ODvS-D50 "Overdrive VERY Special"

Guitar Tube Valve Amp Custom Design Dumble inspired Overdrive Special ODS ODVS-D50 Workshop North Germany Jansen Kemper MCU programmable MIDI D-amp foot switch Hamburg Germany North — The legendary Dumble Overdrive special (ODS), that inspired me and others to put something modern on top!

My OverDrive VERY Special ODvS-D50 versatile D-Style Tube amp now finished in 2022 — My OverDrive VERY Special ODvS-D50 versatile D-Style Tube amp and cabinet (EVM-12L from 1981!) now finished in 2022

My motivation for this project:

My special motivation for this project were several things:

I've never owned or played a Dumble / Clone, but the tone of the guitarists (Ford, Carlton) always matched my dream.

Since I know that the basic design of a Dumble ODS won't give me enough sound versatility (e.g. compromises in clean sounds), I wanted to create a "special" Dumble that contains everything that the original has, but also all known variants (see ampgarage).

When I studied the known circuit designs, I was able to translate most of the differences into switchable "tweaks".

Examples are, among many other things, switching on/off negative feedback of V1b, changing the bias of V1a, various interventions in the stack, switchable HRM and much, much more!

In order to be able to use the whole thing sensibly in the end, I have selected an microcontroller (MCU) control, which then reflects the many switching options as programs that can be saved and which can be called up via foot switches or MIDI.

And if you already have an MCU in the system, MIDI and other nice things are quickly on the wish list:

My knowledge of industrial electronics development allowed me to incorporate predictive maintenance and easier service options (tube bias assistance).

In the end I got my money's worth and had a lot of fun!

I am sure that some more projects will follow on the basis of experience I have created!

ODvS-D50 Feature List:

Amp Type:	D Style inpired Amp	Howard Alexander Dumble Amp inspired
Output Power:	50W.... 5W	Programmable Power Redcution
Pre Amp Tubes:	3 x ECC83/12AX7
Power Tubes:	2 x 6L6GC	max 50W @ Push Pull, Fixed Bias (configurable down to 5W SE)
True Channels:	2 (separate B,M,T,V OD-level, Ratio, Master)	plus each Channel has" D Style" OD extra channel
Logic:	Relays to enable progammable Switching Functions	No change of original signal pathes!
	32-bit MCU, Bias Automation, High Precision ADCs
Footswitch:	yes (assignable)	via standard Ethernat Cable / RJ45 Connectors
MIDI:	In and Out	plus power supply for Power-Over-Midi Cable, send pgm changes to external effects channel dependent
Effect Loops:	Pre, Post	progammable
Instrument/Tuner Out:	yes	progammable
Line Out:	yes	parallel to speaker with pot, no freq. Compensation
Fan:	2	inernal chassis and power tubes, progam controlled
Front:	Instrument Input
	Channel Selection	CH1-A, CH1-B, CH2-A, CH2-B (+ PROMOTE each)
	Pots per Cha: Treble, Mid, Bass, OD Level, Ratio, Master
	Common Pots : Promote, PPIM	New!
	Channel dedicated switching:	all programmable
	Pre-Eff, PAB, R/J, BRI, MID, DEEP, NFB	well known but some exciting new funtions!
	OD, Soft, HRM
	PS FB, CUT, PPIM, PS Power

Rear:	Line In (230V/ 50-60Hz), 2 Fuses	internal reconfiguarable to 115V/240V
	MIDI IN, MIDI OUT, Footswitch (RJ45)	program changes via external MIDI foot switch or DAW, Sending program changes to external effect device
	Speaker 2 x, Impedance 4/8/16 Ohms
	Post Effect Loop, Pre Effect Loop	programmable
	OD Trim	Overdrive pre-level
	Instrument Out	progammable

Inside Chassis:	PPI Sym Trim, BIAS-A, Bias-B	(BIAS-A/B as fall-back biasing)
Outside Chassis:	HRM: Treble, Mid, Bass , Soft Trim, Cut Trim	access without opening chassis