Neumann Vintage U87 Clone : Build Thread.

[roger.unc]

I set up my two completed mics in M/S configuration with the top mic in cardioid and the bottom in figure 8. Here's a short snippet of recorded acoustic guitar with no EQ, compression, or reverb -- just levels adjusted between the mid and side signals:

https://www.dropbox.com/s/sbxfjl92ks1xxhs/u87_test_mid_side_pair_acoustic.mp3?dl=0

Mics were stock BOM and styros with Maiku k87 capsules. Thanks for a great board and kit, Dan!

--Roger

 

[Ricardus]

I've never found there to be a enough L/R information to record an acoustic with that technique.

 

[roger.unc]

Hi Ricardus. I'm sorry the technique never worked out for you. Here is the mid/cardioid only track. It's mono and it's wonderful. I chose the Blumlein/Lauridsen technique to get a stereo spread and I think it worked out beautifully with the guitar about two feet away from the two mics. (It's even better with reverb). To each his own, I suppose...

https://www.dropbox.com/s/u1sr7cyj21cz1g5/u87_test_mono_only_acoustic.mp3?dl=0

 

[Ricardus]

Hi Ricardus. I'm sorry the technique never worked out for you. Here is the mid/cardioid only track. It's mono and it's wonderful. I chose the Blumlein/Lauridsen technique to get a stereo spread and I think it worked out beautifully with the guitar about two feet away from the two mics. (It's even better with reverb). To each his own, I suppose...

https://www.dropbox.com/s/u1sr7cyj21cz1g5/u87_test_mono_only_acoustic.mp3?dl=0

What would be cool is if a mod would move these last 4 posts or so (from when you posted your initial msg about it) to a new thread in the forum area talking about production techniques. I have a lot to say about this and it would be more appropriate there.

 

[Colorblind]

I set up my two completed mics in M/S configuration with the top mic in cardioid and the bottom in figure 8. Here's a short snippet of recorded acoustic guitar with no EQ, compression, or reverb -- just levels adjusted between the mid and side signals:

https://www.dropbox.com/s/sbxfjl92ks1xxhs/u87_test_mid_side_pair_acoustic.mp3?dl=0

Mics were stock BOM and styros with Maiku k87 capsules. Thanks for a great board and kit, Dan!

--Roger

Sounds nice, thanks for sharing!

 

[HosaMogami]

Man, I love the idea of these builds. But I have invested in four of them, and my average Backplate voltage on all 4 is around 7 V  which makes me sad. Pretty much renders figure 8 modes useless. It seems there have been several others on here with a similar issue but no posted resolutions. Granted they all sound good in Cardioid even Omni. But all and all it makes turned off by this kit sadly.

 

[Ricardus]

Man, I love the idea of these builds. But I have invested in four of them, and my average Backplate voltage on all 4 is around 7 V  which makes me sad. Pretty much renders figure 8 modes useless. It seems there have been several others on here with a similar issue but no posted resolutions. Granted they all sound good in Cardioid even Omni. But all and all it makes turned off by this kit sadly.

I posted my resolution.

I had a short between the backplates on my capsule. When I unsoldered the capsule from the circuit and checked the backplates, there was a dead short. It's a little more involved than that (exactly how we think the short happened), but when I resolved the issue with the short and put the capsule back in circuit, my issue was resolved.

U87 backplates from this vintage of the U87 should be completely isolated from one another.  Have you checked that?

 

[HosaMogami]

I posted my resolution.

I had a short between the backplates on my capsule. When I unsoldered the capsule from the circuit and checked the backplates, there was a dead short. It's a little more involved than that (exactly how we think the short happened), but when I resolved the issue with the short and put the capsule back in circuit, my issue was resolved.

U87 backplates from this vintage of the U87 should be completely isolated from one another.  Have you checked that?

Yea Im measuring that voltage even with the capsule disconnected.

 

[Ricardus]

Yea Im measuring that voltage even with the capsule disconnected.

OK, but just for ***** and giggles did you check the backplates?

 

[HosaMogami]

OK, but just for sh*ts and giggles did you check the backplates?

Yes, this is not a capsule issue. Im measuring the PCB pads even without capsule connected. The when set to Fig 8, the voltage drops to approx 7v. Sadness.

 

[hazer-drum]

Regarding JFET choices in the U87 build, I often read people saying to select the lowest Idss available. However my transistors range from 2-5mA and was wondering if 5mA was too low for dynamic range?

 

[Ricardus]

Regarding JFET choices in the U87 build, I often read people saying to select the lowest Idss available. However my transistors range from 2-5mA and was wondering if 5mA was too low for dynamic range?

Same with me. When I went through and graded my Fairchild FETs mine ranged from 2-5. Is there a sweetspot for these? What would happen if I used the 2's?

 

[fsalter]

Although i built many of these, i’m no electronics expert.  I have used anywhere from 2 to 10 ma without problems. I believe that it’s just that the trimpot bias adjustment will vary depending on  the Idss value. Some expert might want to chime in.

 

[Delta Sigma]

Man, I love the idea of these builds. But I have invested in four of them, and my average Backplate voltage on all 4 is around 7 V  which makes me sad. Pretty much renders figure 8 modes useless. It seems there have been several others on here with a similar issue but no posted resolutions. Granted they all sound good in Cardioid even Omni. But all and all it makes turned off by this kit sadly.

This isn't really a "kit". Dany makes these PCBs for DIYers to build mics with. Usually he designs them around known components and donor bodies that are readily available. He even shows pictures of builds and provides BOMs to make things easy.

There are complete mic "kits" available from businesses though. You may pay a little more but they are more of a kit. DIY isn't for everyone but if you have the patience, you'll love the feeling of finally figuring out the problem you're troubleshooting. I think starting with one of Dany's projects is very good path into DIY and this place is a very good resource - even if your question aren't answered right away.

A lot of people have been where you are so don't feel bad about being frustrated; some of this stuff can be infuriating!

Start with looking up the input impedance of your DMM. It should be at least 10M. Read my response to PG_Sax in the Elam 251 thread. It may shed some light on measuring voltage in the Hi-z sections.

There must be something bringing your voltage down if you have audible capsule polarization issues. Knowing how to measure voltage will help in finding what is bringing down your capsule voltage.

 

[HosaMogami]

This isn't really a "kit". Dany makes these PCBs for DIYers to build mics with. Usually he designs them around known components and donor bodies that are readily available. He even shows pictures of builds and provides BOMs to make things easy.

There are complete mic "kits" available from businesses though. You may pay a little more but they are more of a kit. DIY isn't for everyone but if you have the patience, you'll love the feeling of finally figuring out the problem you're troubleshooting. I think starting with one of Dany's projects is very good path into DIY and this place is a very good resource - even if your question aren't answered right away.

A lot of people have been where you are so don't feel bad about being frustrated; some of this stuff can be infuriating!

Start with looking up the input impedance of your DMM. It should be at least 10M. Read my response to PG_Sax in the Elam 251 thread. It may shed some light on measuring voltage in the Hi-z sections.

There must be something bringing your voltage down if you have audible capsule polarization issues. Knowing how to measure voltage will help in finding what is bringing down your capsule voltage.

Thank you for your well written response. Im going to research your post and dig in a little deeper. I know they aren't really a kit, I just find it strange that every one I've done is the same. I have successfully built several kits from Hairball, SoundSkulptor etc.  and you're right, Danys PCBs and BOMs are definitely leaving a little more on your own hands & skills. But I will dive back in after I research your post.

 

[hazer-drum]

Although i built many of these, i’m no electronics expert.  I have used anywhere from 2 to 10 ma without problems. I believe that it’s just that the trimpot bias adjustment will vary depending on  the Idss value. Some expert might want to chime in.

Did you notice any differences in sound between 2-10mA of Idss?

 

[Ricardus]

Thank you for your well written response. Im going to research your post and dig in a little deeper. I know they aren't really a kit, I just find it strange that every one I've done is the same. I have successfully built several kits from Hairball, SoundSkulptor etc.  and you're right, Danys PCBs and BOMs are definitely leaving a little more on your own hands & skills. But I will dive back in after I research your post.

So just to be clear, it's Omni mode that's not working? Not figure 8 mode?

 

[rockinrob86]

Which board fits the Behringer B2 pro mics?

 

[HosaMogami]

So just to be clear, it's Omni mode that's not working? Not figure 8 mode?

No,  figure 8 is not working.

 

[doggy6812]

Hey guys. I am having a problem with one of my builds. I have A his that sounds like White Noise.I have clean this board multiple times serious I remove the poly styrene capacitors to clean the board. I am at a loss. I am using a 797 capsule from a 1st gen c1. And Cinemag transformer. This capsule and tranny worked fine and n another Dany pcb. Anyone else have this issue or had it? I have 23.34 v at the zener. 40 v to the capsuleR14 21.2  r12 11.6