Faking it..... my new U47

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zebra50

Well-known member
Joined
Jun 4, 2004
Messages
2,943
Location
York, UK
I thought some of you guys might like to see this. Here's our brand new shiny U47 ( in good company....)

STU47_a.jpg


Inside....

STU47_b.jpg


and another view...

STU47_c.jpg

;)
 
I think I'm going to call it the STU47

Like a lot of people, I've always wanted a U47 in the studio, but the prices are stupid and most of them are knackered anyway! So, as you can see the Neumann badge is the wrong size and colour, stuck on with sticky tape, and the whole thing is a complete fake in a Flea body.

I used a transformer from Max's MK7, a telefunken EF12k metal can tube, and the capsule is from Thiersch, although I have a capsule from a Gefell UM70  to try in it.

I've done a couple of sessions with it now and it's working out great on male vocals, and I also did a couple of good electric guitar tracks too. Neither of the singers realised it was a fake until I told them.

In some ways it's better than a real U47 - I've wired it to run in just cardioid, or by flicking the switch it becomes multi-pattern rather than just omni, controlled at the power supply.

(The Flea parts are very good quality, btw. Prices are very high though, although a lot less than a real U47, M49 etc.)

I think I'm going to call it the STU47  :)

Stewart
 
nice!
once the skylar bodies come out i'll be embarking on my first microphone adventure.

Did you have to try out a few ef12's before u found a suitable one?
 
Well done about the pattern switching!
I can't see it well on the picture... Is that a U48 head-basket with 3 pins?

What arrangement did you choose for polarizing the cathode?

Axel
 
I think I've used about 4 or 5 EF12s in various things, and they've all been good ones. You find them in Reissmann and RFT microphones, and some old preamps.

Most of the ones I've seen have been RFT EF12k - I believe the 'k' is the selected grade. These come in a painted glass tube, which is slightly taller that the metal can version and will not fit into a 'real' U47. Of course with DIY we can make things fit, but for this mic I found a Telefunken metal can version.

- check out this thread for more info about the size.

http://www.groupdiy.com/index.php?topic=38311.0

mad.ax said:
I can't see it well on the picture... Is that a U48 head-basket with 3 pins?

Well spotted. I did wonder if anyone would notice that. You can't do conventional pattern switching with a normal two pin U47 head, and this is indeed really a U48 style head.

STU47_d.jpg


I went with simple self bias in this case, and no cathode bypass cap either. Personally, I really like the sound of the simplest arrangement.

S
 
I'm green with envy! No wait, I have a genuine one.  ;D
Still, I'd like to have an everyday U47 that runs on an affordable tube.

Anyway, nice work, Zebra.

Are those Syncron mics in that pic?
 
skipwave said:
...Wow!...
I can't take much credit really. I just wired it up. The metalwork is fabulous, and much better than I could manage.

Rossi said:
No wait, I have a genuine one.  ;D
Now I'm green with envy. We should do a shootout sometime!

Still, I'd like to have an everyday U47 that runs on an affordable tube.
Well i think the whole build was about the price of a new TLM49, so good value or very expensive, depending on your perspective. Anyway, tonight we used it just for guide vocals. I'm not sure you would get out a real 47 for that!

Are those Syncron mics in that pic?

That's right. I picked them up about a year ago and have just got them working, almost! But that's another story...
 
Looks great! I've had my eye on the Flea bodies for a while. Glad to see they are truly good.

zebra50 said:
I think I've used about 4 or 5 EF12s in various things, and they've all been good ones. You find them in Reissmann and RFT microphones, and some old preamps.

What about the EF12-Spez (Special)?  Is it compatible?
 
zebra50 said:
Well i think the whole build was about the price of a new TLM49, so good value or very expensive, depending on your perspective.

Before everybody and their mother jump at you, offering €1500 so you could earn money building it for them, let's correct the bill....
Brand new TLM49 cost €1300 inc.VAT.
Flea body is €900 + VAT
Then you need at least a matching tuchel connector (€100 min.), Max's transformer... Wait, we already spent near €1300... ;)
And we still need a capsule, some high quality caps and hard to find resistors, a bit of 6 or 7 conductors mic cable, another couple of connectors, and a whole PSU!
And let's not forget the cost of double sided tape for the badge! ;D
Just teasing... A couple of grands is still a bargain for such a mic, and the possibility of avoiding discussion about Neumann vs DIY with some clients is just priceless...
I just wanted to point out that we all tend to underestimate the real cost of DIY, and that before even talking about the value of our time!

@Tommypiper
According to the datasheet, the EF12 Spez has a tiny different characteristics. Anyways the EF12K is the one to use as K stand for low microphonics.

axel
 
mad.ax said:
...let's correct the bill.... ...we all tend to underestimate the real cost of DIY.

Haha! Yes, indeed. I have a lot of components lying around, so resistors, caps, cables and connectors didn't get counted! And its running off a power supply I had already.

Brand new TLM49 cost €1300 inc.VAT.
I was looking at this one, which gives me another €100 to spend!

Maybe 'about the price of a new M147' would be more like it!

But it's an interesting point. I did think half way through something like 'hey, I could build ten and sell them'. But if you wanted to do something this commercially (like Wunder, Wagner, Flea, Horsch etc), you'd probably need to charge a couple of grand more, even with the economies of a (relatively small) scale production run, to cover time, parts, bills, rent, bank loan and so on.

pucho812 said:
hey as long your faking such high quality stuff, wanna fake me a neve 8048?

Pucho, will you pay me ten bucks an hour?  :p I wouldn't know where to start!
 
Stewart, looking sicker than a poo sandwich.

Can't wait to get mine underway. By the way, circuit-wise, did you do something U47-ish, or did you stick more to Max's circuit design?

I bet if you'd asked us five years ago, nobody would have guessed that we'd be making stuff of this sort of caliber. Awesome.
 
zebra50 said:
Now I'm green with envy. We should do a shootout sometime!

Sure, but you'd have to come to Germany for that; my U47 doesn't like to travel.

Still, I'd like to have an everyday U47 that runs on an affordable tube.
Well i think the whole build was about the price of a new TLM49, so good value or very expensive, depending on your perspective. Anyway, tonight we used it just for guide vocals. I'm not sure you would get out a real 47 for that!
That's that I'm talking about. I mean, I have a UM57 that I could use for a substitute. It's a good mic, but it doesn't feel or sound the same. One of my next projects will be a kind of solid state U47. I'd like to see how close I can get. I still have a couple of Dale M7 capsules and a Gefell UM70S head that I could use for that.

Are those Syncron mics in that pic?
That's right. I picked them up about a year ago and have just got them working, almost! But that's another story...

Pretty cool stuff. Never heard or used one, but I like oddball mics.
 
rodabod said:
Stewart, looking sicker than a poo sandwich.

Nearly lunch time... Cat or Dog? Or goose?  :p

circuit-wise, did you do something U47-ish...

STU47schemo.png


Well I took ideas from U47 and U48, and especially MK7, which of course is very much inspired by U47.

I didn't take the heater supply from B+. There's little point with a 6V filament - too many amps to drop by too many volts, and I didn't bias the cathode from the heater.

For the cathode resistor I started at 1K and then tweaked. The parts there may not be exact, but are more or less right - I'm still tweaking.
 
Great job! This is very interesting to me because I had been thinking about doing the same thing. I like the idea of having a 47-style mic that I could use without feeling like I'm handling a museum piece. Also, I would feel more free to alter the circuitry, change tube type, etc.

A few question: now that you've had a chance to use this mic for a while are you happy with the sound? What value did you settle on for the cathode resistor? Are you using a BV8

The reason that I ask is that I have an EF12K tube on hand, and in theory the simple circuit that you've used is appealing. There is another EF12 circuit that I've seen for a U47-type mic that uses a fixed bias that I've considered trying as well.

Regards,
Scott
 
Hi Scott,

The transformer is the one from max's MK7 kit - it's a nice match to the EF12 tube.

I did vocals for an album on this recently, and the male singer liked it a lot - it had a pretty full sound with a nice proximity effect and not too much 'tube-yness' (after all, it's a mic not a fuzz box!). It's also seen some good duty as a room mic and on some electric guitars.

I set the cathode resistor using a signal generator and looking on the scope for the cleanest reproduction / highest input before clipping. I don't recall the value off the top of my head but somewhere between 1K and 2K would be about right. It's worth experimenting with this, as well as the plate resistor and output cap.

If you used fixed bias make sure you have a really clean filament supply (You could even make it switchable!)
 
Hi Stewart,


  Yum! what a corker! If I'm ever up your way, you can compare it to mine. (mine is original u48, but with EF14 and KK47)

    I have to take exception to your earlier comment about guide vocals. In my experience, there is no such thing as a guide vocal. So very often, the so-called guide vocal is the best performance a singer will give. I have made many records where the original "demo" vocal made the final cut. I ALWAYS use the best mic for the singer, irrespective of whether it is a guide or not. This way, you can never suffer from demo-itis(with regard to the vocal anyway!). Catching the vocalist off-guard, when there is no pressure on them is crucial. Red-light syndrome(red light - brown pants!) is a disease I don't need in the studio.


  KIndest regards,


    ANdyP
 
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