Roland TR-707

Description: Modify the pitch shift of the crash and ride sounds by lifting pin 10 of the TC4040 binary counter and inserting an alternative clock signal. This clock can be derived from any suitable signal obtained from the TR itself. The other sounds do not utilize a counter for address selection, unlike IC34 and IC35 (BD-midTom and HiTom-Tambo). Here, addresses are selected directly from IC30. Both of these ICs are connected to the same address lines, so unless traces are lifted or cut, these sounds will likely be mixed together. Chip Enable (CE) selects which ROM responds to the data lines and can serve as bend points. Note the RA3 and RA4 (resistor arrays); these are simple R/2R digital-to-analog converters (DACs). The inputs can receive signals that will be processed as digital audio and converted into analog audio. This modification can also be applied to the D0-D7 lines between IC35 and ICs 36-37. Implementing these modifications inside the TR-707 is recommended to start with a selection of data lines or to utilize a breakout box. Separate pitch bending can be applied to other sounds, but some sounds are pitch-bent together using the same control knob, particularly those in combined ROM pairs as mentioned earlier. The system is clocked with a crystal, so a simple potentiometer may not be optimal. It is suggested that a custom clock circuit, such as a (CD)40106 clock or oscillator schematic, may be beneficial. Due to the digital nature of the TR-707, a clock modifier is necessary to alter the sample playback rate. Modifying each drum sound would typically require individual circuits; however, to reduce component count, a 558 Quad 555 timer can likely be utilized. The open and closed hat sounds on the TR-707 share the same sample with varying envelopes. This modification adds independent knobs to control the decay of each sound, with the open hat decay knob serving as a master control for both sounds, while the closed hat decay knob adjusts the closed hat decay within the maximum setting of the open hat. Essentially, when the open hat decay is fully set, the closed hat can be adjusted from a faint click to the full open hat sound, but if the open hat is only partially open, the closed hat decay can only range from a faint click to a normal closed hat sound. For those interested, pitch knobs have been added for each sound on the 707, with sounds sharing volume sliders also sharing pitch knobs, while the ride and crash sounds have a single pitch control. Careful disconnection of pins 56, 57, and 59-64 of IC30 from the circuit board is necessary, or alternatively, traces can be cut under the surface mount IC. The outputs of the 555 oscillators must be soldered to the pins, which is challenging due to the small and closely spaced pins. A single oscillator could be constructed and connected to all pins for a global pitch control, though this may not be effective if some sounds operate at different sample rates. Maintaining structural integrity is critical, as any broken pins will result in loss of sound functionality. It is advisable to solder the pins in their original positions rather than having them elevated with wires attached. Lastly, it is essential to reconnect any severed connections between the original pins and the remaining circuitry to restore clock signals, as failure to do so will result in distorted or bent sounds.

The TC4040 binary counter serves as a crucial component in managing the pitch shift for specific drum sounds within the TR-707. By lifting pin 10, an external clock can be introduced, allowing for greater flexibility in sound modulation. This modification is particularly useful for those looking to customize their drum machine's audio output. The digital architecture of the TR-707 necessitates careful consideration of how signals are routed through various integrated circuits (ICs). The interconnectivity of IC30, IC34, and IC35 highlights the importance of addressing lines and chip enable signals, which dictate how sounds are triggered and modified.

The resistor arrays RA3 and RA4 function as R/2R DACs, enabling the conversion of digital signals into audio. This conversion process is essential for achieving desired sound effects and tonal variations. The D0-D7 lines connecting IC35 to ICs 36-37 represent additional opportunities for audio manipulation, allowing for further experimentation with sound design.

For individuals seeking to implement these modifications, careful attention to the circuit layout is paramount. Disconnection of specific pins should be executed with precision to avoid damaging the circuit board. The use of a Quad 555 timer can streamline the modification process, reducing the number of components needed while still achieving the desired pitch control functionality.

Overall, the TR-707 offers a platform for extensive sound manipulation, with the potential for unique audio effects through careful modification of its internal circuitry. The ability to control pitch and decay for various sounds enhances the versatility of the drum machine, making it an invaluable tool for music production and sound design.Hack the pitch shift of the crash and ride by lifting pin 10 of the TC4040 binary counter and insert your own clock in (or just whack it with an additional clock source). This could be any suitable signal you pick up from the TR itself. The other sounds do not have a counter for adress select (like IC 34 and IC35 (BD-midTom and HiTom-Tambo

urin). Here adresses are selected directly from IC30. Both these IC`s are connected to the same adress lines, so unless you lift/cut traces these sounds will probably be bent together. CE (chip enable) selects witch ROM reacts to the datalines. CE can be used as bend points. Notice the RA3 and RA4 (resistor arrays). These are simple R/2R DAC`s. The inputs can be fed signals that will be treated as digital audio and be converted into audio. You can also do this at the D0-D7 lines between IC35 and IC`s 36-37. Well, it`s a long story, loads could probably be done after some study. If you want to implement your bends inside the TR-707 itself, I suggest to start with a selectrion of data lines.

Or go over the top on a breakout box. seperate pitchbend can be done on the other sounds, but some sound are pitchbent together by the same knob. These would be sounds in combined ROM pairs as outlined earlier. It`s clocked with a crystal though, a simple pot here may not be optimal. Maybe Diabolical removed the crystal and made his own clocks. Search for a (CD)40106 clock or oscillator schematic, might do the trick. they sayd: "Because of the digital nature of the 707 a clock modifier is needed to change the sample playback rate.

Doing this mod for each drum sound would require individual circuits to be added, however to minimize the part count a 558 Quad 555 can most likely be used. " "On the TR-707 the open and closed hats sounds use the same sample with different envelopes. This mods adds individual knobs to control the decay of each sound but in order to do this the open hat decay knob has to act as a kind of overall `master` decay for both sounds and the closed hat decay knob sets the decay of the closed hat within the maximum setting of the open hat knob.

Essentially this means that when the open hat decay is set to full, then the closed hat can be set anywhere from a tiny click to the full open hat sound, but when the open hat is set only half open then the closed hat can only sweep from the tiny click sound at minimum to roughly the normal closed hat and full. This is virtually impossible to explain so we hope you get the idea. " in case anyone is interested, i added pitch knobs for each of the sounds in my 707. the ones that share volume sliders also share pitch knobs, and the ride and crash have a single pitch control as 2.

very carefully disconnect pins 56, 57, and 59-64 of ic30 from the circuit board, or find some way to cut through the traces that go under the (surface mount) ic. i ended up slicing through the board with an exacto blade before i realized i could have desoldered the pins, cut the traces and resoldered the pins.

3. solder the outputs of the 555 oscs to the pins. this part is difficult because the pins are small and close together. i guess if you wanted you could just build a single oscillator and solder it to all the pins for a global pitch control. that might not work though, because i suspect that some of the sounds run at a different sample rate.

-structural integrity is extremely important here. if one of the pins breaks off, no more drum sound. it`s best if you can have the pins soldered in their original places rather than sticking up in the air with the wires attached. 5. find all of the connections between the original pins and the other circuitry that were severed when you cut the traces, and reconnect them to the original clocks.

this part took the longest for me. you have to pore over the schematic and find the stuff that gets the clock signals. it sounds distorted and bent without these connectio