Staying within the original Magni budget meant fairly limited changes, but it still did allow for some pretty significant work. The gain stage had originally been designed as a minimal-parts design. With the addition of a handful of parts, though, I could turn it into a constant-feedback design that promised to sound significantly better than the original.
Aside: so what’s all this constant-feedback blather? It’s constant feedback across the audio band. Now, Cordell disproved the old Otala TIM hypothesis, but in my work, I’ve always noted sonic benefits to having an open-loop stage with bandwidth larger than the audio range. So, I extended the open-loop bandwidth to greater than 20kHz with some parts additions and other tweaks, changed the operating point of the front end (it now runs quite a bit more current, and has smaller resistor values for even lower noise), and, of course, put in the gain switch.
Aside to the aside: yes, this is heavy geek-speak. If you know Cordell and Otala and concepts like thermal noise, this makes sense. Though you might not believe what I’m saying about the subjective side of things. That’s cool.
Aside to the aside to the aside: bottom line, Magni 2 sounds better. And it’s not subtle.
How much better? The Magni 2 was originally called the Magni Uber.
But, while I was doing this cost-constrained version, I wondered, “What would we get if we threw some more money at this?” So, I built another super-over-the-top Magni Uber Squared, which had a whole host of improvements, starting with preamp outputs, better, adjustable voltage regulators and higher rails, a complementary-input VAS to cancel even more noise and distortion from the front end (and yeah, I know Self sez you don’t need no complementary VAS, that’s cool, maybe we hear differently), much bigger power supply capacitors and a giant new wall-wart, and a couple of other little tweaks. This super-over-the-top version I figured we might never build, but I had to know how it performed.
How’d it do? So well that we decided to build both of them. One of our listeners said, “Just stop building everything else and do these,” when hearing the Magni Uber Squared prototype for the first time.
Aside: don’t worry, we’re not going to do that. He’s insanely cheap, and that explains a lot of his comment. It is really good, though.
So, with that decision, we knew that we’d have two new amps. There was some production budget left over, so I drew up a small solid-aluminum knob and added an aluminum top to the Uber to make it look a bit fancier.
