Topic: Don't Judge A Book By Its Cover (Microphones)

[Chilly Brioschi]

FWIW, motorboating is "just" low-frequency feedback.
Instead of a squeal, you get a buzzy, poppy sound at regular intervals that sounds a bit like the "putt-putt" of an small outboard boat engine.
So the problem usually is coupling between amp stages, or more to the point, a lack of adequate decoupling.

Busman, Fred W III, ...someone.... help me out on this.... could it be that the FET amp in the mic isn't properly decoupled from input of the Pre? 

[bensyverson]

OK, if any of you are so inclined, I'd like to see pics of the internals (guts!) of these mics.

Okay, I'll bite. here are shots of the CAD. My hunch is that the Avant internals are largely the same, except with a bit of extra electronics for the pad and cut filters. Anyone care to open theirs up?









I'm anxious to see what Chris has done to the internals of his Busman mics as well...

BTW, anyone interested in Chinese mics marketed in the US should read this extremely hilarious thread on GS, in which the marketing dudes for Karma and sE Electronics get into a very public tiff: 

http://www.gearslutz.com/board/so-much-gear-so-little-time/59987-se-mics-karma-mics.html

[illconditioned]

^^^ Thanks for the great pics!!!

Waiting for the Pelusos, if anyone is able.

  Richard

[Javier Cinakowski]

That karma vs Se electronics is crazy!

Here is the Karma K10:

[illconditioned]

Keep 'em coming!  I don't judge a mic by the cover, I judge it by the guts!  Excellent...

   Richard

[bensyverson]

Anyone with some EE experience care to comment? Chris/Busman?

[illconditioned]

Anyone with some EE experience care to comment? Chris/Busman?

Comment about what?  The Karma vs CAD mics?  The Karma looks a little suspicious.  I don't mind a transformer, but I don't trust a lowend mic to have a good one.  Also, shouldn't that transformer be inside a case?  I've seen pictures of the guts of Beyerdynamic, for example, and those have a round metal case around the transformer.  Also, the Karma just looks "cheap".  Surface mount parts on the board, all electrolytic caps, thin pin to the capsule, etc.  The CAD mic looks like the standard (very old) Scheops design.  Basically a pair of (matched) transistors driving a balanced output.  Components on the CAD look a little better.  Similar to the Apex/MXL/etc mics of the same type.

I think the main question is the caps, though.  Hard to tell quality on those.  I'm not keen to taking them apart either...

  Richard

[bensyverson]

I think the main question is the caps, though.  Hard to tell quality on those.  I'm not keen to taking them apart either...

+T on that post! I'm not knowledgeable enough to see anything but a circuitboard with some components, so it's interesting to get the opinion of someone with experience.

I wonder if swapping the caps out on the CAD might be worthwhile... They're only $44 new on eBay, so it might be worth the risk (my soldering skills are pretty terrible)!

[illconditioned]

I think the main question is the caps, though.  Hard to tell quality on those.  I'm not keen to taking them apart either...

+T on that post! I'm not knowledgeable enough to see anything but a circuitboard with some components, so it's interesting to get the opinion of someone with experience.

I wonder if swapping the caps out on the CAD might be worthwhile... They're only $44 new on eBay, so it might be worth the risk (my soldering skills are pretty terrible)!

When I said "caps" I meant capsules.  That is where the quality comes from I would say.  But I don't want to disassemble these...

The CAD mics have pretty good parts (from the picture, anyways).  Nothing obvious to fix there.  Some people might are that different capacitors are needed in this place or that, but I really don't expect that to make much difference.  One thing I *might* consider is those 1G resistors, and the FET.  *Maybe* worth replacing with metal film.  I don't know.  But probably not needed.

  Richard

[bensyverson]

D'oh! Of course, the caps. The FET and resistors look sort of sketchy to you?

[illconditioned]

D'oh! Of course, the caps. The FET and resistors look sort of sketchy to you?

The resistors look sketchy.  The FET, I would have to get the part #.  They all look the same.

That said, I don't think there would be much difference with replacement.  Maybe a slight reduction in self-noise.  But not change in sound, I expect.

  Richard

[bensyverson]

Interesting... thanks Richard!

[Javier Cinakowski]

I noticed that the Karma's distort slightly with really loud bass (think Phil Lesh Bombs)...  Do you think that is due to the transformer?

[illconditioned]

I noticed that the Karma's distort slightly with really loud bass (think Phil Lesh Bombs)...  Do you think that is due to the transformer?

Yeah, probably due to the tranformer.

An interesting hack would be to put an Audio Technica transformer in there.  But really, I wouldn't bother.  Is there a low-cut switch?  Use that when recording bass-heavy shows.  Most shows have too much bass anyways, so low-cut is not a disadvantage.

  Richard

[Javier Cinakowski]

This is no hpf switch, but I only had the bass distort on a outrageously loud show.

I just took the other mic apart of the pair and the boards are a different color and there is a different part near the capsule pin.  That is strange considering they are supposed to be a match pair.....