For Sale By Antique Amplication - Dumble Overdrive Reverb Special

Antique Amplification has recently completed the full restoration of an impossibly scarce 1978 Dumble Overdrive Reverb Special (100 watt).   The owner has requested that we assist in offering this fine specimen of Alexander “Howard” Dumble’s early work for sale.  The ODRS is considered by many of the Dumble amplifier aficionados to be the “Holy Grail” of all Dumble amplifiers.   The exact production of this model is unknown but has been estimated to be less than fifteen total units.   The highest previously known serial number for an ODRS is #0078.   This amp has a serial number in the #008X’s making it very likely the last of its kind produced by Mr. Dumble.   The current owner is the original owner, a 67 year professional guitarist hailing from Ontario, Canada, by the name of Bobby Watson.

The Origins of this Amp
By the time the 1970’s had rolled around, Bobby Watson was already a seasoned professional musician.   He was initially drawn to the Dumble sound while listening to Lowell George on a Little Feat recording.  This prompted Bobby to research Lowell’s gear more closely and this is when he first became aware of the Dumble brand of amplification.   In 1977, Bobby attended an Amos Garrett show at the El Macambo in Toronto.  He thought that the sound of the amplifier Amos was using was familiar and but could not make out what exactly it was as the logo was too small to view from a distance and the cabinet style unfamiliar.   As luck would have it, Bobby knew Bohdan Hluzco who was Amos Garrett’s drummer at that time.  Bohdan introduced Bobby to Amos during a set break and they both discussed his amplifier which turned out to be a Dumble.

At this point in time Bobby made up his mind that he had to have a Dumble of his own.   He contacted Howard Dumble, explaining how he was initially drawn to the Dumble sound by Lowell George and then shared with him his discussion with Amos Garrett.   During the conversation, Dumble explained that the amp model that these musicians were using was called the “Overdrive Reverb Special”.  Howard and Bobby also discussed enclosures, however, given the expense of the amplifier along with the reality that Bobby had plenty of decent enclosures to use, and he elected to purchase a head unit only.   One part of the discussion that Bobby recalls clearly was mentioning that the logo on the amp was too small to read easily and that he suggested to Howard that he enlarge the graphic to solve this problem.   Interestingly, when the amp did arrive, even though it is very obviously an Overdrive Reverb model, the graphic Howard used was the from the much larger “Overdrive Special” logo.   No other known to exist ODRS has this unique feature.

Bobby placed the order for his own ODRS at the agreed upon price of $1,700 USD which was a very large sum of money for an amplifier in those days.  This was the summer of 1977 and he would have to wait a year before it was completed.  Considering the lead times that other Dumble customers contended with over the years, Bobby was actually quite fortunate to have to wait only one year.

In the late summer of 1978, the amplifier was completed and Bobby sent the final payment to Dumble.  The new Dumble amp was immediately pressed into service for a very busy, hardworking professional musician. Little did Bobby know at this time that his amplifier was one of the rarest models Dumble would ever produce and that judging from its serial number, his amplifier very likely was the last Overdrive Reverb Special Dumble ever produced.

The amplifier came appointed with what was standard for the model, black tolex vinyl covered cabinet with a walnut crossbar with the aluminum trim appropriate for the model/vintage.  The front panel is covered in a medium brown suede and the black graphics silk screened directly onto the chassis with a protective clear coat was applied over the face and back panels of the chassis.   The knobs and unique red colored slider switches are consistent with a 1970’s vintage, silver-face Dumble product.   Being a 100 watt (advertised) amplifier, it uses 4 x 6L6GC tubes in the power section.

The amplifier also came with a chrome plated, stamped steel Fender style footswitch for turning on and off the reverb and overdrive features.   A unique and cool feature of the switch is a hand cobbled aluminum placard showing the name “Rob Watson” that was hand fabricated and engraved by Howard Dumble himself.  Since this is a late 70’s vintage amplifier, it was produced long before Dumble made prospective buyers sign legal contracts to protect his intellectual property and keep would be copycats from duplicating his designs.   Additionally, there is no silicone “gooping” covering the pre-amp section as became a common practice by the time Dumble had transitioned into 1980’s produced amps.

Bobby used the amplifier religiously until 1987 when it failed.   Bobby does not recall what exactly failed but he did take it to a local amplifier repair shop at this time since it was impractical for him, living in Toronto, to have Dumble repair the amplifier.  At this time, both the power and output transformers (originally Woodward/Schumacher Fender parts) were replaced with 1960’s vintage Hammond iron and a new bias supply transformer added.   Bobby had some problems getting the repair shop to complete the work and when it eventually was returned, it would power up but had a wicked oscillation and was unusable.

At this point, Bobby became frustrated with the entire situation and he ended up putting the amp into storage in his home for more than two decades.  Meanwhile, he continued his career, eventually moving to Memphis, Tennessee for a number of years while actively employing his craft as a guitarist/singer/songwriter.   During the next 25 years, the Dumble sat broken in Bobby’s Peterborough home until a close friend convinced him to allow a qualified repair shop bring it back to life.

This is where Antique Amplification enters the story.   We agreed to repair the amplifier for Bobby back in January of 2014.   What arrived was a neglected but mostly complete and original Dumble Overdrive Reverb Special.  Unlike many other Dumble amplifiers, it had never been sent back to Dumble for upgrades or modifications.  We set about diagnosing the various issues the amplifier had including the improperly installed, incorrect transformers.   We quickly brought it to life after determining and correcting the polarity hook-up problem with the output transformer caused by the previous repair shop.

It took some time to source correctly date coded original Woodward/Schumacher power and output transformers, identical to what the amplifier would have left Dumble’s workbench with in 1978.   In fact, we managed to locate a “New Old Stock” or NOS Power transformer!   A few other components were a challenge to source as well.   We elected to replace the electrolytic capacitors for obvious reasons.  A considerable amount of time and effort went into the disassembly, assembly, and cleaning process required given the amplifier was used regularly by a working professional musician the first 9 years of its life and then subsequently stored for 25 years.  The amp is, circuit-wise, identical to the way Mr. Dumble conceived the amp in 1978.   No modifications were made to deviate from the original circuit design.

Today, we are proud to point out that Bobby’s amp has been restored to its former glory.   The sine wave is pristine, every control works as designed and the amp now pumps out a very healthy 90 watts RMS (Into 4 ohms).   We have included many high resolution images detailing this seldom seen rarity of Howard Dumble’s highly regarded and highly sought after amplifier production.

We have also included a variety of audio/video examples for your perusal.

Antique Amplification will not provide schematics, circuit layout, circuit details, component values or any images describing or depicting the internal features of this amplifier.

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