U47 hand wired with VF14 and BV8

[speakercoil]

Totally cool... I found a 5 Watt version sold at partsconnexion. I need to find out the core temp first... Then I know weather I have to build my own or if I can get away with it! If I do build my own I might build a bunch and sell them on here for anyone going down this route.

As for the Capacitors... yeah I need a round. I think I might just get something high end and modern. Audionote maybe... or Mundorf, Auricap, or maybe even a duelund if it could fit.

OH... I also think I chose what I want to do with Skylar's body... I need to make sure it will work. But I want to use the schematic of a CV 563 circuit. Not the original though, the one that has been moded over at ProSoundWeb. However obviously that doesn't have interchangeable heads... So instead I am going use a fixer head, but not an M7. I was to use Flea's 4750...
http://shop.flea-microphones.com/index.php?page=productDetail&category=Microphones&prNum=29

I will still use Skylar's head, but put this capsule in it.

Then I have already obtained the blank head of the U47, and then just need to buy flea's body only (minus head)... That way I already invest money in the U47 project, while getting to build a unique mic in Skylar's body.



-Grant

 

[Peps]

Johan,
Do you know the component values (resistors, capacitor) for that ultra-simple SELA T12 circuit? Do you know anything about the transformer?
I seem to remember that SELA liked to squeeze the capsule a bit with high polarisation voltage (for more output) and then design the trafo to compensate for increased high end. But that was in the later T-series models. This one only gets 60 V which is more like a normal M7 voltage so maybe the transformer is a straight one...
Peps

 

[strangeandbouncy]

here is the missing info

 

[speakercoil]

I may build that circuit in the body of a cheap chinese mic I have... How does it sound? It's hard to tell in a mic if a more complicated mic might sound better, or if the cleaner signal path adds clarity. It looks intriguing though.

What ratio do I need on the transformer?

-Grant

 

[strangeandbouncy]

All i can add is that i prefer my Sela T25 (with KK47) over any M49 I have ever used . . . . I didn't know that there was any top end lift going on. It does seem to have a higher polarisation. 120V with 300k/1M giving 82V. Any comments anyone?



  I really must stop telling everyone how wonderful these mics are . . . .it is hard enough trying to find a second one as it is!



        ANdyP


I know that diagram is for T24, but I believe only difference is kk47 on T25, M7 on T24

 

[mad.ax]

Regarding carbon comp ratings and contact noise. Good points, but I thought that the idea was to stick with original components with all their advantages and drawbacks, including mojo and noise...
Original Neumann U47 came with 0.1 and 0.25W resistors. Of course you may improve noise performance by using bigger rating, but if your goal is to improve noise performance, you may as well go all the way and use modern metal film resistors!

Regarding polystyrene caps. C1 is a good candidate as its low value allows for such material.

Regarding R4. Forget about the core temp. whatever the technology of this resistor may be, it will still have to dissipate about 3 Watts of heat. Either you heat-sink this resistor to the body in order to evacuate some of this heat outside the mic, either you don't and the temp inside the mic may reach 160°F.

Regarding Flea 4750 head. It lacks the polar pattern switch that you will need later to build a U47.

Axel

 

[Skylar]

Another problem with FLEA's 4750 headbasket is that they have the shape of the top mesh wrong.
Someone brought this up in the big U47 body thread (within the first 10 pages I think?).
The top mesh of their previous U47 baskets all looked like this, including the baskets sold to Wunder for their clone.

However, if you look at some of the other FLEA U47 products, the headbaskets look correct these days.

So, I guess the question is, if you buy a headbasket from FLEA, will it have the dome top or the flat top?

 

[speakercoil]

Hmmm... You're right the head basket is a little off... I noticed it looked different, but couldn't figure out why. When coming up with this idea I figured it still had the hole where the switch would be, but just had a fixed metal badge instead... Now i realize it is just solid. My original idea was remove the omni badge and have a new switch put in... I wonder if this head is rounded to give more of a M50 style sound from the capsule.

Now here's a question for Skylar. Concerning their head baskets... Do you think they would be swappable with yours... Because if that's the case, I could use that head on your body and your head on the flea body...

Either that or I will just concede and do something different in Skylar's body and just fork over the cash for a whole flea body. My other two idea's for Skylar's body were a G7, and now possibly that Sela T24. I just think it would be cool to have something different from the norm in my collection.

I just eventually want an M50 style head in one of my mics... I may just have to wait and try and build a clone... Though actually I did find an NOS Hiller last night for around 600 bucks on e-bay...

http://cgi.ebay.com/Hiller-MSC2-NOS-NIB-never-used-still-sealed-very-rare_W0QQitemZ220468733540QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3354f5e664#ht_500wt_871

That got me very tempted last night... I had to restrain from outright buying it then and there. If I got that tube though... Then I would end up having to get Flea's M50 body, and would end up doing this whole U47 clone with an M50 as well... Which if I do won't be for a long time. However it would be nice to have the tube for that future project.

I think you are right about the resistors. I am going to try and keep them as accurate as possible. Take the good with the bad. As for R4, I think the 5 Watt mills might fit... They seem pretty small. The diameter is .17 inches. Seems reasonable enough.

I think I might just end up doing both of those Sela's... One in my cheap chinese body, and one in Skylar's.... Probably the T25 in skylar's.

That being said... I purchased my first part for the U47 last night. Some NOS Siemens PIO .01uf capacitors. Obviously I only needed one, but they were some in bulk. I figure I will end up using the rest eventually and will have some for spares!

Once I get all the caps, I am going to work on resistors... Then the BV8... Then the RV14 (which I have decided will have to do for a while until I can afford a real VF14). Then the capsule and the body... I will get a real VF14m down the line, but probably not for a year or two. I mean I could build a whole other mic for the price of one... In the long run though I do want one.

-Grant

 

[speakercoil]

wow crazy... A while back I inquired to Gunter if they still sold any parts for the U47 anymore... I just got a response stating that they stopped selling parts, because they were running out of the materials to reproduce them accurately. I guess they wanted to retain the last of their supply for Wagner's... However these supplies are running low, and they will only be able to make less than 24 from this point out. Or at least that is what I gathered. What a shame that is.

This makes me even more determined to make a close to perfect clone. It shows how low the world is on U47 parts, and I want to make one before I lose the chance to.

-Grant

 

[strangeandbouncy]

I haVE just been told that Grosser does a VF14 sub, and I am also informed that it sounds amazing . . . . .

 

[speakercoil]

what tube does he use??? I checked his site, but it doesn't have any info on it!

Let me know where you found this. Did he make a VF14 replica? Or does he just have a mod to replace it with a different tube?

-Grant

 

[speakercoil]

I haVE just been told that Grosser does a VF14 sub, and I am also informed that it sounds amazing . . . . .

So I had to do a lot of digging to find out even a little bit of info on this... The tube is the VF14ER, which he puts in a mic called the Vertigo VS47... Now, he also uses these on repairs. However I cannot find an e-mail address or website for him. The site I did find is a fan site for him, which I found kind of odd. However I am still nowhere close to being able to contact the man, except for his phone number which is REALLY long distance... Would be nice to just e-mail and save the long distance bills. It would also give me more time to think out my questions.

If anyone knows how to contact Andreas Grosser, please let me know. From what I've read the VF14ER is pretty much the real deal, or at least good enough to fool a lot of good ears. I would interested to know just how close this replacement tube is... If it's a real recreation then I am going to use one of them.

-Grant

PS Why are all the good replacement part makers really hard to get a hold of????

 

[synchroman]

Andreas Grosser has a blog, here you go...

http://www.andreas-grosser.com/

 

[jdbakker]

If I increase the wattage will that reduce the temperature?

Think about it.

Through the power supply you're pumping a certain amount of power into the mic. Almost all of this power turns into heat. There's no (significant) airflow through the mike body, so as a first approximation you can see it as a closed system from a heat POV. Because it's a closed system, power in = heat out of the mic body. In a given environment (your studio) it makes no difference at all to the temperature of the outside of the mike body whether the electrical power that flows into the mic is internally dissipated by a 3W-rated resistor, a 10W-rated resistor, or (for that matter) a glowing 1/4W resistor, or a lightbulb, or a microprocessor... You get the picture.

So what happens inside the mike? By the same reasoning, if the resistor (or whatever) that dissipates the power inside the mic occupies the same space in the mic, the temperature distribution inside the mike body will be the same. Higher-wattage resistors won't save you.

The only two things you could do is (a) thermally coupling the resistor to the mic body, or (b) using a series/parallel string of resistors in different (physical) places inside your mic. That won't reduce your mic body temperature (nothing can), but it can reduce hot spots and temperature gradients.

JD "cannae change the laws o'physics" B.

 

[speakercoil]

so I will go with option A.

Oh and I found that blog a few days ago, but it says it isn't written by Andreas... and there is no info on how to order!?!?!?!

-Grant

 

[Skylar]

JD "cannae change the laws o'physics" B.

I'm really enjoying your nicknames lately.

 

[ioaudio]

pm me, i will forward you to andreas.

-max

 

[rodabod]

I think this may be of interest for some of you:

http://www.compasspointstudios.com/lucas/CS-4/page2/CS-4_Microphone.html

 

[speakercoil]

Wow that is amazing... I wish they mentioned what tube, or showed a picture... of they didn't, but who can blame them after putting so much work into it. However I am sure that info will leak on the web eventually. I mean it's kind of hard to hide something when the name is stamped on the damn thing. I bet those custom Thiersch capsules are devine though. I think I still want to go the VF-14 route, but I would love to know what tube that is so maybe I can make a custom design around it one day!

Oliver is amazingly helpful and I really hope that mic does well. If I had the cash to pony up for one I would, but I have way too many projects in the pipeline right now. However I did just finish my first mic project which was modding an Apex 460 (really a PPA, but yeah same thing)... I put a lot of time and care into it. I did more than just the capsule, tube, and transformer. I refinished it and removed the inner grille. I was hesitant about the grille due to dust possibly getting on the capsule, however after analyzing how sloppy the inner mesh was put in I had to remove it. There were lumps and mounds where the mesh was soldered together sloppily. It obviously would have a substantial effect on the sound so I removed it. Pain in the ***, but it's gone.

The mic looks and sounds fantastic, and I documented the whole thing. I can't wait to finish my video for it and get it up! I really want to start a youtube DIY Audio series for people who wish to do mods and builds.

-Grant