicon heaven ? preposterous ! Where would all the calculators go ?
Hi,
I would really enjoy more if this pedal had a "post-boost" option rather than two dirty channels. Does anyone see possible to turn the crunch channel as the LEAD channel and the actual lead switch and pot be used to turn on a boost for solos?
I believe that this would require to actually merge a booster plate like the MXR Microamp there...
I would really enjoy more if this pedal had a "post-boost" option rather than two dirty channels. Does anyone see possible to turn the crunch channel as the LEAD channel and the actual lead switch and pot be used to turn on a boost for solos?
I believe that this would require to actually merge a booster plate like the MXR Microamp there...
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sorry to necrobump this post but i have a doubt. I bought the "V2.0" of the SS20 and also the SS30 "Bulava" as a backup. Turns out V2 and Bulava has a control output and find this interesting but, counterintuitive. It shouldn´t be control in? so you can control it from outside like a remote switch? I dont understant how it works, manual isn't very clear and it's been a long while since i've made mods or build pedals. If isn't the way i would like it to work, how could i mod it to make it "control in"? I just purchased a Boss MS-3 and would be awesome to be able to control the AMT through the Boss.
- Manfred
- Tube Twister
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I came across this old post and I was interested in this circuit.
I redrew the circuit, replacing the component representation of the semiconductors with the circuit symbols.
I did a simulation with a similar Schottky diode, the MPSA18 BJT and various replacements for the MMBF5459 JFET.
Depending on the type of JFET used, the result was a stage gain in the range of about 60-70.
I redrew the circuit, replacing the component representation of the semiconductors with the circuit symbols.
I did a simulation with a similar Schottky diode, the MPSA18 BJT and various replacements for the MMBF5459 JFET.
Depending on the type of JFET used, the result was a stage gain in the range of about 60-70.
Last edited by Manfred on 24 Jan 2022, 22:07, edited 1 time in total.
- bmxguitarsbmx
- Cap Cooler
Nice Manfred!
That looks like a cascode. The resistor from the gate of the BJT to the Source of the Jfet could probably be used to adjust the bias. Additionally, the 51k is also interesting that it would put a signal on the base of the transistor in phase with the normal operation of the cascode. Something to ponder there.
R5 put to 1M to make it a little easier to drive.
That looks like a cascode. The resistor from the gate of the BJT to the Source of the Jfet could probably be used to adjust the bias. Additionally, the 51k is also interesting that it would put a signal on the base of the transistor in phase with the normal operation of the cascode. Something to ponder there.
R5 put to 1M to make it a little easier to drive.
- Manfred
- Tube Twister
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Thanks for the hint.R5 put to 1M to make it a little easier to drive.
That was my fault I transferred the value wrong in the schematic, 1Megohm is the correct value.
I have fixed the circuit above.
- J0K3RX
- Degoop Doctor
Maybe these will come in handy..?
- Attachments
-
- SS20_2B_assy_mod18_01_13.pdf
- (548.2 KiB) Downloaded 328 times
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- SS20_2B_circuit_mod18_01_13.pdf
- (155.27 KiB) Downloaded 374 times
- Manfred
- Tube Twister
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- bmxguitarsbmx
- Cap Cooler
AMT does a lot of interesting things. I like that 3 jFet amplifier/buffer with the constant current source output circuit using the 2sk208's.