AMT S1 LegendVerified

From the post

Verified but with a caveat. Two people have verified the main board and the cab sim separately, but there are definitely biasing issues dependant on the JFETs you use. This was designed around the 2SK208 SMD transistors and so when using the common through-hole JFET, they will need biasing differently and so it would be a good idea to swap the source or drain resistors for trimmers for all JFETs other than Q4 which already has a trimmer. It may be a good idea to socket those resistor connection points so you can use a single trimmer to work out the required resistance to get the correct drain voltage for each transistor, and then using an appropriate value resistor in the socket rather than having trimmers all over the place.

Thanks to Ice-9 on FSB for tracing and supplying the schematic. The original of this pedal used 2SK208 transistors which are only available in surface mount form. I have opted for J201's in the layout, but a bit of experimentation may be the order of the day in terms of trying other JFETs, and associated components to get them to bias. So this may be one for the tweakers at this stage until we have some good results with the alternative JFETs.

Note that the input to the cab sim, would come from the output of the main board, so you would either have two output sockets (with and without cab sim) or you could have a single output socket and use a toggle to true bypss the cab sim.

From the manufacturer:

The device is intended for the production of sound peculiar to «drive» channels of Soldano* amps. It is distinguished by specific type of overdrive: open, wide and at the same time tough and dynamic.

• AMT Legend Amps provide excellent playing dynamics characteristic for purely tube devices not in the least inferior to them.

• With tube-like limitation the effects of the series provide an amazing density and power of sound. When using AMT Legend Amps you won't feel the need do cut out the most informative middle frequencies which in turn will provide great readability of your guitar in the mix.

• Like tube preamps AMT Legend amps provide gradual increase in the number of limiting stages as sensitivity grows.

• The preamps of the series use the passive circuits of tone formation which completely correspond to the adjustments of original tube overdrives.

• The high level of the preamps output signal (+10dB at maximum Level position) is the same as of tube preamps. It gives you the adjustable signal level which allows to connect the preamp to any input including Input POWER AMP.

Architecture

• The preamps of the series are single-channel devices with passive bypass.

• AMT Legend Amps have two outputs: direct OUT and separate CAB.SIM.( to line-in)