Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)

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micaddict said:
What I can add, based on many earlier times we've "met" in places like these  :)  is that you're probably slightly tuned to the brighter side (more than I am, that is). So that could play a part here.

...yes, exactly my thoughts...you do know me  ;)

micaddict said:
Also, keep in mind that proximity will tilt the balance towards the lows. But you already knew that.

...bingo!
 
...OK, I thought I'd chime in to update the status of the M49b I purchased from Dany a week ago...since the mic had no power supply (and I'm not gifted in the DIY skillset) I had Dany forward the mic to Brian Fox (Foxaudioresearch.ca) who is also in Canada...I've admired Brian's work, and his exceptionally informative website, so I thought this might be a good opportunity to establish a dialog and commission him to modify a PSU to service the M49b...

...Brian has carefully researched the build options (both b and c) and the specific needs in reference to modifying a standard OEM Chinese power supply...he asked me from the get-go if I was locked in to keeping the mic true to Dany's B build specs, or if I would be open to some minor tweaks that might benefit the mic's performance, as per my particular needs...I told him to feel free to suggest options and we would go from there...

...Brian's initial testing focused on the mic's filament bias circuit...noting that in the revised C version, Neumann converted to a cathode bias, he suggested making that modification, to limit the amount of filter capacitance needed in the power supply...he noted the only thing special about the kit supply was that it had enormous amounts for filament power filtering just so the filament bias method would not inject hum into the mic (this was not needed with an indirect heated tube like the 5840)....with my approval, he made the adjustment to generate the bias in cathode as in the C, but it with a fixed voltage of 1.6 like the B...Brian does this by using a red LED in the cathode circuit instead of a resistor, which creates a fixed 1.6 volts with perfect low end response, but with much lower hum and noise than using a filament based bias voltage...

...with that he could re-wire the M49 7pin XLR so that the mic will work with any Chinese supply that is voltage adjusted to 120 volts or less...he modded the OEM chinese supply to produce 116 V volt B+...measurements showed the preamp has a net gain of +1 dB and can produce -10 dBu output before hitting 1% 2nd Harmonic distortion, and distortion is pretty even from 100Hz to 20KHz....

...I hope I have detailed Brian's approach properly (as I'm no "tech" by any measure)...this morning he sent some graphs and a sound file...he offered me the opportunity to further "sculpt" the mic's sonic character, by implementing an EQ cap (270 pF and 470 pF)...but I'm pretty satisfied with what I hear, and would prefer to stay as close to Dany's build, other than the biasing modification...so here is the response graph and sound file...any input or comments are welcomed...

Soundfile: https://soundcloud.com/kidvybes/bouchard-m49-sample-converted

*** Brian assured me that the preamp section of the mic was very flat in it's response, so that the dips in the mic's frequency response chart (from 2K-8K) may be a direct result of this particular M7 capsule's tuned response...

 

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micaddict said:
Great, detailed post, Dennis!

Thanks for sharing.

Just a little sad that it's no longer a true -b, but hey.  ;)



Henk

...revision aside, Henk, how does it sound?...
 
Man, you're fast.

OK, I did a quick listen. Cool of Brian to do that BTW.

Yeah, it certainly sounds good. Very hard to compare, though. Did Brian do a before recording, too?
Dany's first sample still haunts me in my dreams, but that was a different voice, different pre, different distance maybe etc. etc.
And not only was it still a -b then, it also wore a K47 rather than an M7. So apples to oranges really.

I don't know if Brian still has it, but it could be a nice experiment to try a K47(49) in there now. Historically, that would make more sense than a K47 in the -b version BTW, not that it bothered me then.
If you keep the mic, I have a feeling that that is what you'll end up with eventually. Not that it's better than an M7, mind. Just a matter of taste (if I indeed do know you just a little).
On the other hand it's a cool flavor that should complement your other mics pretty well.
 
Oh, and that chart does look interesting.

There's a subtle, long and very gradual "bass" roll off. Despite proximity effect (was it in cardioid?), coming in a little closer than three inches could be a good idea. Kinda like you would on a Gefell UM70 (which also wears an M7, with PVC no less).

Then there's the long mid to high scoop which you'd sooner expect from a CK12. The good news is that the valley is at 6-7k which will attenuate sibilance.

And then there's a rise (or back to 0 more or less) around 10k. So dark it is not.

The plot looks very nice actually.
And it has the true mids somewhat stronger than the high mids and lower trebles.

Also keep in mind that the headbasket on the GT-2B body is very much like the one on a U47.
 
micaddict said:
I don't know if Brian still has it, but it could be a nice experiment to try a K47(49) in there now. Historically, that would make more sense than a K47 in the -b version BTW, not that it bothered me then.
If you keep the mic, I have a feeling that that is what you'll end up with eventually. Not that it's better than an M7, mind. Just a matter of taste (if I indeed do know you just a little).
On the other hand it's a cool flavor that should complement your other mics pretty well.

...actually Brian offered to try one of his Thiersch M7 capsules, but since my budget is limited, I thought it best to avoid placing any further temptation in my path...and considering that I already have both Dave Pearlman's and Ben Sneesby's take on the K47 coupled to a 47/49 circuit, I thought Dany's 49, as it now stands, might be a nice contrast to those two...

micaddict said:
Also keep in mind that the headbasket on the GT-2B body is very much like the one on a U47.

...I've also considered swapping the headbasket for an angled style, but for now I think I will test this mic, once it arrives, on the singers I'm working with before making any more changes or unnecessary purchases...I already commited to selling another of my mics to offset the expense of this new purchase (house rules)...
 
...I've also considered swapping the headbasket for an angled style, but for now I think I will test this mic, once it arrives, on the singers I'm working with before making any more changes or unnecessary purchases...I already commited to selling another of my mics to offset the expense of this new purchase (house rules)...

I didn't mean to suggest you'd swap it. Just that the frequency plot seems to echo some (!) of the typical U47 treats. And that ain't necessarily a bad thing.  :)
http://mixguides.com/microphones/vintage_products/audio_vintage_microphones_part/
 
...just as a point of reference, Brian Fox just compared the Dale M7 to a Thiersch M7 in the same mic...the Dale M7 displayed more bass (proximity effect?) and less pronounced upper-mids than the Thiersch capsule, which shares some similarity to the response of Dany's M49 (w/Dale M7) that I purchased...response graph attached:
 

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micaddict said:
Just for my proper understanding, was this your Dale M7 or another one?



Henk

...this was Brian's own Dale M7 and a Thiersch Red M7 capsule...(my capsule is lost somewhere in the US Custom's labyrinth for the time being)...

Soundfiles:
https://soundcloud.com/fox-audio-research/far-47-long-body-with
https://soundcloud.com/fox-audio-research/far-47-long-body-with-dale-m7
 
Thanks. I asked because, from what I understand, Dale M7s can vary a bit from one to the other. Like the old ones, probably.

Does the Thiersch have Mylar, too (red line)?

Interesting samples. Thiersch sounds more bassy and trebly to me. In other words, Dale is more middy.
In the graph, the lifted treble from the Thiersch shows, but the lifted low end does not. You would expect Dale to be bassier. No?

I like both BTW.
Thiersch somewhat modern and finished. Bigger. Good voice over sound. Perhaps just a little essy.
Dale somewhat olden and smooth. Might suit some singers better.

I'm only on cans now, mind!
 
micaddict said:
Does the Thiersch have Mylar, too (red line)?

...yes, Mylar...here's Brian's own comments:
"Now these recordings were made on different days. I tried to maintain the same distance to both mics. Nevertheless the Dale is warmer than the Thiersch as confirmed by the plots. Both are good, but the Thiersch catches some of that crunch in the high end."
 
micaddict said:
Anyway, good stuff.
We need more graphs and more samples, folks.

...I thought I would post further documentation that Brian Fox provided for the D-M49b he modified for me, for those that might be interested...

Here's page 1:
 

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