On the bench: UREI 530 Equaliser modifications

UREI was a major manufacturer of equalisers through the 70s, 80s & 90s and the 530 was one of the earlier stereo graphics EQs. It’s a pretty standard opamp-based equaliser with ten octave bands, but it’s liked for the way the EQ bands interact

“Those older Urei graphics are proportional Q designs, great for getting sounds as they extrapolate the curve into a smooth one”. Jim Williams, Audio Upgrades

The one drawback with these older UREI Eqs is sticky pots. JJ Electronics in the USA has a cure for this – a new circuit board to mount replacement Bourns pots. The job is more complex than it sounds, as it requires the pots to be mounted closer to the front panel, but this makes the pots much smoother in operation

We’ve recapped this 530, upgraded the power supply and put larger bipolar caps in the audio path. We’ve done the fader replacement & the EQ tests fine. The original knobs don’t fit the new pots so the search is on for new knobs

We can supply XLR pigtails to suit the terminal strips

Removing the old pots, old movies in the background

Laying out the parts – new JJ circuit boards closest to the camera

Test fitting with nylon stand-offs and 40mm M3 bolts

Close up of new board mounted closer to the front panel

Making up wire links to link to the original board

Main circuit board partially recapped

Bigger power supply caps with bypass caps mounted under the board