kip.duff said:
Thanks for posting- I've seen and appreciated many of your other posts.
Some of the things you said confirmed my uneducated guesses.
I am not married to this mic- and am not defending it or dissing it. I got the setup near new for $399 and thought I would check it out. It may be a mic that I will just leave alone with the 1967 Mullard or 1961 Valvo- not consider any major surgery. Maybe some relatively minor tweaks if there are any? Looking at a hand drawn schematic by Gustav, eventhough I'm not real knowledgible about circuits, I can see that this is very different, has a lot of transistors, no Tx, and heater voltage of 5V. Nothing like the popular C12 clones with Tx and 1/2 6072 triode- which I wanna try.
I'm going to take the time to study the 123 page C12 clone thread by Matador and chunger and maybe go that route. Don't wanna be sourcing parts one-by-one and I see they have some complete looking BOMs. I like the idea of the MParts PS with adjustable voltages. Big choices which capsule and Tx.
One question: I'm new to microphones- but so far, I think I would prefer the donor mic bodies that have ability to be mounted via the threaded flange at bottom. That way can use clamp mount or bottom mount technique. I like the K2 because it actually has two sets of threads at the bottom- one larger diameter for the body/sleeve install- and the other (20mm) for a large knurled finger nut for mounting at any degree of rotation position in the basket. So I'm looking for a donor body that has something like that. Many only have enough thrteads for installing the sleeve (22mm I think)- others have extended threads at that location which I believe is for bottom mounting.
Would it benefit to bring the K2 heater voltage up to 6.3?
Thanks, Kip.....
Kip, from my experience change of tube in K2 give some different feeling about the sound of it but not so huge as you could expect. Body isn't the best as a donor (except it is truly great from many reasons), because there's not much space for example for the custom PTP board, transformer with decent core etc. Original circuit since use a lot of smd isn't best for mods, especially for beginners.
With proper heating and underheating there are truly different opinions. Some tubes datasheets will tell you that underheating will decrease lifespan, some people that it will increase. Here heaters aren't part of (for example) biasing scheme, so change it definately will not give you any audible difference like different biasing point, sensitivity etc. You can experiment, there's potentiometer to do that
Recording Engineer said:
Certainly not the simple fact that they’re transformerless. I’m sure there are at least a few people here who could take those capsules and bodies and design a transformerless circuit that would make them sing.
But I digress, maybe I’m completely wrong and no one can... But regardless, I always remind myself that a microphone is a system. I guarantee, there are transformerless mics (tube or not) that do not suck!
I didn't tested any transformerless tube microphone which i would like to be honest. All three mentioned earlier, are much different from eachother, but all have some similarity in sound which i don't like. It doesn't sound fully like tube mike, it doesn't sound like FET microphone
There's a lot of truly great transformerless FET microphones, i can truly agree here.
kingkorg said:
Wow, now i am kind of puzzled. Quite a few people whose opinion i respect don't share my opinion about Rode's K2.
Maybe i just got lucky with the ones i used, but i truly remember them as exceptional mics. Could have been just different version of capsule/circuit?
Ln76d, do you think that transformerless idea is badly implemented, or you generaly don't aprove that?
I remember interview with Doug Ford desinger of Røde mics where he said they used transformerles design to avoid mismatches between transformer coupled preamps. He even called it "heresy", but claimed that the design is superior, and cleaner. In Røde Classic II he used transistor between tube and internal transformer. For example that is the mic Simon Philips uses as main vocal mic and room mic. Not that it means anything, but his production skils are insane.
In video about NT1000 (transformerless tube) he explains negative voltages, crazy 155db spl that mic can take with 1% thd, 143db signal/noise ratio, and several other advantages. And it could be even quieter with aditional biasing in the area of NT1A!
Not sure though if he designed K2.
Not defending my opinion, but there might be some advantages (like high spl/dynamic range) not possible with classic circuits. I just wish there were more videos like these, they are absolutely priceless, and that guy loves to share knowledge.
He explains burn in (aging) process of tubes used in Røde mics, so one might re evaluate if simple change of the tube for something else is actually an upgrade.
He also explains heater voltage of 5v, not that they couldn't have used 6.3 if they wanted.
All these things said kind of explain why i think K2 shouldn't be moded to something in a way inferior (don't kill me for this). This is a modern mic, and it has it's own story and design decisions which arr ment to be improvement over traditional design. I think it's better to sell it than to turn it into something it's not ment to be. Kind of like modding Sony C800 into u47.
Of course capsule upgrading is something else. Tim's capsule costs more than that mic, so it would be improvement. Just check those voltages, the guy at Røde said that polarization voltage of 70v is not in all polar patterns, what ever that might mean.
Matija, you wouldn't believe how often people ask me about any mods for K2 or NTK. I don't think it is bad idea of transformerless tube circuit, but still didn't heard any which i would like. Personally i have no need to experiment with that i just like good iron at the bottom of the body and that's it
Change of the tube, for "selected", NOS, blah, blah, blah 200euro 6072 doesn't change here so much, a little bit gain a little bit impedance etc. But many people believe in that. After - still want to sell the mike
This is not night and day difference. Also from modern tube mikes, K2 is one of the most common in auction sales microphone i'm seeing. Many people even prefer just sold it for cheap than modify it. I'm asking frequently what's wrong in K2 - most answers are like - i don't like how it sounds, it is useless and takes only dirt in my locker.
Personally i tested few K2 and few ntk from different manufacturing period i also don't like the sound of it on any source, maybe except the room ambience, but most microphones cand do the same work (depending on room, source and needs of course).
Rode truly goes to specs than sound, i love mechanical work definately, but truly not the circuits, even if you can get really nice specification on the paper. Main sin for many years was oversized polarisation voltage, to get better specs on the paper. It ended (especially NT1a) on dying microphones, when capsules get a little bit dirty. Even more common to versions with center terminated k67. Current NT1 have 65V and it's still low noise, not dying so frequently
In K2 original circuit i've tried very different capsules. None was sounding as it should in my opinion. Also with pair of capsules i tried AB vs other tube circuits. Rode is trying to make truly universal microphones with great specs but like many universal things... AKG had the sam route from the 90's, still people looks for the old models much more than newer.
Transformerless buffer is also saving of few bucks, rather not some miracle thing. Why? Ask yourself why their flagship model is transformer based microphone and what is true difference between over half less priced K2 and classic. Little bit different body, but the capsule is the same
Why i could "kill you" for this?
For example the pair i'm making it isn't even a mod. K2 here is just donor of great body, PSU which is modified and probably the capsule - but this will be decision of owner. It's just custom build like i'm making with many different donor mics, chinese bodies, Aputis and many others. It wouldn't be K2 anymore
And why K2 as a donor? Because of mechanical work look and properties and because the owner didn't used it at all because he also didn't liked the sound
