D-EF47 Tribute To Oliver Archut U47 Build Thread.

Help Support GroupDIY:

McIrish

Well-known member
Joined
Jun 15, 2016
Messages
71
If it isn't the tube or something in the supply, my guess is the capsule too. I have a Wunder CM7GS M7 and the capsule did that same sound. I baby my mics so I couldn't understand why it would go bad. At the time, I wasn't as experienced with fixing mics and I sent it back to Wunder for repair. Took them weeks to figure out it was the capsule and then even longer to get it replaced. It was gone for months. I believe it's a Thiersch red m7 type, which should be good. Anyway, I've had a K7 in a mic for years with no issues but something must have gone wrong on yours. If you have another capsule, even a cheap one, swap it and test. Is it possible the polarizing voltage is too high?
BTW, I may actually like the K7 more than the Thiersch. Wish I had a couple extra K7's to swap into other mics.
 

wave

Well-known member
Joined
Mar 29, 2005
Messages
609
Location
Nashville
My bet is that the leads are either loose at the center screws or the backplate connection. I would triple check all those connections and make sure everything is super clean. If you have an electrometer measure the bias voltages
 

Minyshka

New member
Joined
Feb 24, 2020
Messages
2
Please tell me if I can use the 0.5W resistors (R1, R2, R3, R4, R5, R6) instead of the 0.25W that are listed in the specification on vintagemicrophonepcbkit.com?

And how to wiring the pattern switch? COM should be connected to OM in Omni, and to CRD in cardioid? Did I understand correctly
 

wave

Well-known member
Joined
Mar 29, 2005
Messages
609
Location
Nashville
Please tell me if I can use the 0.5W resistors (R1, R2, R3, R4, R5, R6) instead of the 0.25W that are listed in the specification on vintagemicrophonepcbkit.com?

And how to wiring the pattern switch? COM should be connected to OM in Omni, and to CRD in cardioid? Did I understand correctly
Yes you can use half watt resistors.
For the switch you seem to have it right. You take COM to the pole of the switch and use one position for Omni and one position for Cardioid.
 

doqmemory

Well-known member
Joined
May 9, 2020
Messages
71
Mic body for this project are now available here




Does anyone know what the screw sizes are for the three screws holding the capsule basket to the body of the Alctron MK47? These are stripping out, but I do not seem to have any other sizes that fit. I may have to end up re-tapping the holes to fit other screws that I have.
 

innercityman

Well-known member
Joined
May 12, 2016
Messages
279
Location
France
Hi there !

Did someone ever use this transformer from Beesneez ? Can't find any pinout, colour codes or informations except the ones on their site. I'd like to compare it with my AMI BV-08R.

Any help on how to wire it would be appreciated.
B-BV08L.png
 

mhelin

Well-known member
Joined
Mar 12, 2005
Messages
548
Location
Tampere, Finland
There are four coils on the left and the right. On the left side probably red and pink are the primary, and the yellow and gray the secondary (may be the other way, too). Just measure the DC resistances so you will know. Lower resistance side is the secondary, and higher the primary. The right side is similar. Now because there are kind of two transformers working in humbucking configuration you have to figure out in which phase to connect the two primaries and secondaries in series (you will hear when they are out of phase). See this post:


So you should actually connect the right and the left side coils "out of phase" (electrically) meaning pink to blue and both grays together, so red and blue will be the inputs and the yellow wires are the outputs (please correct me anyone if you know better).
 
Last edited:

Minyshka

New member
Joined
Feb 24, 2020
Messages
2
Can anyone suggest where to connect pin three of the seven-pin xlr in the microphone?
And where does the shield of the cable go, to pin three of the seven-pin xlr or to the connector housing?
Thank you.
 

innercityman

Well-known member
Joined
May 12, 2016
Messages
279
Location
France
Thanks mhelin !

There are four coils on the left and the right. On the left side probably red and pink are the primary, and the yellow and gray the secondary (may be the other way, too). Just measure the DC resistances so you will know. Lower resistance side is the secondary, and higher the primary. The right side is similar. Now because there are kind of two transformers working in humbucking configuration you have to figure out in which phase to connect the two primaries and secondaries in series (you will hear when they are out of phase)
The only configuration I've been able to get measurements is this one... From left to right... i've measued between red and yellow 403 Ohms, pink and gray 8.7 Ohms, black and yellow 405 Ohms, blue and gray 8,7 Ohms. Could someone interpret these results and help me to figure out on how to wire it... ?

If I follow this schematic, I should bridge yellow wires together and gray wires together. Please tell me if I'm wrong or right.
 

Attachments

  • 39441214940_e7e5d851a7_o.jpg
    39441214940_e7e5d851a7_o.jpg
    177.4 KB · Views: 3
Last edited:

mhelin

Well-known member
Joined
Mar 12, 2005
Messages
548
Location
Tampere, Finland
Yes I think so, then your red (+) and black (-) will be the inputs (in 6.5:1 config) and purple (+) and blue (-) the outputs. Do you have any signal generator (output from audio interface) and DMM (or just use an audio interface input) to measure that the signal will attenuate in 6.5:1 relation?
 

innercityman

Well-known member
Joined
May 12, 2016
Messages
279
Location
France
Yes I think so, then your red (+) and black (-) will be the inputs (in 6.5:1 config) and purple (+) and blue (-) the outputs. Do you have any signal generator (output from audio interface) and DMM (or just use an audio interface input) to measure that the signal will attenuate in 6.5:1 relation?

Yes, I'll try that, thanks for your help !
 

Latest posts

Top