Modding a Røde NTK

How it all began

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I’ve had my Røde NTK for about 10 years. At first I loved it, at that time I was switching from a cheap Behringer condenser mic so it was a huge step up for me! After some time I started to study sound engineering and I got the chance to try out many different high quality microphones. While gaining experience and knowledge I slowly started to realize that there’s something harsh about my beloved NTK. I also noticed how full and smooth those expensive mics sounded, I could hear every detail so clear and there was a certain air around the recordings made with these mics.

After realizing I could not afford to buy a microphone like that I settled with my NTK. I EQ’d the hell out of every recording I made with it after that but I’ve never been 100% happy with the end result.

Years went by and I’ve been thinking about selling it a hundred times to buy another mic, but it never happened… At work we bought a Neumann TLM102 and I finally found a decent sounding mic that where within my price range! Still, my NTK stayed with me…

Then one day, I don’t know how I ended up there but I started reading on the internet about people who build their own recording equipment and modify their existing stuff to turn them into high quality gear.
I turned nuts, I read everything I could find, and I found some people who had modified their NTK’s, mainly people said that switching tube will make the mic shine… But I was so up in the air about this so I wanted to take it further and switch the capsule as well!

After careful investigation I decided to order a capsule from microphone-parts.com, their products were fairly priced and they seemed to have lots of satisfied customers. They have 5 different capsules all based upon classic capsules from Neumann and AKG. I listened to a lot of audio examples and read what other people had to say about them and I decided to go for their RK-12 which is based upon the capsule from the AKG C12 tube microphone.

“It is an excellent complement to a modern C12-style tube microphone mod, and a superior choice for any vocal or voiceover microphone.” /microphone-parts.com

I then followed Dale Simmons advice to go for a Telefunken tube, and I found one from the 60’s at Upscale Audio where the owner raved about this batch of tubes he had being one of the best he ever gotten hold of!

“Made in the 1960’s in Ulm Germany. This is the best made Telefunken 6922 / CCa / 7308 I have ever encountered. In fact… it’s the best testing tube I have ever had here regardless of brand.”

“These are shockingly good, so neutral and beautiful sounding you will name your next child after me.”
/Upscale Audio

Down to business

This was my first ever attempt at modifying any gear at all. It quickly became clear to me that I have to start with practicing my soldering skills, last time I soldered anything was back when I studied sound engineering.

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Switching the tube was a piece of cake, all I had to do was unscrew two screws then slide the stock tube out and slide the new-old 60’s Telefunken tube in and put back the screws.

The capsule was not really that hard to replace either once I mastered the fine art of soldering. Luckily the new capsule fit perfectly inside Rødes capsule holder and I cheated a little bit by borrowing the front cable from the stock capsule so I only had to solder one cable.

So finally, here’s the results! I wanted to actually hear the difference so I recorded some vocals and acoustic guitar first with my NTK unaltered, then with the Telefunken tube and stock capsule, then the new RK-12 capsule with the Telefunken tube and finally I put the stock tube back in just to hear what it would’ve sounded like if I only changed the capsule and to really get an idea what difference each part make. I also made a second recording with RK-12 + Telefunken after letting the tube burn in for another 2 days.

The recordings are made 30 cm away from the mic and goes in to a Motu 8pre, no EQ or compression. Unfortunately I forgot about the noisy computer we have in the studio I did the recordings in (we really have to do something about that), so the recordings are quite noisy but it’s nothing to do with the microphone.

This is it what it sounds like:

Guitar

Stock capsule + stock tube

Stock capsule + Telefunken tube

RK12 capsule + stock tube

RK12 capsule + Telefunken tube

RK12 capsule + Telefunken tube (Burned in)

Vocal 1 (Folsom Prison Blues)

Stock capsule + stock tube

Stock capsule + Telefunken tube

RK12 capsule + stock tube

RK12 capsule + Telefunken tube

RK12 capsule + Telefunken tube (Burned in)

Vocal 2 (Burnin’ And Lootin’)

Stock capsule + stock tube

Stock capsule + Telefunken tube

RK12 capsule + stock tube

RK12 capsule + Telefunken tube

RK12 capsule + Telefunken tube (Burned in)

Vocal + Guitar (Skinny Love)

RK12 + Telefunken tube (Burned in)

With gentle EQ, compression and reverb

Conclusion

I admit it’s not the best test in history, it was my first time doing this so I learned some lessons along the way. Still, the difference is obvious to me!

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My NTK is now much cleaner overall. It’s warmer, fuller and more balanced. Before I had to do surgical EQ adjustment to be somewhat satisfied with the sound of my voice and other recordnings, and I was still not 100% content with the result. Now all I have to do is some gentle EQ adjustments and it sounds better than ever!

I realized how important it is to let new tubes burn in properly, the sound became much cleaner and smoother. I’m also glad that I’ve decided to change both the tube and the capsule, once you’ve listened to the RK12 + Telefunken (Burned in) versions you don’t want to go back to any of the other versions. They both improve the sound of the microphone considerably!

Afterthoughts

 I’m totally in to this Do-it-Yourself business now, I’ve ordered two microphone kits from microphone-parts.com and a ribbon mic kit from diyribbonmic.com, it’s for my work where we gonna set up an electronic workshop where we can build, modify and fix our own gear. I’ve also ordered a PCB for a tube microphone preamp by Pete Millet, I realize it’s probably way out of my league at the moment… but if I have the PCB I’m gonna have to learn this stuff so I can build it one day…

Check out my latest single/video with vocals recorded on my precious NTK:

Now let me hear your thoughts on my NTK mod!

 

42 thoughts on “Modding a Røde NTK

  1. Thanks for posting the samples. I have an NTK and have already done the tube mods. If you get a chance you might try a Mullard tube. A different kind of silky from the Telefunken. That capsule did calm things down and add a nice warmth to the tone. Have you heard of any other capsules being used on the NTK?

    • I assume you have a Mullard then? I’ve ordered the RK47 and RK87 capsules from microphone-parts to put in other microphones, I might try to put them inside the NTK for comparison, if I do I’ll put some sound examples up to help you decide of you’re thinking about switching capsule. I can imagine the RK47 will calm the highs down even more if that’s what you’re after…

      • I ordered the same setup as you described in the blog:
        RK-12 CAPSULE and TELEFUNKEN E88CC / 6922 from upscaleaudio. Nice to hear comparison between the other capsules.
        BTW: is there a need to change the saddle on the NTK with the RK-12? Every hint helps. Thanx in advance.
        Cheers,
        Alex

      • I am curious as to how the other capsules sound. My first thought was to start with the RK47. And yes I have a Mullard and several other tubes. It might have been my imagination, but I thought I could a little rattle out of the Telefunken tube, real low but audible.

  2. Hi,
    Just pulled the trigger. Did some soldering, guitar pedals, mic-preamp by soundskulptor, shruti synth by mutable instruments. Hope that this project will be a success. If I need help, I´ll comment. Thanx for help in advance.
    All the best,
    Alex

  3. Daniel
    Nice tune…Skinny Love…it’s hard to believe that’s an NTK. Sounds like a $1000+ mic. Congrats on a great mic mod….well done. I guess I need to check out the RK-12.

    • Thanks! I’m really pleased with my “new” microphone, partly thanks to you! 🙂 I can definitely recommend microphone-parts.com, really good customer service and great products. I’ve just finished two other mods with parts from them, new posts coming up!

        • I must say I prefer the RK-12 when I compare those two versions you have there. I love the clear highs that it brings out on the violin. Both sound good but when switching back and forth the RK-47 feels a little bit boxy… It sounds a little bit more “old-school”, and if that’s what you’re after then I’d say go with that one. Otherwise my favorite is the RK-12! What do you think?

          • I must be old school, I really preferred the RK-47, the first strike of the bow on the strings really brings out the woodiness of the violin’s resonance.

          • Just swapped the stock NTK for the RK-47. Did you find that the RK-47 wasn’t as tight of a fit as the stock capsule? I am also getting a pretty big bump in bass response with the RK-47. It is also quite subdued in the highs. There is a definite trade off with the NTK capsule and the RK-47 capsule, the stock NTK gives you high end clarity, but can be a little coarse sounding, the RK-47 is silky smooth, but you lose a little detail and definition. The mic takes on a real warm vibey quality with the RK-47.

          • Like you, on the guitar and vocal takes i prefered the RK12…but…with the stock tube. Granted, that’s listening through my pc using Grado S60’s and pre burn in. I too felt the boxiness of the 47. Having said that, my fav mic out of the original U series is the 67.

        • Just swapped the stock NTK for the RK-47. Did you find that the RK-47 wasn’t as tight of a fit as the stock capsule? I am also getting a pretty big bump in bass response with the RK-47. It is also quite subdued in the highs. There is a definite trade off with the NTK capsule and the RK-47 capsule, the stock NTK gives you high end clarity, but can be a little coarse sounding, the RK-47 is silky smooth, but you lose a little detail and definition. The mic takes on a real warm vibey quality with the RK-47.

          • I ended up switching the original NTK capsule back into the NTK. I am thinking of putting the RK47 into an NT1, but haven’t done it yet

  4. I love this thread you guys have going! Thank you for taking the time/spending the effort and money, etc. for others who are considering this mod. Any more revelations as you gain experience with your “new” mic? Your comments are most appreciated!

  5. Hi everyoune, just finished my upgrade. First I swapped the tube to a Genalex Gold Lion 6922 and the mic became far more detailed. Because of the relaxed top end of the tube the sybilants got less harsh, but overall the high ent was still a little hyoed. Yesterday I replace the capsule for the RK12. As I spoke to the mic I already wanted to record something although initially I didn’t intend to, but the sound (above all warm low end that the mic got) persuaded me to dooing it. The mics output got higher in my opinion and the vocal now is truly larger than life and beefier to some extent. Thanks for your post! The fit on the NTKs capsule is not ideal, but sufficient to sit properly.

  6. Thanks for this, Daniel! I bought an NTK secondhand from a guy that runs a professional studio just a short drive from where I live. I was moving up from an MXL 990, so getting a tube mic seemed like a big deal to me. I had the same short love affair with the mic. It was warmer and better than what I was used to, but something seemed off. No matter how surgical the EQ I did, this mic just seemed to emphasis the worst frequencies in the upper range of my voice. The best mic I’ve come across in a studio for my voice was an AKG 414. I don’t have the money for one now, but once I saw your story with about mods along with audio examples (and being the ONLY one I could find on the internet about this subject) it gave me hope that the NTK could deliver the sound that I had originally thought it would have.

    I swapped the tube out a few weeks back and left the mic on for a few days, so it’s definitely burned in at this point. Definitely made the sound richer and a bit warmer (I opted for a Telefunken Black Diamond 6922). I just changed the capsule (the same RK-12 that you used). I had some initial install issues. The capsule worked, but the output seems quieter for some reason? I think I just had a bad ground. I just redid my wiring with some soldering, so hopefully it’s good now. Admittedly, I reused the factory wiring as I was not confident in my soldering abilities that close to the board.

    But again, thank you for this comprehensive write up! My NTK definitely sounded like your “Before” examples. Hopefully after these mods it’ll sound more like the “After” ones. 🙂

      • Finally got the capsule installed right,haha. Had to learn a little more about soldering. It sounds great now! Granted, I’m still probably gonna pick up an AKG 414 at some point, but this is a great holdover for the time being. Much smoother overall sound with a top end that’s detailed but not grating or harsh and a noticeable difference in warmth in the low-mids.

        I have a bunch of songs that I did vocals on that I’m gonna re-record now. I’m gonna keep the original tracks so I can A/B them.

  7. I just did this mod (tube and capsule). My tube is a NOS phillips. How you described the end results is accurate, “My NTK is now much cleaner overall. It’s warmer, fuller and more balanced.” And just like you I don’t have to do much EQ afterward to be satisfied. This is my only C12ish mic and it performs well.

  8. I know it’s been a few years since you wrote this article, but I decided to mod the tube on my NTK too. I swapped in a telefunken, and although the tone is significantly better, the microphone needs waaaaaay more gain now to match recording levels even close to that of the stock tube. This definitely isn’t normal, right? Did you encounter a similar phenomenon?

  9. Hi there and THANK YOU for this post. I would like to understand about the Telefunken 6922 / CCa / 7308 I found by upscaleaudio.com. There are 2 kind of grade, Gold and Platinum. I guess the Platinum is better. Wonder what you have in your, is it the platinum one? Thank you!

  10. Just wanted to leave a comment that I did the same mod and was able to do it Solder free. Just take a small exacto knife or screwdriver and cut away the glue that has been poured over the backplate wire. It unscrews easily. No rerouting of wires or soldering necessary!

  11. Hi,
    So for my mic, they told me to use Amperex 7308 or should i go with Telefunken E88cc tube. ? What is the diffrent is sound? I am am pop/r&b sound.

  12. I just finished this mod. From standard, to tube in December, to rk12 today. I love it. Makes me want to record and record some more… I did the telefunken tube (NOS). I had a track recorded with the NTK and I redid phrase or two with the new rk12 to compare. Night and day difference. So pleased…

  13. if u need a 6922 telefunken tube go to telefunkens websites, they got em for $48, upsacel audio charges over 150…

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