UralTone ODS - active effects loop - build guide

UralTone ODS - active effects loop - build guide

UralTone Overdrive Special Effects Loop integrates the Dumbleator circuit into the UralTone ODS amplifier. Originally sold as a standalone device, the effects loop buffer is now part of the Overdrive Special kit. This integration simplifies the circuit: the loop now receives its power supply directly from the amplifier’s power source.

UralTone ODS Loopeator - BOM

Complete layout of ODS with loop

Schematics

Circuit assembly

Always check first that all parts are included in the delivery. If you find any missing components, contact us by replying to the order confirmation email.

Please note that some components may look slightly different from the photos. Also, the voltage or power ratings of certain parts may be higher than listed. Read the part list notes carefully.

Follow the assembly sequence shown in the images below. We strive to keep the component models the same, but due to availability issues, we may occasionally need to change the manufacturer or model. So, if a part looks slightly different in color, don't worry—every component has its necessary values clearly marked on its body.

The loop circuit requires drilling new holes in the enclosure. Use the included back panel to mark the hole positions on the enclosure.

Drilling should be done using either a step drill or, if using a regular drill bit set, start by drilling smaller M3 pilot holes at all drilling points. Drill the following holes:

• DIN connector: M3 holes for mounting
• Switches: M6 holes (3x)
• Jacks: M9.5 (or M10) holes
• Enlarge the DIN connector opening to M16

NOTE: Also drill any other required additional holes at this stage (front panel + lid) according to the ODS build guide. Depending on the kit's production batch, the number of required holes may vary.

Attach the connectors, switches, and potentiometers to the panel. Note the positioning of the parts: the tip contact of the jacks should point to the right so that it does not touch the enclosure or the preamp tube socket screw. The legs of the potentiometers should be directed to the right.

Same step seen outside of the chassis.

Solder four wires to the DIN connector as shown in the image. The connector’s contacts can be slightly pushed outward to create more space for soldering. Use thin wire for the connections. For now, do not solder the wires that go to the lower solder lugs of the switches. Strip the common ground wire long enough so that it reaches across all three center pins. Leave the leftmost end unsoldered for now.

Solder four approximately 20 cm wire pieces to the switch pins that were left unsoldered in the previous step. These wires will later be soldered to the amplifier circuit board and the loop circuit board.

Solder a jumper wire between the jacks and the center pin of the potentiometer as shown in the image.

Solder the shielded cables as shown in the image:

• Send potentiometer: shielded wire with one conductor: signal to the lower pin, ground to the upper pin
• Return jack: shielded wire with one conductor: signal to the tip of the Return jack, ground to the jack’s body lug
• Return potentiometer: shielded wire with two conductors: white, red, and ground as shown in the image

The sufficient wire length is approximately 15-20 cm.

The circuit board. The board has part numbers printed by type (R1, R2, C1, C2, etc.), and each part has a specified value in the parts list. Not all components on the circuit board are installed, only those that are listed in the parts list.

Attach two M3 - 10mm spacer sleeves to the left side of the chassis at the preamp tube location. Insert the tube socket into the solder side of the board, aligning it with the pads. Turn the board over and secure it with screws to the newly installed spacer sleeves.

Let the socket drop into the mounting hole so that the socket height is correctly positioned. Check that the board is at a right angle, and once both the socket and the board are in the correct position, solder the socket in place. After soldering, remove the circuit board from the chassis.

It is recommended to place the components starting with the lowest ones in order. This way, when the board is flipped over for soldering, the components will sit neatly on the surface of the board. Solder all the resistors (R1, R2, etc.) and the diode (D1). Resistors do not have a specified orientation, but the diode must be installed correctly. Align the stripe on the diode's body with the marking on the circuit board.

Solder the capacitors (C1, C2...) onto the board. Except for C5, which is shown in the image at the lower left of the board, the capacitors do not have a specified orientation. C5 is an electrolytic capacitor that must be installed correctly. The capacitor’s body has a groove at the positive end (shown on the right in the image). Align this end with the outline of the marking on the circuit board.

As last component, solder the relay (K1) on pcb.

Attach the ready circuit board into chassis.

Solder the wires coming from the back panel to the circuit board:

• White footswitch wire to the R- pad
• Wire from the Return jack: signal wire to the RET pad on the circuit board. Ground is isolated and left unconnected
• Wire going to the Send potentiometer: signal wire to the right pad of RV1, ground to the left pad of RV1
• Wire going to the Return potentiometer: RV2 pads from right to left, white, red, and ground

If the loop circuit is installed in an unbuilt kit, proceed to build the amplifier according to the ODS instructions, excluding the SEND/RETURN jack wiring.

In the passive circuit (the original amplifier circuit), the wires going to the effect loop jacks are soldered to the looper circuit board. Additionally, the wires for grounding and anode voltage are run to the circuit board. Follow the layout diagram included with the kit when wiring.

Note: The image above is from a prototype amplifier and may not exactly match the final component placement. The image is intended to give an idea of what the loop circuit looks like when installed in the amplifier chassis.

The finished amplifier is tested as described in the instructions; it is recommended to disconnect the effect loop during testing.