UREI 546 Dual Parametric Equaliser (with Jim Williams Upgrades)


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This UREI equaliser has been rebuilt & modified by Jim Williams at Audio Upgrades in LA. The refurbishment was very comprehensive: The original power transformer was junked in favour of a toroidal unit and the PSU rebuilt with higher-value caps. In the audio path, all the capacitors have been bypassed and the EQ caps replaced with Wima film caps. The opamps were upgraded to Linear Technology LT1359CN chips and high / low-pass filter bypass switches fitted

Vintage equaliser from UREI. The 546 is a two-channel, four band parametric equaliser with variable high- and low-pass filters and input gain controls. In usual UREI fashion, the ergonomics and signal path have been honed to perfection , producing a highly useable, efficient EQ

Each band has a push-pull, in / out switch to bypass that band only. Each channel has a bypass switch and this 546 has been modified with a filter bypass switches. In bypass bandwidth is extended to 200 KHz

The 546 is easy to use with plenty of scope in the controls and well-judged linearity. The tightest filter setting has a high Q is suitable for notching out problem frequencies. At broader settings each band is wider & smoother. The 546 turns out to be my favourite bass equaliser – it’s easy to put weight into a bass sound, or warmth, or depth without it sounding wooly

“I replace the 4741 quad opamps, direct couple the entire audio path = no capacitors. EQ caps are MIT MultiCaps and Wima. I also install filter bypass switches to open the bandwidth to 0 hz to 200k hz. A surgical EQ” – Jim Williams

“The reason I got the 546 and had Jim upgrade was exactly what you say, needing a serious eq and not being able to spend the usual $2,500+ that’s required to get you in the game”

“I had Jim do his mods to my 546 and I like the way it sounds. Cleaner and more open than before, that’s for sure!”

“There’s also a certain curiosity factor with this eq. Every engineer that’s been in my studio since I got it has immediately zoned in on the 546 and been intrigued with it. There were only about 1,000 made, I believe, so it’s not something everyone has seen”

Dual-channel parametric equaliser with separate controls for each channel. Four bands per channel, with individual band defeat switches, and continuously-variable low- and high-pass filters. On this unit the filters have a bypass switch. Inputs & outputs are balanced on XLR and teminal strip. Channels can be cascaded via a backpanel switch to create a single-channel 8-band EQ 110 / 220 VAC input with rear-panel voltage switching. Power input via standard IEC socket. US, UK or Euro Schuko IEC cable supplied on request
Shallow 3U device suitable for 19" racks
Operating manual http://thehistoryofrecording.com/Manuals/UREI/UREI-546_Manual.pdf Gearslutz discussions https://www.gearslutz.com/board/high-end/31780-urei-546-parametric-eq.html https://www.gearslutz.com/board/so-much-gear-so-little-time/24065-curious-about-urei-546-eq.html
Very good used condition. Some rack rash & waviness in the rack ears, but nothing unexpected for something of this age. All knobs are original & in good condition. Tested & working 100% Rebuilt & modified by Jim Williams at Audio Upgrades in LA. The power transformer was replaced with a toroidal unit and the PSU rebuilt with higher-value caps. All capacitors in the audio path have been bypassed. EQ filter caps replaced with Wima film caps. Opamps upgraded to Linear Technology LT1359CN chips. High / low-pass filter bypass switches fitted   Vintage gear All vintage gear will have case scratches and marks. It may also have, or develop, noisy pots and switches. I make my descriptions as accurate as possible and note any existing defects. I test each item before shipping but please understand that vintage gear will not be perfect and adjust your expectations accordingly