MK47 PCB tube mic kit - build thread

A 50x1mm (inner dia. 48mm) is the absolute minimum.

Just a little thought. The relay looks a lot like the mercury wetted type, which are supposed to be great, but I keep hearing they need to be mounted vertically to work properly? Its probably fine like that, but could this cause problems, if youd for example use the microphone hanging upside down or other positions..?

Never used one before so me I dont know. Or maybe it is a regular relay and I worry too much!
/Johan

No problems with the mounting position.
The relais used specifies 70g shock operation environment.

Max,

Just finalizing my PSU here.. one quick question.  How close is that 2.3K for the test load to the actual draw?  Is it going to be pretty spot on, or just a ballpark?  2.3K/5W resistors are a little hard to find, so I could settle for 2.2K or so, or put a few in series to make exactly 2.3K.  I'm thinking it's not so terribly important to be exactly dead on there.  Thanks.

  Brian

So still noone knows the sonic differences between the mk7 and the mk47?

Seems myself and another guy who ask get ignored  :-\

Hopefully when more people finish their build we will know.

The sonic difference is that the MK47 is more creamy with a cherry on the top. 

Why not build and compare yourself, then youll really know.

Besides the different circuit, the housing and capsule play important roles.

Sredna said:

The sonic difference is that the MK47 is more creamy with a cherry on the top. 

Why not build and compare yourself, then youll really know.

Besides the different circuit, the housing and capsule play important roles.

Click to expand...

Sure give me 1000 bucks and I'll let you know.

First you complained about getting ignored, I answered you and now you want 1000 bucks from me!  ;D
If I give you 1000 bucks what then?  :

Sorry, dont want to be a smartass but I think its too early to expect a clear answer to
the sonic differences.

Ive built both circuits and tested with the same housing and capsule (sE Electronics Z3300A, Dale M7)
and my impression was that my MK47 has a bit clearer upper end.
But thats just the first impression, no measurements made.
To be able to say some thing usable for others more testing must be done.

Time will tell....

Peace,

Anders

Got and built my 2 kits yesterday up to the point of mounting the long white unit to the lower body.
I haven't got the body or the diaphram yet. Is that the end of the assembly wiring instructions?
Questions. How do you wire up the plug and the diaphram and do the wires that go to the glass tubes just end there? Is this info posted somewhere?

Well, I dont know what You mean with "mounting the long white unit to the lower body"  

If you look at the PCB where the glass tubes are mounted there's some text: "rear", "backplate" and "front"

When you'll get your capsule, you'll connect the front, backplane and rear of the capsule to these
points. Witch part that goes where I wouldn't tell!  ;D

Does any one finished the PSU and have some photos ?

is it possible to make a special thread for the psu or get the complete part list?

why the 680 and 330 ohms resistance are in parallel in place of a 200 ohms resitance ?
ares they in parallel and Why ?

and a least why a test switch ?

ps: i read the 3 threads about MK47 project but i don't undertand 

Click to expand...

nashkato said:

this was answered before , don't remember where now.
also this would best be asked in the lab thread.
the 680/330R are either - or . not both in parallel .
the 2K3 (test switch) resistor is to give a ballpark figure of the voltages , before connecting the mic.

Click to expand...

so what to do ? plug the 680 or the 330 why this option to have 105 Volts ?

about the 2K3 : sorry but what the goal ? to not distroy the mic ? whynot turn off the PSU before connect the MIC ?

neodyms said:

about the 2K3 : sorry but what the goal ? to not distroy the mic ? whynot turn off the PSU before connect the MIC ?

Click to expand...

Yes, and then turn on the PSU and destroy the mic!  

Do this:

* Build the PSU as in the schematic, with both 680 and 330.

* Close the "Test"-switch

* Connect a voltage meter to the out of the PSU

* Do NOT connect the microphone

* Turn the PSU on

* Measure the output voltage, adjust P1 to get 105 Volts

* If the voltage is to high, cut the 330R or 680. If still too high, replace 680 with 1k (or more)

* If too low, bridge the resistors (0 Ohm)

Hope this helps

ok ! perfect !


2K3 is the microphone's equivalent resistance !

there was a small mistakeon the PSU schematic
the diode ref is 1N4007

Drink a few martinis (shaken) and you'll never notice the typo.

Denyle Guitars said:

Drink a few martinis (shaken) and you'll never notice the typo.

Click to expand...

Alcool + HT = not a good match  ;D

6028 tubes
i don't think anybody didn't find those yet , but who knows .
just bought a 10 pieces lot.
that seller offers 100 piece lots  too for 112 euros .
anybody (maybe from the UK ) willing to do some kind of a groupbuy ?
i'd be in for another 30 .

Hmmm,

I bought a load from a guy here in the UK, I'll contact him and see if he'll be up for selling a load in bulk.

neodyms said:

there was a small mistakeon the PSU schematic
the diode ref is 1N4007.....

Click to expand...

And the LED1 is reversed.

thanks for catching the errors - i corrected the schematics, you might need to re-load the page.

-max