Advice for building a U47 clone

[Delta Sigma]

I'd like to build a U47 because of the extensive use in the Beatles era. I currently work on reenacting Beatles stuff for research purposes, and it would be nice to use a U47 for vocals, guitars. A U67 build is planned- but as a stereo pair.

I get you on the Beatles research, sometimes you want to know, and you have to build and hear for yourself. But for the mic you will end up with, the way you may use it might not be where the U47 shines. For me, when we're talking about the headbasket and amplifier, I find My EF-U47 is a better pop vocal mic than any of my other mics. It sits in front of the mix a little better. In context with '60s recordings, I can see how it could allow a source to pop out a little when the equipment was a little noisy. In context with modern recording equipment, I have found that my M49 (Beesneez M7) gives more of a "Beatles" or '60s sound than my U47.

This is just my experience, so take it with a grain of salt. My DIY versions aren't the same as the originals.

I do really like my EF-U47 on quiet vocals. Most of this recording was my U47. Arienne Flat 47, Dany U47 body, EF802, Moby BV.08. Not recorded by me.



Here's my M49 and U47 in action. Again, not recorded by me.

 

[Accelerator]

Did someone ever said "magical" here ? Hummmm maybe someone made a big ugly straw man ! I promise next time i am offered a dirty vintage U47 i'll throw away this obsolete tube, change this brittle pvc M7 and replace this ugly PSU for a modern regulated stabilized one .... I promise ... or maybe not !!! .)

I totally agree with you but if you want to clone a citroen mehari (classic vintage plastic car) and replace the ugly flat 2cylinder air cooled with an american V8, is it still a Mehari ? This question is debated for centuries in the famous Ulysses's ship paradox (private joke)

“Take your numbered ticket and step in line…”

Stanley Church, the chief engineer of the famous MCM – Acme Studios did it way-way back before, at the early ‘50’s, and he produced nearly 200 “Church” microphones with a Cathode Biased G.E. 6072 (12AY7) tube, Triad JO-23 Output Transformer and a Langevin tube power supply running at 275 (!!!) Volts HT / 12,6 Volts LT before Georg Neumann sued him…

The “reason” that you, I and everybody else, more or less, knows the AKG C-12, ELA-M 251E, SM-203, Sony C-800C, Manley Reference or even the Rode Classic Tube microphones was and is Stanley Church…

 

[garp]

Yes i've seen this frankenmic, that's why we call them "Church" ... not Neumann U47

 

[tomas.borgstrom]

“Take your numbered ticket and step in line…”

Stanley Church, the chief engineer of the famous MCM – Acme Studios did it way-way back before, at the early ‘50’s, and he produced nearly 200 “Church” microphones with G.E. 6072 (12AY7) tube, Triad JO-23 Output Transformer and a Langevin tube power supply running at 275 (!!!) Volts HT / 6,3 Volts LT before Georg Neumann sue him…

The “reason” that you, I and everybody else knows the AKG C-12, ELA-251E, SM-203, Sony C-800C, Manley Reference or even the Rode Classic Tube microphones was and is Stanley Church…

This is not true. The C12 was for sure released 1953. And according to the facts I can find, the Church microphone was "released" 1955 (it was an in-house build not available to the public and from what I've read differed a bit depending on what Stanley Church had on the shelves). The only thing they have in common is the 6072a.

I've never heard that Neumann Sued him. I think they just forbid Gotham Audio to sell him spare parts.

http://recordinghacks.com/pdf/akg/AKG_History.pdf

https://tapeop.com/interviews/107/church-mic-bonus/

EDIT: According to the article in TapeOp it seems that Gotham Audio stopped the Church microphone since they didn't wan't Neumann to sell their products to anyone else in the US.

 

[Accelerator]

This is not true. The C12 was for sure released 1953. And according to the facts I can find, the Church microphone was "released" 1955 (it was an in-house build not available to the public and from what I've read differed a bit depending on what Stanley Church had on the shelves). The only thing they have in common is the 6072a.

I've never heard that Neumann Sued him. I think they just forbid Gotham Audio to sell him spare parts.

http://recordinghacks.com/pdf/akg/AKG_History.pdf

https://tapeop.com/interviews/107/church-mic-bonus/

“The victors write the history as they like” or even “History Is Written by the Victors” by the famous quote which is often attributed to Winston Churchill and no demonstration paper will telling you that the very first AKG C-12 100-piece Batch (included the famous “Ocean Way Studios C-12 microphone" that David Bock tries to mimic by his microphones...) has an ECC81 – 12AT7 valve and the Henry V-3044 Output Transformer, which has 12,3 - 1 Ratio very closely similar to the 12 – 1 Ratio that the Triad JO-23 Output Transformer and the Jensen DB-E Output Transformer have…)

Stanley Church microphones “story” show to the AKG, that if they had to succeeded and “make it big in America” they had to use the 6072 – 12AY7 tube in their microphones, as this tube was the “king” back in time, something very similar to today's ECC83 - 12AX7 - 7025 tube…

RCA, General Electric, Tung-Sol produced them and everybody in America used them, so AKG was not so stupid not to understand that…

And the “story / heritage of Stanley Church microphones goes on and on”, even more with the totally uncorrect value of 1.8KΩ Cathode Resistor for the ELA-M 250E and the C-2 rev.3 aka C-2.0.3 or most well-known to any of us as the AKG-Siemens SM-203 with the 12,3 - 1 Ratio Rhode Schwarz V-2545 transformer, which actually was a “rebranded” Henry V-3044 Output Transformer as Hendry has sold the design of his transformer to Rhode & Schwarz…

In any logical and scientifically aspect, for the 100KΩ Plate Resistor load the center biasing for any 6072 – 12AY7 tube with 120 Volts Plate Voltage, will be the Grid Bias Voltage of -1,23 Volts, at 0.60 mA, at the 60 Volts of the Load Line…

Now if you divided the 1,23 Volts / 0.60mA you will have the most properly and correctly value of 2050Ω Cathode Resistor, not the 1800Ω Cathode Resistor that the AKG failed used…

But as I said they simple “copy & paste” the nearest high by to the 1700Ω Cathode Resistor that Stanley Church correctly used for his 275 Volts “Church” microphone…

 

[Eike]

I get you on the Beatles research, sometimes you want to know, and you have to build and hear for yourself. But for the mic you will end up with, the way you may use it might not be where the U47 shines. For me, when we're talking about the headbasket and amplifier, I find My EF-U47 is a better pop vocal mic than any of my other mics. It sits in front of the mix a little better. In context with '60s recordings, I can see how it could allow a source to pop out a little when the equipment was a little noisy. In context with modern recording equipment, I have found that my M49 (Beesneez M7) gives more of a "Beatles" or '60s sound than my U47.

This is just my experience, so take it with a grain of salt. My DIY versions aren't the same as the originals.

I do really like my EF-U47 on quiet vocals. Most of this recording was my U47. Arienne Flat 47, Dany U47 body, EF802, Moby BV.08. Not recorded by me.



Here's my M49 and U47 in action. Again, not recorded by me.

Oh wow! These are incredible nice sessions!

This is what I recorded in spring for my Beatles research. We tried to keep a Revolver workflow, but hat limited resources, so we cut corners with using the equipment we had. Mostly a Warm Audio WA-47jr.

I will not get THE U47-sound without the VF14. That is totally clear to me. Financial resources are also an issue. So I will try to do my best to find the right way. In the moment, with Danys D47 or EF47, Ariennes flat 47 capsule, UTM transformer, Aliexpress body (not all ship to germany unfortunately) and a robbed tbone-powersupply with Danys PCB.
It will be my first tube mic build, but I'm sure it's not the last one.

 

[kingkorg]

I will not get THE U47-sound without the VF14. That is totally clear to me.

I've gotten on everyones nerves here trying to debunk this myth put in place by hoarders and lucky owners who try to monetize their stash.

There's nothing special or magical about VF14, Neumann used it out of necessity. It's an average tube at best! Go make a great mic, great music with it and don't waste time chasing irrelevant components or doubting your results because something you read from a "guru" online.

P.S. there's no such thing as "the u47 sound" it's a spectrum, due to tolerance, variations, and aging of the original units. That's why everyone has their favorite one, and why there's no such thing as 1:1 clone. It would have to be a clone of a particular serial number.

 

[tomas.borgstrom]

I'm open to revising my knowledge but you're providing me with a lot of information I already know about the AKG microphones. I have no agenda in this matter but correcting other members with long explanations and no sources is quite common in this forum.

not the 1800Ω Cathode Resistor that the AKG failed used…

But as I said they simple “copy & paste” the nearest high by to the 1700Ω Cathode Resistor that Stanley Church correctly used for his 275 Volts “Church” microphone…

It's also very common that DIY:ers think that they are smarter and know more than the engineers at Neumann, AKG, Schoeps etc. These where the engineers that designed and built the some of the best microphones we still know of today. They pushed the sound quality of recording to a whole new level. I'm pretty sure they knew their basic maths.

I've read many times that the schematics you find of the Church microphone are wrong. How did you find out that he used 1k7 instead of 820R as the schematics says?

Side note: If anyone has an explanation why AKG used 2K7 in C24 and 1K8 in ELA M250/251E, I would love to know.

Henry V-3044 Output Transformer, which has 12,3 - 1 Ratio very closely similar to the 12 – 1 Ratio that the Triad JO-23 Output Transformer

The timeline seems wrong to me. The C12 had the 3044 when it was released in 1953. That was before Stanley Church made his microphones with JO-23.

no demonstration paper will telling you that the very first AKG C-12 100-piece Batch (included the famous “Ocean Way Studios C-12 microphone" that David Bock tries to mimic by his microphones...) has an ECC81 – 12AT7 valve

Stanley Church microphones “story” show to the AKG, that if they had to succeeded and “make it big in America” they had to use the 6072 – 12AY7 tube in their microphones, as this tube was the “king” back in time, something very similar to today's ECC83 - 12AX7 - 7025 tube…

Even if the first C12 shipped with ECC81 (source?) and then changed to 6072, a popular tube easily available i the US, I don't see this as an obvious connection to the Church microphone. You put it as the Church microphone was some kind of commercial success. He made about 100 pcs in his kitchen and it was at the time used in film dialog and not studio recording.
I correct my last post. According to the article in TapeOp it seems that Gotham Audio stopped the Church microphone since they didn't wan't Neumann to sell their products to anyone else in the US.

I believe the Church microphone (just like a lot of other rare mythical gear) is getting so much attention because it's unavailable to hear for yourself. Very few, even among microphone enthusiasts, have seen it and even less have used it.

 

[garp]

Jesus ! A Church microphone ? What for ? Predicators ? Sermons ?

 

[Khron]

Jesus ! A Church microphone ? What for ? Predicators ? Sermons ?

In case that's not supposed to be a joke...

https://groupdiy.com/threads/advice-for-building-a-u47-clone.87726/post-1154734

(earlier on this page)

 

[rock soderstrom]

Rhode & Schwarz…

Rohde&Schwarz is the name

 

[rock soderstrom]

In any logical and scientifically aspect, for the 100KΩ Plate Resistor load the center biasing for any 6072 – 12AY7 tube with 120 Volts Plate Voltage, will be the Grid Bias Voltage of -1,23 Volts, at 60 mA, at the 60 Volts of the Load Line…

Really 60mA? Lightshow?

 

[garp]

I promise i will refine my jokes or put a big red noze on my face before

 

[Accelerator]

I'm open to revising my knowledge but you're providing me with a lot of information I already know about the AKG microphones. I have no agenda in this matter but correcting other members with long explanations and no sources is quite common in this forum.

The sourses that you like to see and not a "interview of someone that knows someone, who has tells him something, about someone elses microphone..." on Tape Op...

Make a search for this article in PDF...

Recreating the MGM “Church” Vacuum Tube Microphone by C.H. Preston 2011

It's also very common that DIY:ers think that they are smarter and know more than the engineers at Neumann, AKG, Schoeps etc. These where the engineers that designed and built the some of the best microphones we still know of today. They pushed the sound quality of recording to a whole new level. I'm pretty sure they knew their basic maths.

Yeah, I'm not an iconoclast...
I am an anarchist blasphemer and I don't slavish "raise and praise" for your "holy trinity" of "Neumann, AKG, Schoeps etc."

These were and they are just commersial capitalistic companies in a commersial capitalistic world and as you know by Karl Marx's "Capital" book every commersial capitalistic company in this commersial capitalistic world is looking forword to maximize their profit, even by "taked" - inspired by... - copy and paste, named it as you like it, and as your "holy trinity" of "Neumann, AKG, Schoeps etc." allows you to do so...

If AKG engineers knew their basic maths, then why they did made these basic mathimatical mistakes?...
If Georg Neumann was so sure satisfied about the fixed biasing that he & his team used in the Neumann U-47, U-48, M-49A, M-49B microphones, then why in the Neumann M-49C microphone & for the Microtech Gefell microphones they decided to used the (cheaper & easier) Cathode Biasing, that Church already used in his microphone?...

I've read many times that the schematics you find of the Church microphone are wrong. How did you find out that he used 1k7 instead of 820R as the schematics says?

As you can see, the 820R Cathode Resistor is there in the schematic if you will like to use the 5751 tube, for the 6072 - 12AY7 you will use 1k7 Cathode Resistor...

Side note: If anyone has an explanation why AKG used 2K7 in C24 and 1K8 in ELA M250/251E, I would love to know.

In any logical and scientifically aspect, for the 100KΩ Plate Resistor load the center biasing for any ECC81 – 12AT7 tube with 120 Volts Plate Voltage, will be the Grid Bias Voltage of -1,58 Volts, at 0.60 mA, at the 60 Volts of the Load Line…

Now if you divided the 1,58 Volts / 0.60mA you will have the most properly and correctly value of 2.633,3333Ω Cathode Resistor, not the 2.7KΩ Cathode Resistor that the AKG failed used…

What surprise, what a surprise, again total wrong Cathode Resistors, but this time also for total wrong tubes…
The ELA-M 250 (non E) with AC701 tube used 3,6KΩ Cathode Resistor…

I believe the Church microphone (just like a lot of other rare mythical gear) is getting so much attention because it's unavailable to hear for yourself. Very few, even among microphone enthusiasts, have seen it and even less have used it.

Francis Albert Sinatra (December 12, 1915 – May 14, 1998) has used it and showed with it in the film…

Take a listen...

Test 28 Church U47 CINEMIKE Tube Microphone Vocals Johnny


Test 58 Church 47 Cinimike Tube Microphone made by Stanley Church



Test 30 Church U47 CINEMIKE Tube Microphone Acoustic Guitar Noah Needleman

 

[Khron]

Yeah, I'm not an econoclast...
I am an anarchist blasphemer and I don't slavish "raise and praise" for your "holy trinity" of "Neumann, AKG, Schoeps etc."

A kindred spirit

Now if you divided the 1,58 Volts / 60mA you will have the most properly and correctly value of 2.633,3333Ω Cathode Resistor, not the 2.7KΩ Cathode Resistor that the AKG failed used…

You might, though, want to consider if you put the decimal comma in the right place there 60mA (milliamps, 0.06A) through a 2.7k resistor would work out to a voltage drop of 162V - kinda difficult with a 120V B+, I think you'll agree

1.58V across 2.7k gives me 600uA / 0.6mA...

 

[Accelerator]

A kindred spirit



You might, though, want to consider if you put the decimal comma in the right place there 60mA (milliamps, 0.06A) through a 2.7k resistor would work out to a voltage drop of 162V - kinda difficult with a 120V B+, I think you'll agree

1.58V across 2.7k gives me 600uA / 0.6mA...

The value of the Grid Bias Voltage -1,58 Volts, at 0.60 mA, at the 60 Volts of the 100KΩ Load Line, for 120 Volts Plate Voltage is for the ECC81 – 12AT7 tube, non for the 6072 – 12AY7 tube that the C-24 stereo microphone was loaded…

1,58 Volts / 0.00060A = 2.633,3... Ohms aka 2k633

The AKG logistics & marketing department decides to sells the C-24 stereo microphone with the uncorrected 6072 – 12AY7 tube for this ECC81 - 12AY7 circuit, and that’s why the C-24 stereo microphone sounds much “colder” than the AKG-Siemens SM-203 microphone...

 

[Khron]

The value of the Grid Bias Voltage -1,58 Volts, at 60 mA, at the 60 Volts of the 100KΩ Load Line, is for the ECC81 – 12AT7 tube, non for the 6072 – 12AY7 tube that the C-24 stereo microphone was loaded…

1,58 Volts / 0.00060A = 2.633,3... Ohms aka 2k633

As i was saying...

60mA (milliamps) = 0.06A = 60.000uA (microamps)
6mA (milli) = 0.006A = 6000uA (micro)
0.6mA (milli) = 0.0006A = 600uA (micro)

Please triple-check your numbers, decimal positions and unit multiplier prefixes

 

[Accelerator]

Now, buck to the Neumann U-47 thread, cause we have hi-jacked it with the AKG microphones…

Here is an Article by Antreas Grosser (R.I.P) about all the transformers had been used in U47 microphones…

A description of all transformers in U47 ~ Article by Antreas Grosser fans-web-472260

 

[rock soderstrom]