Neumann Vintage U87 Clone : Build Thread.

[evanmurphy]

Hi folks,
Trying to get John's P-T87 wired up to the board and can't find a definitive color code chart for it. How far off am I ?

RT = red
SW = yellow
WS = Black
BL = green

I'm basing that off of the aurycle trafo so I could be totally wrong? Anyone?

Thanks in advance, and thanks Dany for such a cool project!

Poo, I just ordered his and figured it'd be in there.
Would appreciate this info or I can obtain and post

Here's the chart.

 

[andyfromdenver]

Thanks!

 

[atticmike]

Hey guys,

I just realised i have barely room for the t13 left, just that it fits in the xlr bottom block.

Is it gonna hurt if the transformer is touching the framework? I mean, it is an audio transformer, doesn't it have to be grounded anyways?

Mike

 

[3nity]

Why did you move the boards to the bottom?

 

[atticmike]

Why did you move the boards to the bottom?

Because the pcb would rest on the mountin screws. I mean, it wouldn't hurt to drill another pair a few millimetres above, yet I'd like to know whether it is unorthodox, fuckedup beyond imagination or prolly just not smart thing to do? Because that way, it is quite unshakable.

Mike

 

[wave]

mike,
What kind of donor body is that? If I'm not mistaken I think I had my T13 touching the bottom for a test and I didn't hear any issues. Eric shimmed it up for me when he biased the mic tho. You could wrap the lams with some e-tape to prevent any metal on metal contact tho.

Dave

 

[3nity]

but mounting screws attach ground to the ic body.
that white thing is plastic isnt ?? you need the board to conduct ground to the mic rails.

 

[poctop]

if the xlr pin1  connector tab is well grounded trough the mic,  pin 1 connection would take care of that ,
just want to make sure,
Dan,

 

[atticmike]

if the xlr pin1  connector tab is well grounded trough the mic,  pin 1 connection would take care of that ,
just want to make sure,
Dan,

yup, that's what I thought too. Well. before I put steel railings on the mic but they were touching the soldering holes which would've required another layer of plastic under it.

The mic is a mxl 2010. I mean, the inside is really cramped but the material the body is made of is surprisingly solid, that's what I love so much about the mic.

Plus it has the three pattern switch, pad and LF.

So I'm good if I properly lead the ground? to gd on the board?

I mean, I could wrap the transformer up so it's not touching but isn't that the purpose of a transformer? Remembering that it made quite a difference to ground the transformer's legs of my neve build.

 

[andyfromdenver]

Hey all.
If it's helpful at all to anyone, the CAD GXL2200 makes a good, no switches, donor.
($30 Craigslist w/ shock mount and mega-cheap cable)
The boards fit the pre existing rails and screw holes perfectly and
there's enough room for the transformer.
The silk screen wipes off easily w/ nail polish remover
and suites my label-maker-obsession style
I'm going to try and DIY at least the cut and pad, and am likely
fine with cardiod only (though I have the Peluso capsule).
So much great sharing here, thanks a million!
Andy
*edit. Don't know why pic is upside down!! ok fixed *

 

[Sredna]

Hey, the picture is upside down! 

(And the mic has my name on it!!!)

You could solder pins and use a jumper instead of the pattern switch, that way you'll be able to
get full use of this nice capsule. (got the Peluso as well..)

Best,

Anders

 

[andyfromdenver]

@ Anders, hehe  :
It's been my amp building logo.  We'll have to duke it out in the NWO!! j/k
Thank you for the tip, I know I need to make a switch there too, i've got a drill device that should enable me to go through the curvature.

 

[poctop]

the store will be open today only and then back Jan 7th 2013
Thanks all,
Dan,

 

[Spencerleehorton]

Hi,

this may have been covered before but i wanted clarity on getting the output as high as possible on these U87 builds.
I have used several different transformers but the the P-T87 peluso transformers seem to kick out the most output, and i think they are a ratio of 9.5:1.
The Sowter 9610 which is a 10:1 is about 3db lower.
If i used a 7:1 what impedances would i need to see and would this be a good way of getting more output but keeping the mic within its nominal performance?
I also get that selecting the highest output FET helps, which im now doing.
Also removing the -10db helps.
Do we know of any other improvement within the circuit to get more output?

regards

Spence.

 

[poctop]

Hi,

this may have been covered before but i wanted clarity on getting the output as high as possible on these U87 builds.
I have used several different transformers but the the P-T87 peluso transformers seem to kick out the most output, and i think they are a ratio of 9.5:1.
The Sowter 9610 which is a 10:1 is about 3db lower.
If i used a 7:1 what impedances would i need to see and would this be a good way of getting more output but keeping the mic within its nominal performance?
I also get that selecting the highest output FET helps, which im now doing.
Also removing the -10db helps.
Do we know of any other improvement within the circuit to get more output?

regards

Spence.

The Output of this microphone is actually in spec with the vintage u87i , 
Changing the transformer will change the impedance and will most likely affect the sound , the original tranformer is a 9.5:1 ratio and should bring you to that spec , For sure removing the pad will do the trick 
Best,
dan,

 

[atticmike]

Hi,

this may have been covered before but i wanted clarity on getting the output as high as possible on these U87 builds.
I have used several different transformers but the the P-T87 peluso transformers seem to kick out the most output, and i think they are a ratio of 9.5:1.
The Sowter 9610 which is a 10:1 is about 3db lower.
If i used a 7:1 what impedances would i need to see and would this be a good way of getting more output but keeping the mic within its nominal performance?
I also get that selecting the highest output FET helps, which im now doing.
Also removing the -10db helps.
Do we know of any other improvement within the circuit to get more output?

regards

Spence.

I was also wondering how to determine that? Hooking two legs up together and measuring the drain voltage on the remaining? The higher the drain voltage the higher the output?

 

[poctop]

Hi,

this may have been covered before but i wanted clarity on getting the output as high as possible on these U87 builds.
I have used several different transformers but the the P-T87 peluso transformers seem to kick out the most output, and i think they are a ratio of 9.5:1.
The Sowter 9610 which is a 10:1 is about 3db lower.
If i used a 7:1 what impedances would i need to see and would this be a good way of getting more output but keeping the mic within its nominal performance?
I also get that selecting the highest output FET helps, which im now doing.
Also removing the -10db helps.
Do we know of any other improvement within the circuit to get more output?

regards

Spence.

I was also wondering how to determine that? Hooking two legs up together and measuring the drain voltage on the remaining? The higher the drain voltage the higher the output?

There is some way to have the amplifier having more gain but the things is tha it is always a compromise between headroom and gain ,
so more gain less headroom ,  the matter is nicely Presented by Matador  here :http://www.groupdiy.com/index.php?topic=48030.1340
this is by using 2sk170bl as a fet .  in my case I always prefer to control this variable with my preamp wich most of the case I record average loudness source, with a good preamp this permits also to give it his full coloration The U87 clone output is exactely the same as the the vintage U87 circuit equivalent with 9.5:10 ratio transformer ,  They just cannot be compared to modern mic where the output is arround 10db hotter and some even more,

Hope this helps,
dan,

 

[atticmike]

Hi,

this may have been covered before but i wanted clarity on getting the output as high as possible on these U87 builds.
I have used several different transformers but the the P-T87 peluso transformers seem to kick out the most output, and i think they are a ratio of 9.5:1.
The Sowter 9610 which is a 10:1 is about 3db lower.
If i used a 7:1 what impedances would i need to see and would this be a good way of getting more output but keeping the mic within its nominal performance?
I also get that selecting the highest output FET helps, which im now doing.
Also removing the -10db helps.
Do we know of any other improvement within the circuit to get more output?

regards

Spence.

I was also wondering how to determine that? Hooking two legs up together and measuring the drain voltage on the remaining? The higher the drain voltage the higher the output?

There is some way to have the amplifier having more gain but the things is tha it is always a compromise between headroom and gain ,
so more gain less headroom ,  the matter is nicely Presented by Matador  here :http://www.groupdiy.com/index.php?topic=48030.1340
this is by using 2sk170bl as a fet .  in my case I always prefer to control this variable with my preamp wich most of the case I record average loudness source, with a good preamp this permits also to give it his full coloration The U87 clone output is exactely the same as the the vintage U87 circuit equivalent with 9.5:10 ratio transformer ,  They just cannot be compared to modern mic where the output is arround 10db hotter and some even more,

Hope this helps,
dan,

So what drain would you recommend? 11V as chunger referenced in his thread?

 

[poctop]

The drin voltge settting can be made as an approximation if you do not have a scope to bias and yes 11-11.5V is the guideline ,
Let me know ,
Dan,

 

[Spencerleehorton]

i have been reliably informed that the 2sk170bl is much better for audio applications than the 2n3819, i have ordered some and will be trying them out.
i will post the results, along with a bit more investigation on the transformer ratio.
gonna try a 7:1 in there (sowter 1303)

regards

spence