Rode K2 capsule suggestions

[tgs]

Hi all,

I have a couple of Rode K2 mics that I rarely use these days. I always thought they were sort of lacking personality and a bit too much high-end for my taste. Rather than just having them sitting on the shelf, I figured I could mod them a bit and see if I like them better. I think it primarily would make sense to change the capsule, so I wanted to check if anyone here has done so with good results. I've bought a couple of AK67 capsules from Advanced Audio in the past and put them in ADK A51 mics. It's also very easy to order their capsules from here (Sweden) so I wouldn't mind going with them again. Maybe the AK47 capsule could be a good substitute?

Just to give an idea about the sound profile I like: I usually prefer mics that are a bit on the dark side, especially nowadays when tape is long gone (for me) and I like mics with a lot of color rather than a flat-ish response. I have a couple of U89s that I really like for example, they don't exaggerate the highs so much. Taking it to the extreme, I prefer to work with ribbon mics and crank the treble with an EQ rather than going straight for a bright mic.

 

[kingkorg]

Hi all,

I have a couple of Rode K2 mics that I rarely use these days. I always thought they were sort of lacking personality and a bit too much high-end for my taste. Rather than just having them sitting on the shelf, I figured I could mod them a bit and see if I like them better. I think it primarily would make sense to change the capsule, so I wanted to check if anyone here has done so with good results. I've bought a couple of AK67 capsules from Advanced Audio in the past and put them in ADK A51 mics. It's also very easy to order their capsules from here (Sweden) so I wouldn't mind going with them again. Maybe the AK47 capsule could be a good substitute?

Just to give an idea about the sound profile I like: I usually prefer mics that are a bit on the dark side, especially nowadays when tape is long gone (for me) and I like mics with a lot of color rather than a flat-ish response. I have a couple of U89s that I really like for example, they don't exaggerate the highs so much. Taking it to the extreme, I prefer to work with ribbon mics and crank the treble with an EQ rather than going straight for a bright mic.

I would recommend Soliloqueen's flat k47, you can see the FR and review i did here. It's not really flat, just flatter than your usual k47 which can have an unpleasant bump in the midrange. I've always had a level of skepticism towards AA capsules as they seem like 30$ china re-brands. Maybe ask AA for frequency response graph of those, they should have them. Good M7 capsule would be also great solution. Cheers from Norway.

https://groupdiy.com/threads/soliloqueens-k87-k67-and-k47-capsules.81968/

 

[RuudNL]

Keep in mind that the polarisation voltage in a K2 is close to 78 volts.
For some capsules this may be a bit too much...

 

[tgs]

Keep in mind that the polarisation voltage in a K2 is close to 78 volts.
For some capsules this may be a bit too much...

Very true, good that you point that out. I checked with Advance Audio some years ago and they said all their capsules will work well in the K2.

Kingkong: thanks for the tip! I'll read through the thread when I have the chance. I checked the availability, it's on backorder at the moment. I'm in no way in a rush though.

 

[MusoGreg70]

O.P.R offers a CK12 swap.
I believe Tim Campbell suggested his are a direct swap?, and Beesknees has modded them. You could check with them.
I’ve two K2, and have bought one of the O.P.R NTK’-mods second hand ( apologies to Ben actually, I put my hand up for one of his mics years ago and life dealt me a curve ball, must get back to him).
If it has the K2 pcb’s, as it seems all? NTK do now?, It’s basically the same but without a potentiometer. I’ll know in the New Year.
I want to use both sides of the capsule! So I hope I can turn the NTK into a K2.
I admire the K2 only it isn’t as ‘set and forget’ as the more traditional NTV, and it doesn’t quite respond so obviously to tube rolling in the same way either.
I have heard them sound good in recordings, but in better rooms than I have access to atm.
It’s a very unique circuit, obvs.
Very much hoping the capsule change is as good as I’ve been told.
Should have some answers in the NY.

 

[Khron]

Keep in mind that the polarisation voltage in a K2 is close to 78 volts.

Referenced to what?

 

[OPR]

Referenced to what?

I guess it's in reference to the fact that most conventional capsules are designed to operate at a maximum of 60v ie k47, k67,ck12 M7 is possibly an exception because of the thicker diaphragm material so may survive 78v. But the others will likely fail unless tuned well out of the intended parameters.

 

[Tim Campbell]

I agree with OPR. If you are buying a boutique capsule make sure you tell the manufacturer that you intend to use it with higher polarization. There are also threads about how to turn the polarization down. All Røde mics that I have changed capsules in have sounded better but their newest capsule is much improved over older versions.

 

[OPR]

For sure the newest rode capsule sounds much better than older versions in regards to frequency response but still a little 2D and lacking in dynamics and detail... we can shrink the bind holes to tame the highs but 78v polarisation voltage and tight diaphragm are not conducive to uber hifi sonics.
But really amazing work for mass production in Australia of all places good on them.

 

[oscarhuang]

I tried replacing the capsule of k2. k47 M7 3U "c12". It is true that different capsules have different sounds, but none of them satisfy me. The original diaphragm obviously lacks mid-range frequencies and has many high and low frequencies. But the original capsule in the k2 circuit was OK, so I finally kept the original capsule.

 

[MusoGreg70]

I’m slightly off topic, only with Mark and Tim both here ( and others), I wonder what advice there is on the NTV.
They’re very pleasing mics stock only if that’s with an ‘average’ capsule, I do wonder what they might be capable of.
I’ve a pair.
O.P.R/Mark, thanks for the insight on the NTK/K2… I’d best do some homework on polarisation voltage rather than make a horrible mistake by connecting your capsule upgraded O.P.R NTK, to a standard K2 psu?Thanks for your work btw, the O.P.R 87 is great.
(Perhaps I ought contact you directly).
The NTV though, is it magic waiting to happen?
Cheers.

 

[OPR]

I’m slightly off topic, only with Mark and Tim both here ( and others), I wonder what advice there is on the NTV.
They’re very pleasing mics stock only if that’s with an ‘average’ capsule, I do wonder what they might be capable of.
I’ve a pair.
O.P.R/Mark, thanks for the insight on the NTK/K2… I’d best do some homework on polarisation voltage rather than make a horrible mistake by connecting your capsule upgraded O.P.R NTK, to a standard K2 psu?Thanks for your work btw, the O.P.R 87 is great.
(Perhaps I ought contact you directly).
The NTV though, is it magic waiting to happen?
Cheers.

Hey Greg,
Sorry I'm not familiar with the NTV so I can't help much. The critical thing is making sure the polarization voltage is compatible with the capsule. As mentioned earlier in the thread.
My NTk Ck12 mod capsule is a cardioid only ck12 so it's of no use in the K2 as it needs a dual diaphragm capsule to run the extra patterns.
Hope this helps.

 

[MusoGreg70]

Dear O.P.R, the NTK C12 arrived today.
11/10. I used an SPL creon, no comp no boutique Pre amp, and I’m very much impressed.
I couldn’t recommend this and the 87 highly enough at this budget point.
I’ll try it with a Sebatron/G.E and Telefunken’d G.A.P 2 later tonight, I’ll put the NTV up beside it too, they may well benefit from the same capsule.
Once I’ve met some other obligations I’d certainly like to try the dual capsules also.
Thanks for your advice.
Greg.

 

[MusoGreg70]

Oh and this is the NTV, if anyones interested, thanks to another member here.

 

[OPR]

Thanks for the great feedback Greg! I'm glad to hear that you're enjoying the mics!

 

[Gus]

I have a NTV. I like that circuit because it is different than what you find on other microphones and it sounds fine.

TP1 and TP2 set the circuit bias AND capsule voltage and interact so changing a capsule charge voltage changes the operating points of the tube.

The capsule voltage will be the cathode voltage - the grid voltage (EDIT more correctly the cathode voltage + the negative grid to cathode voltage. I did not word that well before so something like 60VDC - 1. something VDC)

One way to keep this and lower the capsule voltage would be to disconnect the backplate from ground and raise the backplate voltage however you will need think about any leakage current across the capsule elements that might turn on the lower triode more.

 

[zzzzz]

Posting mostly to follow, but working on some K2 "mods" including new capsule over here.

I found some sort of NTK schematic which upon first glance looks fairly similar to the K2, but I've just barely eyeballed it. PSU seems pretty standard with good amount of filtering despite mystery capacitors. The K2 I'm working on was mfg in 2020. Anyone happen to have schematic(s) for reference?

On my K2 PCB, C7 and C8 are 47nf, not 4n7 as notated on the schematic

 

[Khron]

https://groupdiy.com/threads/mod-tube-power-supply-to-work-with-rode-k2.74236/post-947990

And that schematic is the right one.

 

[zzzzz]

TL;DR: attached is a quick shootout between stock K2 and modded K2 with CK12 about 8 feet in front of a drum set. Both mics were manufactured around 2019 or 2020 and are (were) a matched pair. No processing other than hi pass filter (both of our K2’s pick up a lot of rumble)

BREAKDOWN OF WHAT WAS DONE:

• Replaced capsule in one of our two K2’s with the Beezneez CK12.
  • The modded mic was also recapped with Panasonic and Rubycon electro caps and Epcos/TDK polyprop caps. The power supply was fully recapped with Panasonic and Nichicon (originally had mystery caps that didn’t measure well despite only being a few years old…).

• Modded K2 currently has a used-but-good Japanese 6DJ8 (probably Matsushita — not pictured) which can be pretty mid forward in my experience — will shoot out with some other tubes someday. Stock K2 sample has original Electro Harmonix 6922. Lot of my 6DJ8 are microphonic…

• K2 with the Beezneez CK12 needs more a bit more gain on a pre than the stock capsule, but could also be the tube or whatever and is a non-issue.

• Samples were recorded with a stereo pair of Requisite Audio PAL mk3 pres, which are sort of colored so take that with a grain of salt.

• A/B-ed power supplies (stock and recapped) on the stock K2 and could tell a difference, especially in terms of noise floor. Did not record a sample of that, but was noticeable for sure. Previously swapped tubes in the stock K2 with an Amperex 6DJ8 and that was also a noticeable improvement (despite that tube being a bit microphonic) especially with the recapped PSU.
  
  
• did not change polarization voltage or anything of the sort. Ben from Beezneez said their capsule should be fine at the stock Rode voltage.

• GENERAL TAKEAWAY / "HOWEVER" NOTE: as others have noted, the newer Rode mics have totally acceptable capsules that are better than their old ones. The CK12 swap definitely gets the K2 sounding more like what (I personally think) a C12 sounds like! Especially on voice. But stock mic is good too!

INSTALLATION NOTES:

• good info on this gearspace thread: https://gearspace.com/board/low-end-theory/823811-rode-k2-capsule-upgrade-thiersch-pvc-m7.html
  
  
• Beezneez mount uses an M2.5 bolt. Had to get a longer M2.5 bolt than the one they included to get it through the rubber dome.
  
  
• Beezneez mount is taller than the stock Rode capsule mount, but capsule still clears top of the headbasket.
  
  
• Beezneez doesn't label what's the front or rear of their capsule. Also, join the two separate backplane wires and solder to the "Mic C" pad on the K2 PCB.

 

[tgs]

Very interesting, thanks for this! I couldn't get the links to the audio files working though.