Neumann Vintage U87 Clone : Build Thread.

[Jmaffei]

Thanks for your reply @Khron, Yes I have looked for alternative parts with similar specs, the detail I'm not sure about is the capacitor material. I assume Styroflex Capacitors have been selected for a reason, and I'm not sure what would be considered an acceptable capacitor type as a replacement. Any ideas?

 

[Khron]

I assume Styroflex Capacitors have been selected for a reason

Vintage w*nkery, more or less...

Just about any film cap (polypropylene / CBB, polyester) should be fine, as long as it physically fits.

 

[Jmaffei]

Vintage w*nkery, more or less...

Just about any film cap (polypropylene / CBB, polyester) should be fine, as long as it physically fits.

Super helpful thanks!

 

[fsalter]

Super helpful thanks!

You could use C0G / NP0 type capacitors of the same value. They are ubiquitous, and much less prone to damage because of heat.

 

[Jmaffei]

@fsalter Yep that's exactly what I settled on in the end, thanks for confirming!

Went for these:
https://www.mouser.co.uk/ProductDet...=sGAEpiMZZMvsSlwiRhF8quJDYJDbs0w51msnUe/4e5A=

Once I've finished the builds I'll post my BOM with links, quite a few parts in the original BOM are now unavailable. Could be useful for any future DIYers, in the UK particularly

 

[micolas]

Once I've finished the builds I'll post my BOM with links, quite a few parts in the original BOM are now unavailable. Could be useful for any future DIYers, in the UK particularly

Yes, an updated BOM would be useful, not just for UK DIYers but for others as well.
Thanks!

 

[Khron]

Yes, an updated BOM would be useful, not just for UK DIYers but for others as well.

Well, considering he never bothered correcting even the board footprint for that 1G resistor you're supposed to apply the calibration signal to...... I wouldn't hold my breath.

 

[micolas]

Well, considering he never bothered correcting even the board footprint for that 1G resistor you're supposed to apply the calibration signal to...... I wouldn't hold my breath.

I have to agree with you...
But still, someone competent would be useful to update some more delicate aspects for less experienced beginners (or for those comfortable, too lazy, and who want everything offered quickly and for free). Otherwise we always end up repeating the same instructions endlessly.

 

[Khron]

But still, someone competent

... And caring (enough)... But as the saying goes, one should not attribute to malice what can be explained by incompetence, but...

 

[kantaro]

Any body know if www.vintagemicrophonepcbkit.com is still active? I made a purchase about 3 weeks ago and still nothing shipped.

 

[fsalter]

He is still active, probably quite busy. I wouldn’t worry, he always comes through.
I PM’ed you an alternate contact.

 

[fsalter]

Could someone tell me if there is any way to raise the sensitivity of my 87i clone? I have 2. One has a Heiserman capsule and the other has a Maiku. Barring the fact that they sound slightly different, the Maiku has about 3.2db less output. Would inserting a low value capacitor in series with the capsule do it? ..or am i out to lunch

 

[micolas]

Could someone tell me if there is any way to raise the sensitivity of my 87i clone? I have 2. One has a Heiserman capsule and the other has a Maiku. Barring the fact that they sound slightly different, the Maiku has about 3.2db less output. Would inserting a low value capacitor in series with the capsule do it? ..or am i out to lunch

I think Maiku is darker, so the level (real and perceived) is lower.

Have you measured the Idss of the jFET?
A smaller Idss must increase the gain of the circuit.

Or you can add a simple dc/dc to increase the polarization voltage of the capsule.

Another option is to reduce the value of C3 (10pF), it will increase the output level (but it will change the character a bit)

 

[fsalter]

I think Maiku is darker, so the level (real and perceived) is lower.

Have you measured the Idss of the jFET?
A smaller Idss must increase the gain of the circuit.

Or you can add a simple dc/dc to increase the polarization voltage of the capsule.

Another option is to reduce the value of C3 (10pF), it will increase the output level (but it will change the character a bit)

Thanks Micolas, I will try another value at C3.

 

[kantaro]

Any body know if www.vintagemicrophonepcbkit.com is still active? I made a purchase about 3 weeks ago and still nothing shipped.

Please disregard this. It was in my mailbox and may have arrived some time ago. I'm an idiot who rarely checks his mailbox. Thank you Dany!

 

[kantaro]

I'm currently having issues trying to measure the IDSS of my jfets. I am following the Matador method. I have shorted the source and gate which is going to the negative of a 9V battery. Then I have the red probe of my DMM going to the drain and the ground probe going to the positive of the battery. My DMM Brymen 235 is set to measure DC mA however I am getting 0 in the readings. There is continuity. So I really dont know what im doing wrong.

 

[micolas]

I'm currently having issues trying to measure the IDSS of my jfets. I am following the Matador method. I have shorted the source and gate which is going to the negative of a 9V battery. Then I have the red probe of my DMM going to the drain and the ground probe going to the positive of the battery. My DMM Brymen 235 is set to measure DC mA however I am getting 0 in the readings. There is continuity. So I really dont know what im doing wrong.

I proceed according to the scheme:
I use a socket for jFET with the Drain connected so that I can measure jFETs with any pinout.
In the Drain I put a 10 ohm resistor. I measure the voltage on this resistor in [mV] and divide by the value of the resistor, in this case by 10. The result is the Idss value in [mA].
The battery is 9v.

 

[micolas]

I'm currently having issues trying to measure the IDSS of my jfets. I am following the Matador method. I have shorted the source and gate which is going to the negative of a 9V battery. Then I have the red probe of my DMM going to the drain and the ground probe going to the positive of the battery. My DMM Brymen 235 is set to measure DC mA however I am getting 0 in the readings. There is continuity. So I really dont know what im doing wrong.

I quickly improvised a demonstration of measuring the Idss of the jFET, according to the schematic I posted earlier.
I hope it helps you

 

[kantaro]

I quickly improvised a demonstration of measuring the Idss of the jFET, according to the schematic I posted earlier.
I hope it helps you

Thanks! Ill give this a shot!