True fact: I get distracted and sidetracked often... a consequence of unchecked OCD and ADD working together. LOL Though I listed the U48 for sale when I first created the website late last year, I did not get around to prototyping it out until just this month... ironically enough, just a few days before someone ordered the first one. I build the first very crude proof-of-operation prototype of the venerable U48 schematic a couple weeks back, then a working prototype fitted into a mic body, and then 2 more variations testing various component placement/spacing/choices, and finally got it to where its a model deserving the Signal Art name just a couple days ago. Just in the nick of time.
Though in theory, the U48 is only half a dozen parts more complex than the U47, nothing is ever quite that easy and there are always things to consider, scenarios to test, etc. For instance, there are three different NOS (new, old-stock) polystyrene capacitors in the 48 vs only one in the 47, and these have to be positioned and glued down in such a way to be immune to microphonics or EMI/RFI, etc. And the additional parts make the build more complex. Adding to that, I have opted (due to the much lower demand for this less-famous sibling to the U47) to hand-make the entire product without using any printed circuit boards. The power supply board is laid out on a thick 3MM fiberglass turret board with nickel plated steel turrets, and wired point to point. I am now using an even bigger more robust toroidal power supply transformer (a 10vA version), and this upgrade has been carried over to future U47's also. The microphone main board is built in a similar fashion using a 2MM black epoxy fiberglass board and miniature nickel-plated steel turrets and teflon-insulated nickel turrets, hand-cut and hand-drilled, and hand-wired point to point using solidcore and stranded silver-teflon hookup wire. (Sorry I don't have a photo of those at the time of this writing; but will try to update it with one soon.) This process is extraordinarily time consuming; but its worth it. There's not as huge a demand for the U48, so I am OK with that person getting something special that took even longer to build with additional TLC. I chose not to increase the prices due to this; instead just to put in more of my own time to do it right. All things being equal (and part of this comes from living right down the road from the legendary makers of the Komet Guitar Amplifiers, from whom I've learned a few things over the years and I think some of their obsessions shine through onto mine), point to point wiring sounds better, if anything. They say point to point will yield a 'deeper black' in the quiet passages, a richer tone, a starker contrast between the sounds and the empty spaces in between, and just an overall cleaner sound. I tend to agree, even though these differences are minute. I was never a big fan of solder masks and ground planes and multi-layer boards. That being said, some microphones are simply far too complex to ever build this way (FET 47 and M49 I'm thinking of, specifically). I should also note that when I printed the custom PCBs for my U47, they were made to the highest grade available. Wide, pure copper traces that never run at sharp right angles, heavy duty, thick PCBs made of very pure materials... it cost a fortune... So, there's certainly no loss when compared with the few PCBs I have gotten printed; but I would immediately bet that point to point sounds better than most printed circuit boards out there which are not nearly of that level of quality.
The U48 is often overlooked by those seeking out the '47 sound', and I think that's a shame. Very few companies have ever tried to re-issue it. It's actually quite useful, and the figure 8 pattern really opens up some great opportunities that are not possible with the U47, such as recording 2 opposing singers/players onto a single track (which is a favorite trick of mine, the always fun 'group backing vocal' track) and, of course, Blumlein pair stereo recording (for which you will need 2 U48's set to figure 8). The sound of a U48 is basically the sound of a U47, and I don't want to spend too much time splitting hairs on that matter; but it is a more complex circuit and it does have an ever slightly lower polarization voltage due to that. I find the sound to be a touch more rich and 'processed' perhaps, and seems a bit more immune to issues of phase due to that; but again, I am splitting hairs and trying to describe the .05% sonic difference I perceive.
Here's another true fact: Frank Sinatra's favorite mic at Capital Studios was actually a U48 that he used throughout much of his career, not the U47 as a famous Neumann poster that once hung at Guitar Center locations used to claim. At any rate, I'm proud to say we now make the U48 in both a baseline and premium edition, for the same price as our U47's.