Vintage Guitar - February 2017 - Open - 36

A

BY DAVE HUNTER

lexander Dumble's creations were already established as legendary
when we probed our first example in this space back in early 2011.
Since that time, however, Dumbles have become the hot ticket for cloners
on the boutique scene, and originals are perhaps the hottest amps on the
vintage market. The difference in price between used Dumbles and vintage
Fenders, Voxes, and Marshalls? Oh, about 10x... or more.
While all Dumbles are prized, the real
peaches are those with solid provenance and
an intriguing back story - and few are more
enticing than this '80s Overdrive Special.
Dubbed by its creator as the Overdrive
Special OD150 WR, it was one of a pair (yea,
two identical Dumble heads) built along
with four 2x12" cabinets with ElectroVoice
EVM12L speakers ordered by ace studio and
touring guitarist Todd Sharp.
Now a respected Nashville amp tech and
builder/marketer of hand-wired amps (see
his "Builder Profile" in the November '16
issue), back in the '70s and early '80s he was
a hard-working road warrior backing Hall
& Oates, Christine McVie and Mick Fleet-

	

wood, Rod Stewart, and Delbert McClinton,
among many others. Flush with gig money,
he set out to assemble an amazing tone rig.
After playing the amp onstage and in
the studio, including notable tours with
Rod Stewart from 1989 through '91, Sharp
decided he didn't need two massive Dumbles
after all, and sold this one. In a cruel twist,
soon after, its partner was stolen.
Any Dumble amp is a formidable beast,
but this is a particularly complex creation.
The amp generates 150 watts from a quartet
of 6550 (or KT88) output tubes and a set
of massive transformers. Along with a
rendition of the maker's classic input and
EQ stages, there's a tweaked version of his

VINTAGE GUITAR	

36	

February 2017

overdrive circuit, reverb with controls for
Send and Return, and onboard tremolo (a
Dumble rarity). Its clean tones have been
described as a combination of Steel String
Singer and Dumbleland, and its sophisticated overdrive employs a 12DW7/7247
dual-triode. The stage includes two dualconcentric pots (modified by Dumble from
a four-knob OD that had two pots on the
front panel and two on the back), including
a Trigger control to adjust how much signal
is fed to one side of the triode, a Level control to adjust how much is sent to the other
triode, a Taper control to adjust the scale of
the high frequencies, and a Ratio knob to
determine how much overdrive is blended
back in from previous preamp stages.
The amp's tremolo (another unusual
feature for Dumble) has a broad range that
works with the reverb - the same two-knob
circuit often used on Steel String Singer
models to add lush, hypnotic effects to an
already harmonically rich tone. On the back
panel is a 150W/75W (i.e. half-power) switch

1983 Dumble Overdrive Special: Dean Gurr.

DUMBLE OVERDRIVE
SPECIAL OD150 WR

1983 Dumble Overdrive Special OD150 WR
* Preamp tubes: six 7025, one
7247 (12DW7), one 5751
* Output tubes: four 6550 or KT88
* Rectifier: solidstate
* Controls: Volume; switches for Bright,
Deep and Rock/Jazz; Treble, Middle, Bass;
Overdrive controls (on dual concentric
knobs) for Trigger, Level, Ratio, and Taper;
Reverb Send and Return; Tremolo Rate and
Modulation; Master Volume, Presence
* Output: 150 watts RMS



Table of Contents for the Digital Edition of Vintage Guitar - February 2017 - Open

Contents
Vintage Guitar - February 2017 - Open - Cover
Vintage Guitar - February 2017 - Open - IFC
Vintage Guitar - February 2017 - Open - 1
Vintage Guitar - February 2017 - Open - 2
Vintage Guitar - February 2017 - Open - 3
Vintage Guitar - February 2017 - Open - 4
Vintage Guitar - February 2017 - Open - 5
Vintage Guitar - February 2017 - Open - 6
Vintage Guitar - February 2017 - Open - 7
Vintage Guitar - February 2017 - Open - Contents
Vintage Guitar - February 2017 - Open - 9
Vintage Guitar - February 2017 - Open - 10
Vintage Guitar - February 2017 - Open - 11
Vintage Guitar - February 2017 - Open - 12
Vintage Guitar - February 2017 - Open - 13
Vintage Guitar - February 2017 - Open - 14
Vintage Guitar - February 2017 - Open - 15
Vintage Guitar - February 2017 - Open - 16
Vintage Guitar - February 2017 - Open - 17
Vintage Guitar - February 2017 - Open - 18
Vintage Guitar - February 2017 - Open - 19
Vintage Guitar - February 2017 - Open - 20
Vintage Guitar - February 2017 - Open - 21
Vintage Guitar - February 2017 - Open - 22
Vintage Guitar - February 2017 - Open - 23
Vintage Guitar - February 2017 - Open - 24
Vintage Guitar - February 2017 - Open - 25
Vintage Guitar - February 2017 - Open - 26
Vintage Guitar - February 2017 - Open - 27
Vintage Guitar - February 2017 - Open - 28
Vintage Guitar - February 2017 - Open - 29
Vintage Guitar - February 2017 - Open - 30
Vintage Guitar - February 2017 - Open - 31
Vintage Guitar - February 2017 - Open - 32
Vintage Guitar - February 2017 - Open - 33
Vintage Guitar - February 2017 - Open - 34
Vintage Guitar - February 2017 - Open - 35
Vintage Guitar - February 2017 - Open - 36
Vintage Guitar - February 2017 - Open - 37
Vintage Guitar - February 2017 - Open - 38
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Vintage Guitar - February 2017 - Open - 63
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Vintage Guitar - February 2017 - Open - IBC
Vintage Guitar - February 2017 - Open - BC
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