IRP DG-4023 Transversal Equaliser #1


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Super-rare, minimum-phase 1/3-octave equaliser with high- and low-pass filters. I have two in stock

Industrial Research Products is the only company to have brought an analogue transversal equaliser to market. It blends delay line technology with a traditional graphic equaliser layout to produce a unique, minimum-phase equaliser

“Industrial Research Products was founded by Maylon Burkhardt who invented the zero-phase shift transversal eq, completely analogue and as the name implies, zero phase shift no matter how radical the eq setting. They were based in a suburb of Chicago, and rumour has it that Maylon was an ex alumni of early Shure Brothers.

I used a lot of their products in the 80’s on commercial AV jobs, and I did some custom simultaneous translation projects where I used their wonderful Voice Matic automatic mixers and the transversal eq’s. The company fell into hard times in the mid 90’s and was purchased by their German distributor.

The Grateful Dead would ONLY use the Transversal EQ for many years. Great products and sad to see that they have virtually disappeared. I don’t believe a digital implementation of the transversal eq can be as clean” – Wards, Gearslutz

The DG-4023 has 29 bands of equalisation at third-octave centres plus high & low-pass filters. The high-pass filter is 18dB / octave at 20, 40 or 80 Hz and the low-pass is 12dB / octave at 20, 12 or 8kHz. An HF boost switch gives a rising HF response +3dB at 3.2kHz and +10dB above 10kHz

Inputs & outputs are balanced on XLR connectors

Additional information

Weight 5.9 kg
Dimensions 37 × 11 × 55 cm
220V with IEC power connector. UK or Euro power cable supplied on request
In very good used condition with minor case marks. Knobs & switches are all original. Tested & working 100%. Photos show the EQ for sale