Gyraf G7 with interchangeable headbasket (k47, k67, ck12, with sound samples)

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Joekkel

Well-known member
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Joined
Feb 24, 2012
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77
Location
Bern Switzerland
Hi there

I allready posted this in the official G7 help thread. The feedback is unfortunately a little weak. I would really get some feedback on my question about the sound of the CK12 capsule, as it has an immense low end / proximity effect.

I recently finished two Gryaf G7 mics with interchangeable headbaskets/capsules. For bodyparts/headbasket i used 4x this mic: https://www.musicstore.com/de_CH/CHF/Fame-Audio-Studio-CM1/art-REC0004714-000

Had to cut the pcb to fit the diameter of the body (stainless steel tube bought on ebay). A XLR conector is mounted to the interchangeable headbaskets, i even didn't need to drill new holes, as the holes in the metallplate of the headbasket fitted the XLR connector almost perfect :) The capsules are hot-swappable (loud popps happening of course).

I made 4 capsules; 2x OPR CK12, 1x generic chinese K67 and 1x chinese K47 bought from Bessneez Microphones. I always wanted to have a stereopair CK12.

If you're interested in the sound of these mics, you can have a listen to my first test recording in comparison to a genuine Neumann U87AI. I hope you don't mind bad pitch, i'm not a singer at all, i'm a tech..but singing for me is a very good way to hear, how a mic sounds in general:

https://www.dropbox.com/sh/5xo44ch128eo6kg/AAA1JzUfSc6Qux63mKmQPZFja?dl=0

There are 5 comparisons with me singing in both mics simultaneously. 4x singing a swiss folkore (i have no idea why i chose this song..), 1x speech. With the CK12 capsule i did an omni and cardioid comparison, with the other capsules only in cadioid.

I'm surprised, how close the U87 and Gyraf with K67 sound. Of course the Gyraf has more highs, as it features no de-emphasis unlike the U87. And i'm really surprised about the proximity effect and overall bass on the CK12. It' almost too much, which makes me wonder, if the CK12 in a Gyraf would benefit from a higher value output capacitor for a lighter bass. Is it normal for a CK12 capsule to have that much more bass in comparison to the K67? And i don't really care for the sound of the K47, at least on my voice.

Let's hear some feedback!
 

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Yes, CK12 is fat sounding, much fatter than k67. C12 and Elam have high value resistors of about 25Mohm rather than moddern 1Gig and up. Lower value creates a HPF in combo with capsule capacitance so you might want to try that. That could be a better option than just output cap mod because all that low end might saturate input of the tube. This is why i have several body versions for my CK12. Sometimes i use "vintage" values, sometimes "moddern".

Great material, thanks for posting the results!
 
I'm totally digging the ck12 and the k47 sound. As I already own a microphone with k67, I would love to test a k47. Where did you get it from exactly?
Personally, I would mind too much about the proximity effect, since I use microphones for spoken word.
 
Wow, I just started reading about the Gyraf and now I want to go completely down the rabbit hole. Microphones are starting to spark an interest in electronics for me, but I don't really know where to start. I am interested in doing this and the OPA mic from JJules.
 
kingkorg said:
Yes, CK12 is fat sounding, much fatter than k67. C12 and Elam have high value resistors of about 25Mohm rather than moddern 1Gig and up. Lower value creates a HPF in combo with capsule capacitance so you might want to try that. That could be a better option than just output cap mod because all that low end might saturate input of the tube. This is why i have several body versions for my CK12. Sometimes i use "vintage" values, sometimes "moddern".

Great material, thanks for posting the results!

This is EXACTLY the kind of information i hoped for! So its rather normal for a CK12 to be bass heavy in comparison to a K67/47. Thank you very much!
 
Bugmenotor said:
I'm totally digging the ck12 and the k47 sound. As I already own a microphone with k67, I would love to test a k47. Where did you get it from exactly?

Thanks for your feedback! The CK12 i bought from Open Plan Recording from Australia. Its a handmade clone capsule and has great reviews. The K47 is from Beesneez, when they sold some chinese capsules cheap here on GroupDIY. I also have a DIY U47fet with a K47 from Maiku and i really cam recommend these Maiku capsules, they do sound good!
 
Joekkel said:
This is EXACTLY the kind of information i hoped for! So its rather normal for a CK12 to be bass heavy in comparison to a K67/47. Thank you very much!


This is Tim's CK12 in a flat circuit like yours against Rode NT1 which has pretty much the same amount of low end as k47 or k67. Taken at my place.
 
Last edited:
Joekkel said:
Thanks for your feedback! The CK12 i bought from Open Plan Recording from Australia. Its a handmade clone capsule and has great reviews. The K47 is from Beesneez, when they sold some chinese capsules cheap here on GroupDIY. I also have a DIY U47fet with a K47 from Maiku and i really cam recommend these Maiku capsules, they do sound good!
Wow, all of those capsules are not so inexpensive. Wish there were people selling within my country, that would at least make things easier.
 
kingkorg said:
This is Tim's CK12 in a flat circuit like yours against Rode NT1 which has pretty much the same amount of low end as k47 or k67. Taken at my place.


l4NSaLY.jpeg

hah! yeah, thats how i feel the ck12 sounds, midscooped, but in a nice way. instruments at a distance sound nice and full, k67-based mics do sound wrong in comparison.
 
Great project, I'm planning to build one based on the k67 capsule but am not sure what transformer should be more appropiate, which one you used?
 
Then there's the recommended LL1538 transformer. Output impedance of the mic will be a bit high with this low-ish 5:1 ratio. Again, most of the time you won't hear a problem, but with some tube preamp input transformers (very low input impedance) it's going to be bye-bye-bass.

But this one is an easy fix. LL1578 is pin compatible, even same physical size, but is 10:1 ratio. There, fixed.
I used the LL1578 because of the statement above
 

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