OFFICIAL ioaudio MK67 build and support thread

[mica]

Thanks.. tried with a second 15K i parallel, but it will only settle around 207V turned all the way on the 25K pot.. I goes between 205-207 up and down without me touching the pot at max..

/M

 

[ioaudio]

ok - this fluctuation is normal - try bridging the R5 resistor with a piece of wire.

 

[mica]

Bingo! That did it. Thanks.. Stable at 210V..

 

[mica]

Aaaaand im done..

And the family:

 

[patterson]

Just finished the MK67 with a Telefunken tube and Beesneez K6.  It powered up well on first try.  I had a small amount of fluttery noise at first, but after an hour or two of burn in it settled down and is now completely quiet.  The sound is superb.  Thanks to Chunger, Max and everyone else.  This is a great project

 

[ioaudio]

Thanks Patterson!

 

[snork7]

Hi All
Love this site and have built a couple of Dany/Chunger 87's.
I bought the kit for the MK67 from Chunger and just finished the build.  I was able to get the PSU to trim to 210 using a 250K pot across the B+.  But when I plugged the mic in, I can't get the voltage past 80 V even if I jump R5.  I get 7.69 Mohms between pin 7 and 2 on the mic.  Does that sound correct?  Newbie, so not sure what else I can check.  Any guidance appreciated.  Have the Peluso 67 capsule.
Thanks

 

[ioaudio]

Check all connections, including the cable, connectors etc. I assume you removed the test-pot when you connected the mic?

-Max

 

[snork7]

Thanks for the response Max.  Yep, the pot was removed. 
I was hoping not to, but it is the obvious step:  I'll disassemble the mic and double check everything.  How about the 7.69 Megohm measurement between pins 2 and 7... is that reasonable?
Thanks again.
-Charlie

 

[ioaudio]

Oh, sorry i missed that - pin2 (heater) to pin7 (ground) should measure 5 to 6 Ohm, seems like you replaced pin1 (B+) and pin2 (heater)

-Max

 

[snork7]

Ahh.... I'll check the mic input wiring.  I'm usually pretty meticulous, but I do enjoy a Crown Royal or two while working on them, so anything is possible.
Thanks so much!
-Charlie

 

[Category 5]

Ahh.... I'll check the mic input wiring.  I'm usually pretty meticulous, but I do enjoy a Crown Royal or two while working on them, so anything is possible.
Thanks so much!
-Charlie

Whoah!  Crown is great for celebrating but wait until the high voltage sources are all buttoned up!  Good luck w the troubleshooting.  It's the worst part of diy. 

 

[snork7]

Thanks Cat5.  No worries... It's insulation - from pain.


JK!
-Charlie

 

[snork7]

Max - you called it.  I had the pin 1 and 2 reversed in the mic connector.  Was able to trim it to 210 V, but damaged the PSU PCB after repeated attempts trying to put in the perfect R5 under the bad wiring.  (R5 ended up being 22K in case anyone was interested).  Will fix it tonight and then try out the mic.
One question:  When I had it trimmed, the voltage at the mic was about 10 V less than at the PSU output.  Probably line loss, but wondering if when I get the PSU fixed, I should trim it so that it is 210 V at the mic versus the output of the PSU.  Or does that even matter?
Thanks again Max and everyone.
-Charlie

 

[ioaudio]

That was propably just a measuring error, at 1mA there shouldn't be considerable loss.

 

[snork7]

Thanks Max.  So now the PSU is putting out mV!  Tonight I am going through all of the connections with a fine tooth comb.  I just might have to switch from Crown to Chamomille and start ringing some chimes LOL!
-Charlie

 

[michaelanswerer]

Hi folks- i'm wanting to test my build but all i've got for test-capsules is single diaphragms from some beater condensers.  Is it possible so long as the mic is in cardioid?  Is there any risk in not linking up that missing diaphragm's circuit?  Should i just risk my hk67?  Many thanks..

 

[Pip]

So finished the build and all powered up fine. Mic sounds great I think? What I mean is I have never really used a U67 before so have no comparison. My build is Beesneez K6 capsule and Poctop PSU Board.

Here is the one thing I am not sure of. When I plug the mic into my preamp with the power off I get a buzz, nothing new for a tube mic, low but its there. then I power the mic on and all seems fine.  The ouput is a little low but nothing crazy. I am basing this on other mics in my possession and where the gain of my pre is. But when I kick in the pad the volume drops, a lot if you ask me.  The mic still works fine in all patterns etc...  But the buzz is now louder or I should say less masked. What might be wrong?

I have triple checked my grounding while listening to the mic all is as quiet as I can get it.  I have quadruple checked my wiring.  All my voltages are spot on and I have tried multiple tubes. Again the mic sounds fine but I really think I might have a problem. Is it possible C10 is hosed somehow?

 

[poctop]

So finished the build and all powered up fine. Mic sounds great I think? What I mean is I have never really used a U67 before so have no comparison. My build is Beezkneez K6 capsule and Poctop PSU Board.

Here is the one thing I am not sure of. When I plug the mic into my preamp with the power off I get a buzz, nothing new for a tube mic, low but its there. then I power the mic on and all seems fine.  The ouput is a little low but nothing crazy. I am basing this on other mics in my possession and where the gain of my pre is. But when I kick in the pad the volume drops, a lot if you ask me.  The mic still works fine in all patterns etc...  But the buzz is now louder or I should say less masked. What might be wrong.

I have triple checked my grounding while listening to the mic all is as quiet as I can get it.  I have quadruple checked my wiring.  All my voltages are spot on and I have tried multiple tubes. Again the mic sounds fine but I really think I might have a problem. Is it possible C10 is hosed somehow?

Hi Pip , For the psu parts i am glad everything is right on , i have implemented a SHLF jumper to gnd lift the cable shield
you can try to remove it as it is on by definition ,
Best,
Dan,

 

[Pip]

So finished the build and all powered up fine. Mic sounds great I think? What I mean is I have never really used a U67 before so have no comparison. My build is Beezkneez K6 capsule and Poctop PSU Board.

Here is the one thing I am not sure of. When I plug the mic into my preamp with the power off I get a buzz, nothing new for a tube mic, low but its there. then I power the mic on and all seems fine.  The ouput is a little low but nothing crazy. I am basing this on other mics in my possession and where the gain of my pre is. But when I kick in the pad the volume drops, a lot if you ask me.  The mic still works fine in all patterns etc...  But the buzz is now louder or I should say less masked. What might be wrong.

I have triple checked my grounding while listening to the mic all is as quiet as I can get it.  I have quadruple checked my wiring.  All my voltages are spot on and I have tried multiple tubes. Again the mic sounds fine but I really think I might have a problem. Is it possible C10 is hosed somehow?

Hi Pip , For the psu parts i am glad everything is right on , i have implemented a SHLF jumper to gnd lift the cable shield
you can try to remove it as it is on by definition ,
Best,
Dan,

Thanks but I will try it but I don't think thats  it. Alas I see a long trouble shooting session in my future. All components seem to check out in circuit next I will start to deconstruct and check all solder joints etc...