U47 hand wired with VF14 and BV8

OK... So I am sure there has been a thread about this before, but for the life of me I cannot find one... I have come across many discussing alternate parts such as moding the design to use a EF86... However this is not what I wish to do. I want to make a true, hand wired clone of a large badge U47. Since I first heard one in person when I was a teenager, I have been mystified by it's sound. Obviously everyone here knows, nothing sounds quite like it. Why? Well probably because nothing else uses a VF14 and BV8. So, I have decided to take on the task of building one.

I have done a few mic preamp builds so far, and built dozens of stomp boxes, and am moded guitar amps. However I have not worked on a mic yet. This will change soon though, because I am about to do a G7 build with Skylar's body. Though that mic will get a lot of use, I decided this will be my practice run and wish to build the real deal after.

I have been doing my research and this is what I have so far.

Schematics and machine documentation from :http://www.danalexanderaudio.com/micinfo.html

The body will be from http://shop.flea-microphones.com/index.php?page=productDetail&category=Mechanical+kits+%26+Parts&prNum=14&group=U47

The transformer will be from TAB Funkenwork (provided they still sell BV8's to consumers)

and unless I get lucky and find a VF14 online somewhere, I am going to go with the RF14m (unless anyone knows where to get a better cloned tube or an original).

The capsule I am probably going to go with Beeskneez, as I heard the Peluso is a bit brighter than real U47's... If this baby comes out really good, I might send it off to Korby to be fine tuned.

OK... that being said... Here is what I need. Does anyone has really good inside pictures of an old U47 so I can get a look at how they squeeze everything in, placement of parts, etc... The diagrams I have are useful to an extent, but not high enough resolution to tell where everything goes. It looks like the mic was designed for everything to squeeze in pretty tightly.

Also better quality schematics of the U47 or a written out parts list would be EXTREMELY helpful. All the schematics I have come across are handwritten and sometimes I can't tell if a black smudge is a period, and other times I cannot make out the numbers. I don't want to end up screwing up all these expensive parts by putting in the wrong cap or something.

ALSO! I know by the transformer there is supposed to be an electrolytic in reverse somewhere... Anyone know which cap this is?

Has anyone out there built a clone like this? I am sure they have... If so... Please let me in on any issues you had, or any tips and tricks...

Thanks!

-Grant

PS: Money is not an option as I plan on spending about 6 months to a year obtaining parts and building this bad boy.

There are plenty of threads on this forum discussing the design of this mic. You'd be best searching for single terms like VF14, BV8, etc. until you locate most of them and read them. Also search in Klaus Heyne's mic lab and pay attention to what Oliver Archut has to say.

Anyway, I think quite a few of us are probably in a similar boat, and some others have already built some of our own "clones". I'll give a few of my opinions and I'm sure others can contribute and agree/disagree.

Regarding mics in general, the sound is greatly affected by the transducer. Condenser capsules vary wildly in sound, as do supposed "clones" of capsules compared to their real counterparts. If you really wanted a close U47 sound then I'd be aiming for a Neumann M7 or K47, or perhaps a re-skin performed by someone reputable. On the cheaper end of the spectrum, there are also caps by Gefell and Dale Ulan which were recently demo'd by Martin Kantola.

The question of valves is tricky. The price of VF14s has gone through the roof. That leaves you with either cashing out big bucks, or choosing a close equivalent. There was a fair bit of discussion regarding Saturn Sound's RV14M over a PSW. I have not used it myself. There are other similar valves which can be used such as the EF14, EF42 and EF80 although these require modifications to the original circuit design, and it has been argued that the sound is not quite the same. This is something which you really need to hear for yourself, as there is quite a lot of disagreement. Part of that possibly lies with the fact that people have made poor modifications in the past, eg. changing valve to a more available model and then converting operation to self-bias rather than fixed-bias in order to get around noise issues, etc. , etc.

I think this schematic is decent:  http://www.nijnkonijn.nl/machmat/schema/studio/u47.gif

I wasn't aware of the plate-transformer coupling cap being reverse biased. I would doubt this.

Roddy

http://cankar.ath.cx/u47

Thank you so much for your reply. I have read a lot of the other posts regarding the building of the mic, however I haven't searched for specific parts of the mic like the BV8 or VF14... I am going to do that in a minute. I have found out more since i posted as well... For example http://makingmyu47.tumblr.com/post/305295312/a-tube-by-any-other-name is a blog about a guy doing the same thing. He is opting the EF14 route. However I do not wish to alter the original design. I don't wish to tamper with the original design, even if that requires only minor changes.

I read in detail how the RV14m is made, and some reviews on how it differs... I guess there is a top end boost which is quite pleasant. I think it's like +2 dB at a certain area. However it does have lower noise from what I understand which is a plus. However I also found old NOS VF14's for 2k and in stock... The one downside to this is that I heard a lot of the old stock VF14's are actually not up to spec. Hence why they weren't installed in mics and still in the box. They were meant for use in some old Telefunken radios. I am not sure if the ones I found are "m's" or not either... Which makes it hard to dish out 2k for. If I did get some good M VF14's I would probably cryogenically treat them as well.

That schematic is EXACTLY what I needed... Something typed out. All the ones I found prior have been hand written original Neumann schematics, which were creased, sloppy, and hard to read.

I also found some decent pics inside the mic as well at http://www.coutant.org/u47/index.html

All the other articles I have read on prodigy-pro seem to be EF14, or G7's (and only discussing the 47 in passing). So I wanted to focus on an absolutely accurate replica.

If possible it would even be nice to know what brands of resistors, and capacitors they used in the old ones. I want this sucker to be dead on accurate (which means I will most likely shell out for a VF14). However I may do the RV14 for a while just to get the thing up and running and tested.

If possible I want this thing to be like a U47 right off the assembly line in 1949.

-Grant

Oh and I love the idea of just going for a vintage real M7 capsule... That's a good alternative to these clone ones out here. I may also talk to Korby and see if he can make me one. After interning at Blackbird in 06, I fell in love with the work Korby did... They serviced all of Blackbird's mic's and match some of the tuning on the mics... They know their U47 caps possibly better than any company out there (including the Telefunken USA and Neumann tech's). I am sure Korby would probably just sell me the capsule without one of his heads if I requested.

I am excited about this project the more and more I look into it... The Schematic seems so incredibly simple... Regardless I am going to take my time with this build. All my care and effort are going into this beauty. I am even going to get a custom badge made for it.

-Grant

OK so I am assuming TAB Funkenwerk makes a transformer from what I have read... So that's that (I am using this in my U47 clone as well)... I found a site selling the Hiller tubes NOS for 275 a pop... Not too bad... Much more reasonable than a freaking VF14 NOS! So I might end up making this before my U47 clone.

http://www.bavodekker.com/equip.html#tubes

-Grant

There are good constructional pictures in Klaus' forum, in particular these threads:

http://recforums.prosoundweb.com/index.php/mv/msg/28469/0/0/0/

http://recforums.prosoundweb.com/index.php/mv/msg/28699/0/0/0/

http://recforums.prosoundweb.com/index.php/m/437132/0/


There is no 'reversed electrolytic'. Just NP caps for both transformer coupling and supply rail decoupling.

Good to know about the capacitor... Can't remember where I read that, but it popped out at me so I remembered to ask about it. So I have been looking at vintage M7 capsules and pricing them out... This sucker is gonna cost me a fortune, but to me it's better than buying a vintage U47... Mainly because I know it will be pretty damn authentic AND it will be more reliable... I won't buy it and then have to have it serviced 2-3 years down the line... AND with the knowledge from building it, I will be able to service this mic once it does start to give me issues. So right now I am looking at getting a vintage M7 and VF14m if I can... Just be as authentic as possible. However any more thoughts on the RV14 would be nice. I found some more VF14m's for 875 bucks, but they aren't NOS. Still might be worth it.

-Grant

Without a great capsule I don't think it's worth an attempt. Accurate resistors and capacitors will not help much, but an original Neumann made K47 would be a great start. When you get that far, make sure you have access to a real U47 for comparison of sound. That will tell you everything you need to know

Martin

Magnetosound: AWESOME link... Those are the type of pictures I was looking for. However most were from a Nuvister U47

However it still helps a lot....

I guess a lot of the old ones used Bosch caps.

Martin: I have decided to go with one of three options for the cap... Either an original M7, a Flea F7, or a Thiersch STW 7.1

I unfortunately don't have access to a U47 to compare... However once completed I may book out a few hours at a studio with one... Maybe I can call in a favor to Blackbird and see if John would be interested in shooting out his favorite 47 with my new one. It would have to be on a day when not much was going on... Or see if I can book a half a day and sit down and do a shoot out with Lowell in Studio D. If I do that... I will definitely post clips.

Actually for the sake of people who want to make this endeavor in the future, I plan on videotaping all of this and doing a series of my adventure on VIMEO. I do a lot of videography work, so it should be fun to combine all four of my passions... Playing music, Recording audio, Building gear, and Videography...

I agree it would be useful to do a shoot out and compare. Before I do that, I think I will have Korby take a quick glance at the mic and possibly tune the capsule for me.

Of course there will be pictures posted once I get going on this project. I am currently finishing up a Drip Redd 47. All I need to do is buy the tubes, install the transformers, and machine the housing. Next up is the G7 in Skylar's body, and then will be this bad boy...

-Grant

speakercoil said:

Before I do that, I think I will have Korby take a quick glance at the mic and possibly tune the capsule for me.

Click to expand...

You can't 'tune' an M7 really, the diaphragms are glued in place. And should you get your hands on a Neumann K47, better leave it untouched anyway IMHO.

Have fun with the project!

Martin

I own a U47, and I absolutely agree that the capsule is the most crucial part. A lot of people talk about the M7, but there are quite a number of variants, and the arguably best variant, the Berlin M7 is not in production anymore. That said, I think its successor K47 is an excellent capsule and maybe even better than an M7. The K47 is a bit smoother and has more bass response. It's also about two dB louder.

Contrary to common belief, the U47 does not contain any electrolytics. The round Bosch caps may look similar, but they are in fact bipolar oil/tar film caps. Also, a proper working U47 is *very* low noise. I get the impression that lot of people use the U47 as a point of reference without ever having heard one. My U47 is lower noise than a lot of FET mics.

Unfortunately the VF14 is a crucial part, and the BV8 is specifically made for this tube. The body (which is lightweight aluminum and not resonant) and the grille as well as the way the capsule is mounted are additional factors. I have a Gefell UM57 and a UM92. Both use M7 capsules, but different electronics and bodies. While they do have a Neumann-ish signature, they don't sound the same. They're nice, but they're not quite in the same league.

Which is to say that you need a great capsule first, but that doesn't make the body, the tube, and the rest of the components unimportant. Don't get hung up on long body vs. short body or large badge etc. That's just cosmetics. Good luck with your project, and be warned that it may take a lot longer than you think. I wouldn't know any commercial clone that's *exactly* like a NOS Neumann U47.

To add to what has been posted so far in this thread

IMO you will need to read and study about triodes and how they operate underheated.  I build and test and measure and listen and take notes.  Don't believe what you read on the web about microphones without testing it yourself, don't believe me, test and measure yourself.

I think one could build a "better" u47 like circuit with different tubes and a little different circuit design.

Funny thing is with the simple triode plate design of many microphone tube amps almost every part matters.  What rings in the body, how microphonic the tube is, noise, circuit operation points, the power supply, the capsule and capsule environment, tube to transformer interface, microphone preamp after the microphone loading(transformer input vs transformerless and loading) etc.

I have a few designs using tubes one design is a little different and might be a very good match to Skylars body.

Why a G7 in Skylars body?  There are lots of other microphone schematics on the web.

Speakercoil,


  Bavodecker sight List last updated: August / 26 / 2002 . . . .


  good luck, I think you will need it to find a Hiller tube at any price


  ANdyP

Wow... Martin I had no idea M7's were glued in place... I guess that makes sense looking at them, because visually I haven't been seeing screws as with the K47. I never even considered a capsule being glued in place... I guess that explains why over time a lot of them sound so radically different. Obviously the membrane is going to give a little bit and change the tuning... It would be like a guitar string being glued tight instead of attached to a tuner...

That being said... One of my favorite U47's I have ever heard was the very first one I ever got the chance of recording with. It was 100% original (well at least the capsule, BV8, and VF14 were). It sounded absolutely breath taking. VERY low noise as Rossi stated. Since then I have heard many good ones, including a large selection at Blackbird. I have also heard the commercial clones... I haven't heard a Wagner, but I have heard the Wunder CM7, Korby KAT5 (with the U47 head), and a few others. They are all wonderful microphones, but still my favorite is that original U47 I heard.

Obviously even if I get all the parts 100% the same as they would be coming off the assembly line, it is still going to sound different. This of course being because all tubes, capsules, and transformers have a unique character. This is fine, I am going in understanding this.

Parts that will be easy to obtain:

The Body thanks to Flea... That I believe also has the dampening ring with it.
The transformer thanks to Tab Funkenwerk

The tube I am more and more opting for an original... They have them at TubeDepot for 2k, but it doesn't seem to specify if they are M's or the rejects for tube radios.

The capsule... I see these come up on e-bay from time to time (M7's that is). I am debating maybe purchasing one from a CV563 head and just removing it from the housing. Is there any difference between that M7 capsule and the original? I don't believe there is, but it would be good to know before investing that sort of money.

As for making a "better" U47 clone... IE making changes and using a different valve... I plan on doing that with other mics to get a similar tone, but I still want a U47.

Strangeandbouncy: MAN!!!! I didn't see that... That sucks.... Well there goes my M50 project. What are the M50 clones from Wunder, etc using?

OH! and Gus: I would be interested in other designs besides the G7 for Skylar's body... However I haven't really heard much about a specific one. I have seen a few on here, but it would be nice to have testimonials about them. Also, the G7 has an easy to purchase PCB, TONS of building threads, and just seems the easiest mic build. HOWEVER... I would be interested in good alternatives if you have any to recommend.


Now for the Bosch Caps... OK... So the pictures I saw didn't have the round Bosch, they had square ones. Now my question is... Did all early U47's use one form of Bosch, or did they just use whatever capacitors they got their hands on? It's hard to tell which caps are original, and which are from repairs...

Also does anyone know what kind of resistors were used? Even if not a specific brand... Just knowing Carbon Comp or Tantalum, etc... would be useful.


Thanks for everything so far!!!! Keep the info coming... I intend for this project to beat out all of the commercial clones!!!!!!!
-Grant

Grant,


  this might fit the ticket


    http://www.tubedepot.com/nos-ac701.html


  ANdyP

'Nother option for you.


  http://cgi.ebay.co.uk/1-NOS-Tube-AC761-RFT-equivalent-Telefunken-AC701k_W0QQitemZ130321355886QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item1e57c2146e


  NOT as good as ac701k, but you gets whats yous pays for inn it?



  ANdyP

As I understand,


  Ac701 and AC701k interchangable, slight construction differences, and some ac701's are a tad noisier. I had KM56 with AC701, and it was pretty darn quiet, as I recall. AC761 is also i believe interchangable, but with a noise penalty, some being ok, and others noisy. Check what Klaus's forum has to say about this. I would go for AC701 myself . . . .


  Hiller is NOT the same, 2v heater(?) for instance. I think that there are some differences in the m49/m50 depending on the tube. Please someone who KNOWS aBOUT 'DIS . . . .


      ANdyP

strangeandbouncy said:

As I understand,


   Ac701 and AC701k interchangable, slight construction differences, and some ac701's are a tad noisier. I had KM56 with AC701, and it was pretty darn quiet, as I recall. AC761 is also i believe interchangable, but with a noise penalty, some being ok, and others noisy. Check what Klaus's forum has to say about this. I would go for AC701 myself . . . .


   Hiller is NOT the same, 2v heater(?) for instance. I think that there are some differences in the m49/m50 depending on the tube. Please someone who KNOWS aBOUT 'DIS . . . .


      ANdyP

Click to expand...

Awesome... That's good to know... Yeah I mean that's one of the reasons I am leaning toward the real VF14 in the U47, because of a change in schematic. Especially since the VF14 was famously underpowered which people claim is one of the key reasons the mic sounds the way it does... Hence me not wanting to use an EF14. However with the M50 I might be out of luck, in which case that seems to be the next best option... Not too bad considering some were manufactured with this tube... So it will be an authentic M50, just not an early one. Which would be interesting, because I have only heard an early one before... The one at Blackbird I believe is one of the first made if I remember correctly... Like somewhere within the first 5, may even be the first (not prototype, but first official)... I remember them point it out to me. I got to hear it on a number of occasions and fell in love with that mic... Then of course listening back to old Decca Tree recordings, and classical scores... Possibly the best room mics ever made. I really want to try one as a mono overhead.

-Grant