AMT Electronics - S1 Legend series  [schematic]

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Ice-9
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Post by Ice-9 »

Great, I can measure those for you, it will have to be tomorrow though as I am working tonight.
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 ?

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temol
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Post by temol »

That's great. I'm waiting patiently.

Meanwhile - short comparison of three 5150's. VST sim, 5150 by TrueVAL and AMT P1 on a breadboard. Separate recordings for L and R, Marshall cab IR. Soundcloud link.

T.

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Post by temol »

Ice-9 - can you also check the diode D7/VD6, the one next to VT10? Is it BAT54 or 1N4148?

T.

Ice-9
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Post by Ice-9 »

temol wrote:Ice-9 - can you also check the diode D7/VD6, the one next to VT10? Is it BAT54 or 1N4148?

T.
I have taken measurements for VT1-VT10 as they are marked on the original AMT P1 PCB.

First though VD6 is a small Glass SMD type diode with no visible markings which I can't remove as it has been glues to the PCB before solder flowing. Educated guess is that it is NOT a BAT54 as there would be no reason to fit this type of package diode when all other BAT54's are SOT-23.

PSU VOLTAGE READING on pcb = 9.46V

VT1 Gate =1.76V , Drain =9.32V Source = 2.1V
VT2 Gate =3.55V , Drain =9.32V Source = 4.8V
VT3 Gate = 0V , Drain =1.77v Source = 0v this jfet may be part of the psu switching for the cab sim ? (i really can't remember and haven't time to trace it out)
VT4 Gate =3.7mV , Drain =5.41V Source = 200mV
VT5 Gate =51mV , Drain =7.36V Source = 360mV
VT6 Gate =52mvV , Drain =4.92V Source = 223mV
VT7 Gate =12mV , Drain =4.98V Source = 183mV
VT8 Gate =33.2mV , Drain =5.39V Source = 240mV
VT9 Gate =0V , Drain =1.45V Source = 5.09V

Hope this helps for now, any questions or checks you want to make just let me know.
VT10 Gate =0V , Drain =3.72V Source = 53.5mV
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 ?

Ice-9
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Post by Ice-9 »

Just to clarify, VT3 is not the cab sim PSU switching device as that is only on the AMT 2 series pedals, VT3 looks like part of the actual cab sim.
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 ?

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temol
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Post by temol »

Ice-9 wrote: First though VD6 is a small Glass SMD type diode with no visible markings which I can't remove as it has been glues to the PCB before solder flowing. Educated guess is that it is NOT a BAT54 as there would be no reason to fit this type of package diode when all other BAT54's are SOT-23.
I've tried BAT85 and 1N4148. With BAT85 output signal is a bit lower, and drain voltage drops about 0.2 - 0.3V. With 1N4148 or without any diode - I could not hear any difference.
Ice-9 wrote: VT1 Gate =1.76V , Drain =9.32V Source = 2.1V
VT2 Gate =3.55V , Drain =9.32V Source = 4.8V
VT3 Gate = 0V , Drain =1.77v Source = 0v this jfet may be part of the psu switching for the cab sim ? (i really can't remember and haven't time to trace it out)
VT4 Gate =3.7mV , Drain =5.41V Source = 200mV
VT5 Gate =51mV , Drain =7.36V Source = 360mV
VT6 Gate =52mvV , Drain =4.92V Source = 223mV
VT7 Gate =12mV , Drain =4.98V Source = 183mV
VT8 Gate =33.2mV , Drain =5.39V Source = 240mV
VT9 Gate =0V , Drain =1.45V Source = 5.09V

Hope this helps for now, any questions or checks you want to make just let me know.
VT10 Gate =0V , Drain =3.72V Source = 53.5mV
My voltage readings are not much different. Sometimes 0.3V off.. sometimes 0.5V off. The biggest difference - VT5, 7.36V vs 6,3V. It sounds even better after fine tuning some resistor values.
And (I hope ) last question: R45 on this schematic is before C29. In this configuration the pedal is too bassy. I had to set bass pot almost to zero to get rid of thumping lows. With R45 after C29 it ok. I've checked some photos of AMT series pcb's - looks like the resistor is after the capacitor (like on this schematic).

T.

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Post by Ice-9 »

I would say R45 after C29 should be correct, ie C29 directly to treble pot wiper
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 ?

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temol
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Post by temol »

Thank you very much for your help.

T.

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temol
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Post by temol »

Here's my P1.

ImageImage

T.

mensur
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Post by mensur »

How does it sounds, can you make any clips?

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temol
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Post by temol »

mensur wrote:can you make any clips?
Sure. Soon.. :)

T.

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Post by blacky »

temol wrote:Here's my P1.

[ Image ][ Image ]

T.
Hi man I'm new here but this is looking amazing, great work, how does it sound?

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Post by rutgerv »

Does anyone have a hi-res picture of the V1 or access to a schematic of it? I found one schematic, but don't yet trust it enough to start building it.

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Post by phbrick »

Hi, here is a gut shot of the V1:
AMT_V1_gut_shot.png
I compared to this schematic: https://guitarplayer.ru/equipment-effec ... ach=862994.

The topology seems to be the same, but the component
values seem to differ.

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