Banzai's KM84 DIY Body & PCB kit build thread

[Zim]

Thanks McIrish - just so I can try to understand though... the leg of R2 I was talking about connects to leg 2 of the trimmer via the trace at the moment. So my thinking was, that disconnecting that leg of R2 and connecting it directly to the new 5k resistor which would then be soldered to the leg of the trimmer (I assumed leg 2 of the trimmer As that was what R2 was connecting to in the circuit. That way it only requires desoldering one leg on R2 rather than 3 legs on the trimmer.

Wouldn’t we be basically be doing the same thing but you’re connecting R2 to the new resistor through the board, and I’m just talking about doing it directly.

I’m certainly not disagreeing with you, just trying to understand what it is that I’m not understanding with my thinking at the moment - looking to keep learning.

Really appreciate your help

 

[McIrish]

Don't lift the ground leg of r2. It won't do what you are thinking. It has to remain connected directly to the ground You want the extra resistance on the pot. Nowhere else. Hope that helps.

 

[Zim]

Don't lift the ground leg of r2. It won't do what you are thinking. It has to remain connected directly to the ground You want the extra resistance on the pot. Nowhere else. Hope that helps.

Ahhh - yup, thank you! I was completely missing that I would be lifting that leg from ground! Thanks for taking the time

managed to get the trimmers out (think I’m going to need to invest in one of those hakko desoldering guns in the future). Think I’m going to just go for a 25k trimmer rather doing anymore soldering and desoldering on those pads.

Out of curiosity, where did you end up for that FET - the extra 5k let you bias it as expected I take it? (Is it unusual for there to be such a large swing in values for FETs - as Kato had said others were using 6-7k and we’re going +20k)

 

[McIrish]

One of my FETs biased around 18.5k and the other was around 21.5k-22k. Those numbers are fine for the FETs in the new order. The previous order used a different brand of FET and that's why the numbers are so different from previous builds. It's all ok. Just bias it for symmetrical clipping and you are all set. I don't believe the brand is going to have any impact on the sound. Like all microphones, the capsule accounts for at least 75-80% of the sound. Then the transformer. The capsule might even be 90% of the sound on such a simple circuit.

 

[waltzingbear]

OK, so one of my capsules is falling apart. The grill and retaining ring have fallen off. What kind of glue is used to hold the screen on?

 

[Banzai]

OK, so one of my capsules is falling apart. The grill and retaining ring have fallen off. What kind of glue is used to hold the screen on?

Fix with thin layer of superglue. Won't move again.

 

[waltzingbear]

I tend to prefer fixing things like luthier‘s, no glue that can’t be undone.

 

[McIrish]

Quick note and question. I finished two of these mics and put them up against a KM84 and did some recording tests. There is quite a bit more low end in these mics when compared. Looking at both schematics, I see that C3 and C4 are not the same value as the originals. C3=4.7uF instead of1.5uF. C4=4.7uF instead of 1uF. Due to the larger caps, I measure a pretty large increase in 250hz and below. It becomes even more prominent off-axis. I'm thinking of changing the caps to the original spec on one mic and see how it sounds. Anyone else notice this?

 

[JerryPbury]

I use 1uf for C4, C3 is 4.7uf in this later revision.

 

[McIrish]

Thanks for the info Jerry. I had not seen that revision schematic. BTW - I don't want anyone to get the impression that I don't like the Maiku capsule. It's a bit different from the KM84 I have but that's OK. It has a smoother top end and bigger bottom. I was actually looking for something like that so it may work out perfect. The KM84 has a bit more upper mid push. Yes, I know everyone thinks the KM84 is flat, but out of all of them I've used, they all have a slight push that makes acoustic instruments come forward. The KM84 is great. The Maiku capsule is a little different but in a good way. I may give it a shot on fiddle as I'm always trying to tame the bow scratch. This mic might be just the thing.

I did make a bunch of quick recordings with the Bansai clone and a few other mics. let me know if anyone is interested in hearing it and I can edit it down to a few good clips to show the sound differences. Funny thing; I was half expecting the Maiku to be a bit too bright and thin. I could not have been more wrong. It's kind of the opposite. I will swap out the C4 cap when I get a chance and do a few more test recordings.

 

[Zim]

Definitely interested to hear your recordings of this Maiku mic compared to other mics. And hoping you get a chance to update with your thoughts on swapping out C4 once you’ve tried that

 

[Dylan W]

Thanks for the info Jerry. I had not seen that revision schematic. BTW - I don't want anyone to get the impression that I don't like the Maiku capsule. It's a bit different from the KM84 I have but that's OK. It has a smoother top end and bigger bottom. I was actually looking for something like that so it may work out perfect. The KM84 has a bit more upper mid push. Yes, I know everyone thinks the KM84 is flat, but out of all of them I've used, they all have a slight push that makes acoustic instruments come forward. The KM84 is great. The Maiku capsule is a little different but in a good way. I may give it a shot on fiddle as I'm always trying to tame the bow scratch. This mic might be just the thing.

I did make a bunch of quick recordings with the Bansai clone and a few other mics. let me know if anyone is interested in hearing it and I can edit it down to a few good clips to show the sound differences. Funny thing; I was half expecting the Maiku to be a bit too bright and thin. I could not have been more wrong. It's kind of the opposite. I will swap out the C4 cap when I get a chance and do a few more test recordings.

I'd love to hear some comparisons of the Maiku to other mics, especially a KM84. Would you be willing to post the clips?

 

[McIrish]

Here is the link to a comparison I did using four SDC mics on multiple instruments. I have some posts on other forums where people are guessing what mics were used. Since this is all about the Bansai KM84 clone, I will say that it is Mic D. The other three mics are very well known and I will reveal those fairly soon but I'd like others to have a chance to hear it unbiased by brand/model info.

SDC Comparisons


Signal Chain: Mics -> Daking Mic Pre IV -> Lynx Aurora -> Nuendo 11 (level matched using LUFS meter and channel gain controls. no other processing)

Guitar is a Collings 0002H - 12" from neck body joint on axis
Irish Bouzouki is a Petersen Level 2/3 - 12" from neck body joint on axis
Mandola is a Collings MT (f-fole) - 12" from lower f-hole
Mandolin is a Gibson Fern - 12" from lower f-hole
Banjo is a Deering Eagle II six string - 12" from center of the head
Piano is a Yamaha U3 - 3 feet back from the hammers, centered on the piano. Also recorded 90 degrees in each direction to show the off axis sound of each mic.

 

[TwentyTrees]

Thanks McIrish - I love that sort of test, so this is really helpful. I also love what I was hearing, so I'm definitely going to investigate Shadowfields (I assume that's your band!).

 

[McIrish]

OK... the big reveal.

A = Beyerdynamic MC930

B = Oktava MC-012 (capacitor and resistor mod)

C = Neumann KM84

D = Bansai KM84 Clone (capsule made by Maiku)

So... How did you do? And did you change your mind after seeing the answers? The KM84 IS a great mic... but it's not the only one that can give great results. I'm absolutely positive ANY of these can be used in critical recording situations.

 

[Icegoldnixon]

Anyone know how to get the capsule off? I'd like to get the body powdercoated if possible.

 

[JMan]

Anyone know how to get the capsule off? I'd like to get the body powdercoated if possible.

Turn it counterclockwise. It’s just screwed on to the threaded end of the body.

 

[Whoops]

Here is the link to a comparison I did using four SDC mics on multiple instruments. I have some posts on other forums where people are guessing what mics were used. Since this is all about the Bansai KM84 clone, I will say that it is Mic D. The other three mics are very well known and I will reveal those fairly soon but I'd like others to have a chance to hear it unbiased by brand/model info.

SDC Comparisons


Signal Chain: Mics -> Daking Mic Pre IV -> Lynx Aurora -> Nuendo 11 (level matched using LUFS meter and channel gain controls. no other processing)

Guitar is a Collings 0002H - 12" from neck body joint on axis
Irish Bouzouki is a Petersen Level 2/3 - 12" from neck body joint on axis
Mandola is a Collings MT (f-fole) - 12" from lower f-hole
Mandolin is a Gibson Fern - 12" from lower f-hole
Banjo is a Deering Eagle II six string - 12" from center of the head
Piano is a Yamaha U3 - 3 feet back from the hammers, centered on the piano. Also recorded 90 degrees in each direction to show the off axis sound of each mic.

HI Mate,
I still didn't see the results, so here are my thoughs by doing the blind test in my DAW.

A - More Mid Scooped, More HF extension. My Favourite on the Acoustic Guitar

B - More MID presence

C - More High Mid Presence. My Favourite on the Piano

D - More Lows, More Low Mids, Sounds darker than all the other ones, Less High Mids and HF. It's by far my least favourite of all.

Anyway, although there's differences any of them sound good enough to be used to do a great record. EQ would be used anyway to make it fit in the song.
My Favourites were A and C, although in different instruments.

And now I'm curious to check the results

 

[Whoops]

checked the results,
WOW The Banzai KM84 is D. Well thats not good news to me, I was expecting to do this project, but I really didn't like the sound and it's in no way similar to the Neumann KM84, it actually sounded like a cheap mic when I was listening to the files, there's no Beauty in the High Mids and Presence area, just shallow and bass heavy.
Being the circuit the same as the KM84 and the sound being so different it means there's something wrong with another component, something is not good, can be the Capsule, the transformer, the body head or a combination of these 3, but something is not right for sure.

So unfortunately this project is a no go for me any of the other mics are much better, the Oktava MK-012 is just 190€

Thank you so much McIrish for the files you saved me around 300€ that I would spend in 2 units of this project

 

[RuudNL]

checked the results,
WOW The Banzai KM84 is D. Well thats not good news to me, I was expecting to do this project, but I really didn't like the sound and it's in no way similar to the Neumann KM84, it actually sounded like a cheap mic when I was listening to the files, there's no Beauty in the High Mids and Presence area, just shallow and bass heavy.
Being the circuit the same as the KM84 and the sound being so different it means there's something wrong with another component, something is not good, can be the Capsule, the transformer, the body head or a combination of these 3, but something is not right for sure.

So unfortunately this project is a no go for me any of the other mics are much better, the Oktava MK-012 is just 190€

Thank you so much McIrish for the files you saved me around 300€ that I would spend in 2 units of this project

Unfortunately I agree with you.
I bought a pair from a previous batch, but they didn't sound anything like a real KM84.
So I sold them...