Neumann Vintage U87 Clone : Build Thread.
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kante1603
Well-known member
Any other writings on them?
Use a magnifiying glas under good light,sometimes hard to read,but there are values on them normally like "470J" for 470pF .
You don't have a capacitance meter handy,no?
Can you remember who you bought them from or at least the subject title,did they come from france by accident?
Udo.
Edit:You should find a number often followed by a capital letter there.
The number is the capacitance in pF,the letter is the tolerance unless written otherwise.
F=1% G=2% H=3% J=5% und K=10%.
Use a magnifiying glas under good light,sometimes hard to read,but there are values on them normally like "470J" for 470pF .
You don't have a capacitance meter handy,no?
Can you remember who you bought them from or at least the subject title,did they come from france by accident?
Udo.
Edit:You should find a number often followed by a capital letter there.
The number is the capacitance in pF,the letter is the tolerance unless written otherwise.
F=1% G=2% H=3% J=5% und K=10%.
kante1603
Well-known member
Hi B.,
No,since these are film caps they aren't polarized and go in either way round.The marking then is just the start or end of foil.From what I read sometimes needed in circuits where impedance is critical,but not here.
So no worries.
To explain what a styrene capacitor is:
It's a plastic film cap consisting of a metal foil,most of time from aluminium.That's why they have this silver look.This metal foil is the plate then.
The dielectric part is a polystrol foil.Both are wound and then heated in the factory,the polystrol shrinks during this process and forms a solid piece after cooling down.Two wires attached,cap is done.Btw,the german word is "Styroflex".
Hope to have helped,
Udo.
No,since these are film caps they aren't polarized and go in either way round.The marking then is just the start or end of foil.From what I read sometimes needed in circuits where impedance is critical,but not here.
So no worries.
To explain what a styrene capacitor is:
It's a plastic film cap consisting of a metal foil,most of time from aluminium.That's why they have this silver look.This metal foil is the plate then.
The dielectric part is a polystrol foil.Both are wound and then heated in the factory,the polystrol shrinks during this process and forms a solid piece after cooling down.Two wires attached,cap is done.Btw,the german word is "Styroflex".
Hope to have helped,
Udo.
kante1603
Well-known member
These resistors form a voltage divider.We need to get a precise voltage off of them,close to 24 vdc.
Udo.
Udo.
I thing I'm done with my first U87. I had some troubles that I will specify here, maybe there is something I need to correct?
At first test the signal was very low. I read in the thread that it's normal, but I thought it was way to low plus the polarity was switched 180, compared to my other mics. I used a T13 transformer and soldered it like this: http://farm8.staticflickr.com/7241/7174554600_240a084539.jpg
After reading Studio 939's build blog I read that his T13 had it's cables the other way around to avoid flipped polarity. After trying this, the polarity was still the same but the output level was way higher.
After comparing it with some other cheap mics I found that a CAD GXL220 (which I use for donor body) had more bottom end in the sound. Could something be wrong with my Diy87 or maybe the CAD just has a low boost? Or could it be that the capsule is wired wrong?...
...I'm not 100% sure I wired the capsule in the right way. The images on the first post in this thread makes me a bit confused. To me it looks like the photo and illustration is telling the opposite info. I use a RK87 from microphone-parts.com and I tried soldering the back plates in two different ways. I now have the saddle screwed to FC, and the wire to FC-bdy is attached to the saddle screw. The wire to RC-bdy is screwed to hole #2 (as in the illustrated picture). I also tried to other way around, but then it only worked in Cardioid mode. I read a lot of posts about how to wire the capsule so I feel a bit stupid that I'm still not sure.
Maybe I can get some questions answered?
I played some noise from a speaker to compare the freq response with the CAD, just to confirm the low end difference. The blue line is the 87 and the orange is CAD. (I also think I need to treat the acoustics of my room, damn...)
Thanks.
Ulf
At first test the signal was very low. I read in the thread that it's normal, but I thought it was way to low plus the polarity was switched 180, compared to my other mics. I used a T13 transformer and soldered it like this: http://farm8.staticflickr.com/7241/7174554600_240a084539.jpg
After reading Studio 939's build blog I read that his T13 had it's cables the other way around to avoid flipped polarity. After trying this, the polarity was still the same but the output level was way higher.
After comparing it with some other cheap mics I found that a CAD GXL220 (which I use for donor body) had more bottom end in the sound. Could something be wrong with my Diy87 or maybe the CAD just has a low boost? Or could it be that the capsule is wired wrong?...
...I'm not 100% sure I wired the capsule in the right way. The images on the first post in this thread makes me a bit confused. To me it looks like the photo and illustration is telling the opposite info. I use a RK87 from microphone-parts.com and I tried soldering the back plates in two different ways. I now have the saddle screwed to FC, and the wire to FC-bdy is attached to the saddle screw. The wire to RC-bdy is screwed to hole #2 (as in the illustrated picture). I also tried to other way around, but then it only worked in Cardioid mode. I read a lot of posts about how to wire the capsule so I feel a bit stupid that I'm still not sure.
Maybe I can get some questions answered?
I played some noise from a speaker to compare the freq response with the CAD, just to confirm the low end difference. The blue line is the 87 and the orange is CAD. (I also think I need to treat the acoustics of my room, damn...)
Thanks.
Ulf
kante1603
Well-known member
Hello Ulf and welcome to the thread,
a lot of us got the T13 with the wire colours swapped compared to the pic on the ami site.
So if you've got a way higher output now you have them right concerning what is primary and what is the secondary winding.
If you are really sure your mic is out of phase then just swap the output wires,either on the pcb or on the xlr (pins 2 & 3).
Sadly I can't comment on the bass response issue since I'm not familiar to your capsule.
Bass is huge normally on U87 mics,especially when close to the source,that's where in cardiod mode the proximity-effect drops in quite heavy.
Hope to have helped,
Udo.
a lot of us got the T13 with the wire colours swapped compared to the pic on the ami site.
So if you've got a way higher output now you have them right concerning what is primary and what is the secondary winding.
If you are really sure your mic is out of phase then just swap the output wires,either on the pcb or on the xlr (pins 2 & 3).
Sadly I can't comment on the bass response issue since I'm not familiar to your capsule.
Bass is huge normally on U87 mics,especially when close to the source,that's where in cardiod mode the proximity-effect drops in quite heavy.
Hope to have helped,
Udo.
Thanks Udo!
I already switched the output cables to fix the polarity issue. I just thought that maybe the problem is somewhere else. Maybe still at the transformer. But if it's just as good just changing the output wired I won't bother changing any more soldering connections.
The only thing I will add to it is switches for Pad and Low cut.
Ulf
I already switched the output cables to fix the polarity issue. I just thought that maybe the problem is somewhere else. Maybe still at the transformer. But if it's just as good just changing the output wired I won't bother changing any more soldering connections.
The only thing I will add to it is switches for Pad and Low cut.
Ulf
kante1603
Well-known member
Cool,have fun,
Udo.
Udo.
wave
Well-known member
uffetuff said:
I have experience with how the DU87 should sound when an RK-87 is installed. Can you post a sound sample?
Dave
wave said:
Great!
Yes I have some clips of some poor drum playing, voice and distorted guitar. I have the same vid the CAD mic. Same distance and as close to each other as possible. To me biggest difference is at the guitar. The only thing that bothers me is that the CAD has more bottom end. But other than that I feel that the 87 is much smoother and I would probably don't reach for EQ as much to cut annoying frequency peaks.
http://www.hoborec.com/download/ULF87.wav
http://www.hoborec.com/download/CAD.wav
What are the sonic differences if I hook up the backplates in the wrong way?
Ulf
pasarski
Well-known member
- Joined
- Jan 29, 2010
- Messages
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uffetuff said:
No sound. I think your wiring is correct and the mic sounds healthy (and a bit unispiring to me, like a u87
)Looks like ~ -2db at 47hz compared to the CAD, not much. And the roll off under that doesn't matter really (if you're recording music with the mic that is
). Looking at the U87 frequency plot, it starts to roll off at 60hz so that's also in line with your test results. Looking at your graph, CAD seems to be bit more scooped - broad dip at 2khz - that could also make it sound bassier.Bass loss, if there really is some, could happen if there's flux or other dirt at the high Z area
pasarski said:No sound. I think your wiring is correct and the mic sounds healthy (and a bit unispiring to me, like a u87
Looks like ~ -2db at 47hz compared to the CAD, not much. And the roll off under that doesn't matter really (if you're recording music with the mic that is
Bass loss, if there really is some, could happen if there's flux or other dirt at the high Z area
Thank you for your time!
I'm making a second one, so I'll try to be more careful with cleaning and getting flux away to see if it makes a significant difference.
Thank you and everybody else who's posting all great info!
I haven't been able to get the WIMA 220pF 2.5% or the WIMA .01uF 5%, however, I can get them both with a 10% tolerance. Will this be ok?
If anybody in Europe has either of these parts I'd be mighty grateful if you wouldn't mind selling me a couple?
Cheers Folks
B
If anybody in Europe has either of these parts I'd be mighty grateful if you wouldn't mind selling me a couple?
Cheers Folks
B
Hi guys,
Just recently started this project, and have all the components on the boards except my JFET and the resistor for bias. I'm trying the method described earlier in the thread to measure IDSS of the JFETs, but I'm not getting readings on my multimeters. I've tried 2 different ones, but no luck on either. Any ideas for what I could be doing wrong?
Thanks,
Craig
Just recently started this project, and have all the components on the boards except my JFET and the resistor for bias. I'm trying the method described earlier in the thread to measure IDSS of the JFETs, but I'm not getting readings on my multimeters. I've tried 2 different ones, but no luck on either. Any ideas for what I could be doing wrong?
Thanks,
Craig
poctop said:
Thanks for the tip. I'll try this method tonight.
Thanks for all the help I've received so far. I want to try to bias the FET using the Room Capture software to measure THD. Do I measure from the drain of the FET for this method? Also, does the transformer have to be disconnected?
Thanks,
Craig
Thanks,
Craig
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