Other ADA Gear > ADA Cabinet Simulaters

Ampulator

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Yazoo55:
I know the Ampulator is very rare and expensive to buy second-hand. I came across a post on the GroupDIY site by Curtis who built a modified version a while ago. Unfortunately all the picture links he posted are now dead. I have tried contacting him but I haven't had a reply yet.

I found the Ampulator schematics but they do not include the pcb, unlike the Microcab schematics. Has anybody seen the pcb layouts or do you know of any photos? It would be great to have a go at building the Ampulator.

GuitarBuilder:
Here's what I have!

Yazoo55:
Many thanks for posting this!

Yazoo55:
I have been working on this, recreating the Ampulator in Kicad. I've still got a bit of work to do but I would appreciate some advice.

There is a section of the power supply which splits off to go to a line labelled "MUTE". This goes to the base of three FET transistors connected to the signal out and XLR out outputs. My main query is the reference to "GND2" in the power section for this line. It isn't used anywhere else in the schematics. Should this GND2 be linked to the main GND line?

If you have the patience, what is the function of the transistors? I'm guessing when voltage is applied to the base of the transistors, the output signal is shunted to ground, muted. I don't understand how this is switched on/off though.

This is the power section:

MarshallJMP:
Well it should be grounded since it's a Delon voltage doubler. Maybe they mean the "yel" connection on the transformer.(which is also grounded)
When powered on the output voltage of the mute line is slightly positive and goes in a little more then 2 seconds to around -24V.Since the FET's are N types they have a low resistance when the voltage is near zero (50 ohm for 2SK364)  on the gate and go to higher resistance (cut off) when the gate voltage goes negative.

Which transistors do you mean?

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