Mod'ing two Rode NT2s

Jettison · Post by **Jettison** » Thu Aug 09, 2012 7:13 pm

Just wondering what anybody thinks about replacing the stock capsules in my NT2s with the RK87 capsules from microphone-parts.com.

Worth it or not?

Any other suggested mods for the NT2?

Thanks

roygbiv · Post by **roygbiv** » Thu Aug 09, 2012 10:31 pm

I'm curious too, as i have one NT2, and two NT1's I wouldn't mind modding.

FYI, in the link for that site, http://microphone-parts.com/rk47-microphone-capsule/, there is testimonial (right side of the web-page) from two people who did what you are asking about:

"Just got my RK47 capsule in, and I mounted it into my Rode NT2. It?s an amazing difference! No harsh highs anymore. Really nice smooth sound!" Merlijn Verboom

and this guy,

"Just tried the modded NT2 with the RK-47 capsule on Kick drum. Subs sound great. Turned this NT2 into a very usable mic." Eric Beam

He also put together a nice description of how he went about doing the mod to his NT2, and testing it afterwards:

http://rhythminmind.net/1313/?p=3894

So, I'll be curious to see what experience TapeOpers have with using these capsules with Rode mics, especially the NT1's, which are cheap enough (you can get them used for ~ $100) that I wouldn't mind trying to mod mine with a new capsule - the NT1's are pretty quiet, so it may be they do not need any other upgrades other than the capsule.

And one last thing - on the Microphone Parts site they also state that, in regards to their RK7 capsule:

"due to its smaller physical size, the RK7 is an easier drop-in replacement for microphones from companies such as Rode, whose proprietary capsule mounting systems can be challenging for DIY modification/replacement. "

So you may want to consider that capsule instead.

EDIT: Ha! I guess one more last thing - I just stumbled across this comment on the RecordingHacks website (the same guy apparently runs the Microphone Parts site), a very interesting quote about the Rode NT1 from the legendary Jim Williams:

" I designed it with super low-noise Hitachi transistors and a Siliconix rf JFET. As you can see it has German Roederstein metal film resistors and Wima polypropylene film caps. As it is there is little to do to improve it. It was built ?modified.? Jim Williams
http://recordinghacks.com/microphones/Rode/NT1

So there you go - I've always wanted to get something from Jim Williams, turns out that for more than 10 years I've had two mics he designed.

vvv · Post by **vvv** » Fri Aug 10, 2012 5:35 am

Y'know, I seem to recall reading at mebbe GS that Mr. Williams had some issues with the way the his design was implemented?

Jim Williams · Post by **Jim Williams** » Fri Aug 10, 2012 8:39 am

Yes, there are a couple of problems in the NT2's I designed. First, the inductors off the output leads need to have a series resistor installed, I use 56.2 ohms. That stablizes the mics driving long lines and rejects rf.

Then the capsule polarization voltage is set too high. It needs to come down to +60 volts. To do that, I install a series resisor (1.5K) from the + V line feeding the oscillator pcb. Then a zener diode is fitted to clamp that voltage down until +60 volts is reached. Anything from 6.2 to 8.5V zeners will get there, select imperically.

Other mods include removing the input coupling caps and wiring the capsule switch directly to the jfet gate. That requires polarizing the capsule back plate instead of the diaphram. Then the output wires are reversed from pin's 2+3 on the XLR to retain phase.

Other fixes include raising the capsule post a bit to eliminate the dome reflections that creates a bump at 200 hz. There is also a lot of oscillator leakage into the outputs, you can see that on a scope. A piece of copper foil across the rear of the oscillator pcb stops that.

The circuit was designed flat to 50k hz. If you use the original or a k-67/87 capsule, those have a large hf lift that needs to be attenuated. Replace the 470 pf green Wima FKP-2 caps with 5600 pf to smooth those out, including the original capsules.

Jettison · Post by **Jettison** » Sat Aug 11, 2012 2:34 pm

Nice! Thanks Jim! I'll do all those mods.

Thanks to all!

roygbiv · Post by **roygbiv** » Sun Aug 12, 2012 2:45 pm

hey Jim

Yes, thanks for the info. Not to thread-jack, but any thoughts on if it would be worth trying the RK7 capsules in my Rode NT1's? I love their build quality, they are just a little bright for the usual digital recording. They are also cheaper than a Rode NT2, thus, if i screw up the installation, I was less of a bone-head, monetarily speaking anyway.

roy

Jim Williams · Post by **Jim Williams** » Mon Aug 13, 2012 7:56 am

I have a k-7 in a MCA SP-1. It's the most dark of all the chi-com capsules, too dark for me.

roygbiv · Post by **roygbiv** » Mon Aug 13, 2012 2:07 pm

Jim Williams wrote:I have a k-7 in a MCA SP-1. It's the most dark of all the chi-com capsules, too dark for me.

Ahh, good to know - you would recommend the RK47 instead then? I only suggested the k-7 as somewhere on the web site they said it fit more easily into the Rode mics than the RK47, but obviously the best sounding capsule would be the most important criteria in my decision tree, which is sometimes fertilized with BS.

Jim Williams · Post by **Jim Williams** » Tue Aug 14, 2012 8:12 am

k-47 capsules have that gravel lift at 3~5k hz, limited usefulness. The stock capsule does sound pretty good IF you tune it down using those 5600 pf caps I mentioned. If that doesn't get it, then replace the capsule.

Sean Sullivan · Post by **Sean Sullivan** » Thu Aug 23, 2012 5:20 am

Jim, thanks for all the information on NT2 upgrades. I've been wanting to a pick a couple up as utility microphones. The microphone mod is a little extensive but I'm going to give it a try.

2leftears · Post by **2leftears** » Tue Nov 20, 2012 7:11 pm

Michael Joly has a mod for NT2's. I have not upgraded mine, so I have no experience w/one.

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Mod'ing two Rode NT2s

Mod'ing two Rode NT2s

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