Crazy, Pseudo 67 style tube mic, or terrible, horrible, no good, very bad idea.
- Thread starter Wordsushi
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King, thanks for doing those sample recordings and the frequency graph. The frequency plot definitely confirms the big low end bump I'm hearing on mine and the need to goose 6k. May I ask how you do your frequency readings? That's pretty cool. Also, the modded Perception is much better than I would have expected.
Sorry to hear it didn't work for your tube mic. As I've only heard this capsule on my spoken voice, it was nice to hear a drum recording for comparison.
Sorry to hear it didn't work for your tube mic. As I've only heard this capsule on my spoken voice, it was nice to hear a drum recording for comparison.
Don't take those measurements too serious, they are made in my control room, with regular two way monitor, not ideal for that sort of thing. However, that is why i have u87 and c1 as well known references( u87 flatish standard, C1 typical OEM HF hype we all try to stay away from) to compare to. I usually have a flat measurement mic there too. So if there is a dip in 6k area, not present in other mics, or a bump, or what ever, it is pretty clear mic i am measuring has that bump, or dip. Even though measurements dont look like published graphs we are used to.
U 87 has LF roll off in it's circuit, so yes compared to that 3u capsule is through the roof, but it is maybe +2 db above true zero.
I don't mind it didn't work in tube mic, it has to do with grille, that capsule is not meant to be used in u47 style body anyways. It will end up eventually in a Behringer b2 head, and then i'll use it in both tube and FET circuits. In u87 style body that dip is about 2db shallower.
U 87 has LF roll off in it's circuit, so yes compared to that 3u capsule is through the roof, but it is maybe +2 db above true zero.
I don't mind it didn't work in tube mic, it has to do with grille, that capsule is not meant to be used in u47 style body anyways. It will end up eventually in a Behringer b2 head, and then i'll use it in both tube and FET circuits. In u87 style body that dip is about 2db shallower.
FWIW, I asked Guosheng and he told me that Chris is using the Warbler 1 capsule, not the newer smooth top capsule, in the BA-67.
Man, i have been using this smooth capsule lately, tested it against everything i have, true vintage u87, it is really something special. Amazing capsule, way above it's price range. I don't think there is any capsule widely available that hits this middle ground.
Recording Engineer
Well-known member
Wordsushi said:
Makes a lot more sense... He’s been doing those BA-67s for some time now and these capsules seem to be brand brand new.
kingkorg said:
Something special is right. It really is wild how great this capsule sounds.
dmp
Well-known member
I'm not sure what a flat U67 style capsule is. Isn't that just a U47 capsule?
Maybe you guys all know this, but there are flat capsules (47 & C12) and high freq boost capsules (u67).
Both the C12 and the U47 & M49 style circuits were flat freq response. The key capsule distinction was C12 style are edge terminated and U47/U67 are center terminated. In my opinion, cheap Chinese copies of edge terminated style do a better job than center terminated, in comparison to boutique capsules, like Theirsch (47) or Tim Campbell (12).
The U67 however had a filter rolling off the highs to restore a flat response after using the high boost capsule. They did this to reduce the white noise of the mic.
You can obviously mix and match flat capsules with flat circuits. I would not match a flat capsule with a U67 circuit without removing the high filter. And I would not put a 67 style capsule with +10db at 15kHz in a flat style circuit. Unless you want a really bright mic.
The other key feature of the different mics is in how they bias the tube. The C12/251 uses a cathode resistor with a bypass cap, the U47 uses the heater current to make a stiffer cathode resistor without a cap, and the U67 uses a negative heater voltage to set the bias and ground the cathode directly. The M49b used the U47 method, while the M49c used a cathode bypass cap (C12). The capsule bias in my opinion imparts a distinction to the mic sound that is hard to describe but easy to hear.
Building mics is a ton of fun and mixing and matching these characteristics is really cool. You'll be able to hear the difference.
Maybe you guys all know this, but there are flat capsules (47 & C12) and high freq boost capsules (u67).
Both the C12 and the U47 & M49 style circuits were flat freq response. The key capsule distinction was C12 style are edge terminated and U47/U67 are center terminated. In my opinion, cheap Chinese copies of edge terminated style do a better job than center terminated, in comparison to boutique capsules, like Theirsch (47) or Tim Campbell (12).
The U67 however had a filter rolling off the highs to restore a flat response after using the high boost capsule. They did this to reduce the white noise of the mic.
You can obviously mix and match flat capsules with flat circuits. I would not match a flat capsule with a U67 circuit without removing the high filter. And I would not put a 67 style capsule with +10db at 15kHz in a flat style circuit. Unless you want a really bright mic.
The other key feature of the different mics is in how they bias the tube. The C12/251 uses a cathode resistor with a bypass cap, the U47 uses the heater current to make a stiffer cathode resistor without a cap, and the U67 uses a negative heater voltage to set the bias and ground the cathode directly. The M49b used the U47 method, while the M49c used a cathode bypass cap (C12). The capsule bias in my opinion imparts a distinction to the mic sound that is hard to describe but easy to hear.
Building mics is a ton of fun and mixing and matching these characteristics is really cool. You'll be able to hear the difference.
dmp said:
Guosheng have three different types of k67 if i remember correctly. Other like edge terminated k67 called ck12
D) and k47 at least two different type of tuning. Didn't tested that "flat" k67 but i wouldn't be surprised if it would be similar to well tuned Chinese k12. Not so long time ago i modified AKG perception/Superlux (don't remember all these Chinese factories names) one sided k67. 4dB lower of HF boost fitted my needs to use it in tube microphone for guitar cabinets.
