AMT Electronics - S1 Legend series [schematic]

[lugburz2000]

Hi
Finally here is the corrected scheme of B1 pedal.
The drawing does not include the speaker simulator.
But I do not think it's very different from the S1, P1 ...

Regards.

[IvIark]

Hi, is the only difference the added final stage? I did a vero layout for the first schematic you did and someone was in the middle of building it so I want to make a little addon daughterboard for him so he doesn't have to start again.

Hi
Finally here is the corrected scheme of B1 pedal.
The drawing does not include the speaker simulator.
But I do not think it's very different from the S1, P1 ...

Regards.

[lugburz2000]

[quote="IvIark"]Hi, is the only difference the added final stage? I did a vero layout for the first schematic you did and someone was in the middle of building it so I want to make a little addon daughterboard for him so he doesn't have to start again.

Hi
As you say, the main difference is in the final stage.
but do not forget the low pass filter from the tone control
to the volume potentiometer.
The latter scheme also includes a few more electrolytic capacitors
that help the filtering of power supply. If using a stable voltage source,
are not necessary the use of many filter capacitors.
Long ago I built a circuit based on the first scheme on a proto board.
For the first stage, I used a 2N5457 jfet, and for the rest of stages used J201.
I did some sound samples to compare the actual pedal versus the proto board
version. As I suppose you might be interested to hear them, when I get home
I will try to add them to the forum.
You could see that they do not differ much from one another, perhaps the sample
from of the pedal contains more presence of low-end.

Regards

[Ice-9]

For polarity protection in all my builds i now only use Mosfets these days, I never use the standard diode protection.

Can you draw a simple picture of how you do that?

[/quote]

I used the info over at R.G. Keens site for the mosfet protection. Have a look over at geofex for the details. Using the mosfet way give a tiny amount of voltage drop

[Ihunda]

Thanks to all, this is great. I am going to try finding a matching diode for the good old 2N5457, it would make think much easier

[mensur]

Thanks to all, this is great. I am going to try finding a matching diode for the good old 2N5457, it would make think much easier

Matching diode for BAT54 are BAT85's, matching FET for 2SK208 are 2SK30A-R, and the last diode for for the post tonestack stage can be 1N4148 or BAT47. 2N5457 FET is used for the first gain stage only,cause of the high VGS.

[lugburz2000]

Hi
Well as yet I've got the B1 pedal assembly, using a field effect transistor 2N5457 and three J201 on a protoboard,
and based on my first schematic. I've added the filter corresponding to the corrected schematic and formed by
the 10n capacitor in series with a resistor of 56k. Then i have recorded one audio sample.

So here you have 3 audio tracks:

(This is the audio sample of the Amt B1 pedal)


(This is the audio sample of the circuit on a protoboard)


(This is the audio sample of the circuit on a protoboard with the filter that lacked)

Greetings.

[sugab]

Hi
Well as yet I've got the B1 pedal assembly, using a field effect transistor 2N5457 and three J201 on a protoboard,
and based on my first schematic. I've added the filter corresponding to the corrected schematic and formed by
the 10n capacitor in series with a resistor of 56k. Then i have recorded one audio sample.

So here you have 3 audio tracks:

(This is the audio sample of the Amt B1 pedal)


(This is the audio sample of the circuit on a protoboard)


(This is the audio sample of the circuit on a protoboard with the filter that lacked)

Greetings.

with cabsim??sounds pretty same

[lugburz2000]

It's a randall cabinet impulse response, the same is used for three samples .

[J0K3RX]

Hi
Well as yet I've got the B1 pedal assembly, using a field effect transistor 2N5457 and three J201 on a protoboard,
and based on my first schematic. I've added the filter corresponding to the corrected schematic and formed by
the 10n capacitor in series with a resistor of 56k. Then i have recorded one audio sample.

So here you have 3 audio tracks:

(This is the audio sample of the Amt B1 pedal)


(This is the audio sample of the circuit on a protoboard)


(This is the audio sample of the circuit on a protoboard with the filter that lacked)

Greetings.

I couldn't hear a difference! Great Work!!!

[J0K3RX]

So, the first sounds sample is the "real B1"

The second sound sample is the protoboard based on your first schematic.

The third sound sample is the protoboard based on your latest schematic.

Is that correct?

Thanks,
~Jim

[lugburz2000]

Some time ago I read a lengthy article by Victor Kempf, the designer of these pedals. A good reading but it is in Russian. So I had to translated
to English with google tradductor. Although not everything is intelligible, but enough to understand many interesting things about the use of a diode
in a stage of field effect transistor.

In fact, the electronic assemblies that based on the B1 pedal I have made in proto board are modifications of the two schemes I presented at the forum.
The most important change is not using schottky diodes. Instead I use silicon diodes 1N4148 or similar. These diodes are connected from gate to ground.
This is not my invention but it is an idea patented by Peavey.
At first, as I had no schottky diodes, and because I just wanted to mount the pedal for fun, not pretending nothing serious, I decided to test the idea from peavey.
So, having some knowing about the type of signal that we need at a stage of jfet with schottky diode, I started testing with silicon diodes. To help me with my tests
I used an oscilloscope.
And the result was the scheme presented below.
With this assembly, I did the sample number 02.
The values ​​shown for drain resistances are not standard values​​. I used adjustable resistors and when all was ready, I measured the resistance with a tester.

[lugburz2000]

And this is the schematic for the sample number 03.
The only difference from the above scheme is the low pass RC filter connected between tone control and volume potentiometer.
This filter is in the original pedal but component values ​​are different from that I use. With the original values, and my assembly I could not hear any noticeable change.
So using a circuit simulator, I tried different values ​​of capacitor and resistance by comparing the frequency response obtained in my schematic assembly versus the original pedal.
on the pedal, the capacitor and resistor values ​​are 10nF and 56k, respectively. The ones I use are 47nF and 10k.
It may not be very distinguishable but with the filter the bass sound is more pronounced.
Regards

[lugburz2000]

If anyone is interested in the article by V. Kempf here is the link:
http://www.sugardas.lt/~igoramps/article68/article.htm

[Ice-9]

If anyone is interested in the article by V. Kempf here is the link:
http://www.sugardas.lt/~igoramps/article68/article.htm

I have read Victor Kempf's articles before but as you say the translation is difficult.

[rcustoms]

my contribution,components layout and pcb
regards

S1.pdf

(335.64 KiB) Downloaded 697 times

[J0K3RX]

my contribution,components layout and pcb
regards

S1.pdf

Nice job!!! I assume you have verified after all that work huh?

I made one for the B1, not nearly as nice as yours for the S1 but should work...

[J0K3RX]

rcustoms - Could probably also use the SMD 2SK208 transistors with the way you layed out the solder pads? Nice!

[rcustoms]

B1 based on lugburz 2000
regards

B1.pdf

(236.65 KiB) Downloaded 690 times

[rcustoms]

my contribution,components layout and pcb
regards

S1.pdf

Nice job!!! I assume you have verified after all that work huh?

I made one for the B1, not nearly as nice as yours for the S1 but should work...

I have not checked yet but I think it's okay,your work is awesome sound realy good