Dolby 360-1 with modified Cat 22 Dolby Trick card


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Dolby 360-1 processor in excellent condition. This has been refurbished with a recapped power supply and new bulbs for the switches & meter. Photos shows the unit for sale

This is fitted with a modified Cat.22 Dolby Trick card. Bands 1 & 2 have been disabled so only bands 3 & 4 – the mid & high frequencies – are processed. Use in encode (record) mode to get high-frequency enhancement

I have a setup guide for using this hardware here

The Dolby 360, and the later 361, were ubiquitous throughout the 1970s, 80s and 90s. They were the standard single-channel Dolby mother units, compatible with the original 1965 Cat 22 Dolby A card and the later Cat 280 Dolby SR cards. Every studio had a couple of 361s but they are now surprisingly rare on the secondhand market

As a double-ended noise reduction system, Dolby A encoded the signal and applied reciprocal decoding on playback. If the tape machine was aligned correctly the system was pretty transparent and gave a significant noise reduction, particularly at higher frequencies

Post-digital, Dolbys are obsolete except for archiving and for doing the Dolby Trick. Dolby A splits the audio spectrum into four bands, applying varying amounts of compression to each. Compression is level-dependent so, as levels rise, compression backs off. At higher frequencies, where tape hiss is more obvious and average signal levels are relatively low, a fair amount of compression could be used, resulting in a dramatic perceived reduction in tape noise & hiss

Dolby 360s date back to the 1970s & 80s. This one is unusual in having original switch caps, working meters & bulbs. It is in excellent condition and very original. Tested to encode only, working 100%. Supplied with a modified & tested Cat 22 (Dolby A) card

The Dolby Trick
The Dolby Trick uses the high-frequency compression of Dolby A as an audio effect. By encoding the signal, but not decoding it, it lifts the harmonics & airiness of sounds in an attractive way. It works like a charm on backing vocals but it’s also useful on guitars, drum ambience & etc

Used with standard Cat 22 cards the effect is subtle. We have modified the Cat 22, bypassing processing on the lower two frequency bands, to create a more pronounced effect. See our setup guide

The 361 was patched into tape machine feeds & returns and switched from record to replay mode as required. There's a remote socket on the back panel for automatic record / repro switching but most 361s were switched manually

Built like a brick outhouse, the 361 is a 1U device weighing in at 5.5 Kg. There are no electronics in the 361 but inputs & outputs are transformer-coupled. It contains a power supply, dedicated input / output switching section and a slot for the noise reduction card

This 360-1s uses a non-standard power connector. A matching power cable is supplied. Voltage is switchable 110 / 220 VAC

Standard 1U device suitable for rack-mounting. The 361 is heavy (5.5 Kg) so should be mounted with care


Dolby 360-1 processor in excellent condition. This has been refurbished with a recapped power supply and new bulbs for the switches & meter. Fitted with a modified Cat.22 Dolby Trick card. Tested to encode only & working 100%. Correct power cable supplied. Photos shows the unit for sale