Bad Cat minicat Sampson Era

[Paulus01]

Hello. I trying build this amp last 2 month. But something I doing wrong. I found just one mistake heaters resistors must be 220 Ohm. And i using power transformer hammond 290 wex. Are somebody build this thing?

[sluckey]

We can help even though we may have never seen or built this amp. But you have to provide more info. I see one error on the schematic that will prevent this amp from working properly, so if you built according to this schematic your amp cannot work properly.

[Paulus01]

12ax7: On the first pin 237 v, 6 pin 160 v. Voltage after bridge 285 v. Master volume not work. And am not using pair 220 Ohm resistors on the heaters. Thanks for help! On the photos others amps not my.

[sluckey]

The error I'm referring to is...

Look at the schematic. The right side of the master pot ***MUST*** be grounded for the amp to work.

[Paulus01]

Report!

And finally Amp work. But! If insert cabinet, amp have 50-60 Hz hum, if using as preamp and insert (as amp) in reactive load box, it is noiseless. This is little beast can all from clean sound to dirty (if using pedals). Line out not working with 10 ohm 10 watt resistor, and I changed to 8 ohm.

Thanks for past  advice!

[Paulus01]

Hello. I would like have mid range control! For example 370 Hz, -6 dB. Do you have  ideas?

[darkbluemurder]

I recommend the Chieftain midrange control as I found that it works very well and has little insertion loss. Experiment with the pot value - start with 250k as in the original and adjust lower or higher depending on what you want.


Cheers Stephan