We're closed for a holiday. Online ordering will resume when we re-open. Local UK buyers, please email shop@bn1studio.co.uk if you require something urgently & can collect

Symetrix 501 Compressor / Limiter (dbx VCA)




This Symetrix 501 has been refurbished and recapped. The power supply has been upgraded with higher-capacity Panasonic caps. The input & output caps have been replaced with higher-value Panasonic bipolar caps. The pots have been cleaned & lubricated. Photos show a 501 sold previously

Symetrix is an American company producing outboard gear. Not that well known in the UK, they have a good reputation in America for cost-effective and well-engineered products

Early models of the 501 used the EGC-101 VCA from Valley People Inc. Later models – like this one – used the ubiquitous dbx 2181 VCA

The 501 is a compressor / limiter with front panels for Attack, Release , Threshold & Ratio. The peak limiter has a separate threshold control and the compressor & limiter sections have independent in / out switches. There’s a switchable auto attack / release setting and an output gain pot. Stereo linking is switchable from the front panel, allowing a pair of 501s to be stereo-linked. Unusually the sidechain insert is also switchable from the front panel

Fire up the 501 and you’ll find the compressor section is punchy & adaptable with good control over attack & release times. As you’d expect, higher compression ratios sound tighter & more focussed but low ratios with fast attack & release are great for pumping room mics. Switch the compressor out and fire up the limiter and you’re in for a treat – this is a great-sounding limiter

The 501 is built in the usual Symetrix tough steel chassis and the controls have a quality feel. It has both balanced and unbalanced connections so it’ll be equally at home in a studio rack or a home setup

“The 501 is a really fun box, that I used to use before distressors came out for room mic distortion and limiting. They can do pretty insane amounts of limiting, and the diode clip on the output is awesome as well. For destruction, I love them”

“For the money? yes please”

“501’s work great for bass. Not shabby on vocals either”

“Especially nice for electric bass”

“had one back in the day, it lived on the insert point for Bass DI. To my ears, that is what it excelled at”

“501 is a really great compressor for crushing rooms. I have a dynamite & a pair of Levelors, 9 times out of 10 the 501 gets more useable results”

“Its really cool on drums especially drum OHs/room”

“KEEP THE 501. They work on most anything !”

In my tests I found the 501 to be as useable & transparent as other Symetrix compressors. The controls are well-judged so setting thresholds is easy & accurate. The limiter is brutal & characterful and adds a bit of attitude to the traditional smooth Symetrix compression. The 501 is a great tool for bass & drum crushing and it’s easy to see why it has developed such a reputation. In an ideal world you’d have four – two for compression and two set permanently to limit

Balanced inputs & outputs are on XLR connectors and unbalanced on TRS connectors. Sidechain insert is on two TRS jacks (send & return) rather than on a single insert jack. Stereo link is via a TRS jack. Standard operating level is +4 dBu and the operating manual has comprehensive details on impedances, matching, levels & connector wiring protocols

Standard 19" 1U device suitable for all 19" racks. 220 Volt AC, captive power cable with standard UK power plug

Owners manual




Gearslutz threads (long)



TapeOp Forum thread


Ovnilab review



This Symetrix 501 has been refurbished and recapped. The power supply has been upgraded with higher-capacity Panasonic reservoir caps and new film bypass caps. The input & output caps have been replaced with higher-value Panasonic bipolar caps. Tested & working 100%. Photos show a Symetrix 501 sold previously

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