newbie builds ioaudio MK47 microphone

What about a lil thingy like this to feed off the mains and then the meter. Just around$3. Any noise issues? I guess one should shield a thing like that in the psu, as well as put it in the back far from your audio things.

http://www.ebay.com/itm/5V-700mA-AC-DC-Power-Supply-Buck-Converter-Step-Down-Module-CA-/361102127670?pt=LH_DefaultDomain_2&hash=item54135d3236

This way one would not depend on the trafo itself to feed the meter separately.

Here the specs:

-Input voltage of AC 85 ~ 265v 50/60 HZ
-Output voltage DC5V?±0.2V?
-Output current 700MA
-Power 3.5w
Use Environment
- Working temperature:-20 ~ 60?
- Relative humidity?40  ~ 90%RH
Technical requirements
- Input voltage range:85~ 265v
- Input current:0.0273A (AC110V)
                0.014A (AC220V)
- Input Inrush Current: 20A
- Output voltage range:4.80~5.2V 0~700mA
                     
- Output power:0 ~4.5 W
- Output efficiency:80%
- Size:3*2*1.8cm

On other thoughts, any word on the voltage reading accuracy? As discussed in the C12 thread, the meter impedance is becoming a parallel load with the mic, thus eating some volts. That was in the case of a DMM. Would be good to relate that to the use of these small digital meters.

Edit: Further research indicated that those meters have a 100K input impedance. Quite different from the 10M DMMs have. However, still this should be interpreted as per what changes would be introduced in the circuit from a constant read.

I found Matadors word on this, from the C12 thread:
"Measuring the polarization voltages is at beast approximate:  the high impedances make measure these with regular DVM's inaccurate.

For example, measuring the polarization voltage right at the PSU "P3" node will cause the meter current to drop across R11 (1 MEG).  A 10MEG meter will induce a 10% voltage error.  A 1MEG meter will cause a 50% error.   So a 10MEG meter will always measure 60V (the cardioid setting) as 54V due to the meter impedance alone.  120V will measure as about 110V.  The bias node "P4" has a similar problem caused by R5, however a 10% error on 1V is only 100mV. 

If you know your meter impedance you can "derate" the reading.

You can't measure anything on the capsule, because the meter current will go across the astronomically high impedances and clobber the results:  think of a 250M / 10M voltage divider:  the series resistance will clobber 97% of the measured voltage."

does anybody know witch capsule + holder fits in the Alctron GT-2B.  ordered the kit from chunger and trying to get the capsule right. i just ordered the stw7.1 since chung said the stw7 didnt fit, but then i read on a post there are different sized holders... do i even need a holder with the stw7.1 since it has the extra bore holes?

Hi,

I've been trying to bump the other case thread in the WM to get some info/ETA on the cases from Dan but to no avail...

Chung, do you know where this stands? Would love to build the PSU with your PCB and Dan's case for my lonely MK U47...

fazeka said:

Hi,

I've been trying to bump the other case thread in the WM to get some info/ETA on the cases from Dan but to no avail...

Chung, do you know where this stands? Would love to build the PSU with your PCB and Dan's case for my lonely MK U47...

Click to expand...

I'm curious to know where this stands as well?

I've spent the last couple days trying to get a list together of all the parts to build a 47, and I'd love some feedback if anyone cares to look it over and tell me if something won't work right. I'm a newbier newbie.

Body: MK47 from http://store.studio939.com/product/mk47-microphone-body-kit

PCB: from http://micandmod.com/en/pcb-u47/101-u47-vintage-microphone-pcb-set.html

BV8: AMI or Peluso

Capsule: studio939 or Peluso or Thiersch, etc.

Tubes: Ebay or wherever

I'm using the BOM from vintagemicrophonepcbkit.com, but I tried to delete everything that was for the PSU. I probably missed some things but that's okay. Here's a link to my project:
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=EF9E82008E

As for the PSU, I've already ordered a case from Dan at Collective Cases. I plan on using Zayance's PCB and BOM, which is why I deleted the parts from the original mouser cart from vintagemicrophonepcbkit.com.

My questions and concerns:

-I didn't order the PCB set from vintagemicrophonepcbkit because I didn't need the PSU pcb, BUT it says something about the Styroflex cap kit. Can't I just use a cap with the same value? Why Styroflex?

-Also, the tube sockets from vintagemicrophonepcbkit. Like...why? $13 shipping for these small parts? Can't I just use a similar 7-pin tube socket?

Here's a link to my PSU project:
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=87e89d395d

uh-oh...

I'd recommend NOT supporting a company like micandmod as they tend to copy their designs from reputable people on this forum, but if you do decide to use their kit, best of luck to you.

Timh said:

I've spent the last couple days trying to get a list together of all the parts to build a 47, and I'd love some feedback if anyone cares to look it over and tell me if something won't work right. I'm a newbier newbie.

Body: MK47 from http://store.studio939.com/product/mk47-microphone-body-kit

PCB: from http://micandmod.com/en/pcb-u47/101-u47-vintage-microphone-pcb-set.html

BV8: AMI or Peluso

Capsule: studio939 or Peluso or Thiersch, etc.

Tubes: Ebay or wherever

I'm using the BOM from vintagemicrophonepcbkit.com, but I tried to delete everything that was for the PSU. I probably missed some things but that's okay. Here's a link to my project:
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=EF9E82008E

As for the PSU, I've already ordered a case from Dan at Collective Cases. I plan on using Zayance's PCB and BOM, which is why I deleted the parts from the original mouser cart from vintagemicrophonepcbkit.com.

My questions and concerns:

-I didn't order the PCB set from vintagemicrophonepcbkit because I didn't need the PSU pcb, BUT it says something about the Styroflex cap kit. Can't I just use a cap with the same value? Why Styroflex?

-Also, the tube sockets from vintagemicrophonepcbkit. Like...why? $13 shipping for these small parts? Can't I just use a similar 7-pin tube socket?

Here's a link to my PSU project:
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=87e89d395d

Click to expand...

I'll swallow my pride and say that I already bought the mk47 pcb off micandmod because I honestly thought it was the same guy that was selling them here. THAT BEING SAID: I bought it just for sh*ts and gigs. It was $25. Oh well. If you guys say that it's worth more to buy the ioaudio kit, then I'll do that. Honestly, I know it's really shallow of me, but I way rather have the long body form of the MK47 rather than the GT-2B short body. I just want to get the right parts from the get go. Ya know?

I could always buy the ioaudio bare bones kit and put it into a MK47 body....my best bet?

EDIT: I just want to say that; Chunger, not only have you answered my emails at 2AM, but you have to be the continuously most hopeful source for dummies like me trying to build shit they know nothing about. I have had a few beers tonight, but let's give it up to Chunger. A true Gentleman.

All kit origins and community drama aside, the main reason someone would pick the Dany Bouchard/Micandmod PCB would be to choose their own transformer.  Ioaudio's mk47 kit is sold only with the transformer included. . . which is likely the most expensive part of the kit besides the capsule.  That being said, max makes a nice sounding transformer for mk47 and it works great. . . but a lot of people prefer the larger, vintage-reproduction-style transformer like he uses in his MK-U47 kit but the cost gap is large between the 2 options.  MK-U47 is a true cost-no-object premium build (and the details show) where mk47 even in the nicer body is a medium-priced option.

Ioaudio's mk47 kit (available as bare-bones kit via studio939 in the US) fits just fine in the Chinese Alctron "mk47" (no relation to ioaudio) body.

Well now I'm confused... the BV for the M47 is not the same BV for the MKU47?

I had ASSumed they were the same, why would one be different?

...can't believe I never noticed..  the BV.08c core on my mk is about the same size a stack you'd expect to find on a BV.12...  is this the same bobbin Max uses for his BV.12?

Why the smaller stack on a BV.08 for a "u47" style microphone?  Surely this has been discussed and I don't mean to be redundant but I've never seen this pointed out before.  Sorry for derailing.

How does the coil geometry differ from the mk47 vs the mku47 BV?

MicDaddy said:

How does the coil geometry differ from the mk47 vs the mku47 BV?

Click to expand...

...I'm no expert on the subject, but if I understand correctly, the BV.08 in the MK-47 has 2 chambers per bobbin (for a total of 4 chambers) and the BV.08 in the MK-U47 has 4 chambers per bobbin (for a total of 8 chambers)...

You will not be disappointed with Max's kit.  It's a fun build and sounds killer.  He also has a full size BV08 with 8 winding chambers that should fit if you use the MK47 Body.

regarding the power supply and the 1k potentiometer - would a 4watt pot be sufficient?

thank you all,
andi

I'm not quite understanding how to wire up the jack on the mic.

B+..........105v.....pin1
B-...........48v pat......pin2?
A+..........audio+.....pin6?
A-............audio-.....pin5?
Then bridge pins 4 and 7?

But what's the P for on the pcb?

This wouldn't be the way to wire the pins on the mic, would it?

Since I never got any responses, I took my best guess on wiring the connecter of the mic and the results were *shocking.* The mic sounded great when testing it, but it kept making little popping noises and when I wiggled the cable at the connector I got a good shock. Yikes.

My wiring went like this
pin 1- B+
pin 2- P
pin 3- n/a
pin 4- jumped to pin 7
pin 5- A-
pin 6- A+
pin 7- pin 4

But that still left me with an open spot at B- on the pcb, so I figured that was a chassis/ground and (this is where you know I have no clue what I'm doing) I just literally soldered it to the mic frame. Oops?

Can anyone point me in the right(er) direction?

Tim, the wiring pin-out can be whatever you want it to be as long as it's consistent on the PSU side. Make sure the two sides match up and you're done: if you need help with verifying this, take a picture of the inside of your PSU and post here.

Afterwards, just make sure your phase is correct by connecting A+ to PIN 2 and A- to PIN 3 of the audio XLR.

Banzai said:

Tim, the wiring pin-out can be whatever you want it to be as long as it's consistent on the PSU side. Make sure the two sides match up and you're done: if you need help with verifying this, take a picture of the inside of your PSU and post here.

Afterwards, just make sure your phase is correct by connecting A+ to PIN 2 and A- to PIN 3 of the audio XLR.

Click to expand...

Yeah, I understood that, and I followed Chunger's diagram of his PtP build. What I'm having trouble with is figuring out and confirming that B- is 0v and P is for 48v pattern on the pcb. I didn't run into a "B-" until this point so I was thrown off.

Using this:

pin 1- B+
pin 2- P
pin 3- n/a
pin 4- jumped to pin 7
pin 5- A-
pin 6- A+
pin 7- pin 4

Run a wire from 'B-' to PIN4 or PIN7, and another wire from 'P' to PIN2. Make sure it matches on the PSU side before powering on the mic, and you're done.

Timh said:

Yeah, I understood that, and I followed Chunger's diagram of his PtP build. What I'm having trouble with is figuring out and confirming that B- is 0v and P is for 48v pattern on the pcb. I didn't run into a "B-" until this point so I was thrown off.

Click to expand...

So I have finished the first of my,  granted empirical, tube tests and here is what I have garnered.

The two best  408a tubes on the market are the Philips Miniwatt TS62/6028/408a and any of the GE branded 408a .

This does not mean that there aren't some problems here. The TS62 sounds awesome, very clean with a bright but not harsh top, but has microphonic issues. There is a ringing sound that is made when you touch the mic.  The GE sounds awesome but to my ear not as good as the TS62, it has a little more noise and the top is mellower. Both sound very musical.

Both of these tubes will cost you more then the JAN Philips or the WE branded tubes. The best news is that so far none of the GE or the TS62 tubes I have burned in or tested suffered from noise artifacts like popping or the like.

My final decision with these two tubes was to use one of each in this build. Yes sir the best of both worlds.

P.S. Does any one have a data sheet for the GE 6028/408a tube by chance.