RODE NT2 J.W. MOD - schematic attached

[Krumlee]

Nice work dhammer. Where is L5 located on your NT2? Is it board mounted or a bead on the wire? I know there's a ferrite bead on the other schematic but I don't seem to have one on my mic. I actually added a ferrite bead to the wire myself, though it's presumably just there for RFI.

 

[dhammer]

Nice work dhammer. Where is L5 located on your NT2? Is it board mounted or a bead on the wire? I know there's a ferrite bead on the other schematic but I don't seem to have one on my mic. I actually added a ferrite bead to the wire myself, though it's presumably just there for RFI.

You found a mistake on my drawing (THANKS!) – that's actually a 1 Meg resistor.  It's in the compartment between the capsule board and the mic body along with the (extra?) 1n film cap.  It's pulled out if you follow the OP's mod schematic.

I fixed the drawing and replaced on my previous post.

Does everything else match your NT2?

 

[Krumlee]

Ahh - I was just doing it from memory! Yes, I see what you did now.

That extra cap compartment design always seems really odd to me. No idea why it was done that way. If JW looks in on this thread, I'd love to know.

I'm going to pull apart my mic again (probably over the weekend) and I'll trace mine against your schematic and post any differences. Thanks again for doing the work...

 

[Krumlee]

Well this is getting interesting! I was a bit curious about your R12 when I saw your drawing because I didn't remember it.

There are different versions of the NT2 - see this thread for some other pics - http://www.gearslutz.com/board/low-end-theory/895061-rode-nt2-version-1-vs-version-2-a.html

Although mine doesn't exactly resemble either of them - it's closer to the V2 but there are no version markings on mine, which has serial number B40027

I've attached pics of mine that should make it easier to trace - I'm just doing that now. Maybe you could post pictures of your amp board. I can't see R12 on any of the other pics posted online, but maybe I'm being dim. It would be nice to discover any  change in the design along its history.

Other points: You've got collector and emitter reversed on Q3, and you've got D3 reversed - zeners work in reverse bias.

I'll post more later.

 

[dhammer]

Well this is getting interesting! I was a bit curious about your R12 when I saw your drawing because I didn't remember it.

There are different versions of the NT2 - see this thread for some other pics - http://www.gearslutz.com/board/low-end-theory/895061-rode-nt2-version-1-vs-version-2-a.html

Although mine doesn't exactly resemble either of them - it's closer to the V2 but there are no version markings on mine, which has serial number B40027

I've attached pics of mine that should make it easier to trace - I'm just doing that now. Maybe you could post pictures of your amp board. I can't see R12 on any of the other pics posted online, but maybe I'm being dim. It would be nice to discover any  change in the design along its history.

Other points: You've got collector and emitter reversed on Q3, and you've got D3 reversed - zeners work in reverse bias.

I'll post more later.

Thanks for the corrections, Krumlee.  I'll put them in and repost later tonight.

R12 on my scheme is a numbering error -- that resistor is R7 which you have on your board.  R7 on my drawing is a component you don't have -- it's there in series with the Zener.  It actually doesn't have a number on the silk screen.  When I first went through the mic and saw it, I thought maybe mine had been modded -- it is one of the changes JW talks about.  BUT then I saw that GS post you linked -- the resistor is there on the right-hand board in the pix, the one marked NT2PRE4.  That is the same board I have though I have WIMAs and Panasonics instead of what you see on those pix. 

Your pix are a big help.  I posted a link on an earlier post to a folder of pix of my boards.  I'll see if I can figure out how to get them inline as you did.

Thanks!

 

[Krumlee]

OK, I found the pics of your board - thanks. I saw that weird arrangement of D3 and its series resistor on the GS pics but I didn't understand it. Your pics are clearer, so I can see now that it's two components mounted vertically. I thought that must be an earlier version than mine, but it seems clear now that it's a later version.

So we've now got two versions of the circuit design and several versions of component source (Wima/Panasonic and whatever that other version is in the GS pics).

Interesting. And hopefully useful to others.

 

[dhammer]

Updated schematic attached.  Thanks to Krumlee and Ricardo for proofing.

(Attachment removed for corrections)

 

[Krumlee]

Good stuff - you still have D3 reversed though...

 

[RuudNL]

R1 is 1 G. instead of 1 M.
R8 is not is series with the gate!

 

[blamblam]

dhammer, thanks for your excellent work! 

I'm curious - I just had a quick look at the preamp board in my NT2, and it looks very similar to your photos.  Where is C6 (47uf 50v) in your schematic?  Is it where you have C20 (1uf)?  I don't see a C20 anywhere on my boards (or yours).

 

[dhammer]

Good god I hope I have it right now.... thanks to all for help and friendly patience 

I made corrections pointed out by Krumlee, Ruud and Blamblm.  I also took out the component numbering for the caps and resistors in the capsule head.  They have no numbers on my mic and it seems less potential confusion this way. 

 

[dhammer]

Here's a pair of photos showing the small board below the capsule and the two components in the compartment between that board and the mic body.

 

[ln76d]

Good god I hope I have it right now.... thanks to all for help and friendly patience  .

I think there's a few mistakes.

Check D3 and 6,8K resistor, R7, FET is reversed, "omni" position is on the right.

It's hard to compare with the genuine schematic, since you drew it reversed

 

[dhammer]

Glad to see you back on the thread!

It turns out the schemo you started from wasn't official.  It was drawn by someone on this board a while back.  Have a look:

http://groupdiy.com/index.php?topic=1494.0

I decided to redraw it by tracing the pcbs and component layout.  See page 3 of this thread for posts about all this.  Ricardo suggested comparing this circuit to Zapnsparks's GenChinaMod schematic, which is why a flipped the drawing.  The orientation also matches the original Schoeps circuit schemos.

I haven't touched my mic since doing the drawing.  Have you solved the omni vs card issue?

Re your notes:  that 6.8k resistor in series with D3 is there in my mic though without an indication for it on the pcb.  It turns up on someone else's NT2 – Krumlee found pix of that on on a GS thread.  I'll look at the switch.  About the FET, I'll label the pins so it can be clear.

I think there's a few mistakes.

Check D3 and 6,8K resistor, R7, FET is reversed, "omni" position is on the right.

It's hard to compare with the genuine schematic, since you drew it reversed

 

[ln76d]

Glad to see you back on the thread!

It turns out the schemo you started from wasn't official.  It was drawn by someone on this board a while back.  Have a look:

http://groupdiy.com/index.php?topic=1494.0

Good to know
I was 100% sure that this is genuine schematic

I haven't touched my mic since doing the drawing.  Have you solved the omni vs card issue?

Mike is waiting for the better times. Still have no time and patience I need to disassemble mic and check all connections, especially cutted traces for mod etc.

Re your notes:  that 6.8k resistor in series with D3 is there in my mic though without an indication for it on the pcb.  It turns up on someone else's NT2 – Krumlee found pix of that on on a GS thread.  I'll look at the switch.  About the FET, I'll label the pins so it can be clear.

Mine too has D3 in series with 6,8K without marking on PCB.  I need to check that again, but i'm not sure did you drew a good connection of those parts (same with R7). From what i remember,  those parts were connected as in the "genuine" schematic.
Labeling pins would be the best

 

[Stillcrazy13]

Hi everyone
After being off the beaten path, does anyone have a positive view for a novice like me owning an original nt1 and can you post after mod ahootout as jim is RIP now and the mics are orphans now!
Which mods do you suggest as critical for me to plan?
Thanks for your time and effort

 

[bremusound]

jim is RIP now

Don't think so. His last post @gearslutz  is from 2 days ago.

 

[Stillcrazy13]

http://www.edn.com/electronics-blogs/readerschoice/4368121/Analog-guru-Jim-Williams-dies-after-stroke

 

[ln76d]

It's different Jim Williams. Anyway original circuit design and his mods aren't worth time.

 

[havazli]

Hi guys, first of all I am sorry for my bad English, it's not my first language.
Thank you for taking the time and efforts for researches abot this mod.
I have Rode NT2 mic, which I want to mod according to suggestions here. I've read the whole topic with all comments and recomendations. In the end I expected a common opinion about the mods and respectively a schematic with the exact modifications. In mcbuilders yahoo group there's no such file named  "GenChinaMod.pdf"(at least I can't find it) , I find a file named "zapnspark-schema-de-micro-generique-chinois-mod-470687.pdf" Hope this is the same file. So I've made my humble editings in schematic drawn by dhammer according to suggestions of ricardo here and zanspark file . I'll attach the edited schematic with the mods hopefully someaone, especially ricardo take a time end make comments.  Thank you!