Neumann Vintage U87 Clone : Build Thread.

[kante1603]

No No scope so remove one of the capsule wires???

Yes,on both sides so the following circuit doesn't "see" the capsule.

Best,

Udo.

Edit:Same wires on both sides,so both diaphragm wires or both backplates.If you are sure that you have it in cardiod mode then you must only lift one of the front connections since the back capsule isn't connected in this mode anyway.If you are unsure then lift all wires.

 

[jonathanmorbin]

Hi,

I have built microphones with both AMI T13 Transformers and P-T87 in both combinations of capsule. Microphone parts capsule and Erics capsule. i have only recently built a couple with the T13 transformer and it seems to be 10db quieter than the P-T87. Is this sormal or have i wired the T13 wrong?

 

[HellfireStudios]

Hi,

I have built microphones with both AMI T13 Transformers and P-T87 in both combinations of capsule. Microphone parts capsule and Erics capsule. i have only recently built a couple with the T13 transformer and it seems to be 10db quieter than the P-T87. Is this sormal or have i wired the T13 wrong?

By "quieter" are you referring to the mic's self noise or its output level?

-James-

 

[jonathanmorbin]

Quieter output level

 

[HellfireStudios]

The T13 may be wired backwards. They had that problem with the early batches of those transformers. It could also be that you have the P-T87 wired as step-up instead step-down, and the T13 is ok. Check the earlier posts in this thread on how to check the transformer with a DMM.

-James-

 

[kante1603]

Quieter output level

T13's primaries and secondaries swapped?

Best,

Udo.

Edit:Oooopppssss.....double post,hi James!

 

[HellfireStudios]

Edit:Oooopppssss.....double post,hi James!

It happens, and hello to you.

 

[EEMO1]

james,

how did you connect a sine wave and the alesis dock to measure at least something with the scope app?

 

[HellfireStudios]

james,

how did you connect a sine wave and the alesis dock to measure at least something with the scope app?

Unfortunately, I was unable to use the iPad scope, but I did use the app's sine wave generator. Also the I/O Dock was used for its proper line level output of the sine wave. I ended up buying a 150MHz Tektronik scope off of ebay.

BTW, I used a short cable with one end attached to a 1/4" guitar plug, and gator clips attached to the other end for the sine wave output cable. I had a second one built as a scope probe when I was trying to use the iPad scope app, but it was rendered moot once I realized an analog scope was the only way to go. I tried running the sine wave part of the Signal Scope Pro app out of the I/O Dock's output, and hooked the "probe" end up to the input preamp but I was not greeted with anything usable for biasing... I hope that helps.

-James-

 

[EEMO1]

I was interested to do some signal sweeps to measure the freq response... that's why I asked.


thanks!

 

[HellfireStudios]

Your mileage may vary, but I could not get anything usable through my o-scope app. Just oscillation on the screen. Check my screenshots earlier in this thread to see what I mean.

-James-

 

[burglar]

Hi folks,

For the styrenes, I have sourced some in the uk but on arrival it appears they are polarised and the markings on the PCB's suggest that they dont need polarity?  Have I got the wrong caps?

Also, C8 & C10 are not market with a value on the pcb?

 

[dissonantstring]

Styrene caps are not polarized (although I have seen an occasional red band on one particular old brand which I do not know the name of).  I believe that on those styrene caps the band indicated the side connected to either the start or end of the foil roll (can't remember which one).  Perhaps a pic of the cap can help us determine if it is actually a polystyrene cap & whether or not you should be concerned.
Best,
Grant

 

[kante1603]

Hi folks,

For the styrenes, I have sourced some in the uk but on arrival it appears they are polarised and the markings on the PCB's suggest that they dont need polarity?  Have I got the wrong caps?

Also, C8 & C10 are not market with a value on the pcb?

Hi,

I second Grant's advice to show a pic just to get sure and his explanation about markings.
For the both mentioned caps,why not look at the bom or the schemo? ;D
For C8  it is 22uf/6,3 volts/10% tantalum or as an alternative a lytic cap.
For C10 it is 4,7uF/35 volts/10% tantalum or a lytic.

Cheers,

Udo.

 

[electrisizer]

@udo

have you ordered the styros of the project in germany? is there a good source?

 

[kante1603]

@udo

have you ordered the styros of the project in germany? is there a good source?

Some of them I wasn't able to find at that time from mouser,but normally I get them from Banzai Music,look here:

http://www.banzaimusic.com/search.php?mode=search&page=1

I know Reichelt stocks some too,here:

http://such001.reichelt.de/?SID=13UVdCcH8AAAIAAGXiAak4572d5b72b0164d1d4b50babab3c3734;ACTION=446

Since you're in germany like me I can easily send you some single caps if you can't find them,ask me,I might have them already.

Cheers,

Udo.

 

[burglar]

Thanks for your replies.  I have two different kinds.  Yes, one of them has a tainted red end but the others have a black line round one end and appear to have been market with a pen?  Here are some pics.  Sorry for the bad quality.

http://imageshack.com/photo/my-images/195/imagearz.jpg/

http://imageshack.com/photo/my-images/802/imageqeh.jpg/

http://imageshack.com/photo/my-images/442/imagecytm.jpg/

Are there any pros & cons to using tantalum vs lytics for C8 & C10?

B

 

[kante1603]

Hi B.,

at a first sight they look like styrenes,the pics are really blurry.But I can see the wires are not centered,looks like them being more on the outside,so that's a good sign.
Can you read anything on them and maybe post some better pics?

Udo.

Edit,have overseen your last question.
The lytics are alternative types,tantalums were used in the original builds.I went for tants here.

 

[burglar]

Hi Udo,

Yeah, sorry.  here are some better quality pics.  The marked ones say "Suflex" on them.  The other type just have a slightly tinted red end?

B

 

[kante1603]

Hmmmmm......now they look a bit strange indeed,not like styrenes.The red marked thing looks more like a diode or something.
Did you buy them as styyrenes?Where did you buy them?
At the moment I'm quite uncertain,may be best to buy some new from a good known source,all styrenes I've seen and used so far are silver shining (from the foil inside),are very light weight and have thin wires coming from the sides top and bottom.

Udo.