Neumann U47FET Clone: D-U47 FET Microphone Project PCB Build thread

[EvLoutonian]

I Love the accent as well, we dont have those arround here

Haha - Kiwi accent?
I wasn't sure if it's "bonza" Ozzie accent or "minty" Kiwi.    -Maybe different depending on which capsule?    ...harr harr

 

[Bassniac]

I built one Mic with an RK7 capsule and one with the generic K47 -Beesneez capsule. Both sound just fine for the money. The one with the K47 was a budget project for a friend. My own with the RK7 will be mainly used on Bassdrumd and Speaker Cabs so i didnt see the point putting in a more expensive capsule. Cant go wrong with both of them.

Did anyone check the Advanced Audio capsules?

Cheers.

 

[OPR]

Did anyone check the Advanced Audio capsules?

I'm 99.9 %sure the RK7 And AA capsule are the same thing.

 

[Andydrum82]

Hey Just finished mine. It sounds great. I used the Beesneez AK47 capulse

 

[Andydrum82]

And another picture

 

[mgronroos]

Hi Guys!

I'm reporting back to HQ here with my finished D-U47fet build!
It has a Cinemag CM-13101 and for the moment an RK-47 capsule.

I must say that I am very impressed with this mic!
It has authority, detail and presence. Basically a really good mic.

It is absolutely not dark, probably due to the RK47, and still handles sibilance very well.
It gives the detail of the TLM 103, without being harsh or thin, and with much more authority and punch. I really like it.

My plan was to change the capsule to a Thiersch or original Neumann once it was operational, but now I'm not sure anymore..
I think the RK47 performs really well in this config, and I can imagine it will sound very good on acoustic guitar.
It will probably work great as vocal mic too in many situations. 

So the new plan now is to build another one with a Neumann capsule and see if the difference is worth the money.

A big shout out to Poctop for making this wonderful kit, and to Chunger for making the GT-2B bodies available to us!

Best regards,
Michael

 

[mgronroos]

Another pic of the D-U47fet with its clothes on, hard posing on the console.

Hmm...should I powder coat it..?
Maybe matte black as the cool looking one MicDaddy did?  8)

//Michael

 

[poctop]

Another pic of the D-U47fet with its clothes on, hard posing on the console.

Hmm...should I powder coat it..?
Maybe matte black as the cool looking one MicDaddy did?  8)

//Michael

,
Best,
Dan,

 

[taliska]

Hey all,

Just thought I'd post and chime in on my findings after finishing off my fet47. I used a cinemag 13101 and RK47 in my build.

Good points: straight forward build, t.bone body is solid.

Bad points: rk47 has got horrible mids. On voice will only be useful if keeping to a lower register, or wanting something approaching a telephone style effect. I'm going to try it on acoustic guitar as a last chance, but in all likeliness I'll be putting the stock capsule back in tomorrow.

<edit> Take the next bit with a pinch of salt, I may have been a little harsh... (I've kept it in there as it was my actual initial reaction) </edit>

To sum up, the 32mm capsule that came with the t.bone sounds more balanced and takes eq better than the RK47. Of course, perhaps that's what a 47 is supposed to sound like, but I highly doubt it. Seriously, I'm usually pretty reserved when it comes to product criticism, but do yourself a favour and choose something else...anything else...

Cheers,

Kaz

 

[mgronroos]

Hey Taliska,

I understand your frustration in not liking your mic!  :-[

However, what you describe does not sound like my build at all, and there are several others here who have liked their U47fet builds.
I have compared it to several other good mics I have (Neumann, Manley and my C12, M251 builds etc.), and I think I would have noticed if it would have "horrible mids".

Maybe you got a bad RK-47 capsule? Or perhaps the wrong value in a component? Maybe something got overheated? Contamination? Ground issue?
These are just suggestions that you might go over the circuit again and double check for errors before you discard this (in my opinion) wonderful mic!

I am actually so fond of it that I am building another one right now, so I strongly suggest that you give it another try.. 

BTW: Did you make the self bias (I did) or the a bit more tricky one?
Let us know what you find!

Best,
Michael

 

[taliska]

Hey Taliska,

I understand your frustration in not liking your mic!  :-[

However, what you describe does not sound like my build at all, and there are several others here who have liked their U47fet builds.
I have compared it to several other good mics I have (Neumann, Manley and my C12, M251 builds etc.), and I think I would have noticed if it would have "horrible mids".

Maybe you got a bad RK-47 capsule? Or perhaps the wrong value in a component? Maybe something got overheated? Contamination? Ground issue?
These are just suggestions that you might go over the circuit again and double check for errors before you discard this (in my opinion) wonderful mic!

I am actually so fond of it that I am building another one right now, so I strongly suggest that you give it another try.. 

BTW: Did you make the self bias (I did) or the a bit more tricky one?
Let us know what you find!

Best,
Michael

Hi Michael,

Thanks for the support!

I think it probably comes down to expectations vs personal preference quite a bit. I'm not saying it's completely unusable, but just falls outside what I would call useful based on the way I would like to work which is as follows (I'm a hobbyist so my techniques are a work in progress):

- Try to get the source sounding roughly correct on the way in (we're not talking about nailing it, just ballpark, generally with a max of a couple of tweaked eq bands on the way in).
- Once ITB, "nudge" the sound in the right direction with a little more eq to make it work in the context of the arrangement.
- The idea is basically sound refinement by a few minor tweaks, rather than taking big leaps.

Now I have nothing against "coloured" mics, but super coloured mics are almost always going to fall down on that first step. I'm probably always going to choose something else if the frequency response is too biased, which is where I'm at with the RK47.

I don't have a huge mic collection, but I'm trying to cover the bases slowly. All my points of reference are first-hand store bought specimens. I've got a K2, C214, RE20, and a SM58 to compare it to. I like to experiment with various styles, and I've got a selection of (cover) tracks that I've set up projects for in Logic that I try all those mics on for the sake of comparison and they (my other mics) all basically work without having to try too hard (lost kitten-metric, since i fell for you-nina simone, walkaways-counting crows, wicked game-chris isaac). I can honestly say that the K2/C214/RE20 are all awesome and are all equally likely to be chosen as the best fit for a particular song even though they're quite different sounding (K2 I would say is dark-ish, C214 is crisp, RE20 is somewhere in the middle plus has that whole different sound due to how dynamics handle transients).

I also did my first power up with the stock capsule and the sound was actually quite usable apart from the slight raspiness (I'm referring to sound quality here, not frequency response) at the top end which I expect to hear with cheap capsules.

Today I've tried the RK47 on acoustic guitar and the problem I have with it is this: I can actually make it sound quite nice once I'm ITB...where it fails is just at a common sense level. If I'm having to try too hard to make it sound good, then it's probably not a good choice. Again, I managed to get it sounding pretty nice, but I don't expect to have to be so surgical with my eq for a mic that's capturing ordinary sources in ordinary situations.

Oh and yeah, I suppose I should elaborate on horrible mids. That's what I thought I was hearing, but after more investigation today, I'd say it's got more to do with some pretty strong roll-off from 5khz upwards. In fact, what I'm hearing is pretty much exactly the graph they have on their site. I've attached it for reference. The rk47 might work better in a circuit that exaggerates the high frequencies, but I don't feel that the d-47 is that kind of circuit (just because I've never read that complaint in this thread).

At this point I'm pretty confident in my building abilities and the reasonable response from the stock capsule makes me think that things are working as they should. Check my post history for context, but I've been getting my hands fairly dirty for a while now, and while I'm lacking a bit in terms of the theoretical aspects of being a solder monkey, I don't think I've made a mistake in the build, especially as things tally with the mparts graph.

Anyway, I'm glad that you're getting on with your RK47 ok. Apologies if I came off a little bit harsh in my previous post...I'm not trying to get anyone in trouble, but I also can't see other people finding this capsule particularly usable in this circuit and I wanted to provide another viewpoint to balance out your previous enthusiastic post (it was actually your post that motivated me to try it out...before that I was going to avoid it as that guy posted samples compared with a dale m7, which had put me off getting it).

To sum up, the RK47 didn't sound like I expected it to, but it's entirely my own fault. It matches the graph they publish, but I just didn't think it would be that extreme. As always, this is just my opinion and other people should feel free to make up their own minds!

Cheers,

Kaz

P.S. Here's a link to some screenshots of eq settings in logic that I had to use to push the raw recordings where I wanted them. For these I didn't use any eq on the way in, as the rk47's freq response was something of a mystery at the time. For anyone not familiar with the UI, for each track (vocal, guitar) I've included two images (pre-eq-curve, post-eq-curve). The eq settings are the same between pre and post images, but different between vocal and guitar images for obvious reasons. It's the frequency distributions at the bottom of the images that you should compare. The pre and post screenshots weren't taken at corresponding moments in time, so shouldn't be compared precisely, but rather just used to examine the trends.

https://www.dropbox.com/sh/9878lr9aa22tfvy/AADBsy8c-hhuhHhLcQjzhlN4a?dl=0

 

[mgronroos]

Thx for your elaborate response, I think I understand where you come from a bit better now! 

Your reference mics are what one could call "modern sounding" in that sense that they are quite open in the higher frequencies.
The U47fet is more of a vintage sounding mic, and the K-47 capsule is part of that. Ironically, the RK-47 is too much on the "bright" side for some..  :-\

If you prefer modern mics, you will find most vintage mics "dull".
People who prefer vintage mics will find modern mics "over bright".

So I guess it is just up to what you are used to, what you like and what you expect to hear.

Bear in mind that the DIY scene is quite focused on the vintage "unobtainable" mics, since good quality modern mics, like your AKG, are available cheaper than the cost of building one..
I am sorry if I mislead you to think that the D-U47fet is a bright and modern sounding mic. I was speaking in relative terms, trying to be politically correct.
Some people here would certainly discard "my" U47fet for being too bright (although for what we do, I think it is absolutely perfect!).

Take a look at the Numann TLM103 if you haven't tried it. It can be had quite cheaply second handed.
It is a high quality modern sounding mic. Too bright for some, but no doubt very usable for modern recordings, and sits well in a mix without too much tweaking.
It may work for you! We have used it a lot.

Given that there is nothing wrong with your capsule it may just be that you, as you point out, do not like the darker character of the U47fet.
But I strongly urge you to give it some time. Let the electronics "burn in" for a couple of days (although not a tube mic), record some more and try to get the feel for its relative qualities.
Maybe you will learn to appreciate it for what it does?

I come from the same "modern mic" background as you, so I have made the same journey! 

Best,
Michael

 

[taliska]

Thx for your elaborate response, I think I understand where you come from a bit better now! 

Your reference mics are what one could call "modern sounding" in that sense that they are quite open in the higher frequencies.
The U47fet is more of a vintage sounding mic, and the K-47 capsule is part of that. Ironically, the RK-47 is too much on the "bright" side for some..  :-\

If you prefer modern mics, you will find most vintage mics "dull".
People who prefer vintage mics will find modern mics "over bright".

So I guess it is just up to what you are used to, what you like and what you expect to hear.

Bear in mind that the DIY scene is quite focused on the vintage "unobtainable" mics, since good quality modern mics, like your AKG, are available cheaper than the cost of building one..
I am sorry if I mislead you to think that the D-U47fet is a bright and modern sounding mic. I was speaking in relative terms, trying to be politically correct.
Some people here would certainly discard "my" U47fet for being too bright (although for what we do, I think it is absolutely perfect!).

Take a look at the Numann TLM103 if you haven't tried it. It can be had quite cheaply second handed.
It is a high quality modern sounding mic. Too bright for some, but no doubt very usable for modern recordings, and sits well in a mix without too much tweaking.
It may work for you! We have used it a lot.

Given that there is nothing wrong with your capsule it may just be that you, as you point out, do not like the darker character of the U47fet.
But I strongly urge you to give it some time. Let the electronics "burn in" for a couple of days (although not a tube mic), record some more and try to get the feel for its relative qualities.
Maybe you will learn to appreciate it for what it does?

I come from the same "modern mic" background as you, so I have made the same journey! 

Best,
Michael

Hi Michael,

Thanks for the feedback. Yeah, it's quite possible that it will grow on me, so I'm going to give it some time and see how things go.

Regarding the dull vs bright stuff. Don't worry I wasn't misled by your description in your original post, I acted upon it more because of how happy with the result you were than anything else, but that's totally on me!

I was certainly expecting something a little different than my usual mics frequency response wise and that was part of the reason for building this...(I haven't got much use for microphones that all sound the same!)

I'm feeling a bit better about the sound at the moment, though I'm not really hearing the big bottom end that I was expecting from the 47fet so I'll keep on experimenting and see what happens.

FWIW, those previous eq curves were for a rather bright song, definitely brighter than I'd normally go, so that probably doesn't quite give an accurate representation of my typical target, but that was kind of the point...it was an exercise in trying to make it work in a situation where I just put up my c214 and recorded with minimum tweaking. Perhaps it was a flawed comparison from the start!

I'll stop polluting this thread now, but just to help those that come after me, and also to give you a bit more context on why I think it's lacking in bass, here's a clip (forgive the singing and the room! ):

https://www.dropbox.com/s/f6oyxhzb174pesf/tired%20of%20you-snippet.wav?dl=0

First take is C214, followed by RK47, followed by RE20 (with high pass engaged on mic).

Chain: mic -> SSL9k500 -> EQN(bypassed) -> F76 -> audio interface.

Completely flat, nothing applied apart from the side chain HPF on the F76...which should make the bass more obvious I guess. I think my C214 & RE20 both have more bass than the rk47...

Cheers,

Kaz

 

[poctop]

The Capsule Plays a Major Role in the sounds of this mic it does not have a very complex feedback circuitry for taming the HF as per neumann capsule needs,

Best,
Dan,

 

[kidvybes]

I'll stop polluting this thread now, but just to help those that come after me, and also to give you a bit more context on why I think it's lacking in bass, here's a clip (forgive the singing and the room! ):

https://www.dropbox.com/s/f6oyxhzb174pesf/tired%20of%20you-snippet.wav?dl=0

First take is C214, followed by RK47, followed by RE20 (with high pass engaged on mic).

Chain: mic -> SSL9k500 -> EQN(bypassed) -> F76 -> audio interface.

Completely flat, nothing applied apart from the side chain HPF on the F76...which should make the bass more obvious I guess. I think my C214 & RE20 both have more bass than the rk47...

Cheers,

Kaz

...to best judge a vocal mic on a particular voice, it's sometimes more productive to evaluate with a backing track similar to what will be used in the actual final mix...often, what vocal track sounds best soloed, will not be the best choice when combined with the other backing tracks...in most cases, during the mix process, you'll be rolling of low-end on the vocal track anyway, so mids are more critical...of the 3 mics on that clip you posted, the RK47 sounds fine, IMHO...

...try putting those clips on the intended backing track and listen again...it may change your entire perspective...

 

[taliska]

...to best judge a vocal mic on a particular voice, it's sometimes more productive to evaluate with a backing track similar to what will be used in the actual final mix...often, what vocal track sounds best soloed, will not be the best choice when combined with the other backing tracks...in most cases, during the mix process, you'll be rolling of low-end on the vocal track anyway, so mids are more critical...of the 3 mics on that clip you posted, the RK47 sounds fine, IMHO...

...try putting those clips on the intended backing track and listen again...it may change your entire perspective...

Thanks for the guidance kidvybes. I'm not overly experienced as you can probably tell, so my whole adventure in DIY is part of my commitment to spending more time learning about this stuff and it all definitely helps!

Yeah, those takes were just for test purposes, so nothing to put them up against, but I take your point. I've actually been dealing with that very issue today in a busy mix. I decided to stay up until 3am last night noodling on my acoustic guitar in logic with the RK47 to try and get a feel for it. I'm actually liking it quite a lot for guitar at the moment. Once it's EQ'd it seems quite full and umm "blurry" (in a nice way!) for want of a better word. Obviously can't say how much of that is the capsule, transformer, or circuit...but hey, it's working at least!

Of course as these things do, it all got out of control and my guitar noodling turned in to some kind of attempt at an emo-rock song. It probably started off with around 6 acoustic tracks and nothing else, and ended up with 3 acoustic tracks and a massive drop in to a short distorted rock chorus. I ended up with so many tracks (for me anyway), that it was certainly a task to notch out all the various bands to make it work. It's still a bit busy, but it kind of got there in the end. Anyway, my reason for mentioning that is that in the chorus refrain, I think I decided to use the RE20 as it seemed to be working best for those vocal lines...but because it has to weave in between the main vocal line for the chorus, it did indeed end up being heavily cut at the top and the bottom.

I've attached a screenshot of the eq I ended up using on the RE20, and as you say, clearly the rk47 frequency response wouldn't have been a problem being used in that situation given that amount of cutting I needed to do to make the lines sit right.

The jury's still out a little bit on how well it will work on my vocals, but it's all good fun and I'm totally happy to put the time in to work out it's intricacies...

Cheers,

Kaz

 

[kambo]

Also the test confirms my thoughts, the RK-47 (well the one I bought anyway) is junk.

i dont think its fare to compare 100$ capsule to 325$ capsule...
(unless u paid 300$ for ur rk-47)

i have one with cheap capsule too,
it gives incredible sparkle, when combined with coles 4050 8)

 

[Nyquist]

Plenty fair I think. I have a RK-87 and it sounds very good and extremely close to the original. As I said the RK-47 I bought was junk. Does not mean others out there are. 

 

[kambo]

i think u are not understanding what i am trying to say.
we dont call other peoples products junk here, u may go to grsltz and call it what ever u wanna call...

respect...

if its not sounding good enough for you, its not good enough.... thats fair...
i listened to your recordings... there is nothing sounding junk...
you have no respect at all....

Plenty fair I think. I have a RK-87 and it sounds very good and extremely close to the original. As I said the RK-47 I bought was junk. Does not mean others out there are.

 

[kidvybes]

One has to wonder if all the interest in DIY classic mic clones was the inspiration for Neumann's (Sennheiser) latest decision to re-issue the 47fet...a friend at the AES show said that the Neumann rep said that based on the interest in this 47fet re-issue, they may decide on additional classic re-issues for the future...I suspect the DIY clone market was an, albeit small, but still a partof that decision making process at the Sennheiser headquarters...

http://www.u47fet.neumann.com/content/en/index.html