Dumble Amplifiers | Overdriver Reverb

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Overdrive Reverb

Tube Amplifier
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An Overdrive Special amplifier with an internal Reverb Circuit. The Overdrive Special is a two channel amplifier, with a clean channel and a second “overdrive” channel. This overdrive channel is described as “cascading” from the first channel into at least one additional gain stage in the overdrive channel. This means that the clean channel tone stack and gain stages “cascade” into the gain stage of the overdrive channel, causing the clean channel to become “overdriven”. In a sense, the overdrive channel sits “on top” of the clean channel. This is easily Dumble’s most popular model, and subsequently is the most frequently seen. That said, the ODS (Overdrive Special) varies considerably from decade to decade, and serial number to serial number. For example, although most ODS amplifiers use 6L6 tubes in the power section (commonly associated with Fender amps), some have EL34 tubes (commonly associated with Marshall amps). On the other hand, even among the many 6L6 versions of the ODS, there are considerable variations. For example, some have a clean channel that stays clean “all the way up to 10” (referencing a gain potentiometer ranging from 1 – 10). Others have a clean channel that will start to “break up” around 3. Some overdrive channels can only reach a minimal amount of breakup, even when dialed up. However, most ODS overdrive channels have a large amount of tube distortion available if so desired. Along these same lines, many later versions of the ODS have “HRM” controls on the inside of the amplifier, which is a “Hot Rodded Marshall” tone stack that sits “on top” of the overdrive channel, or in other words comes after the Overdrive channel tube gain stage.

There are certain commonalities across all ODS amplifiers. Firstly, the ODS amps are known for their harmonic richness in the overdrive channel breakup, and transparent “open-ness” in the clean channel. The overdrive channel is often described as “sustaining”, “blooming”, and “musical”. The clean channel is often described as “fast”, “huge”, and “responsive”. Robben Ford describes the tone of the ODS as having “a perfect sonic curve, the lows are deep and rich but not unclear, it doesn’t mush out like some amps will. You have the frequencies there for your use. The mid range is punchy and clear and the high end, bright, clear but doesn’t hurt your ears. It’s loud but it sounds good.

In an interview with Premier Guitar, Robben Ford claims that Dumble told Ford that the original inspiration for the Overdrive Special came while watching Ford play live in the 70s at a bar in Santa Cruz. Ford was using a mid-60s blackface Fender Bassman, and running a tube screamer in front of it to overdrive the tubes to breakup. Supposedly, Dumble thought Ford sounded so good, and while contemplating his sound had the revelations that led him down the path that eventually birthed the original Overdrive Special. Since buying his ODS, Ford has almost exclusively used his original Dumble or an exact clone of it live.