NT2 upgrades... which is better?

[dp]

So I have the NT2 (not the A model) and was wondering about the two options I have for fixing the overly-bright issues.

As far as I can tell, I can either:

1) Upgrade the capsule to a "47 style" capsule
or
2) Change C4 and C5 to something in the range of 1500 to 2200pF (as designer Jim Williams has suggested)

<<<edit: and now thanks to user kingkorg, apparently there is a third option which sounds maybe like the way to go... (see post #4)>>>

Does anyone have any insight as to which I should do? It seems to me that the cap swap would be best because the capsule upgrade is suggested because the circuit does not have any compensation for the brightness of the capsule-mismatch choice in the original mic... but the cap swap seems to be the fix for that issue?

$150+ depending on the capsule chosen vs pennies for the caps (well $10 or so after shipping costs... lol)... if the caps are going to get me where I want to go, then it's a no-brainer?

 

[Banzai]

Nothing to lose by trying 2 first.

Cheap and simple.

 

[dp]

Nothing to lose by trying 2 first.

Cheap and simple.

Yes, I totally agree, but I guess what I am really asking is does the capsule swap impart some other sort of "mojo" that the capacitor swap doesn't do?

 

[kingkorg]

#2 did nothing for me.

I ended up adding two 10k resistors and 1n capacitor. It's part of MP mod for SP C1 mod. After that i got the mic to match HF response of u87. You can add a pot/switch as well.

http://www.audioimprov.com/AudioImprov/Mics/Entries/2014/2/8_EQ_Pt.3_-_Transformerless_Mics.html

It would be also a shame to waste that wonderful 797 audio capsule. Headbasket is better for a k67 capsule style mic. And it looks like a u87.

 

[Khron]

... Or alternately, a small (nF-range) capacitor in parallel with the JFET's drain resistor.

 

[dp]

#2 did nothing for me.

I ended up adding two 10k resistors and 1n capacitor. It's part of MP mod for SP C1 mod. After that i got the mic to match HF response of u87. You can add a pot/switch as well.

http://www.audioimprov.com/AudioImprov/Mics/Entries/2014/2/8_EQ_Pt.3_-_Transformerless_Mics.html

It would be also a shame to waste that wonderful 797 audio capsule. Headbasket is better for a k67 capsule style mic. And it looks like a u87.

Wow thanks... this is great info! Is that your website? I could (and will) spend a lot of time reading all that info there.

So, you have done this to an NT2 and liked the results?

Sounds like you are a fan of the stock capsule...

 

[kingkorg]

It's Henry Spragens page, its phenomenal.

I made this quick mod image for a friend, that is pretty much what i did with mine. You add the red components. You can go with or without the pot, or use a switch instead of it.

Yes i love that capsule, even without HF attenuation in some cases, Acc guitar for example. Just do a search, 797 Audio k67. It has been used in some well regarded mics, like Røde Classic I, or lately Townsend labs Sphere. Some people, way more experienced than me, consider it to be improvement over original Neumann design.  The problem is, almost always they get used paired with wrong circuit.

 

[kingkorg]

Here is the measurement of mu modded NT2 vs Vintage U87.

Bass response of Røde is better, as the capsule has better low end response, and there is no LF attenuation in Røde circuit due to lack of deemphasis network. So in most of my shared blind shootouts people thought NT2 was the Neumann

If you ignore the LF difference, they can easily be used as a matched pair.

 

[Khron]

https://groupdiy.com/index.php?action=post;quote=917866;topic=71586.240;last_msg=919448

Capacitor numbers refer to the schematic found here:
https://groupdiy.com/index.php?action=dlattach;topic=71586.0;attach=67338;image

Demonstration of the concept (the right side): https://groupdiy.com/index.php?topic=71586.msg917861#msg917861

 

[dp]

Holy cow... thanks you guys. I'll order the parts next week! This thread saved me $100 or so and it looks like it will be a better solution.

 

[dp]

... Or alternately, a small (nF-range) capacitor in parallel with the JFET's drain resistor.

OK I am looking at your posts here a little more closely. So, are you saying that strapping a 1nF cap across the R2/2k resistor (from the Rode schematic posted in kingkorg's reply) will basically get me the same thing as what kingkorg is proposing? If so, that's a whole lot easier to do. Or are you saying do it in addition to those changes?

 

[Khron]

It's an alternative.

"Just" a capacitor in parallel with the drain resistor will have the effect of a low-pass.
A capacitor in series with a resistor, added in parallel with the drain resistor, will have a high-shelf effect (as kingkorg's suggestion).

Although some have reported an increase in the noise-floor, by adding series resistors between the JFET and the PNP bases.

OK I am looking at your posts here a little more closely. So, are you saying that strapping a 1nF cap across the R2/2k resistor (from the Rode schematic posted in kingkorg's reply) will basically get me the same thing as what kingkorg is proposing? If so, that's a whole lot easier to do. Or are you saying do it in addition to those changes?

[Edit: correction]

 

[dp]

got it. thanks.

 

[Icantthinkofaname]

Here is the measurement of mu modded NT2 vs Vintage U87.

Bass response of Røde is better, as the capsule has better low end response, and there is no LF attenuation in Røde circuit due to lack of deemphasis network. So in most of my shared blind shootouts people thought NT2 was the Neumann

If you ignore the LF difference, they can easily be used as a matched pair.

Is the NT2 as good as your Behringer B2 Pro U87 builds? It's just too bad that the NT2 is only 2 pattern. Though that could easily be remedied with extra mods.

 

[kingkorg]

Well, i kept the original circuit with NT2. My B2s have mostly transformer coupled circuits, one of them de emphasis network.

They are slightly different beasts, but as i like to believe 90% of the sound comes from the capsule and headbasket, yes they are fairly similar.

I like NT2 headbasket type better, its one layer, and it is better looking. More transparent i'd say as well.

I haven't measured, but by design NT2 should have slightly higher noise floor.

 

[dp]

You can go with or without the pot, or use a switch instead of it.

What did you use for the pot? A multi-turn trimmer?

One more question... how did you secure it all so it's not flopping around inside?

 

[dp]

Tell me if this makes sense...

1) Remove C2, C3, C4 & C5 from the PCB
2) Move C2 and C3 to a separate daughter PCB
3) WIre the rest of the circuit on the daughter PCB
4) Strategically place trimmed-off leads from the daughter PCB to secure it to the main PCB, and those would form the correct connections to/from the main PCB.

This could be my first test of my Silhouette Cameo CNC vinyl cutter to make a PCB mask to etch a daughter card... I'm liking this project on multiple levels already...

 

[kingkorg]

I just soldered point to point, it ended up being rather solid. I used a regular trimmer, not multi turn.

Mictophone Parts uses an aditional board for SP C1 eq mod. You can check it out.

 

[dp]

Thanks again. I really appreciate your time helping with this.

 

[kingkorg]

No trouble, i hope you'll be pleased with the results.