Neumann Vintage U87 Clone : Build Thread.

[Arkenberg]

Have measured 56 jfets to find a matching pair. I have two in the 13ma range and two in the 7ma range. Which might make a better matched pair?

 

[fsalter]

Definitely the 7ma ones.  The lower the Idss, the better. I have done a couple recently with 4ma.

 

[Arkenberg]

Definitely the 7ma ones.  The lower the Idss, the better. I have done a couple recently with 4ma.

Thanks for the info

 

[Arkenberg]

Ok guys my project is nearly finished but I am having issues understanding how to bias my circuit with an oscilloscope. I have already biased with the DMM but I want my bias to be better. I have read the post on how to do it but I am just not understanding. If it is possible can someone draw out a schematic on how to do this. Also I have a signal generator as well.

Thanks Again Guys for all the help

Jonathon

 

[fsalter]

Hi Jonathan
I'm sending you an excellent pictorial on how to bias with an oscilloscope.
Good luck
Fred

 

[fsalter]

....and part two

 

[Arkenberg]

Thanks that should help greatly! So if this is method B what is method A?

Thanks
Jonathon

Hi Jonathan
I'm sending you an excellent pictorial on how to bias with an oscilloscope.
Good luck
Fred

 

[fsalter]

Method  A is the way you did it; using a DMM. There is also another way; by ear.  But he scope remains the best way.
I hope this helps
Fred

 

[vinylwall]

Here are some pics of my build.  Cinemag CM-13113 transformer, V-K87 Vintage Microphones Capsule, SYT-5 Type body from Mic & Mod, Neumann Purple Badge (hahaha).

 

[vinylwall]

Inside

 

[vinylwall]

other inside

 

[Arkenberg]

Where might I ask did u find the badges? I really like them. You mic looks great!

Here are some pics of my build.  Cinemag CM-13113 transformer, V-K87 Vintage Microphones Capsule, SYT-5 Type body from Mic & Mod, Neumann Purple Badge (hahaha).

 

[Arkenberg]

Thanks for the info as well. You guys have been a great help!

 

[vinylwall]

Where might I ask did u find the badges? I really like them. You mic looks great!

Here are some pics of my build.  Cinemag CM-13113 transformer, V-K87 Vintage Microphones Capsule, SYT-5 Type body from Mic & Mod, Neumann Purple Badge (hahaha).

I found them on eBay

 

[Arkenberg]

Well guys I think I botched my build! Both mics worked yesterday but one had a bit of static that came and went like it was cycling, the other sounded perfect and had great tone. So I tryed to fix the one with static, I thought it was just the trimmer resistor I used and pushed over. I thought I had broken the inside. But after replacing it, it did not fix a thing. All voltages are good and the bias was set to 11.5 but it was really flaky and kept bouncing.
Now the other I think completely blew up! It worked great but I had to try and make it better. So I tryed the oscilloscope biasing method and for some reason I could not get my new oscilloscope to cooperate. I think it is broke or something, the probes would not even adjust properly. So I reset the bias via DMM at 11.5 and went and pluged it in. It gave me massive amounts of static and popping. So I unplugged and went to check the out come. Right now the voltage coming in is only 16v but when I unplug my phantom power it shows 48.7. I am really confused by this. Now my bias shows 1.8 and the voltage at the Zener diode is 1. something.

I did try and prove around to find a fault resistor or cap everything seemed healthy.
Any clues on these two problems guys?
In need of a lot of help, going crazy right now!!!!

Thanks in advance
Jonathon

 

[poctop]

Well guys I think I botched my build! Both mics worked yesterday but one had a bit of static that came and went like it was cycling, the other sounded perfect and had great tone. So I tryed to fix the one with static, I thought it was just the trimmer resistor I used and pushed over. I thought I had broken the inside. But after replacing it, it did not fix a thing. All voltages are good and the bias was set to 11.5 but it was really flaky and kept bouncing.
Now the other I think completely blew up! It worked great but I had to try and make it better. So I tryed the oscilloscope biasing method and for some reason I could not get my new oscilloscope to cooperate. I think it is broke or something, the probes would not even adjust properly. So I reset the bias via DMM at 11.5 and went and pluged it in. It gave me massive amounts of static and popping. So I unplugged and went to check the out come. Right now the voltage coming in is only 16v but when I unplug my phantom power it shows 48.7. I am really confused by this. Now my bias shows 1.8 and the voltage at the Zener diode is 1. something.

I did try and prove around to find a fault resistor or cap everything seemed healthy.
Any clues on these two problems guys?
In need of a lot of help, going crazy right now!!!!

Thanks in advance
Jonathon

you must have busted the zener diode , probing arround, those are very sensitive ,
replace the zener diode and start from there ,.
Best,
Dan,

 

[Arkenberg]

Well guys I think I botched my build! Both mics worked yesterday but one had a bit of static that came and went like it was cycling, the other sounded perfect and had great tone. So I tryed to fix the one with static, I thought it was just the trimmer resistor I used and pushed over. I thought I had broken the inside. But after replacing it, it did not fix a thing. All voltages are good and the bias was set to 11.5 but it was really flaky and kept bouncing.
Now the other I think completely blew up! It worked great but I had to try and make it better. So I tryed the oscilloscope biasing method and for some reason I could not get my new oscilloscope to cooperate. I think it is broke or something, the probes would not even adjust properly. So I reset the bias via DMM at 11.5 and went and pluged it in. It gave me massive amounts of static and popping. So I unplugged and went to check the out come. Right now the voltage coming in is only 16v but when I unplug my phantom power it shows 48.7. I am really confused by this. Now my bias shows 1.8 and the voltage at the Zener diode is 1. something.

I did try and prove around to find a fault resistor or cap everything seemed healthy.
Any clues on these two problems guys?
In need of a lot of help, going crazy right now!!!!

Thanks in advance
Jonathon

you must have busted the zener diode , probing arround, those are very sensitive ,
replace the zener diode and start from there ,.
Best,
Dan,

Nope diode checked fine. What would cause it to cut the phantom power when pluged in?
Also any idea on the static in the other mic?
Thanks again guys
Jonathon

 

[poctop]

Well guys I think I botched my build! Both mics worked yesterday but one had a bit of static that came and went like it was cycling, the other sounded perfect and had great tone. So I tryed to fix the one with static, I thought it was just the trimmer resistor I used and pushed over. I thought I had broken the inside. But after replacing it, it did not fix a thing. All voltages are good and the bias was set to 11.5 but it was really flaky and kept bouncing.
Now the other I think completely blew up! It worked great but I had to try and make it better. So I tryed the oscilloscope biasing method and for some reason I could not get my new oscilloscope to cooperate. I think it is broke or something, the probes would not even adjust properly. So I reset the bias via DMM at 11.5 and went and pluged it in. It gave me massive amounts of static and popping. So I unplugged and went to check the out come. Right now the voltage coming in is only 16v but when I unplug my phantom power it shows 48.7. I am really confused by this. Now my bias shows 1.8 and the voltage at the Zener diode is 1. something.

I did try and prove around to find a fault resistor or cap everything seemed healthy.
Any clues on these two problems guys?
In need of a lot of help, going crazy right now!!!!

Thanks in advance
Jonathon

you must have busted the zener diode , probing arround, those are very sensitive ,
replace the zener diode and start from there ,.
Best,
Dan,

Nope diode checked fine. What would cause it to cut the phantom power when pluged in?
Also any idea on the static in the other mic?
Thanks again guys
Jonathon

cold solder

 

[Arkenberg]

Well guys I think I botched my build! Both mics worked yesterday but one had a bit of static that came and went like it was cycling, the other sounded perfect and had great tone. So I tryed to fix the one with static, I thought it was just the trimmer resistor I used and pushed over. I thought I had broken the inside. But after replacing it, it did not fix a thing. All voltages are good and the bias was set to 11.5 but it was really flaky and kept bouncing.
Now the other I think completely blew up! It worked great but I had to try and make it better. So I tryed the oscilloscope biasing method and for some reason I could not get my new oscilloscope to cooperate. I think it is broke or something, the probes would not even adjust properly. So I reset the bias via DMM at 11.5 and went and pluged it in. It gave me massive amounts of static and popping. So I unplugged and went to check the out come. Right now the voltage coming in is only 16v but when I unplug my phantom power it shows 48.7. I am really confused by this. Now my bias shows 1.8 and the voltage at the Zener diode is 1. something.

I did try and prove around to find a fault resistor or cap everything seemed healthy.
Any clues on these two problems guys?
In need of a lot of help, going crazy right now!!!!

Thanks in advance
Jonathon

you must have busted the zener diode , probing arround, those are very sensitive ,
replace the zener diode and start from there ,.
Best,
Dan,

Nope diode checked fine. What would cause it to cut the phantom power when pluged in?
Also any idea on the static in the other mic?
Thanks again guys
Jonathon

cold solder

Will try resoldering and get back with u on the out come.
Thanks
Jonathon

 

[errba]

Hey there, I am soldering my parts to my build buy i coudln't really find which direction the bias pot is supposed to go.

The little arrow on the pot is on the opposite side of the adjustment knob, -- my hunch is that it goes with the adjustable knob facing the left direction pointed away from the jfet but if anyone who did the u87M could provide me a pic i'd be stoked..


kudos