D-EF47 Tribute To Oliver Archut U47 Build Thread.

[Cgaines]

Don't take offense, but what you're doing is too dangerous. You have no idea what you're doing and you're fiddling around with things that could easily kill you.

That's why no one likes to help you kill yourself, the danger is totally real.

Don't you know anyone you can at least do the power supply with? You could learn and then do it yourself later on. This is really too dangerous, your mains connection knows no mercy and even if you don't get a direct electric shock, you can put yourself and your family/friends in real danger later with a faulty power supply--> fire hazard!

Don't get me wrong, but the questions you're asking clearly show that you're beyond your capabilities and it's just too dangerous for that here. Seek help locally...

No offense taken at all. I wish there was help locally, but this is kind of a dying art so knowledgeable people are few and far between. I’m too involved at this point. I’ll get it figured out, one way or another.

 

[duantro]

It looks like you might have the wrong power transformer wiring. That’s way too high.

 

[Cgaines]

I’ve made good headway on this project after a few snags. Can anyone explain why a higher value dummy load won’t draw as well as a smaller value? A 150k load won’t draw the current properly, but a smaller load, such as a 15k load will.

 

[Hibernate Audio]

Hey everyone - I just finished my build and have found that it is quite a bit brighter, and harsher in the upper midrange than I was hoping. I've never heard a real U47 of course, but just personal preference for my voice I'm hoping to tame that area a bit and get a little bit "softer" of a sound.

I've been doing A/B tests with my Mojave MA-300 (same takes, capsules as close as possible) and finding that while the D-EF47 is significantly lower SNR (which I love), I actually prefer the timbre of the MA-300. With my D-EF47, I find myself immediately doing this kind of thing on my voice:



It's got an aliexpress body, AMI BV8R, no-name EF-80 from tube supply depot, and a Beesneez M7.

I've thought about a couple options:
- leave it as is, it is a solid microphone
- upgrade tube to a NOS telefunken EF800 from miktek
- swap the capsule for an Arienne Audio Flat K47

I know this is all super subjective - but wondering if ya'll have any thoughts about where to go next? Don't really want to put a bunch more money into chasing something it'll never be.

 

[duantro]

Hey everyone - I just finished my build and have found that it is quite a bit brighter, and harsher in the upper midrange than I was hoping. I've never heard a real U47 of course, but just personal preference for my voice I'm hoping to tame that area a bit and get a little bit "softer" of a sound.

I've been doing A/B tests with my Mojave MA-300 (same takes, capsules as close as possible) and finding that while the D-EF47 is significantly lower SNR (which I love), I actually prefer the timbre of the MA-300. With my D-EF47, I find myself immediately doing this kind of thing on my voice:

View attachment 133421

It's got an aliexpress body, AMI BV8R, no-name EF-80 from tube supply depot, and a Beesneez M7.

I've thought about a couple options:
- leave it as is, it is a solid microphone
- upgrade tube to a NOS telefunken EF800 from miktek
- swap the capsule for an Arienne Audio Flat K47

I know this is all super subjective - but wondering if ya'll have any thoughts about where to go next? Don't really want to put a bunch more money into chasing something it'll never be.

View attachment 133422
View attachment 133423

I have my build with an ef14 and a beesneez k7 and it’s not too bright. I’d say try Ari flat 47 and see if that changes it without that lift in the upper frequencies. I have a pair of her flat 47’s in fet 47 mics and they sound really smooth.

 

[Spencerleehorton]

Hey everyone - I just finished my build and have found that it is quite a bit brighter, and harsher in the upper midrange than I was hoping. I've never heard a real U47 of course, but just personal preference for my voice I'm hoping to tame that area a bit and get a little bit "softer" of a sound.

I've been doing A/B tests with my Mojave MA-300 (same takes, capsules as close as possible) and finding that while the D-EF47 is significantly lower SNR (which I love), I actually prefer the timbre of the MA-300. With my D-EF47, I find myself immediately doing this kind of thing on my voice:

View attachment 133421

It's got an aliexpress body, AMI BV8R, no-name EF-80 from tube supply depot, and a Beesneez M7.

I've thought about a couple options:
- leave it as is, it is a solid microphone
- upgrade tube to a NOS telefunken EF800 from miktek
- swap the capsule for an Arienne Audio Flat K47

I know this is all super subjective - but wondering if ya'll have any thoughts about where to go next? Don't really want to put a bunch more money into chasing something it'll never be.

View attachment 133422
View attachment 133423

Hi, I found the same problem with the mid range and changed to EF800 and edge terminated capsules and much less mid honk!!

I would change the tube first then see what you think.

 

[Purplenoise]

Hey everyone - I just finished my build and have found that it is quite a bit brighter, and harsher in the upper midrange than I was hoping. I've never heard a real U47 of course, but just personal preference for my voice I'm hoping to tame that area a bit and get a little bit "softer" of a sound.

I've been doing A/B tests with my Mojave MA-300 (same takes, capsules as close as possible) and finding that while the D-EF47 is significantly lower SNR (which I love), I actually prefer the timbre of the MA-300. With my D-EF47, I find myself immediately doing this kind of thing on my voice:

View attachment 133421

It's got an aliexpress body, AMI BV8R, no-name EF-80 from tube supply depot, and a Beesneez M7.

I've thought about a couple options:
- leave it as is, it is a solid microphone
- upgrade tube to a NOS telefunken EF800 from miktek
- swap the capsule for an Arienne Audio Flat K47

I know this is all super subjective - but wondering if ya'll have any thoughts about where to go next? Don't really want to put a bunch more money into chasing something it'll never be.

View attachment 133422
View attachment 133423

The u47 is a forward mic in the upper mids. It is not suitable for every voice.
Now….a tele ef 800 might give you a smoother sound in the upper mids…I have found that some ef80/ef800 brands tend to emphasise the upper mids more around 4/5k. Another thing is to try a 10:1 transformer ( bv11 style). I believe it works much better with ef800/ ef80 tubes. Also both filter and output caps affect the sound ( c2,c3). Maybe experiment there also…the caps that you have there are good but the mids and highs might feel a little “dry” and hard compared to a nice mp cap.

 

[Hibernate Audio]

Thanks for the ideas ya'll! Totally understand that the U47 isn't exactly a universal mic choice. Still fun to tweak

Just swapped in the Flat K47, much happier with where it's at. I'm going to try the EF800 too - $10 EF80 from tube supply depot might just be the weak link.

That said, I honestly am wondering if something is up with this beesneez capsule - it sounds almost lo-fi compared to the flat k47 and compared to my Mojave MA300. Think "telephone" / laptop mic.

Biggest takeaway from this project so far - the Mojave is a very good mic haha. A little noisy, but very good.

 

[Delta Sigma]

Thanks for the ideas ya'll! Totally understand that the U47 isn't exactly a universal mic choice. Still fun to tweak

Just swapped in the Flat K47, much happier with where it's at. I'm going to try the EF800 too - $10 EF80 from tube supply depot might just be the weak link.

That said, I honestly am wondering if something is up with this beesneez capsule - it sounds almost lo-fi compared to the flat k47 and compared to my Mojave MA300. Think "telephone" / laptop mic.

Biggest takeaway from this project so far - the Mojave is a very good mic haha. A little noisy, but very good.

Can you measure the capsule with an LCR meter? Each diaphragm to backplate. You could contact Ben if you think there is a problem with the capsule. An M7 will sound different than a K47. It might not be for everyone, but I prefer the M7 sound.

I have a Beesneez M7 in an M49 build and it's the best vocal mic I've ever heard. Almost as versatile as my U67 build. I have an Ari Flat 47 in a EF-U47 and it sounds great. Just doesn't sound nearly as good as the M49 for vocals. The only times the EF-U47 wins out (on vocals) is with soft almost spoken vocals or pop sounding vocals.

 

[vitopower]

Does anyone have an vocal clip they'd be willing to share of this circuit with an ef184?

Thank you!

 

[Hibernate Audio]

Got some measurements and recordings. Measurements were performed by one my acoustical engineer friends in the anechoic chamber at work.

At this point - I think my first experience with the BeesNeez M7 was maybe with a cold solder joint or some assembly issue. It sounded very telephone-y, not a great sound. But the second time I installed it (to get measurements), it sounded much more balanced and full. Super happy with where the mic is at overall, now that I have the BN M7 and a NOS telefunken EF-800 in there.

Was not a huge fan of the Flat K47. In a blind test between the signal sounds and the d-ef47 flat k47, it was extremely obvious which was the signal sounds U47. The D7 had much more low end, much smoother in the upper mids and high end. I preferred it on my voice, anyway. See the last plot for a comparison of all three freq responses.

Comparing all three (and the Mojave), the BN M7 is a huge improvement (on the second try). The BN M7 is extremely close sounding to the takes I got with the signal sounds D7 U47. My D-EF47 had a lower noise floor and I think is slightly better shielded than the signal sounds U47. Still unclear on why the Flat K47 and D7 in my mic are supercardioid, and the Dany D7 in the signal sounds is cardioid.

I’ll try to put together some A/B samples, but the takes are a little rough. Carry on if you want all the plots…

AA Flat K47​

First up, here’s the AA Flat K47. Surprised to see that it is more supercard than cardioid.



Cardioid freq response:



Cardioid freq response without head basket:



Omni freq response:



D-EF47 Flat K47 (bold) vs Signal Sounds U47 with Dany D7 (regular):

Beesneez M7​

Still wasn’t very happy with the Flat K47, put the BN M7 back in just to hear it again (and to get measurements of that configuration).. And oddly enough it sounded right this time around.

D-EF47 BN M7 Cardioid:


D-EF47 BN M7 Omni:



Cardioid: Signal Sounds U47 Dany D7 (regular) vs D-EF47 Flat K47 (dotted) vs D-EF47 BN M7 (bold):

 

[rock soderstrom]

Got some measurements and recordings. Measurements were performed by one my acoustical engineer friends in the anechoic chamber at work.

Wow, that's really interesting. Thanks for posting

 

[AndyM]

Hello all,
this is my first post on this forum after reading a good share on this subject. I'm building a U47/U48-like microphone based on a EF800 (860 or 802). Still in the process of gathering all the parts and as much info as possible. The schematic of the mike would look like this:
View attachment 125728
...

Thought I’d share the result and some impressions along the way of my take on the D-EF47. Which is actually rather a D-EF48, but without the downside of the lower backplate voltage in cardio mode. Figure of 8 seemed to me more useful than omni, so I thought, why not have both?
I didn’t like the structure inside the current Equiox bodies using several long brass standoffs to form 2 rails. So I came up with an adaption to the classic 3 rails/ribs design.

Anyway, here we go:
Bending the threaded flaps in the ribs/rails

… using a piece of brass



Acrylic board with the switch for the pattern and backplate voltage:


Tools for cutting the foam ring:


Finished microphone


The actuator for the switch:




A big THANK YOU! to member rock soderstrom for helping me with the PSU and suggesting the voltage tripler (https://groupdiy.com/threads/diy-pr...mps-buffers-or-microphones.84324/post-1144358)

Resistors soldered temporarily to the leads of the caps to try different values until the voltages were spot on.


Finished PSU:


Raised resistors for better ventilation:


Found a suitable case and some leftovers of rather strong foam to make a box from. Sure, it’s not as fancy as a wooden box and an aluminum case, but it does the job.


Hope there might be something inspiring or helpful in some of the above.
Cheers,
Andy

 

[rock soderstrom]

Well done Andy

 

[Murdock]

I find it weird that still nobody has measured the actual output impedance of the EF80(0) tube in that circuit. I read several claims that the stock 6.5:1 ratio is too low. But also a lot of folks saying it fits perfectly…

I finally did it myself. Don’t know if I did it right but I fed a signal into the grid and hooked the output of the mic to a Rohde & Schwarz level meter where I can choose different input impedances. When changing from 10k ohm to 600 ohm load the level drops exactly -3dB. This means the output impedance seems to be around 250 Ohms. That is with a 6.5:1 ratio transformer.

 

[John McDougal]

I finally did it myself. Don’t know if I did it right but I fed a signal into the grid and hooked the output of the mic to a Rohde & Schwarz level meter where I can choose different input impedances. When changing from 10k ohm to 600 ohm load the level drops exactly -3dB. This means the output impedance seems to be around 250 Ohms. That is with a 6.5:1 ratio transformer.

K