Chinese U47 Donor? BaiFeLi V47

[ostrol]

Just came across this model of a FET47 (?) and I'm heavily considering ordering one. Other members have raved about their cheap 414 and V10 (kinda Austrian Audio 818 clone) so could be interesting turning one of these into a nice tube mic...
Anyone ever tried one of these?

https://ephyh.en.alibaba.com/produc...?spm=a2700.shop_index.111720.8.1f002af4e0tPxy

 

[mhelin]

I don't like the Chinese companies cloning western mics like the Telefunken TF47 and the Austrian Audio ones which are still manufactured, please don't support them.

 

[Khron]

Well, the "western" part of that is debatable (?) - some might argue items like this Baifeili V47 is "just" the TF47 (or whatever the similar looking solid-state one is - TF11 FET?) at a more honest price... possibly?

 

[RuudNL]

Personally I don't care.
The only thing that is important to me is the ratio quality/price.

 

[kingkorg]

I don't like the Chinese companies cloning western mics like the Telefunken TF47 and the Austrian Audio ones which are still manufactured, please don't support them.

I don't like Telefunken brand name owners (whom have nothing to do with historical Telefunken) rebranding chinese microphones and selling for 10x the price making false, indirect connections to Neumann and others by exploiting couple of numbers and letters.

Vintage Telefunken mics were more less rebrands of AKG and Neumann which is no longer the case. Hence i don't see much value even in modern Telefunken u47, elam, c12 models they sell. They are not worth a dime above the sum of the parts they used. Modern Telefunken is a rip-off of the European heritage. And the fact capsules, transformers in higher end models are made in USA doesn't help either, as it's yet again just a rip-off of the originals without any consent from the original manufacturers. Just exploitation of expired patents. High end Behringer business model.

Austrian Audio is something else, there's no chinese clone besides couple which roughly cosmetically resemble the AA ones.

 

[ostrol]

@Khron you're right it looks like a TF11, wonder if it's got a c-12 type capsule,then. I was thinking of getting a capsule upgrade as a first experiment, but c12 capsules are not the most budget-friendly upgrade path. Appreciate you sharing the knowledge!

 

[Wordsushi]

Ok, so BFL sent me a V47. Body construction is pretty good. Shell is solid. Not brass, but heavy. Whole mic weighs about 530g and shell weighs 226g. Guts look great for $100 mic. Obviously, schoeps variant. Maybe real Wima caps. Fet is K170. But, I'll say this, it is fairly quiet. Other BFL mics have had a much higher noise floor (but nothing that good noise reduction like Cvox can't fix), but this one has low self noise. I'll probably swap out their K67, which isn't super bright, with Arienne's flat 47.

 

[evil grill]

Ok, so BFL sent me a V47. Body construction is pretty good. Shell is solid. Not brass, but heavy. Whole mic weighs about 530g and shell weighs 226g. Guts look great for $100 mic. Obviously, schoeps variant. Maybe real Wima caps. Fet is K170. But, I'll say this, it is fairly quiet. Other BFL mics have had a much higher noise floor (but nothing that good noise reduction like Cvox can't fix), but this one has low self noise. I'll probably swap out their K67, which isn't super bright, with Arienne's flat 47.
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Very nice!
Have you measured the polarization voltage?

 

[rock soderstrom]

Ok, so BFL sent me a V47. Body construction is pretty good. Shell is solid. Not brass, but heavy. Whole mic weighs about 530g and shell weighs 226g. Guts look great for $100 mic. Obviously, schoeps variant.

Not bad, I think this is a good experimental platform for this type of circuit. Is the solder post for the connection between capsule and FET insulated with ceramic?

 

[Khron]

Surprising that it's relatively low noise - i don't see any isolating posts there, but lots of flux / wash residue. Gotta love the two different 1G resistors though...

PS. 4 diodes on the output of the bias voltage oscillator - should be easy enough to upgrade to multipattern, assuming you can find a suitable switch and are willing to make an access hole for it in the body.

 

[Wordsushi]

Very nice!
Have you measured the polarization voltage?

Get ready to laugh. I just checked it. Wanna guess? It's 13v! 13! I checked 3 times to make sure. So, disregard keeping this circuit. Initial report above was based upon visual inspection and just plugging it in to see how noisy it is, so a more detailed check reveals that there are issues.
Also, it seems like the mic is out of phase. I checked to see if XLR pins 2 and 3 were mis-wired but it appears they are wired correctly from the board which probably indicates there may be a misprint on the board or something else going on.
So, the kit it comes in comes with a metal cutaway shock mount and a Hakan pop killer knock off, so if that along with the body for $100 is worth it to you, then sure, but otherwise, as a mod platform, you'd probably be better off just buying one of those TF-11 style bodies off Aliexpress.

Hey Rock. No ceramic. Plastic.

 

[Khron]

Hmmm... Where did you measure that voltage, though?

If it was right on the capsule wire, whatever series resistance "upstream" of that would have skewed the measurement. A 1meg series resistor would form a divider with the (usually) 1meg input impedance of your meter and show you about half the unloaded voltage. Higher series resistance would increase the real-to-measured ratio.

But if that's not the case, the two inductors being nowhere near each other AND at 90deg to each other may be at least part of the cause.

 

[kingkorg]

Get ready to laugh. I just checked it. Wanna guess? It's 13v! 13!

Sure? Did you check before the high value resistors? Sometimes Hartley Oscillators simply refuse to work, and give the low output voltage, similar to what you describe. It could be they just copy/pasted the circuit from somewhere else and didn't bother to check. Wrong value or arrangement of the inductors?
Edit:
@Khron beat me to it

 

[RuudNL]

On the PCB I see Sw1 marked: C - 8 - O.
So it seems they thought about creating a multipattern microphone.

 

[Wordsushi]

I measured it at the backplate wire right where it screws into the capsule, so I just assumed that was the voltage the capsule was getting.

 

[kingkorg]

I measured it at the backplate wire right where it screws into the capsule, so I just assumed that was the voltage the capsule was getting.

Nope. Without analyzing the circuit, i'd just check the voltage at all the diodes at the back PCB, the highest voltage is probably what capsule gets.

 

[rock soderstrom]

Get ready to laugh. I just checked it. Wanna guess? It's 13v! 13! I checked 3 times to make sure.

High impedance and your DMM playing tricks on you.

 

[Wordsushi]

Nope. Without analyzing the circuit, i'd just check the voltage at all the diodes at the back PCB, the highest voltage is probably what capsule gets.

Wow. I had no idea the voltage could be different than what the meter sees at that point. Thanks for the info. Ok, so the highest voltages I'm getting are across the topmost diode and I get 76.2v at the cathode and 42.0 at the anode.

 

[Khron]

On the high side, but still workable. No doubt, part of the reason for the lower-than-average noise.

 

[Wordsushi]

I'm wondering if this phase issue is because of a simple printing error on the board, which would mean they're probably all coming off the assembly line with reversed phase.