AKG C3000B 5 min mod - Awesome mic!

[Paul W]

Does the C3000B electret capsule have similar desirable off-axis properties to a true CK12, or does it only sound good on-axis? Does it have any extra complications to its chambering/delay network compared to other cheapish capsules? Is this a poor person's CK12, or just a nice sounding mic in its own way?

Has anyone measured the off-axis FR?

(Maybe that was addressed in whatever MagnetoSound linked to in post #20, but that link is dead now.)

[Edited to add: I'm similarly interested in whether the C 214 has good off-axis performance. It seems that whether it's an electret is less important than the chambers, damping etc.]

BTW in Eargle's The Microphone Book, he says about electrets that "The material is virtually the electrostatic equivalent of a permanent magnet, and if a capacitor backplate is coated with one of the newer electret materials, the resulting microphone will have the same performance characteristics as a standard capacitor capsule with an effective polarizing value of about 100 V."

If that's true, it makes me wonder why anyone bothers with external polarization. Is it that it's hard to make an electret as microscopically flat and rigid as a piece of brass?

 

[cyrano]

I've been told it's hard to make electrets with a large diaphragm...

Besides, some electrets slowly lose their charge over the years. Heat was mentioned as a cause.

 

[kingkorg]

I've been told it's hard to make electrets with a large diaphragm...

Besides, some electrets slowly lose their charge over the years. Heat was mentioned as a cause.

Myth for the most part. This AKG one is electret, and large. I have some 70's Primo capsules, with same diameter as new ones, and they have the same output, so no charge loss, at least with good ones. Even if it got lost, nothing wrong with applying polarization voltage and using them as externally polarized.

 

[micolas]

Myth for the most part. This AKG one is electret, and large. I have some 70's Primo capsules, with same diameter as new ones, and they have the same output, so no charge loss, at least with good ones. Even if it got lost, nothing wrong with applying polarization voltage and using them as externally polarized.

I did some crazy tests. I applied external voltage to a medium electret capsule in a new T.bone (I did not exceed 35v) I was hoping for a significantly higher capsule output level and better SNR (of course with compromises in THD and headroom). It works , but the differences are not as big as I expected.

 

[cyrano]

Well, I have dozens of small diaphragm electret mics that have more hiss today than what I remember from when I got them years ago...

Of course, my ears also deteriorated, and I have no reliable measurements from when they were new.

And other components could cause that too, but these capsules are super simple. Just one FET, one resistor and one cap. I'm not gonna replace internal FETs, and I don't know if there's any mic in there that has an external FET.

 

[kingkorg]

I did some crazy tests. I applied external voltage to a medium electret capsule in a new T.bone (I did not exceed 35v) I was hoping for a significantly higher capsule output level and better SNR (of course with compromises in THD and headroom). It works , but the differences are not as big as I expected.

Maybe you applied wrong polarity. Depending on the capsules baked in charge, you might need negative voltage.

 

[micolas]

Maybe you applied wrong polarity. Depending on the capsules baked in charge, you might need negative voltage.

Many years have passed, I don't remember, but I think I also tried the inversion of the external voltage. I think I had too high expectations and gave up quickly

 

[k brown]

The oldest electrets did lose their charge over time. Since the development of 'back electrets', the loss is insignificant.
https://www.soundonsound.com/sound-advice/q-are-back-electret-mics-any-good

 

[micolas]

The oldest electrets did lose their charge over time. Since the development of 'back electrets', the loss is insignificant.
https://www.soundonsound.com/sound-advice/q-are-back-electret-mics-any-good

For decades I read Paul White and SOS. I didn't agree with him on some of the reviews, but now I'm going to agree with him

 

[k brown]

For decades I read Paul White and SOS. I didn't agree with him on some of the reviews, but now I'm going to agree with him

Indeed - quoting facts and science is quite different from writing a product review.

 

[RoadrunnerOZ]

Does the C3000B electret capsule have similar desirable off-axis properties to a true CK12, or does it only sound good on-axis?

Looking at the polar response diagrams for both the C12VR and the C3000b it would appear the C3000b has better off-axis HF response compared to the CK12 capsule in the C12.
C3000b:



C12VR:

 

[kingkorg]

Looking at the polar response diagrams for both the C12VR and the C3000b it would appear the C3000b has better off-axis HF response compared to the CK12 capsule in the C12.
C3000b:
View attachment 121885


C12VR:
View attachment 121886

C3000b is a hypercardioid capsule, c12vr is dual cardioid. So it makes sense.

C3000 with dual capsule has the same HC capsule + OMNI! capsule on the top. When turned to cardioid mode the omni capsule signal is added to HC capsule at reduced level, just enough to push the HC towards cardioid.

 

[CarlosDIY]

I have a c3000B from many years ago..Is the c303 mod still worth doing? Or Is it the same as taming the highs through mixing desk/post eq?
Anyone ore/post mod comparison audio files?

 

[RoadrunnerOZ]

I have a c3000B from many years ago..Is the c303 mod still worth doing? Or Is it the same as taming the highs through mixing desk/post eq?
Anyone ore/post mod comparison audio files?

I would suggest just trying your hand at the mod and see what you hear as a difference. It’s easy to do and undo - you could even include a dip-switch to switch the mod in and out. You will never get exactly the same results from post EQ but that also depends on the system EQ you have as well.

 

[kingkorg]

I have a c3000B from many years ago..Is the c303 mod still worth doing? Or Is it the same as taming the highs through mixing desk/post eq?
Anyone ore/post mod comparison audio files?

If you make this curve, and invert it, it would be the same as removing the cap. Like Roadrunner said, you would have to make exact same curve.

https://groupdiy.com/threads/akg-c3000b-5-min-mod-awesome-mic.67911/post-862995

 

[RoadrunnerOZ]

Edited to add: I'm similarly interested in whether the C 214 has good off-axis performance. It seems that whether it's an electret is less important than the chambers, damping etc.]

Once you get to a certain off axis angle on any mic vocals will sound way different. There is a distinct although arguably slight difference between the two mics (414 & 214) in the top end, but having used both types over many years and also all versions of the 414 they are both still great sounding mics.
If you look at my post #111 it has the polar diag for the 3000B
It’s down to the sound with any mic and what it’s used for - specs on paper are all very well but they never tell you what a mic will sound like and what it’s best used for - I’ve experienced a great mic not working with certain guitars/vocalists/other instruments and yet a cheap one doing a great job, which is why it’s always good to have a choice of mics in a studio - you can never tell. A lot of vocalists I’ve worked with have their own mic they bring to a session that they know works with their voice. I’ve used the budget AKG Drum mic kit and got really good drum recordings in a client’s home studio - purpose built proper studio excavated under his house but without a big budget for gear.
C414 XL II:


C214:

 

[gearhunter]

Does anyone now if C3000B circuit fits C414 B XLS body? I have a spare one that I would like to use but if it is not possible I'll be selling it

 

[RoadrunnerOZ]

Does anyone now if C3000B circuit fits C414 B XLS body? I have a spare one that I would like to use but if it is not possible I'll be selling it

The boards have a different footprint and the switches are in different positions. You could with a bit of modification get one to fit as long as it’s not wider than the interior space of the 414 but the switch holes for switches the 3000B does not have and in a different position will be open and allow dust etc to leak in over the PCB and would need to be sealed. Those switches in the wrong positions in the 3000B are different to the 414 XLS ones and would also need access to operate. Bit of a butcher job to get it to work.

 

[Johnny1234]

Thank you Kingkorg. Just did the mod to my C3000B and it is night and day difference for the better. Capacitor was easy to remove with a piece of chem wick. Advice to anyone doing the mod make sure the screw just above the xlr connector is very secure or the mic will hum when cable is moved. Also the two screws that hold the basket are best removed and tightened with a 99-22 allen wrench.

 

[Riley Casey]

At the bottom of the first page of this thread a link to a document was posted describing the differences between the various models of C3000s but the link is dead. Does anyone have this doc or a new link for it?

http://www.silentway.com/recording-tricks-akg-c-3000-mic