Banzai's KM84 DIY Body & PCB kit build thread

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craigmorris74

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Yes. My personal belief, based on tests I have done, is that the capsule is going to account for at least 75-80% of the sound of a mic. That is taking for granted that the circuit is well designed. I don't think there is anything in the circuit that is attenuating the >10KHZ frequencies. It just seems that Maiku has decided to make the capsule a little smoother and dare I say "warmer" than the original KM84 capsule. I've used 4 different KM84s over the last few years on a somewhat regular basis. They all sound similar. The two capsules I got from the kit also sound very similar to each other. They just don't sound similar to a KM84. That isn't to say they sound bad. They actually sound good and with a little EQ, they can sound very much like a KM84.

One thing I'm curious about. I wonder how an Oktava MK-012 capsule would sound with the kits body. I have not checked the threads but I have a feeling it wouldn't be a direct replacement but could be a fun experiment. I've used the Oktava mics (modded) that I have in place of KM84s all the time. When doing close micing, they sound closer than anything else I've ever tried.
that is fantastic information!

curious to see what you thought of the clips I made (post #323) comparing the Warm omni capsule to the kit capsule. If you could get.the Oktava to fit, it would be interesting too.
 

Spino

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It seems that C7 and C8 are out of stock as of now at Mouser and backorders are showing 21 weeks...

The only close caps that seem to fit are rated 63 V instead of 100. Do they really need to go up to the whole 100? (Let me guess... probably yes?). If anyone could say "don't worry, just order the 63V you'll be fine" it'd be so good!

Another way would be go larger but I'd need somebody to reassure me with tolerances, original c7 and c8 are rated 4.6x3x7.5 (WLH), I believe there are higher rated at 7.2x2.5x6.5 but it seems they're sensibly larger. Any opinion? I could manage different pin spacing but if there's no space for the actual condenser it's tougher.
 

RuudNL

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With phantom power being 48V, the voltages inside the microphone can never be higher than 48 V!
So, everything higher than 48 V should be fine! (An argument for a higher voltage could only be valid for a capsule coupling capacitor, because capacitors with a higher voltage rating usually have a lower DC leak current.)
 

McIrish

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I had some messages with a respected mic builder on another forum. He too had bought a couple of these kits. he believes the Maiku capsule is fine and that my high frequency attenuation is most likely from the transformer. Maybe I will purchase an upgraded transformer and give it a shot. I originally bought the 3U transformers. Maybe I should try the AMI.
 

corgan4321

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I had some messages with a respected mic builder on another forum. He too had bought a couple of these kits. he believes the Maiku capsule is fine and that my high frequency attenuation is most likely from the transformer. Maybe I will purchase an upgraded transformer and give it a shot. I originally bought the 3U transformers. Maybe I should try the AMI.
I enjoyed reading your findings regarding the transistor swap you did.

I have all Cinemag transformers and all of my mics are brighter than my Neumann KM86s. I’m still curious if it’s possible to implement a Hi Cut circuit like in the U87s.
Be aware that I found the Cinemags to have uncontrolled bass. I feel I successfully tamed it by changing C3 to a lower value. 1uF feels good to me. Take a look at my REW curves with different values for C3 & C4 if you’re curious - especially if you’re swapping to the Cinemags.

I’m also 100% with you about the polar pattern. I feel that a HUGE part of the KK84 capsule (and what differentiates it from so many other high quality SDC capsules) is how even the response is off axis. It’s really quite amazing how much you can control the room/source ratio by turning a KM84 a few degrees. I’ve got a 3D model of a replacement backplate that more closely resembles a KK84 that I need to find the time to have machined, might try to have it 3D printed for kicks too…
 

FarisElek

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Oct 26, 2019
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I had some messages with a respected mic builder on another forum. He too had bought a couple of these kits. he believes the Maiku capsule is fine and that my high frequency attenuation is most likely from the transformer. Maybe I will purchase an upgraded transformer and give it a shot. I originally bought the 3U transformers. Maybe I should try the AMI.
Interesting. I tracked an album with the kits as as cymbal mics. They are darker than I expected (I also used the 3U transformers). Admittedly, I like dark mics and I much prefer it being a little dark than bright so I can't complain. I love the way my tracks turned out with the kits. Would love to know if you get AML's for your kit and how it changes the mic.
 

mrgrooves666

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Feb 1, 2021
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Please share your results, thanks!
I bought an AMI T8 transformer to try in the mic. Expensive! It should show up next week and I should get a chance to test it against a couple KM84s and the original 3U transformer. I will report back once I have a chance to test it.
 

McIrish

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Jun 15, 2016
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I installed the AMI T8 in one of the kits and re-ran my comparison. The playing is horrible so I won't post it. I will do more tests with a different KM84 as well. Anyway, changing the transformer from a 3U to the AMI provided more gain. The overall sound did not change very much at all. Possibly there was a bit more clarity on top but it might only be 1dB. I was hoping for a bigger change. The AMI transformer is super well made. I was quite impressed with the build quality. It sounds nice but maybe not much better than the 3U. Anyone else do a comparison with different transformers?

Honestly, in the comparison I did this time, I did prefer the kit with the AMI over the KM84. The mic was placed about 15" from the guitar (12th fret) and mandola (f-hole) I tested with. Those instruments needed the extra warmth at that distance. The KM84 seemed a bit thin. If I recorded a bit closer, I know I would prefer the KM84 once proximity kicks in.
I may run some other tests when I have time. I'm not sure I will invest in another AMI transformer. It does sound a bit better but the cost is pretty high.
 

Zim

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Feb 18, 2020
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Anyone else do a comparison with different transformers?
I bought one if these kits which I got the AMI for and then added another kit with the 3U as I wanted to compare. In the end though to get the 3U to fit was going too take some filing of the board and, as I wanted to end up with a matched pair I ordered a second AMI when I was getting some of their other transformers for an la2a build. Interesting to hear there's not an awful lot of difference.

I've got both built now, but have about 10db gain difference between the two capsules, but saw in a previous post that Banzai was offering to take back capsules with a large discrepancy and replace with a better match, so will be taking him up on that.
 

McIrish

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Jun 15, 2016
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I too have a 3dB gain difference between capsules. Surprisingly, they sound very similar.
The AMI T8 was much easier to install. I wouldn't have had to file out the hole if I bought that first.
 
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