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727 ROM expansion

727 ROM expansion  ·  Source: HKA Designs

It’s a ROM expansion from HKA Design that adds a bunch of legendary sounds to your TR-707 or TR-727 from the TR-808, TR-909 LinnDrum, LM-1 and DMX.

ROM Expansion

It gives the machine 8 banks of sounds including the original ones from the 707 and 727 plus a mix of the two. The other banks are samples taken from the Roland TR-808 and TR-909, LinnDrum, the Linn LM-1 and Oberheim DMX. All of the sounds are stored as 8-bit linear PCM at either 12.5kHz or 25kHz, across two Hitachi HN61256 32kB mask ROMs and read out using a multiplexing system. The last two sounds (crash & ride / quijada & chime) are not multiplexed and instead have their own dedicated counters and DAC.

Here are the new banks:

The 808 and 909 samples were provided by Sunshine Jones who also lent them the TR-727.

The kit which you’ll need to install consists of a PCB with ROM installed, a ribbon cable, and 28-way IC socket. You will need to solder this bad boy in and be completely happy with taking the back off your 707 or 727 and lifting out the main PCM assembly. You’ll then have to desolder and remove IC34 and IC35 and put the IC socket in place of IC35. The expansion board then plugs into the socket you’ve just soldered in place. Connect the ribbon cable and you’re good to go. It’s actually more complicated than that but there are decent instructions to show you what to do.

HKA Design 707 ROM Expansion

HKA Design 707 ROM Expansion

HKA Design 707 ROM Expansion installed

HKA Design 707 ROM Expansion installed

You can then select the soundbank by holding down a specific key when starting up your machine.

The expansion kit is currently sold out but more should be available in September for £60.

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