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The genesis of the Gradient Box

Writer: Srajan Ebaen
Financial interests: click here

Wicked R&D. A December 2020 email from Liscarney hurried to Manchester. "Did you see this? It's an unusually flexible purely analog precision solution [since discontinued – Ed.]. I know of only one other that's not quite as functionally advanced but sells for double. There could be a bigger market for this if remote control could do the adjustments from the listening chair. Perhaps an option for your cost-no-object preamp version?"

"Thanks for the xover suggestion. What's your opinion on adding two programmable notch filters to the multi-frequency filter to treat the two biggest room-mode components? This could be very basic fully analogue room correction. The measurement of the room and calculation of notch filter settings won't be a walk in the park for beginners but I have ideas how to do it with a cheap iOS app measurement and sending the results to me. I'd send back the rough setting and the customer can fine-tune by ear."

The Irish had his opinion. "There once was the Rives Audio Parc purely analog EQ with three notch filters for the three primary modes of room width, length and height. It worked in stereo so each channel had its own adjustments for frequency, width and attenuation. That company is no more. For the average customer I'd probably not bother with measurements. Just have them plug their basic room dimensions into an online calculator and voilà, it spits out the three main axial standing-wave frequencies. Now they know where to roughly set the notch filters and the rest can be done by ear. For more advanced customers, they measure how severe peaks are in their sitting position to calculate Q and width of the notch filter."

The Hungarian expat in Manchester had his opinion on that opinion. "Good thinking. In slightly modified form, I want to bring back fine but past tried'n'tested gear like I already did with the Slagleformer passive from John Chapman. The number of notches is flexible, I'd only need some more space on the board and in the box. You are right with the calculations, too. Based on the technical IQ of the user, it's worth to try different methods. It could be new entertainment for some audiophiles beside tube/op-amp rolling, cables swapping etc. During the coming Christmas break, I'll do some experiments with my enabled iPad, my miniDSP nanodigi + UMIK-1 + REW to see and hear the differences. If it works well in DSP, l'd consider making an analogue room corrector as part of an advanced icOn or as a standalone crossover + corrector. If I can do it, the first SE room corrector will come your way for review."

If this exchange told you too little, catch up here and here. Those reviews covered background in extensive detail. The above is for the pimp-my-icOn crowd; what designer Pál Nagy calls the audio jewelry version. He'd already ordered VU meter and nixie-tube samples. But it'd be no super icOn if it were just about cosmetics or a more luxurious full-size build. It must also incorporate more upscale functionality or at least make it optional. Given how comprehensive the icOn 4Pro platform is already, that requires clarified brain grease. Ghee whiz miracle whip?

Thankfully Pál is full of it. Where normal people look forward to Year's End holidays to chill and get fat, he looked forward to time away from production to don his R&D cap.

"I just finished a Model 5 for an Australian customer which I like very much. It's exactly a Model 1 from the outside and works as the Model 1 but inside has two autoformer pairs like the Model 4. Perfect for the audiophile who has one main source like a DAC with balanced output but there's also an RCA input for a single-ended phono. Sometimes less is more."

With no details or time table—it all depends on what the wood-shack process cooks up—this simply alerts us. Something's brewing in Manchester. A tube buffer and exotic hardwood chassis are already on the burner. "I love wood boxes. For the modular icOn's outer skin I would like many options including wood and various non-magnetic metals with artistic finishing. The professional German-made 19" 3U Schroff Eurorack will be the inside frame."

"For the variable filters I'd probably use the same analogue switches as in the 4Pro. I have many strange ideas for the icOn Ultimate which I'll still analyze to map out a rough build plan with technical details and features. Only one thing is sure already: it will be very unique, truly ultimate and built with state-of-the-art parts, materials and solutions." No sooner had that virtual ink dried …