cardioid design?

[Nappylady]

If this thread needs to be moved, so be it. It just seemed that since most loudspeakers are cardioid by design, this would be a logical place to look.

I know there are omnidirectional and cardioid (directional) microphones, and I know the difference. (I know about other types as well.) I'm wondering what exactly makes a microphone decide to be directional or omni; actually, the whole reason I'm asking is because I wan to see if I can come up with some kind of slide-on adaptor to turn my $40 Behringer measurement microphone into a cardioid condenser mic for vocals, etc.

Does anyone know of any good web pages on microphone design, or have some theory to share, or something to discuss, that can help me in my quest?

Thanks in advance.

[transducer]

There are very few speakers that are cardiod by design, it's actually quite difficult to do. I've been doing a bit of research on it, because I want to try to build one, not an easy task.

Do a google search on cardiod mike designs, there's bound to be lots of info out there. I don't think you'll have an easy time modifying your Behringer.

RonS

[Thunau]

Very briefly, a microphone is directional when sound can hit the diaphragm from the front and the back. That's why you see small vents behind the diaphragm of small condenser mics. In vocal mics it all happens under the capsule. Sound coming from the side hits both sides the diaphragm with equal pressure resulting in no or little movement. By offsetting the diaphragm inside a tube you can steer or shape the pattern somewhat. The shotguns with very tight patterns have to be so long due to long offset required.

The large diaphragm vocal condensers with multiple patterns acomplish the task by using two diapragms back to back and polarizing them either in phase or out of phase or by turning one of the diaphragms off altogether. The ones with continous pattern control have a variable voltage going to the rear diaphragm resulting in it's variable sensitivity. It's not very complicated in theory, but I don't think you can simply whip up a omni to cardioid pattern adapter for your Behringer. It would require drilling holes in the housing of the mic.
Just get one of the chinese condenser mics on eBay. They're cheap and decent sounding.

[Pjotr]

Hi,

Have a look at this site:

http://home.earthlink.net/~gottapes/micdiyers/main.htm

Also do a Google search on blumlein and/or blumlein+microphones

Forget about to make an ECM8000 directional. It is basically an omni-directional pressure microphone.

Cheers

[Nappylady]

I had my eyes on some Oktava large-diaphragm condensers, 2 for $99, but they keep not being in stock at Guitar Center...

Alright, well, this tells me what I need to know. Thanks all!

[RHosch]

This thread at homerecording.com forums is an absolute must read for anyone wanting to understand what the difference between omni, cardioid, hypercardioid, figure-8, etc. microphones are, what causes that pattern, what their uses are, etc. Mr. Harvey Gerst has put a lifetime of experience into the explanations he gives. Absolutely invaluable information!

What is great about that thread is that after reading it, you will not only have the answer to your question but you'll know exactly why it is that way, and what other alternatives might be!

[Steven]

Originally posted by transducer
There are very few speakers that are cardiod by design, it's actually quite difficult to do. I've been doing a bit of research on it, because I want to try to build one, not an easy task.

Do a google search on cardiod mike designs, there's bound to be lots of info out there. I don't think you'll have an easy time modifying your Behringer.

RonS

Philips CSS (later renamed to Philips CSI) and now part of Bosch Security Systems used to have a range of cardioid loudspeaker columns. See: http://www.fulltec.be/Loudspeakers/D...LBC3053-04.pdf
You will not find the datasheet anymore on the Bosch site, since this range has been discontinued recently after some 30 (!!) years. That's why the design is old-fashioned by current standards. They have been replaced by the XLA3200 range of loudspeakers. The original cardioid loudspeakers were very popular for PA use in difficult acoustic environments, like railway platforms, airport terminals, churches, etc. Because of being cardioid they sufffered less from wall reflections and because they were columns they suffered less from ceiling and floor reflections.

Steven