Drunk Beaver's Pedal Drop #34 is a really cool take on the Roland Jazz Chorus Preamp Section - specially as per the JC-120H and JC-77 Editions of Amps

The Mariupol Jazz Preamp is a noise-free, high-fidelity reimagining of the legendary Roland Jazz Chorus preamp section, specifically targeting the op-amp topology found in the stereo JC-77 and the James Hetfield-approved JC-120H head.

While the original amps are iconic, they are a family of varied designs; we (Vitalii) focused on perfecting the op-amp architecture by completely redesigning the circuit for the modern era. To eliminate the noise floor inherent in the vintage units, we downscaled the resistance values and replaced the standard 4558 chips with Hi-Fi-grade LM4562 op-amps for superior audio performance. 

We didn’t stop there — the signal path is populated with high-quality film capacitors, even in the pico-farad range, a luxury never seen in the mass-produced Roland amps. Powered by a custom modern switch-mode supply that boosts 9V to a massive 30V internal rail.

Whether used as a pristine clean preamp, a boost, or a 4-band EQ with Fender-style interactive voicing, the added Hi-Treble control ensures your tone retains that crucial ’spark’ (sparkle) even at lower volumes.

Controls - Bass, Middle, Treble, Volume, Hi-Treble.

I’ve been long trying to persuade Boss to do a full-range take on the legendary Jazz Chorus JC-120 Amp - with both Chorus and Reverb included - per my 2023 visualisation.

I would have quite liked for Vitalii to have attempted that - while he has done an exceptional find job of replicating and improving the vintage Jazz Chorus fidelity and noise floor.

It’s certainly a great tool for those who play somewhat Clean and Spakly. Every bit as legendary as the early Fender types which deliver similar profiles - while the Jazz Chorus is obviously a solid state amp.

Would be nice to get the full stack pedal at some stage - there certainly seem to be enough that are interested in that. Instead and for now - we have the finest take on the Roland Preamp to date. There are a couple of other brands that do a take on the Jazz Chorus Preamp - while I wager none of those do it quite as well as Vitalii has here!

The Mariupol Jazz Preamp will be available for orders as soon as you see this post - of course course of the Drunk Beaver Rocks Webstore, where there are just 30 units that will be made available - at $150 each!

Of course this is another rapid prototyping release with no time for arranging demo videos - so we will refer to a couple of pertinent sound samples - to give you a flavour of the tonal delivery here! 

Note once more that this is just the Preamp, and not the accompanying Chorus and Reverb!