DiY AMI U47

[Phrazemaster]

...Also not to become Captain Daunting but there is a fair amount of machining and fabrication in your future.

Pip I had to laugh at this comment, so true! I am finishing a build of a DU67 and I had the body machined at a local shop for some work out of my league. I thought I was done; just had to replace a cheapie chinese capsule with a Sneesby K6 and lo and behold...I had a LOT of machining/drilling to do on the new plastic base to interface with the existing metal base on the donor mic...so...yes, to DIY is to machine and get used to making lots of dust and learning how to screw things up in infinitely new and nuanced ways!

Mike

 

[sr1200]

@phrazemaster are there significant changes to the schematic for the ef tube?  I found some decent resources on the tab funkenwerk website which is where i might be getting my donor body. Unfortunately skylars doesnt have a port for the pattern switch which i really want ON the mic.

 

[Phrazemaster]

@phrazemaster are there significant changes to the schematic for the ef tube?  I found some decent resources on the tab funkenwerk website which is where i might be getting my donor body. Unfortunately skylars doesnt have a port for the pattern switch which i really want ON the mic.

Yes - I got my version from Andreas Grosser, but he requested I not post it Bummer because it's nice to have open exchange of info but this is his proprietary design so I must honor his request.

I think if you contact him directly he may be amenable to giving it to you...he's super kind.

 

[Melodeath00]

@phrazemaster are there significant changes to the schematic for the ef tube?  I found some decent resources on the tab funkenwerk website which is where i might be getting my donor body. Unfortunately skylars doesnt have a port for the pattern switch which i really want ON the mic.

There is no info on the EF12 on the Tab-Funk site. The EF14 is different.

Also just FYI, it's possible Oliver may not desire to sell you the version with the pattern switch hole on the basket. He heavily pushed me towards the remote-polarity version. In the past, people have had issues getting the Telefunken-Elektroakustik switch to work with Oliver's body, so I think that has something to do with it. Of course, I also wonder if maybe Oliver hasn't made that version in a long time as a result, and that is part of the equation, along with both companies having little desire to support each other.

 

[sr1200]

I just realized that.  So any thoughts on the difference between the 12 and 14?  In addition, the email i got from them didn't even mention a version of the body with a pattern switch.  The tab funkenwork site though does have a body available for slightly more $$ that HAS the switch available and they carry the transformer and theishe (spell?) capsules as well.  Considering going that route instead, but wish i knew someone that had a TAB body.  I know someone with skylars and its of amazing quality.

 

[Melodeath00]

I suppose you mean you wish you knew someone in person with the body? All the pictures I posted in this thread are using the Tab body, and I could take some more pictures if you wanted.

EF12 versus EF14. I have used neither, but obviously both are modified circuits from the U47, not only because of the tube difference, but because they require a separate heater. I was talking with someone recently about how even the use of a separate heater probably alters the sound of the mic from the original, which makes sense to me as I learn more about how tubes work and their behavior.

Flea markets the EF12 as being the closest to the VF14 in sound, but we do not know their precise circuit. I was told by someone who no longer works at AMI that Oliver does not believe the EF12 sounds closer than the EF14, and indeed there is only EF14 info on the Tab site. Regardless, they use a Telefunken glass tube in their Lucas CS-4, which I have read sounds practically identical to a U47 when you use the same exact capsule and A/B. Of course, others have told me otherwise, but they are not transferring their capsules, and U47s differ from mic to mic.

There is a thread here on the forum about using the EF12, but ultimately the threadstarter (I think) wound up using an EF800 like I did.

Speaking of the EF800, I bought a couple more and they are quiet and sound great in my U47. I also went back and re-tested the second EF800 I got from Oliver, and that one is no longer noisy. I wonder if something was on the pins before. Regardless, I now have three backup EF800 tubes, so I think I am all set for life. I may get an EF802 to test, but I don't think I want to alter the circuit in my mic. I hate desoldering, and I feel fortunate my mic works as well as it does, so I don't want to mess with it too much. Besides, the mods Oliver makes for the EF802 are so small I wonder how much they really affect the sound. I may build another U47 with a 408a plus mods. Possibly the MK-47.

 

[Moby]

After hearing the flea side by side to a original u47 I decided I like the EF12K more than the original but that's just me.

Anyway this is the same exact circuit as the flea mic for whoever wants to build one. I made a wiring diagram so maybe people will understand it better. Just remember you need -6V heater and 120V for A+ and you are good to go.

Aaron

Nice share.

 

[sr1200]

OK so now that you guys have dashed my hopes and dreams.... lol. 
Anyone have any input on transformers.  Im between the TAB and the Peluso.  Price isn't that much of a difference that it's an issue, but sound wise, whats closer?

 

[Pip]

I just realized that.  So any thoughts on the difference between the 12 and 14?  In addition, the email i got from them didn't even mention a version of the body with a pattern switch.  The tab funkenwork site though does have a body available for slightly more $$ that HAS the switch available and they carry the transformer and theishe (spell?) capsules as well.  Considering going that route instead, but wish i knew someone that had a TAB body.  I know someone with skylars and its of amazing quality.

Tube is not as important as the capsule. If you want to go the Thierche (they are awesome) route you can contact them directly. They are very pleasant to deal with.

The switch that is on the U47 for pattern, only switches the back capsule in and out of circuit. It is truly nothing fancy. You can use just about any switch or a relay. Check out how Oliver does it at TAB-FUNKENWERK.COM. He has his remote switching schematic up on the site.

I myself would go with either the IOAUDIO or AMI BV8 transformer.

Just another opinion.

Either way you go with metal tubes that are of mic quality you are looking at at least $100.00 plus a tube EF12 or EF14 they ain't cheap and you must get Y8A Octal 8 PIN sockets on ebay believe it or not they are hard to find in the States. You can find EF80 or EF800 tubes for far less money.

 

[sr1200]

Pip thanks for the input, i think im going with the EF12K tube.  The Theirche blue is the capsule im going for and im probably going with the AMI (since it looks like ill be getting just about everything through them at this point (body capsule and trafo).  Only suck thing now, is, I ordered all the parts for the nuvistor version of the mic (except the nuvistor itself) So a lot of spare parts in my future.  The PS is totally different for the EF tubes (bc of the heater voltage needed) Trafo is different for the PS as well, so thats all a loss, but from what folks have been saying, the EF12 is the way to go on this mic. 

(PS im in NY as well out on the island)

 

[micaddict]

As an alternative for the EF12, Ben Sneesby uses a Russian steel tube for the popular BeesNeez Arabella:

http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=55

A couple of years ago a guy in my country offered a "truck load" of these for next to nothing. Should have jumped on it, I guess.


BTW for the BeesNeez Tribute 1 (U47), Ben uses an EF14. Some say these can make mics hot, in the literal sense.

 

[pasarski]

The switch that is on the U47 for pattern, only switches the back capsule in and out of circuit. It is truly nothing fancy. You can use just about any switch or a relay.

Actually I think it's not that simple. You need a very high insulation resistance switch/relay. Maybe not so much of an issue with original U47 values than with 1G resistors like in AMI circuits. Also the magnentic field of the relay can give you problems, so you need a shielded one. Just having a buzz issue with IL05-1A72-71L-MEDER (which I thought would be ok). Also you have to count in the current draw of the relay if you use heater supply for switching voltage and want the heater voltage to stay same regardless of the pattern.

 

[Moby]

OK so now that you guys have dashed my hopes and dreams.... lol. 
Anyone have any input on transformers.  Im between the TAB and the Peluso.  Price isn't that much of a difference that it's an issue, but sound wise, whats closer?

Unfortunately none of nowdays bv.-08 replicas sounds exactly as original because they use the diferent (modern) lamination alloy. Haufe used the VAC's material but unfortunately they don't produce the bv.-08 anymore. I already opened the "can of worms" on this subject  (other u47 thread) and now I hope that it will not happen again

 

[Pip]

The switch that is on the U47 for pattern, only switches the back capsule in and out of circuit. It is truly nothing fancy. You can use just about any switch or a relay.

Actually I think it's not that simple. You need a very high insulation resistance switch/relay. Maybe not so much of an issue with original U47 values than with 1G resistors like in AMI circuits. Also the magnentic field of the relay can give you problems, so you need a shielded one. Just having a buzz issue with IL05-1A72-71L-MEDER (which I thought would be ok). Also you have to count in the current draw of the relay if you use heater supply for switching voltage and want the heater voltage to stay same regardless of the pattern.

Sorry. Did not mean to imply that the circuit application did not need to be considered. I was just pointing out the simplicity of the circuit. On the U47 the switch is literally a knife switch at the capsule base mounted on the plexi base. As to the relay, I believe that a latching type is the prescribed solution. IOAUDIO has achieved a great solution as has Oliver with his C12 clone.

 

[Melodeath00]

Pip, do you mean his Blackspade UM25? I don't think there's a relay in his C12.

What I still plan to do is install a switch inside my 47 for cutting off the rear diaphragm. That way I have the best of all worlds, and can truly test the difference as well between "true" cardioid and remote-pattern cardioid

 

[Pip]

OK so now that you guys have dashed my hopes and dreams.... lol. 
Anyone have any input on transformers.  Im between the TAB and the Peluso.  Price isn't that much of a difference that it's an issue, but sound wise, whats closer?

Unfortunately none of nowdays bv.-08 replicas sounds exactly as original because they use the diferent (modern) lamination alloy. Haufe used the VAC's material but unfortunately they don't produce the bv.-08 anymore. I already opened the "can of worms" on this subject  (other u47 thread) and now I hope that it will not happen again

Yes please don't

 

[Pip]

Pip, do you mean his Blackspade UM25? I don't think there's a relay in his C12.

What I still plan to do is install a switch inside my 47 for cutting off the rear diaphragm. That way I have the best of all worlds, and can truly test the difference as well between "true" cardioid and remote-pattern cardioid

Yes.

 

[chaserose1]

I have been working on my Tab-funkenwerk 47 utilizing the EF-800 and the alternative tube schematic and find that the PSU I have been provided by Tab is supplying 134 B+. Is anyone familiar with the supply, is this a problem-- heater voltage is spot on.  Thanks in advance for any direction.  Also thanks to previous posters for the heads up on the Binder Connector, that certainly saved me a big headache.   

 

[Aaronrash]

I have been working on my Tab-funkenwerk 47 utilizing the EF-800 and the alternative tube schematic and find that the PSU I have been provided by Tab is supplying 134 B+. Is anyone familiar with the supply, is this a problem-- heater voltage is spot on.  Thanks in advance for any direction.  Also thanks to previous posters for the heads up on the Binder Connector, that certainly saved me a big headache. 

Are you measuring on the power supply or at the actual tube inside the microphone? Voltage is lost as it travels through the cable, it's such a small current.

I've never worked with Oliver's PSU but you should be able to adjust all those parameters. Inside the supply there should be trimmers.

Aaron

 

[AusTex64]

Cool to see this thread continue on. A few comments:

I believe Wagner and Wunder use AMI BV8 transformers, and I've forgotten who else. Oh, Lucas of course. I've not encountered anyone who knows more about this transformer than Oliver Archut. BTW, he just posted an excellent article on his website about BV8. http://www.tab-funkenwerk.com/id146.html

Someone mentioned original materials for BV8 not being available. AMI offers BV8 with both NOS laminations and Oliver's modern lams of the same high nickel materials.

Oliver said on the Lucas forum that "EF802 is the closest glass tube to VF14 in specs and sonics", and that's what he uses in CS-4. I have one in my mic and it sounds godly. YMMV.

I found Oliver sells Thierch capsules for the same price that Thiersch sells them for directly, with lower freight and less wait too.

I posted the correct relay part number and the Mouser part number earlier in the thread. Works great, have it in my mic. Same one Oliver uses in CS-4. It was pretty easy to implement rear diaphragm switching from the PSU using the relay. I reckon it's a lot easier that sourcing the parts to do the switching at the mic head, and a hell of a lot cheaper too. Also, I did not measure ANY drop in heater voltage with the relay engaged or not. Apparently it must not draw too much current.

To the fellow with 136V from the PSU - must measure those voltages inside the mic, under load.