PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2980 on: October 23, 2018, 11:30:40 AM »
Ok can anyone tell me what I've done. Mic is biased and sounding great so far in testing.

Buuuuuuuuut, am comparing to an old U87 and the waveform is inverted on my mic compared to the U87?

Anyone have any ideas what that could be?

I haven't got the polarity switched on the pre etc.

Its ok think I've got it solved transformed is wired wrong way round..doh
« Last Edit: October 23, 2018, 12:14:33 PM by PG_Sax »


PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2981 on: October 23, 2018, 12:32:15 PM »
Could anyone confirm this for me?

Green Wire - RT - Primary High +
Blue Wire - SW - Primary Low -
Brown Wire - Blau - Secondary Low -
Grey Wire - Weiss- Secondary High +

Wiring the Sowter 1303

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2982 on: October 31, 2018, 08:40:19 PM »
Hey Guys! I am trying to build one of these microphones and I am having an issue. I have too much current at the drain. I can adjust the trimmer from 17v to about 22v. I have 23.21v at the zener. What can I do to fix this? Thank you guys for your help! Randy

ln76d

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2983 on: November 01, 2018, 05:48:41 AM »
Change FET or use different potentiometer value.

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2984 on: November 01, 2018, 06:07:30 AM »
I wonder, if I only use the heart - pointed capsules, what should I delete? Please help me, thank you

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2985 on: November 08, 2018, 09:15:25 AM »
Has anyone tried increasing C5 to a higher value and got any feedback on the results?

Going to experiment with increasing C6.
« Last Edit: November 08, 2018, 11:20:06 AM by PG_Sax »

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2986 on: November 08, 2018, 11:27:32 AM »
Also if anyone is interested, I have run a couple of sweep tests on the D87 and my friends old U87 which used to belong to me.

The D87 spec is,

HK87 capsule
Sowter 1303 Transformer.

U87 is from the 1980s I think its 1987.

I couldn't exactly match the input level of both mics so the D87 is 0.5db louder than the U87.

Low end is pretty spot on taking this into account.

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2987 on: November 08, 2018, 11:30:16 AM »
Here is U87.

Will post the results of the C6 change, when I've done it.

HosaMogami

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2988 on: November 08, 2018, 12:32:33 PM »
I just finished up another one of these and it sounds great except for the figure 8 pattern. I just get a very big volume drop when in that pattern. Everything else works great. Any ideas where to look? Switch PCB or Output transformer wiring?

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2989 on: November 08, 2018, 01:26:11 PM »
I just finished up another one of these and it sounds great except for the figure 8 pattern. I just get a very big volume drop when in that pattern. Everything else works great. Any ideas where to look? Switch PCB or Output transformer wiring?


Are you getting a volume drop on just one side? Or both sides? I would definitely check pattern selection switch wiring.

« Last Edit: November 08, 2018, 01:37:08 PM by PG_Sax »


Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2990 on: November 08, 2018, 11:44:39 PM »
Also if anyone is interested, I have run a couple of sweep tests on the D87 and my friends old U87 which used to belong to me.

The D87 spec is,

HK87 capsule
Sowter 1303 Transformer.

U87 is from the 1980s I think its 1987.

I couldn't exactly match the input level of both mics so the D87 is 0.5db louder than the U87.

Low end is pretty spot on taking this into account.
What software is used for such tests? Can I test the capsule with it?

HosaMogami

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2991 on: November 09, 2018, 01:01:51 AM »

Are you getting a volume drop on just one side? Or both sides? I would definitely check pattern selection switch wiring.

Definitely both sides equally. No distortion, just a volume drop. Will check switch switch wiring soon.

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2992 on: November 09, 2018, 05:44:19 AM »
What software is used for such tests? Can I test the capsule with it?

I'm using a program called Fuzz Measure by Rode to perform sweep tests. With my setup its far from scientific but I'm using an old U87 I know to be good as a reference.
« Last Edit: November 09, 2018, 05:49:20 AM by PG_Sax »

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2993 on: November 09, 2018, 05:47:40 AM »
Definitely both sides equally. No distortion, just a volume drop. Will check switch switch wiring soon.

Yeah I'm not knowledgeable enough to be that helpful unfortunately. Maybe also check C2? And go over the boards.

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2994 on: November 09, 2018, 11:44:58 AM »
I realised that I made a mistake yesterday with my measurements, so I remeasured.

Here are the two mics on the same graph. This time they are matched to within a tenth of a db.



« Last Edit: November 09, 2018, 12:08:27 PM by PG_Sax »

HosaMogami

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2995 on: November 11, 2018, 02:51:41 PM »
Ok, looking at the schematic: https://www.gearslutz.com/board/attachments/geekslutz-forum/226308d1300729000-mxl-v67-mic-mods-u87sch.jpg

and the Cinemag CM1113 data sheet, I'm thinking that it should actually be:

RT = P+ = Brown
SW = P- = Red
BL = S- = Yellow
WS = S+ = Orange

So can anyone officially confirm if this is correct for the Cinemag 13113?


 

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