MK47 PCB tube mic kit - build thread

[ioaudio]

I think it's ok - i probably have seen a build with it? Not quite sure atm, better check the dimensions.

 

[Winetree]

Tried the 1950's  Miniwatt gold pin "D " getters.
Didn't like them.

 

[MicDaddy]

Hi guys, for anyone who has used the Binder 691 series connectors for this or other builds I have a question.

On Binder site, these connectors are noted as  "non-shielded"  http://www.binder-usa.com/psearch#q=product_series%3D691  What does this mean?  I see no lug to the shell to tie a shield, what am I not understanding here.  With an XLR 3,5 or 7 I'd tie the pin1 or shield to the shell of the connector. 

I'm asking how to tie shields to the connectors?  I plan to use Gotham GAC-7 and Binders on both ends with a Binder female at the PSU. 

*edit  I'm currently digging through the thread and have seen a few others pose this same question.  I'm thinking of adding a solder lug eyelet to the screw for mounting the binder into the PSU chassis and then tie the shield here. 

 

[micaddict]

Tried the 1950's  Miniwatt gold pin "D " getters.
Didn't like them.

Were those TS62s, too, or another type?

And what did you not like about them?

 

[tfp]

Hi guys and Andreas,

I finished this beautifull project one month ago and the mic worked great with the standaard Philips Jan 6028 tubes, Thiersch red line and Ami body . The mike sounded great but with a voice-over recording it needed some serious low cut. I decided to change the tubes with two 1957 WE 408a tubes. I also changed the height (higher) of the capsule with 6mm so it is as high as the original U47.

Now the strange part, I tested the mic today and it sounded almost the same(did analyse signals), but below the 90Hz there is about -10dB less bass so the sound is more mid focused.

My question: Is this possible with changing tubes and/or changing the capsule height? Or do I damaged something in the proces? For example last night the wire of the backplate was broken and I kept microphone on for quite a time!

Thanks for answering!

RJ

 

[North]

Some pics of my build

 

[Winetree]

Were those TS62s, too, or another type?

And what did you not like about them?

Yes, only compared them to new JAN 6028s.
They sounded more lo-fi, smaller, different tone, unlike what a U-47 should sound like.
Just my opinion.

 

[tfp]

Hi Max (sorry for Andreas I mixed something completely up),

I finished your beautiful project one month ago and the mic worked great with the standaard Philips Jan 6028 tubes, Thiersch red line and Ami body . The mike sounded great but with a voice-over recording it needed some serious low cut. I decided to change the tubes with two 1957 WE 408a tubes. I also changed the height (higher) of the capsule with 6mm so it is as high as the original U47.

Now the strange part, I tested the mic today and it sounded almost the same(did analyse signals), but below the 90Hz there is about -10dB less bass so the sound is more mid focused.

My question: Is this possible with changing tubes and/or changing the capsule height? Or do I damaged something in the proces? For example last night the wire of the backplate was broken and I kept microphone on for quite a time!

Thanks for answering!

RJ

 

[micaddict]

Were those TS62s, too, or another type?

And what did you not like about them?

Yes, only compared them to new JAN 6028s.
They sounded more lo-fi, smaller, different tone, unlike what a U-47 should sound like.
Just my opinion.

Thanks.
And your opinion is much appreciated.

 

[ioaudio]

Hi Max (sorry for Andreas I mixed something completely up),

I finished your beautiful project one month ago and the mic worked great with the standaard Philips Jan 6028 tubes, Thiersch red line and Ami body . The mike sounded great but with a voice-over recording it needed some serious low cut. I decided to change the tubes with two 1957 WE 408a tubes. I also changed the height (higher) of the capsule with 6mm so it is as high as the original U47.

Now the strange part, I tested the mic today and it sounded almost the same(did analyse signals), but below the 90Hz there is about -10dB less bass so the sound is more mid focused.

My question: Is this possible with changing tubes and/or changing the capsule height? Or do I damaged something in the proces? For example last night the wire of the backplate was broken and I kept microphone on for quite a time!

Thanks for answering!

RJ

Hi Rj,

well, first try putting back the old tubes and see if it gets back to normal.
The broken backplate wire should'nt be a problem.

hope that helps
-max

 

[tfp]

Hi Max,

Thanks I was already affraid for that...  The tubes in the mike are difficult to reach because I hung your PCB is in rubberbands. But anyway I am ging to do it because I wanna make sure there is nothing wrong!

All the best!

 

[JW]

Hey folks,

I'm gonna try to mod my MK47 to a MK48 like the schematic adjustments on this page of this thread: http://www.groupdiy.com/index.php?topic=41379.940

Anyway, how high does the voltage rating need to be for those caps? 1000pF, .01uF?

I'm also curious about the voltage requirement for C1 in the original MK47 schematic (which is also a .01uF cap) I'm thinking about putting a little russian PIO in there if the rating is high enough 200V

 

[adrian]

hello!
here are some comparison sample of my first MK47 with a thiersch red line capsule and philips ECG 6028 tubes, (+ Zyance PSU PCB and sommer cable "octave tube" wiring)
all mics are directly plugged into a Fireface800,

the mic doesn't sound bad but I wonder about low end, I was thinking there was more low on a U47 (to sound a bit "darker"..)

on drums (mics were close to each other at approximately 2 meter in front of the drums) (cardioid) :
Original U87 :  https://dl.dropboxusercontent.com/u/20193579/drums%20U87.aif
Original M149 : https://dl.dropboxusercontent.com/u/20193579/drums%20M149.aif
Original CMV563 (with original M7 capsule) : https://dl.dropboxusercontent.com/u/20193579/drums%20CMV563.aif
MK47 : https://dl.dropboxusercontent.com/u/20193579/drums%20MK47.aif

On speach vocal (I had to add some gain digitally because I was far from these mics (approximately 1 or 1,5 meter) (cardioid) :
schoeps M221 : https://dl.dropboxusercontent.com/u/20193579/speach%20M221.aif
Original M149 : https://dl.dropboxusercontent.com/u/20193579/speach%20M149.aif
Original CMV563 (with original M7 capsule) : https://dl.dropboxusercontent.com/u/20193579/speach%20CMV563.aif
MK47 : https://dl.dropboxusercontent.com/u/20193579/speach%20MK47.aif

(here is a ZIP file with audio files if you want download : https://dl.dropboxusercontent.com/u/20193579/MK47%20comparisons.zip )

an other strange thing is polarity,
my MK47 is out of phase but I don't think it's a faulty wiring because when I check with a multimeter  the Audio+ of the mic PCB goes to the PSU XLR out pin 2 ,

so what about the sound? is that the same color as your mics?

 

[wave]

Adrian,
I haven't used our MK47 as a kit mic yet but the vocal test sounds a lot like mine and I'm using a different capsule.
Our DIY FET47 has more low end then our MK47 for sure.

Did you record all the drum tracks at once, i.e. one performance with all the mics live?
If so, how did you position them? Is that you playing the kit?

Dave

 

[adrian]

hello,
yes I put all these mics in front of my drum kit (approximatly 2 meters) and recorded all of them simultaneously,
the mics where 1,5 meter high from the ground,

I have to check my PSU voltage because I adjusted the 105 Volt at home (where I have 242 volts on the electrical network),
but I wonder if the voltage at the studio is more about 230v wich will change the output voltage of the PSU....

(is that possible that the voltage feed to the mic change the low end response?)

and did someone checked the phase of his MK47 between others?

(sorry for my poor english !)

 

[Melodeath00]

an other strange thing is polarity,
my MK47 is out of phase but I don't think it's a faulty wiring because when I check with a multimeter  the Audio+ of the mic PCB goes to the PSU XLR out pin 2 ,

so what about the sound? is that the same color as your mics?

I recently built a U47 (not the MK47), and my polarity was inverted as well. I just switched the audio wires inside of the PSU to fix it. Any reason you don't want to do that?
Thanks for the files by the way. I will listen soon.

Adrian,
I haven't used our MK47 as a kit mic yet but the vocal test sounds a lot like mine and I'm using a different capsule.
Our DIY FET47 has more low end then our MK47 for sure.

Is that expected? I would think a U47 might have more low end than a FET47.

 

[tfp]

Hi Guys,

I changed the tubes in my mk47 back to the philips jan 6028 (from WE408a 1957) and conducted a couple of tests. The test were very confusing. With normal speech the Philips have more lowend energy below 80 hz and sound better than the WE tubes. But when singing louder the WE sound better  to my ears! :-\

When playing some music through my BM6a's and recording this with the mk47, the difference at close distance is none. But when setting up the mike at about a metre from the speakers the WE tubes sound slightly better!!!

So at this moment I do not know which tube to choose!

Another remark: the height of the capsule is also important for the sound. I am using the Ami body (great body and service) and raised the height of the capsule centre from 3,9 cm to 4,5 (original U47 height). The mike now sound a little bit less airy, I think this is due to the capsule sitting behind the ring of the basket (just like the old pensil trick).

All the best!

RJ

 

[Pip]

an other strange thing is polarity,
my MK47 is out of phase but I don't think it's a faulty wiring because when I check with a multimeter  the Audio+ of the mic PCB goes to the PSU XLR out pin 2 ,

so what about the sound? is that the same color as your mics?

I recently built a U47 (not the MK47), and my polarity was inverted as well. I just switched the audio wires inside of the PSU to fix it. Any reason you don't want to do that?
Thanks for the files by the way. I will listen soon.

Adrian,
I haven't used our MK47 as a kit mic yet but the vocal test sounds a lot like mine and I'm using a different capsule.
Our DIY FET47 has more low end then our MK47 for sure.

Is that expected? I would think a U47 might have more low end than a FET47.

Not my experience at all. FET 47 have great low end thats why they make great distant kick drum mics. In a good room of course.

 

[adrian]

I made some other tests,
my PSU output 105v is OK at the studio,

with a shelf EQ to add between 6 and 9 db below 80Hz it just sound incredible,

 

[MicDaddy]

ok, so i didn't build an MK47, but rather adopted one from the blackmarket.

I did however build the psu.  Case is from Collective.  I tried to use Chunger's point to point layout, soon found that it wouldn't fit.  With some creative component placement, and removing the dummy load from the circuit, I was able to get it together.

The mic sounds very stellar, I'm extremely happy with it.

I also built a poctop fet47 and it stands up well to the MK47, with a touch more low end and maybe a tad less 'magic'. (whatever that means..)

I thought I'd add my own mic-badge to the Equanox body, but felt bad removing the builder's signature mic-badge, so I leave it as I got it. 

The only mod I performed on the microphone, was to move the B- to pin 7 of the binder, to allow that to make contact before any of the other pins. 

Binder connectors are expensive, but I feel worth the extra money, they are robust and just have a great look and feel, what I expect from a high end microphone.  The cable is GAC-7 Tube from Chunger... (the damn cable was ~$100 to build)

Here's how I implemented the dummy load: