D-EF47 Tribute To Oliver Archut U47 Build Thread.

[neowalla]

I just finished my DEF47 tonight and wow, it sounds nice. The capsule is a 3U M7, tube is a "WF" EF800, and the trans is a Beezneez BV08. The body is an Art T4. I'll attach a few shots of the innards. I still need to photograph the finished product and the power supply closed up, and record something with it to post a sound sample, but just a preliminary hand-held test sounded very nice. I may have to build another with one of Solioqueen's 47's.
Thank you to all here in this thread who asked a lot of the same questions I had while building it, and those who took the time to answer. Thank you to Dan for making this project, and of course to the spirit of Oliver who designed it.

 

[terry setter]

When you follow that capsule with a decent circuit (which you did) you get a great mic.

 

[Greenie]

I just finished my DEF47 tonight and wow, it sounds nice. The capsule is a 3U M7, tube is a "WF" EF800, and the trans is a Beezneez BV08. The body is an Art T4. I'll attach a few shots of the innards. I still need to photograph the finished product and the power supply closed up, and record something with it to post a sound sample, but just a preliminary hand-held test sounded very nice. I may have to build another with one of Solioqueen's 47's.
Thank you to all here in this thread who asked a lot of the same questions I had while building it, and those who took the time to answer. Thank you to Dan for making this project, and of course to the spirit of Oliver who designed it.

HI. I see you have what seem to be 3 transformer? What is the third?

 

[rock soderstrom]

HI. I see you have what seem to be 3 transformer? What is the third?

B+ choke?

 

[Greenie]

B+ choke?

Ok. Thanks.

 

[paolomunarini]

Hi! I'm troubleshooting a build here.
I have a strong crackling coming from the mic. I tried swapping tubes but with no result.
Grounding is ok. Every point that should be grounded "Beeps" with respect to the PSU chassis.

Voltages (H+ and B+) are in spec.

I have no clues here...

 

[rock soderstrom]

Hi! I'm troubleshooting a build here.
I have a strong crackling coming from the mic. I tried swapping tubes but with no result.
Grounding is ok. Every point that should be grounded "Beeps" with respect to the PSU chassis.

Voltages (H+ and B+) are in spec.

I have no clues here...

Crackling noises can indicate, in my humble experience, contaminations in the high impedance area around the tube. Clean everything very well with 99.5% isopropanol.

If that doesn't help, try replacing the capsule.

 

[paolomunarini]

Crackling noises can indicate, in my humble experience, contaminations in the high impedance area around the tube. Clean everything very well with 99.5% isopropanol.

If that doesn't help, try replacing the capsule.

In order to isolate the issue can I replace temporarily the capsule with some caps?

 

[rock soderstrom]

In order to isolate the issue can I replace temporarily the capsule with some caps?

Yes, you can do that. Small cap in 70pF range could replace the capsule

 

[paolomunarini]

Yes, you can do that. Small cap in 70pF range could replace the capsule

I replaced the two sides of the capsule with two 50pf 500V silver mica in series.

The crackling is gone.

Is it the capsule for sure?

 

[Андрій Чубака]

If gone. Then you need try other capsule. 99,5% problem is there. Other 0,5% you can do something wrong.

 

[trail]

I just finished my DEF47 tonight and wow, it sounds nice. The capsule is a 3U M7, tube is a "WF" EF800, and the trans is a Beezneez BV08. The body is an Art T4. I'll attach a few shots of the innards. I still need to photograph the finished product and the power supply closed up, and record something with it to post a sound sample, but just a preliminary hand-held test sounded very nice. I may have to build another with one of Solioqueen's 47's.
Thank you to all here in this thread who asked a lot of the same questions I had while building it, and those who took the time to answer. Thank you to Dan for making this project, and of course to the spirit of Oliver who designed it.

Ooh awesome, those are almost the same parts I had in my head to try this project out, do you have any audio samples that I can listen to?

 

[neowalla]

Ooh awesome, those are almost the same parts I had in my head to try this project out, do you have any audio samples that I can listen to?

Not yet. It has a hum I need to hunt down yet. I have been digging through the thread and tried everything I have come across for the power supply. My next step is to sand off some of the anodizing on the mic body. If that doesn't do it I will put the guts into another U47 body I have that isn't anodized. The body I'm using is an ART T4 that is black.
If I can get the hum out, it would probably be my "steady" micfriend as it has a nice sound otherwise.

 

[egroys]

Friends!

I'm hoping someone can point me in the right direction--periodically and seemingly at random, my mic signal drops by ~20dB and sounds very thin.
It's currently a room mic so it's far from being bumped.

I found that turning the pattern switch to omni and back to cardioid 'fixes' it. I'm currently not using omni enough to verify the inverse.
I ensured all of the connections in the PSU were solid and nothing else seemed out of the ordinary.

I also can't seem to reproduce this intentionally.

Any ideas on what I can check?

 

[duantro]

Friends!

I'm hoping someone can point me in the right direction--periodically and seemingly at random, my mic signal drops by ~20dB and sounds very thin.
It's currently a room mic so it's far from being bumped.

I found that turning the pattern switch to omni and back to cardioid 'fixes' it. I'm currently not using omni enough to verify the inverse.
I ensured all of the connections in the PSU were solid and nothing else seemed out of the ordinary.

I also can't seem to reproduce this intentionally.

Any ideas on what I can check?

I’d check the hi z connections and make sure flux has been removed with cleaner. Are the voltages correct on the pattern selector? Could be the transformer wiring, or jack has a bad connection.

 

[Spencerleehorton]

Yeah sounds like a cold solder joint around the switch area, reflow and clean connections.

 

[Delta Sigma]

Friends!

I'm hoping someone can point me in the right direction--periodically and seemingly at random, my mic signal drops by ~20dB and sounds very thin.
It's currently a room mic so it's far from being bumped.

I found that turning the pattern switch to omni and back to cardioid 'fixes' it. I'm currently not using omni enough to verify the inverse.
I ensured all of the connections in the PSU were solid and nothing else seemed out of the ordinary.

I also can't seem to reproduce this intentionally.

Any ideas on what I can check?

Is there noise along with it? Like wind or rustling noise?

Has it been used as a vocal mic without a pop filter?

You could try putting the it in a sealed plastic bag with a large desiccant for a week. I did this with a friend's U67 in a sealed vacuum seal bag (WITHOUT VACUUMING) with a 40 gram desiccant and it fixed similar symptoms caused by moisture.

 

[egroys]

Is there noise along with it? Like wind or rustling noise?

Has it been used as a vocal mic without a pop filter?

You could try putting the it in a sealed plastic bag with a large desiccant for a week. I did this with a friend's U67 in a sealed vacuum seal bag (WITHOUT VACUUMING) with a 40 gram desiccant and it fixed similar symptoms caused by moisture.

There is no noise and I always use a pop filter for close vocals.

I added and reflowed the pattern switch pads on the PCB...we'll see if it reemerges!

 

[Silas]

Hi Guys,

I wondered if anyone might have a clue as to what’s going on here:

I get rustling and loud hiss/crackle when moving my tube mic cable. I’ve rewired with fresh cable and it’s not fixed it. Also tried only grounding the cable shield at PSU end (mic shield still connected). I wonder is it potentially a build up of capacitance somewhere in the cable?

The other mic I’ve built has an identical cable but with of course different parts. No issue at all on either mics with this cable - same issue on both with the current cable.

I had thought perhaps the cable was damaged but with the above fault finding am now wondering if it’s the connectors?

Many thanks in advance

Silas

 

[Silas]

DEF47 mics here btw