Inexepensive SDC on blowout 33€ (Avantone CK1/MXL 603)

[kingkorg]

I just found graph, this response of Avantone CK1 hc capsule confirms what my measures show in average. There is that bump below 1K Magneto noticed, and it is broader than it seems in my graph. And that 6-7K peak.

 

[RuudNL]

I expect my SubZero microphones coming Monday.
So: from what I read it seems impossible to put the knobs on the slide switches back when you have removed them?  :-\
Are they glued?

 

[Khron]

Looks like there's SOME lighter-coloured residue on them - at least on those bits that stick out the ends.

https://groupdiy.com/index.php?action=dlattach;topic=67447.0;attach=54957;image

So: from what I read it seems impossible to put the knobs on the slide switches back when you have removed them?  :-\
Are they glued?

 

[kingkorg]

I dont think they were glued, came easily off. There has to be a way to put them back, i just didn't figure out how. Didn't try too hard either.

Black caps slide onto them sideways.

Now that i think about it, maybe place black caps into holes in blue flange, point them downwards so that they stay in place, slide in pcb under an angle and just twist into propper position.

 

[RuudNL]

Yeah, that is what I thought I would try.
Especially because it seems the knobs are bigger than the holes.
They did it at the factory, so it should be possible.
As my old dad used to say: They did put it together, so it must be possible to take it apart, and vice versa!

 

[kingkorg]

Anyone has an idea where we could find these grilles without capsules?

 

[kingkorg]

I managed to get rid of that 7K boost. It is the grille that is causing it, so i got rid of it on one of the capsules with angle grinder. It was causing resonance on 'S' sounds. However, grille is also attenuating area above 7k, so while that bump is gone 10K area and above is getting boosted. See the picture.

Green is stock mic, Red is without front grille. Flat circuit

Green looks flatter, but it isn't. Due to my room and speaker imperfections, tah area around 6K is actually a boost. When i look at waterfall i see that 7K is actually resonating, and ringing. With modded it's gone. 

 

[kingkorg]

Now. We have that huge 10K and above boost. That's where HF attenuation in the circuit kicks in.
Blue is no grille with HF attenuation. Green is stock microphone.

Stock mic
https://app.box.com/s/u548ikzo20ezcn3rxuhx1kuhwbi01lts

Modded mic
https://app.box.com/s/onwa721pv13qelfqhn4aw7pj60fi88cd

Takes are normalized, modded mic seems louder as high end is under control, and more low end comes through.

 

[kingkorg]

And special treat as Neumann u87 is still with me:

Neuman u87
https://app.box.com/s/07093fmf165emlqau76gx2b8wey3levq

SubZero with full mod:
https://app.box.com/s/r1x4vab5oizs9hs3vk5q8247y06uzk2v

 

[e.oelberg]

what about an adapter to mount gefell nickel capsules, it could be a great combination

 

[kingkorg]

That would be awesome

Here is capsule without grille, doesn't look pretty, but since i have 4 it provides more options.

 

[Marik]

Yes. High end is stock roughly in between  modded and C1.

I am really sorry for graphs looking like this, it's very, very, rough way of just presenting what is going on. I simply do not have time to move speakers, change the room, it would be too time consuming.

However i think i found the ultimate, and possibly easiest way to flatten out capsule response.

I tried varying almost all the elements of one of the capsules today. Closed holes, used thicker spacers, even put thin mylar dot between membrane and backplate to simulate center termination,  I thought i could widen the holes, but just before that i found an element that directly impacts response of high end, with little to no effect on polar pattern.

It's these copper washers between metal and plastic backplates that determine volume of the air chamber. There is two of them. Remove one of them, and you get instant hi end boost and crazy 7K peak. I added one washer made of thinnest paper  i could find today, everything up to 5k boosted for about 5db, i got -3db bell cut at 7KHz, and rest of high end remained at the same spot. That would say i got -5db of very linear HF reduction with no roloff, and additional cut at very harsh sounding spot.  And yes, it was actually boost, so capsule sensitivity improved. I guess membrane is too dampened by stock chamber? Just guessing.

By the way, this is all in a flat, stock mic, without modded circuit.

However i think that is too much, as the capsule isn't so bright. This paper washer brought it into Oktava MK319 without HF disk world.  I just want to make it as flat as possible, and flatten out that 7K peak it seems to have. I will experiment, and give you feedback. Shame i dont have a micrometer.
It seems that this backplate is exactly what Marek was tweaking. Just by looking at the picture of his mod.

Hi Kingkorg,

My two main issues with that capsule were lack of good and deep low end response and hyped top response.
It is very tricky to tune aperiodic type of capsules--we have damping and resonant system together (which contradict each other) right behind the diaphragm. Any of the parameter a little off and we get all kinds of frequency anomalies. A good example is KK67/87 capsules. While there is a talk about their 'intentional boost', in reality it is just easier to leave the boost there and deal with the problem with electronic EQ. Of course, in mass production it is very attractive--it is much easier and cheaper to make two back plates for 2-chamber design than three for 3-chamber one.

What I did with that capsule was I converted it into 3 chamber, so I could adjust the damping on the diaphragm and resonant chamber independently. It takes HUGE amount of time and work to fine tune a capsule and find correct parameters...

Best, M

 

[MagnetoSound]

I can't help but wonder why this is so difficult. Why does the AKG CK1 (series) sound so good?
If you take it apart there is nothing to it!

(Or the other screw-on capsules from Calrec, etc?)

 

[ln76d]

Anyone has an idea where we could find these grilles without capsules?

Alieexpress, chinese bottle mics - you will have to make adapter.

I can't help but wonder why this is so difficult. Why does the AKG CK1 (series) sound so good?
If you take it apart there is nothing to it!

(Or the other screw-on capsules from Calrec, etc?)

Why - because it use different backplate pattern.
Some MBHO capsules also use similar backplate design and they sounds really good.

 

[kingkorg]

Awesome. Thanks Marik, and rest if the crew.

 

[MagnetoSound]

Why - because it use different backplate pattern.
Some MBHO capsules also use similar backplate design and they sounds really good.

I suppose we can only guess at why the Sub-Zero guys chose this pattern then ... easier to produce?

 

[DjaiTeam]

@Kingkorg
Look on evilbay or aliexpress for the BM8000 mics models.

 

[Marik]

I can't help but wonder why this is so difficult. Why does the AKG CK1 (series) sound so good?
If you take it apart there is nothing to it!

All ingenious is simple. While it looks like there is nothing to it, I am sure there are hundreds of hours of very intense R&D into it. The main problem is there is no good and precise way to model it and simulations could give you only approximate ballpark, so there is a lot of empirical work involved. That needs whether a good team of machinists, or CNC. All of the holes, their number, their sizes, all of the chambers, all spacings, all thicknesses, etc. are very precise. Everything works as one system. You change the number of holes in one place, you should compensate at another. Those CK1 capsules were designed and made when there were no CNC machines, yet, so everything was done by hand. I am sure AKG had a good team of machinists to make all those changes and they went through hundreds of back plates and combinations of different spacers, sizes, etc. before all the parameters fell into right place.

Sure, it looks simple and as if there is not much into it. On the other hand, for example, look at the holes in that standard Chinese capsule--there are only 12 of relatively large diameter. On the other hand the CK1 has much more holes and their diameter is much smaller, so we need to spot the holes first, we need to feed the drill much slower, and we probably need to peck the holes. Smaller diameter means there is much bigger problem of tool breakage. Also, smaller capsule diameter means harder to hold the piece while drilling.

Just judging by machining time--that would take about 30 sec the most to drill out that Chinese capsule and some good 5-10min just for the front backplate alone on the CK1. Pay attention, the second backplate of the Chinese capsule is molded, so production cost probably somewhere a few pennies or so. The all other hardware probably made by a screw or Swiss machine, so also costs pennies on the large production scale. My guess, if that Chinese capsule was sold at wholesale for a couple buck a pop they probably still make about 100% profit.

Best, M

 

[MagnetoSound]

Sure, it looks simple and as if there is not much into it. On the other hand, for example, look at the holes in that standard Chinese capsule--there are only 12 of relatively large diameter. On the other hand the CK1 has much more holes and their diameter is much smaller, so we need to spot the holes first, we need to feed the drill much slower, and we probably need to peck the holes. Smaller diameter means there is much bigger problem of tool breakage. Also, smaller capsule diameter means harder to hold the piece while drilling.

Just judging by machining time--that would take about 30 sec the most to drill out that Chinese capsule and some good 5-10min just for the front backplate alone on the CK1. Pay attention, the second backplate of the Chinese capsule is molded, so production cost probably somewhere a few pennies or so. The all other hardware probably made by a screw or Swiss machine, so also costs pennies on the large production scale. My guess, if that Chinese capsule was sold at wholesale for a couple buck a pop they probably still make about 100% profit.

Best, M

Yeah, that's kinda what I figured. Designed to be manufactured as quick and cheaply as possible (China) as opposed to designed and built to a standard (AKG) ... ultimately, we are lucky to get anywhere close by fettling alone, aren't we?  Judging from the graphs, I think kingkorg has done pretty well.

 

[kingkorg]

I gave up modding internals of the capsule for now. I played with spacers, and even tho its easy to disassemble, fiddling with spacers gave very inconsistent results.

Interesting thing is that middle bars of grille when plucked ring exactly in the 7K area

Next thing i will try to do is make honeycomb pattern grille like on km84 capsule and see what will happen. Or try to use the same pattern as stock , but make bars out of something else that doesn't ring.

It is Alctron TK130 we are after for detachable grille. I contacted them, hopefully, they will sell only that.