PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2980 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 #2981 on: November 08, 2018, 11:30:16 AM »
Here is U87.

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

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2982 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 #2983 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 #2984 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 #2985 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 #2986 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 #2987 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 »

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2988 on: November 17, 2018, 03:22:13 AM »
Thanks for replying!

Its a 25k pot, I have another one but they both seem to be working when I hook up them up to the meter.

I forgot to mention I can also see the sine wave on scope and it looks normal. Ive also been able to hear it on headphones although the ground noise is quite bad without body.

Could it be FET?  Is the source voltage 2.1v ok?

When the mic is first supplied with phantom fet voltage is around 12-13v but it moves around a lot and gradually starts falling?
How did you solve the problem? My FET will not work for 5 minutes after starting up because the voltage is too low, but will slowly rise to 9V after 5 minutes and maintain a perfect sine wave. It makes me sad

PG_Sax

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2989 on: November 18, 2018, 04:42:27 PM »
How did you solve the problem? My FET will not work for 5 minutes after starting up because the voltage is too low, but will slowly rise to 9V after 5 minutes and maintain a perfect sine wave. It makes me sad

For me the was a electrolytic capacitor that was orientated the wrong way. Think it was C8.


HosaMogami

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2990 on: December 01, 2018, 02:20:59 PM »
I should mention that I feel like my issue is revolving around R13... I just can't figure out why. That seems to be where I'm losing voltage. From there I get nothing at R8 or R15 or R16... Also nothing at C11 or C13... All of these parts have been replaced and I'm making no progress.

TillM

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2991 on: December 02, 2018, 04:56:32 PM »
as far as I understand you was able to fet the bias ?
what happened with an installed capsule ?
Do you get sound ?

HarmonyUnited

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2992 on: December 02, 2018, 06:41:04 PM »
Has anyone sketched up an exact schematic of this circuit with all the connections?

Ricardus

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2993 on: December 02, 2018, 08:17:48 PM »
So I'm about to begin building two D87s, and I have a question or two. Is the BOM on Dany's site still accurate? It seems like it calls for more components than it appears the build requires. I haven't actually counted components on the built examples I've seen but it seems smaller.

For example, the BOM calls for 3 2N3819's. Doesn't the mic only need one?
Audio mastering for hire..

fsalter

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2994 on: December 02, 2018, 08:28:49 PM »
There is redundancy in the BOM to give you options. Some resistors like the 2.2 k ones have to be closely matched. Buying many will permit you to find a matching pair. Also, there  are Polypropylene options to the Styroflex caps if you chose to go that route. You have to find a 2N3819 with a low Idss.  Ideally below 10ma. You may find it hard to find those jfets. Let me know if you want any, i have a few.

Ricardus

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2995 on: December 02, 2018, 08:33:50 PM »
I found some 3819s and bought a dozen from a reputable site (not ebay!) so I should be fine. OK. I didn't realize there was redundancy built into the BOM. I bought the BOM from Mouser and the styroflex caps from Dany's site.

I also found another supplier for 3819's that a friend hipped me to. A place that supplies educational institutions. Not sure if they're as high quality as the dozen I bought. They didn't ship after 2 days though, so I suspect they have no inventory. I'm going to call tomorrow to see.
« Last Edit: December 02, 2018, 09:47:31 PM by Ricardus »
Audio mastering for hire..

Ricardus

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2996 on: December 04, 2018, 12:52:14 AM »
..the last two batches of 2N3819 I bought turned out fake, just some rebranded generic NPN transistor..

They were branded, with laser marking:

(Fairchild-Logo-F)
BJ12
2N3819

 Yeah, I bought some of those myself and some fairly well known mic techs I know on FB guaranteed me they were fake. I actually made a claim with ebay and they refunded all of my money!
Audio mastering for hire..

Ricardus

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2997 on: December 04, 2018, 01:27:08 AM »
I was looking at the build thread for the D87M and when he mounts the switch PCB he was using some sort of spacers or offsets. I don't think those are part of the BOM. Does anyone have a part number for those?
Audio mastering for hire..

TillM

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2998 on: December 04, 2018, 01:38:13 AM »
I was looking at the build thread for the D87M and when he mounts the switch PCB he was using some sort of spacers or offsets. I don't think those are part of the BOM. Does anyone have a part number for those?

You don’t need them

Re: Neumann Vintage U87 Clone : Build Thread.
« Reply #2999 on: December 04, 2018, 07:45:50 AM »
Hello,

I am preparing to build this u87 clone mic.

When trying to order this BOM http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=1AD602D54E
the website gives me an error with the 610-2N3819 RF JFET Transistors N-CH -25V 10mA > I need to order 5.000 or more
Is there a comparable component I can get that is not the bulk pack? Im having a hard time figuring out which one is the correct one to order, since I am not experienced with this and the mouser website is huge.

thanks

Chris


 

Related Topics

  Subject / Started by Replies Last post
0 Replies
2470 Views
Last post March 12, 2012, 11:30:21 PM
by poctop
752 Replies
181497 Views
Last post March 29, 2019, 08:32:07 AM
by Govinda Doyle
337 Replies
77068 Views
Last post January 28, 2018, 06:14:53 AM
by Nele
3 Replies
893 Views
Last post April 02, 2018, 05:30:35 PM
by Wordsushi