Condensers: Good vs. Bad

Discussion in 'Microphones' started by asknone9, Oct 25, 2009.

  1. asknone9

    asknone9 Guest

    Alright, there is some technical stuff I would very much like to understand, but the information I've found so far doesn't seem to do any one explanation justice. I'm going to use Audio-Technica mics as sort of the reference for examples here, as the AT's and Blue Mics comprise all of what I own in the condenser world. Now, I've have been told many things in regard to distinguishing a cheap condenser from higher quality ones. Some of these characteristics include smaller diaphraghm capsules, tranformer circuitry, and polarization methods. In every aspect there is another mic contradicts any of these things.

    For example, the AT2020 has a 3/4" capsule. Standard size is about 1" for a large diaphragm from what I've gathered. Two examples tell me that size alone doesn't make it bad quality: 1) The KSM32, which seems to be pretty highly regarded. 2) SDC mics are certainly not of lesser quality because of their smaller diaphragm, they merely have a different transient response.

    I've also been told that transformers are found in cheap condensers. Well, the only thing I've come to understand about transformers is that they allow a signal to travel through longer cabling more effectively. Not to mention the Blue Mouse has a transformer, is not cheap, and sounds awesome. Blue did make a transformerless Mouse though? Why would this be beneficial. Is there distortion involved?

    Now, specifically with AT mics, the lower end 20 series condensers have this listed under Element: Fixed-charge back plate, permanently polarized condenser. The 40 series condensers have this listed, excluding the 4033: Externally-polarized (DC bias) condenser. The 4033 has the same element as the lower end mics. However, I find that 4033 has a nice reputation too. What I've heard in regards to this element thing is that the first element listing (fixed-charge back plate, permanently polarized condenser) can lose its polarization over time, degrading the sound. Has anyone with a 4033 noticed this? I haven't. Is it even relevant? How do these two different elements really differ? In addition to that, Blue lists their transducers as "pressure gradient." Is this another name for what AT does, or something completely different/unrelated?

    Finally, what is your opinion/factual knowledge on the differences between low quality and high quality? I know this is a lot of information, but I needed to collect my thoughts somehow. Please keep in mind that none of these questions above are to inspire analysis alone; I actually don't know, or I'm not sure, so whatever you can give me, go for it.
  2. Boswell

    Boswell Moderator Distinguished Member

    Home Page:
    The designer of a capacitor (condenser) microphone has a lot of parameters to juggle with. The size of the diaphragm determines largely the usage to which it will be put. The AT4033a is an MDC (medium-diaphragm condenser), and so, in principle, finds a greater application area than either LDCs or SDCs. In practice, it's difficult for an MDC not to inherit the disadvantages of both its larger and smaller brothers and not make up for it in advantages. The 4033a is one of the very few that pulls this off.

    Another design decision is whether to use a permanently-polarized capsule or a powered one. Provided the designer has done his job well, there should be no audible difference between the two, and you are looking at things like possibility of fall-off in charge retention against ability to run off a 9V battery (as power is only required for the output buffer) when considering whether to give any weight to this property.

    As for transformer versus non-transformer output, again this is a matter for the designer. It's probably more expensive to use a good transformer rather than capacitor blocking of the phantom power coupled with FET buffers for impedance-changing, and a transformer will be one factor in giving a microphone its characteristic sound.

    The purchaser may have his or her own views about wanting a transformer-less mic, but ultimately it should be the overall sound, polar response, robustness and similar factors that should determine which models of condenser mics are used for what purpose rather than the microphone's internal design choices.
  3. asknone9

    asknone9 Guest

    Thanks Boswell. That clears things up some more for me. Would you say that in the common studio, the choice to use a transformer would be more based on sound coloration than its specific ability to increase the distance a signal can effectively travel?
  4. Davedog

    Davedog Distinguished Member

    Pacific NW
    Bos pretty much summed it up in saying the perogative of the designer is usually what determines the use of a transformer in a capacitor mic.

    I dont find most manufacturers building studio specific microphones to be overly concerned with transmission distance issues rather than sound quality as well a distinctive sound signatures.

    Some of the best mics in the world do not use transformers in their design while on the same hand the very same company offers models that very much are based around the transformer.
  5. Boswell

    Boswell Moderator Distinguished Member

    Home Page:
    It's only badly-designed mics that would have any issues with driving cables up to several hundred metres, and so that factor should not come into your quest for a good microphone.

    As for output transformers, manufacturers of high-end microphones may have several product lines, some being transformer-coupled and some not. The Neumann U series and the TLM series is an example here (although there are transformerless models in the U series).

    I suggest you concentrate on the overall external properties of the microphone, particularly how it sounds in your application (guitar cabs, female vox etc). Choosing a sound you like at a price you can afford will automatically choose whether the mic has a transformer-coupled output or not.
  6. asknone9

    asknone9 Guest

    Thanks again guys. I just wanted to be certain. With the information I've been presented with until now, I've been lead to believe that one is staunchly favored over the other. Yet again, though, I am realizing that it's really the preference of the individual using the equipment, and sometimes the skill to work with what is presented to them. In any case, then, quality is quality.
  7. rmburrow

    rmburrow Active Member

    western PA
    If you make a recording at a venue located near the antenna of a broadcast station, you will be thankful your condenser mic has an output transformer. High RF fields from a AM, FM, or TV transmitting antenna can interfere with a lot of equipment, and the P-N junctions in solid state circuits are natural rectifiers. (The "old-line" term for this type of interference is "Audio Rectification".) A good transformer (like a Jensen, the old WE and Peerless, some UTC's) will stop RF, and are essentially transparent to audio. My gear box includes several UTC LS types wired 1:1 for blocking RF interference on mic lines in particular. Certain items at a venue can also generate electrical interference, and recognizing and treating the interference "before the tape rolls" is a skill obtained primarily on remote in the field. Be extremely careful with grounding (equipment grounds, ground loops, etc.).

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