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Here are some internals of the T-Rex Yellow Drive. The Yellow Drive is produced for Guitar Center in the US exclusively by T-Rex. The circuit is a copy of a Proco RAT circuit with some minor variations affecting the low end roll off and available gain. No surprise that the T-Rex Mudhoney and Mudhoney 2 are the same basic RAT type circuits. It also shows how a classic circuit can be marketed as a “different” pedal with only minor changes.

The A side of the Yellow Drive uses a 4k7 gain pot and a low end roll off @720Hz. The B side has 47k gain pot and a roll off @1kHz.  A useful combination to dial in a medium gain on A and a high gain sound on the B side. One other change that T-Rex implemented in  their variations on the RAT circuit is add a 150 ohm resistor in series with the gain pots to set the minimum gain to a usable level.

I don’t own an original RAT to compare but I think the Yellow Drive is a good option to a new production RAT considered it’s flexibility with two circuits in one box and the ability to fine tune the A channel for low to medium gain sounds.


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