It's been a long road.... to the M49

I know it seemed as if the day would never come; but we finally did receive in our M49 bodies at long long long last... that only took about a year! LOL

I do feel like these are worth the wait. I would like to finally take a moment to explain what has gone into the M49 in some detail.

Starting with the circuit design, we did develop our own board set based mostly on the original M49RevC with one element inspired by the RevB... but also with a number of improvements of our own. To my knowledge, the classic Reissue M49 is based on the RevC, so I would call ours an unofficial 'RevD', or what a RevD might look like if the original company had moved the design forward.

The main update we did was to bring out the once hidden 'easter egg' feature which was always present on most 49 Revisions but always required full disassembly and surgery to access: that being the 'pattern defeat' switch floated and wired point-to-point in the high-z section. I always understood the usefulness of this feature. When you just need cardioid mode, you can achieve a slightly hotter, punchier sound with better s/n specs, and the slight increase in output finally puts the mic into the same realm as the output levels of most other tube condensers... where as naturally the M49 levels are always a tad shy compared to other mics, mostly due to the lower Mu of these subminiature tubes. As useful as the feature is, few people want to spend an hour or two doing surgery on their priceless mic, and so the feature largely went unused and unknown. We converted that switch over to a hermetically sealed, mu-metal shielded, vacuum sealed reed relay (a $40 part) and remote controlled via the power supply. Now you can access 'true cardioid' mode (pattern bypass) whenver you need but bring it back to the classic 3 pattern mode whenever duty calls. The switch does cause an audible pop in the audio (mute the preamp or turn it down before switching) but doesn't hurt the circuit or capsule to be engaged when live.

After that, we took a fresh approach to the design of our BV11 transformer. After learning more about the history of that part than I ever thought I should, I came away with more questions than answers. The M49's BV11 was, of course, the basis for the later improved version of the BV8 used in the latter 47's and u48's, and then onward into other products as well. Over the course of the product's life, starting with the earliest M49 (which used a Hiller tube, pre AC701k), the transformer ratio varied from as low as 7:1 to as high as 14:1 based on different specimens anlyzed. Of these, the 7:1 and 10:1 seemed to be the most popular, with (unless I'm wrong) the 10:1 being the final standard-bearer and the winding ratip used on the 'V' reissue... Nonetheless, I wanted to judge this by ear and make a few transformer variants and arrive at a final determination based on listening. To my ears, the 10:1 was the most smooth and musical option, which tended to give the mic greater subtlety and control. It's a perfect compromise between the most extreme specimens, and seems to be where the original design stabilized and landed on. You do get a bit more of a contemporary output level with 7:1; but lose some of the sublime nature of the mic... it becomes slightly more 'shouty', for lack of a better word. Granted these are subtleties, but that's the kind of things I really fret over. I also experimented with different shielding configurations, trying a dual Faraday shielded version vs an unshielded version vs one with only an outer Cu foil shield and drain wire. The latter I chose, because it still offered some good RFI/EMI protections without any of the slight 'pinching' or parasitic effects that seemed to accompany the internal shields. Again, we are dealing in subtleties; but again, these are the things I fret over. So, other than an added outer shield, we made a faithful 10:1 BV11 replica, wound in the USA to our specs.

With regard to the amplifier circuit, we analyzed every 'mod' and ECO that had ever been done on the design... as many know, there are 4 or 5 'voicing' mods that can be done by tweaking/removing/replacing certain component values to increase output, extend low end response, extend high-end response, etc. We didn't 'remove' any component value; but did subtley tweak about 4 component values which merely allow the mic to come through ever slightly wider and bigger, without changing the core characteristics of the mic. We didn't want it to go off the rails; but we did every so slightly widen the rails.

With regard to tube, we have stockpiled a number of tubes that are suitable for the M49 (more than 4 different ones) that all yield really good results. We plan to mostly ship with the Russian 6S6B-V valve, which is the same tube used in the M49'V' reissue and the FLEA M49... This tube is fully interchangeable with the US-made JAN (military grade) 5703, which is basically the Western equivalent of the same tube. We can use them interchangeably and/or on request. These tubes will be cleaned (de-scaled) and burned in for at a minimum of 72 hours if not more, and meticulously tested for noise.

With regard to power supply, we developed a new fully discrete power supply which is, as usual, massively overkill. Custom wound toroidal transformer, over-sized resistors, filtered power, and all electrolytic caps fully film-capacitor bypassed. Extra thick mil-spec PCB material, 1/16 steel chassis,all hand-made. We have two different pattern circuit options. We are able to provide the PSU in both a fully variable (omni to figure of eight) nine position rotary switch using precision resistors, or the classic three position pattern switch (omni, cardioid, figure of eight). This will be selectable by the customer.

With regard to capsule, we are using a custom selected K49 capsule designed for us by Arienne Audio, because, a.) we love the capsule and feel it compliments this mic especially well, and b.) currently Ari is the only provider who can get us 'K47' style capsules graded with the stringent front-to-back matching required to make the capsules suitable for 'K49' grade, which requires exceptional matching in order to do critical figure-of-eight type recording. Other capsules will be available; but this will be our highly preferred go-to for the above reasons.

OK, so why isn't the mic on the site yet and available for sale?

Because this is the busiest time of the year for me for both companies and I have about a dozen very patient pre-order cusomers to take care of, I have decided to wait until after NAMM to officially list the mic for sale on the website. Hopefully after the busy end-of-year madness and I'm recuperated from my travels, we will be able to hit the ground running and start building these with an employee helping me full time, probably. This mic will be the most labor intensive product we've attempted yet under Signal Art, and I'm going to need backup. haha In the meanwhile, if you are one of the lucky twelve, thank you for your patience and your mic will be in your hands before year's end. For everyone else, after NAMM! Until then, hope everyone has a great rest of the year and I'll try not to be a stranger. Yes, we are still taking orders for the Signal Art U47 and U48.

PS: People have asked me about the M50 (spherical capsule). We are indeed working on it! With a lot of luck, we'll announce something about that in January at the same time.

Chad