Ricardus

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3100 on: February 18, 2019, 11:17:05 PM »
I just graded all my FETs with that 9 volt battery method described here somewhere. The NOS Fairchilds had IDSS ranges from 2 to 6. The NTEs went from 5 to 8. So I bagged them all separately and labelled them.
Audio mastering for hire..


roger.unc

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3101 on: February 19, 2019, 05:19:04 PM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3102 on: February 19, 2019, 08:48:17 PM »
I've never found there to be a enough L/R information to record an acoustic with that technique.
Audio mastering for hire..

roger.unc

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3103 on: February 20, 2019, 01:07:21 AM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3104 on: February 20, 2019, 12:52:28 PM »
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.
Audio mastering for hire..

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3105 on: February 20, 2019, 01:09:46 PM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3106 on: April 08, 2019, 07:46:18 PM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3107 on: April 09, 2019, 06:18:06 PM »
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?

 
Audio mastering for hire..

HosaMogami

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3108 on: April 13, 2019, 11:44:09 PM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3109 on: April 14, 2019, 01:03:07 AM »
Yea Im measuring that voltage even with the capsule disconnected.

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


HosaMogami

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3110 on: April 21, 2019, 03:55:18 PM »
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.
« Last Edit: May 08, 2019, 07:10:01 PM by HosaMogami »

hazer-drum

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3111 on: April 23, 2019, 07:02:17 PM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3112 on: April 24, 2019, 09:02:09 AM »
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?
Audio mastering for hire..

fsalter

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3113 on: April 24, 2019, 09:24:34 AM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3114 on: April 25, 2019, 11:07:00 AM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3115 on: April 27, 2019, 04:49:05 PM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3116 on: April 28, 2019, 07:32:18 AM »
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

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3117 on: April 29, 2019, 09:39:22 AM »
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?
Audio mastering for hire..

rockinrob86

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3118 on: April 29, 2019, 09:43:27 AM »
Which board fits the Behringer B2 pro mics?

HosaMogami

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #3119 on: May 06, 2019, 08:43:47 PM »
So just to be clear, it's Omni mode that's not working? Not figure 8 mode?

No,  figure 8 is not working.


 

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