General FAQ


Repair procedure

We ask you to follow these repair note if one of our units has to be repaired: 
If the device or module is still under warranty please return it to the dealer where you purchased the device. Please do not forget to add a detailed description of the fault and a copy of the invoice.
If the device or module is no longer covered by warranty and you stay within the EU (European Union) you may send it alternatively directly to our address. The working time and the spare parts required to repair the unit will be charged as well as the shipping costs.
If the device or module is no longer covered by warranty and you live outside the EU you may also send the module for repair to our address. But you have to pay attention that all required documents (copy of the invoice, repair advice) have to be attached outside the package (OUTSIDE is essential !). Otherwise there will be problems during the importation. This may cause additional customs and tax charges much more than the actual repair costs. If documents are missing (outside the package !) we have to pick up the goods from the customs office which is about 50 miles from our location and have to pay the import charges and tax immediatley cash. Otherwise the consignment will be not released. This will require about 2-3 hours of working time plus travel expenses which have to be charged. Only if you are within the EU (European Union) these documents are not necessary ! If there is a Doepfer representative in your country we recommend to contact them to arrange the repair. For details please refer to the dealers overview on our website. You also have to keep in mind the shipping charges to Germany and back to your country if you send the unit directly to Germany !
In all cases please add a detailed description of the fault !
Payment of the repair charges is possible only by bank transfer ! We do not accept credit card, paypal or other forms of payment.

Special design on demand (English)

In principle we are able to make special designs. But most customers underestimate the time and consequently the costs for a special design. Normally there are three steps for a custom design: development of the hardware (provided that none of our existing hardware products can be used), development of the software (provided that the design includes a microcontroller) and design of the mechanics (e.g. controls, housing, provided that the customers is not able to built his own case). The hardware and software design is carried out in our company, i.e. design of the schematics, pcb layout and software. All mechanical parts of the design - i.e. pcb manufacture, housing, treatement of the housing like drilling holes, milling slits, varnishing, printing and so on - is carried out by other companies specialized in such things. We have no mechanical working place in our company. The main problem for a special design is that all nonrecurring costs - i.e. design of schematics, pcb layout, programming the software, initial charges for the pcb manufacture, case/housing production and silk-screen printing - have to be payed by one customer only. Even for a small design these nonrecurring costs reach the few thousands Euro range. Normally these charges are divided by the number of devices that are manufactured (a few hundred or thousands as a rule). Please keep in mind all these notes if you ask for a special design. If you are willing to pay for all these steps of work we can make a quotation for you. 

Sonderanfertigung nach Kundenwunsch (deutsch)

Prinzipiell sind wir in der Lage Sonderanfertigung auszuführen. Die meisten Kunden unterschätzen jedoch die hierbei anfallenden Kosten. Im wesentlichen besteht eine Sonderanfertigung aus 3 Schritten: Entwicklung der benötigten Hardware (vorausgesetzt, dass keine existierenden Baugruppen verwendet werden können), Entwicklung der Software (sofern in der Schaltung ein Microcontroller verwendet wird) und Entwicklung der Mechanik (Gehäuse, Zahl und Anordnung der Bedienelemente etc., sofern nicht auf ein Gehäuse verzichtet werden kann). Die Hardware- und Software-Entwicklung kann in unserem Haus durchgeführt werden. Dies sind im wesentlichen der Schaltplan-Entwurf, das Entflechten der Leiterplatte und die Programmierung des Microcontrollers. Alle mechanischen Teile der Entwicklung werden außer Haus durchgeführt. Hierzu gehört die Herstellung und Bestückung der Leiterplatte, der Entwurf und die Programmierung des Gehäuses, die Herstellung und Bearbeitung des Gehäuses einschließlich Lackier/Eloxier-Arbeiten, Bedrucken des Gehäuses usw. In unserem Hause haben wir keine mechanische Fertigung. Das Hauptproblem bei einer Sonderanfertigung ist, dass die Grundkosten bzw. einmaligen Kosten - d.h. die Arbeitszeit für Schaltplan und Leiterplatte, Grundkosten der Leiterplattenfertigung, Programmierung und Werkzeugeinrichtung für die Gehäuse-Fertigung, Siebdruck-Grundkosten usw. - ein einzelner Kunde tragen muss und diese nicht auf viele hundert oder tausend Exemplare - wie bei einer Serienfertigung - umgelegt werden können. Selbst bei einem kleinen Projekt kommen hier schnell ein paar tausend Euro zusammen. Nur falls auf eine bestehende Elektronik zurückgegriffen werden kann oder diese nur geringfügig modifiziert werden muss, halten sich die Kosten in Grenzen - aber auch nur, wenn auf ein Gehäuse verzichtet werden kann. Wir bitte Sie diese Hinweise zu beachten, wenn Sie bezüglich einer Sonderanfertigung bei uns nachfragen. Falls Sie bereit sind die genannten Kosten zu tragen, können wir Ihnen gerne ein zunächst grobes Angebot machen. In der Regel stehen jedoch die Kosten in keinem Verhältnis zu dem Ergebnis - von wenigen Ausnahme abgesehen (z.B. geringfügige Modifizierung eines bestehenden Produktes, wie etwa Pocket Electronic, CTM64, MTC64 usw.).

USB connection principles

Each USB network requires a so-called USB host (or "master") to which the USB devices (or "slaves" or "clients") are connected. The USB host is usually a computer and is equipped with a A type USB connector. The devices are equipped with B type USB connectors and A-to-B cable(s) are used to connect the USB device(s) to the host. It's not possible to connect only "slaves" among each other via B-to-B cables (e.g. one cannot connect an USB mouse to an USB printer because the supervising host is missing). In the meantime even stand-alone Midi-USB hosts are available (e.g. by Kenton).

USB Netzwerk Hinweise

Es ist grundsätzlich nicht möglich in einem USB-Netzwerk zwei sogenannte USB Devices or Slave Clients miteinander direkt zu verbinden. USB Devices sind z.B. Dark Energy, Dark Time, Dark Link, A-190-3, ein USB/Midi-Keyboard, ein USB-Drucker, eine USB-Tastatur oder eine USB-Maus. Zur Verwaltung mehrerer USB Devices ist immer ein sogenannter USB Host erforderlich. Normalerweise ist das ein Computer mit mehreren USB-Anschlüssen und entsprechenden Betriebssystem-Routinen. Es gibt aber mittlerweile auch eigenständige Midi-USB-Hosts (z.B. von  Kenton).

Converting Gate to Switched Trigger (S-Trigger)

In some devices only gate outputs are available (e.g. Doepfer MAQ16/3, Dark Time, Schaltwerk, Regelwerk, MCV24). This means that a positive voltage (e.g. +5V or +8V or +12V) is used to trigger the device controlled by the gate output. Some devices (especially Moog synthesizers) require instead of this a so-called switched trigger or S-trigger. This means that a short circuit (connection to GND) is used to trigger the unit (example: a foot switch making a short circuit when actuated).

A simple electronic circuit made of a 10k resistor and a standard npn transistor is used to convert a gate signal to S-trigger. The sketch below shows this circuit. The resistor and transistor can be built e.g. into the case of the 1/4" jack. If you have problems to assemble yourself such a cable please ask your local dealer. We offer such a special cable with a 3.5 mm miniature jack plug on one side and a 1/4" jack plug with built-in electronics on the other side. The cable lenght is about 1.2m. It is suitable e.g. for the gate outputs of  A-100, MAQ16/3, Dark Time, Schaltwerk, Regelwerk, MCV24 and so on. You find the price in the accessories section of our price list.
For other applications cables with other plugs may be necessary (e.g. 1/4" on both sides). If your synthesizer is equipped with an original Moog S-Trigger connector a so-called Cinch-Jones plug is required instead of the 1/4" jack plug on the S-Trigger side..

S-Trig schematics

Our Midi/CV interfaces MCV4 and Dark Link (new version) are already equipped with the conversion electronics described above and the user can select between gate and S-trig by different jumper settings. For details please refer to the corresponding user manual.

Sync specification

The SYNC standard was introduced in the eigthies by Roland for synchronization of sequencers, drum machines, arpeggiators and similiar devices. The SYNC standard uses the signals clock (or tempo) and start/stop (or run/stop). The signals are TTL compatible. This means the low state is 0V, the high state is about +5V. The clock signal defines the speed of the sequence or drum pattern. The start/stop signal defines if the sequence is running (start/stop = 0V -> stop, start/stop = +5V -> running).
The SYNC standard uses 5 pin DIN sockets (same as used for MIDI but uses different pins) with the following pin-out:

sync.gif (5452 Byte)

In some applications the remaining pins (4 and 5) are even used as "tap", "fill in" or "reset and start". But this differs from device to device.

To connect two SYNC devices a cable with a a 3 or 5 pin plug on each side has to be used. The pins 1, 2 and 3 have to be connected (in contrast to MIDI that uses the pins 4 and 5). A standard MIDI cable is not suitable as here the pins 1 and 3 may be unconnected !

SYNC Input/Output: Some SYNC devices have SYNC In and SYNC Out sockets Others have only one socket that can be switched between input and output (e.g. TR808). The third group uses switched sockets. This means that the socket is switched to input if a plug is inserted (e.g. TB303). If you want to use this socket as output a special plug without ring has to be used as the ring of the plug operates the switch. For details refer to the user's manual or service manual of the regarding device.

Connection of MIDI and SYNC equipment: We offer some interfaces that convert the corresponding MIDI messages (MIDI clock, start, stop) into SYNC compatible signals (e.g. MSY2, MAUSI, MCV24, REGELWERK, SCHALTWERK). In all these cases MIDI is used as an input. This means the incoming MIDI messages are converted to SYNC signals. SYNC is an output in this case. Interfaces with the reverse direction (SYNC = input, MIDI = output) are not usual. We do not offer such interfaces.


Controlling TB 303 with CV and Gate

The TB-303 is not equipped from the factory with CV and Gate input but only CV and Gate output. Consequently the TB-303 has to be modified to have CV and Gate as inputs available. We have a document available that describes the modification - but only in German language so far (go to the FAQ overview for the link). In any case electronic experience is required to carry out the modification. We recommend to ask a specialist for the modification. Sorry we do not carry out such modifications.

MIDI Interface für Roland Juno-6, Juno-60, Juno-106 oder Korg Poly 61

Wir können leider kein MIDI-Interface für den Juno-6/60/106 oder Poly 61 anbieten. Diese Geräte sind in gewisser Weise ein "Zwitter": Sie verfügen zwar über eine analoge Klangformung (VCF, VCA), aber digitale Oszillatoren (DCOs , keine VCOs), so dass sie über MIDI-CV-Interfaces nicht gesteuert werden kann. Der Juno 60 verfügt jedoch über eine sogenanntes DCB-Interface. Roland hat früher unter der Bezeichnung MD-8 ein MIDI-to-DCB-Interface angeboten, mit dem der Juno 60 über MIDI gesteuert werden kann. Vielleicht können Sie dieses Interface auf dem Gebraucht-Markt finden (wird leider von Roland nicht mehr angeboten).

MIDI interface for Roland Juno-6, Juno-60, Juno-106 or Korg Poly 61

We do not offer a MIDI interface for Juno-6/60/106 or Poly 61. These devices are kind of "hermaphrodites": they use analog sound processing (VCF, VCA), but digitally controlled oscillators (i.e. DCOs , no VCOs). Consequently they cannot be controlled by Midi-to-CV interfaces. The Juno 60 features a so-called DCB-Interface. Roland offered a Midi-to-DCB interface called MD-8 that enabled to control the Juno 60 via Midi. Maybe you can find this interface second hand as it is no longer manufactured.

MIDI interface for Korg Polysix

The Korg Polysix is not equipped with CV and Gate inputs. Consequently it cannot be controlled by an external Midi-to-CV interface. Only the arpeggio speed can be controlled via Midi e.g. by MSY2 (MSY2 clock output -> Polysix arpeggio clock input).

Controlling the Moog Prodigy via CV/Gate

In the following table you find the jack sockets available with Moog Prodigy and our recommendation how to connect them to the CV and Gate outputs of our devices (e.g. MCV4, MAQ16/3, Dark Time, Dark Link) :

Progigy MCV4/MAQ/Dark Time Remark
S-Trig In/Out Gate S-Trig cable has to be used in combination with MAQ16/3 or Dark Time, the MCV4 or Dark Link has to be jumpered to S-Trig 
KYB In/Out no connection  
Osc In CV1 connected to the pitch CV output of the unit in question (e.g. CV1 of MCV4)
VCF In CVx connected to another CV output of the unit in question depending upon the type of VCF control (e.g. for MCV4 CV2: via velocity, CV3: via after touch, CV4: via MIDI controller
Sync In no connection  

As the MCV4 uses 2 stereo jack sockets for CV1...CV4 a special cable has to used for the connection between MCV4 and Moog Prodigy (1/4" stereo plug -> 2 x 1/4" mono plug). If the trigger is reverse (i.e. sound when key release and no sound when key pressed) the trigger polarity of the MCV4 has to be changed. For details please look at the user manual of the unit in question.

Controlling the Moog Source or Moog Rogue via CV/Gate

If you want to control a Moog Rogue or a Moog Source from the CV and Gate outputs of our devices (e.g. MCV4, MAQ16/3, Dark Time, Dark Link) you have to pay attention to the unusual assignment of the jack sockets of these synths:

As most devices output the pitch CV at the tip of the socket one needs a special cable that connects the ring of the plug at the Moog side to the tip of the plug at the other side. E.g. a so-called insert cable may do this job (i.e. a cable with a 1/4" stereo plug on one side and two 1/4" mono plugs on the other side).

For the gate/trigger connection a standard mono 1/4" cable can be used if the MCV4 is set to S-Trigger mode (jumper inside the MCV4) and the trigger polarity is changed. For details please refer to the MCV4 manual. If the interface only features a voltage gate another special cable has to be used that connects the voltage gate to the ring of trigger socket.

Controlling the ARP2600 via CV/Gate

The ARP2600 requires a gate voltage of at least 10V to trigger its envelope generators. For the MCV4 or MCV24 the gate voltage has to be set to this value. Please look at the corresponding user's manual: MCV4 manual resp MCV24 manual (e.g. for the MCV4 the gate jumper has to be set to +U voltage gate and a external power supply with at least 10V has to be used, we recommend the usage of a 12V power supply for this application, for the MCV24 the gate level is software controlled). The gate voltage of the MAQ16/3 corresponds to the power supply used for the MAQ16/3. Consequently a power supply with at least 10V (better 12V) has to be used for the MAQ16/3 to trigger the ARP2600. As the supply voltage range for the MAQ16/3 is 9...12V this is within the specified supply voltage range.
In addition the gate output of MCV4/MCV24/A-155/MAQ16/3 has to be connected to both gate and trigger inputs of the ARP2600. Otherwise the envelope generators of the ARP2600 will not start !

Controlling EMS synthesizers (e.g. VCS3)

The VCOs of the the EMS synthesizers do not follow the 1V/octave standard. E.g. VCO1 and VCO2 of the EMS VCS3 use the very unusual 0.32V/octave scale and VCO3 uses 0.26V/octave. Therefore the MCV4 cannot be used without modification as the CV scale of the MCV4 can be adjusted only within a small range around 1V/octave. The modification for the MCV4 (0.32V/octave) is available upon request (about Euro 20.00 additional charge).

Controlling Roland MC-202

In principle the MC-202 can be controlled via MCV4 or MCV24. But the MC-202 has one special quality: the external CV input is not connected to the VCO directly and the external gate input is not connected to the ADSR directly. Rather both CV and gate are processed by the MC-202 microcontroller before they reach the VCO and ADSR resp. This causes delays for both CV and gate, and in addition a quantization for the CV. The external interface (e.g. MCV4 or MCV24) is not the reason for these peculiarities but the signal processing of the MC-202.

Controlling Synthesizers with Hz/V standard

Synthesizer with Hz/V characteristics for the CV input cannot be controlled with Midi-CV interfaces that follow the 1V/Oct standard (e.g. MCV4, MCV24, A-190), MAUSI). Sorry we have no Midi-CV interface available that follows the Hz/V standard. E.g. these synthesizers are Hz/V.:

Only for the Korg MS-10 and MS-20 there is a solution to use 1V/Oct Midi-CV interfaces: Controlling Korg MS20 with Volt/Octave Midi interfaces (A190,MCV4,MCV24)

Spezial-Kabel und Kabel-Adapter

Wir werden oft nach einer Bezugsquelle für Spezial-Kabel gefragt. Ein Hersteller, der nahezu alle vorkommenden Spezialkabel anbietet, ist die Firma Schulz Kabel (Lilienstr. 12, D-34621 Frielendorf, Tel. 05684-8279, Fax 05684-8963, Internet:, email: Hier einige Beispiele aus dem Lieferprogramm der Fa. Schulz, nach denen wir häufig gefragt werden:

Im Lieferprogramm von Schulz finden Sie nahezu alle gängigen Kabelkombinationen (Klinke 6.3mm, Klinke 3.5mm, Cinch, XLR, DIN usw.). Sehen Sie auf der Internet-Seite von Schulz-Kabel nach oder lassen Sie sich von der Fa. SChulz einen Katalog zusenden.

Special cables and adapters

Many customers ask for a supplier of special cables. The German company Schulz Kabel (Lilienstr. 12, D-34621 Frielendorf/Germany, Phone +49-5684-8279, Fax +49-5684-8963, Internet:, email: delivers a lot of special cables. Here are some examples:

Please look at the web site of Schulz-Kabel for details and prices or ask for a catalogue.

Lebensdauer von Akkumulatoren (verwendet zur Datenspeicherung)

In einigen unserer Geräte werden Akkumulatoren zur Speicherpufferung verwendet. Diese Bauteile haben eine begrenzte Lebensdauer und sollten mindestens alle 2 Jahre überprüft werden. Vor der Überprüfung muss das betreffende Gerät vollständig vom Netz getrennt werden ! Zunächst muss optisch überprüft werden, ob der Akku noch dicht ist und kein Elektrolyt austritt. Dann folgt die elektrische Kontrolle, die das Messen der Spannung des Akkus umfasst. Die Spannung sollte um nicht mehr als 10% vom Sollwert abweichen. Der Sollwert (2,4 oder 3,6V) ist auf dem Akku angegeben. Falls die optische oder elektrische Kontrolle auf einen Fehler hinweist, muss der Akkumulator ausgewechselt werden. Dies sollte nur von Fachpersonal durchgeführt werden, da Lötarbeiten erforderlich sind. Sie können den Akkumulator als Ersatzteil beziehen (siehe Preisliste / Abschnitt Ersatzteile), falls Sie in der Lage, sind den Austausch selbst durchzuführen (alten Akkumulator auslöten, neuen Akkumulator einlöten). Es kann jedoch jeder andere Akkumulator verwendet werden, der die gleiche Spannung aufweist (z.B. 3,6V) und der mechanisch passt (siehe untenstehende Maßskizze). Der alte Akkumulator muss fachgerecht entsorgt werden. Er darf nicht zum normalen Hausmüll gegeben werden.
Folgende Geräte sind bzw. waren mit einem Akku zur Datenspeicherung ausgestattet:

Typische Bauformen der verwendeten 3,6V-Akkus Maßskizze der verwendeten 3,6V-Akkus

Lifespan of rechargeable batteries (used for memory backup)

In some of our devices rechargeable batteries (accumulators) are used for memory backup of preset data. These electronic parts have a limited lifespan and have to be inspected at least every two years. Before the inspection the device has to be disconnected from mains voltage ! If the battery has a leak or if the measured voltage of the battery differs more than 10% from the target voltage the battery has to be replaced. The target voltage (2.4V or 3.6V) and is printed on the battery. The replacement should be carried out by qualified personnel only. The old battery has to be removed (desoldered) and the new one put in (soldered). If you are able to carry out the replacement yourself you can purchase the rechargeable battery as a spare part from the Doepfer representative in your country. But any other rechargeable battery with the same voltage (e.g. 3.6V) can be used provided that it fits mechanically (see dimensional drawing below). It is not allowed to put the old battery to the normal garbage. Please forward the old battery for recycling to a suitable receiving office.
These devices are (or have been) equipped with a rechargeable battery for memory backup:

typical shapes of the batteries dimensional drawing of the 3.6V batteries