1. Register NOW and become part of this fantastic knowledge base forum! This message will go away once you have registered.

Do I need a pre-amp, question from an on the fly novice

Discussion in 'Recording' started by Joshu, May 2, 2005.

  1. Joshu

    Joshu Guest

    hello out there,
    just discovered this great forum. I have a iriver ihp 120 (the old model) which records in compressed and uncompressed formats. Its not too bad considering its just an extra feature on the mp3 player.

    Anyways, I am about to buy these mini binaural mics. I was wondering if binaural mics require a preamp with phantom power or if i can plug them right into the line in (iriver has a special line in for mics). The binaural mini mic im considering is the 139 dollar model on soundprofessionals.com. Im not sure what they are technically called.

    I am looking mostly to record acoustic performances on the go (ensembles (chamber quartets etc) and acoustic guitar/vocals live. I know it will not be very good quality but it doesnt need to be. Thanks in advance.
     
  2. bowmandj

    bowmandj Guest

    From the soundprofessonals site at url they show the only 139 dollar model

    http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?item=SP-BMC-6&type=store

    so I assume that you are referring to the SP-BMC-6.

    If this uses two Audio Technica AT803b lavalier mics

    http://www.audio-technica.com/cms/wired_mics/ae531e7972b44137/index.html

    If the product does truly use two AT803b then the spec at the At page says that it needs phantom or battery. It also says that this power is supplied by a power module (see the At spec it has the dimensions of a power module at 5 ounces and with a three pin standard XLR). This power module will basically convert the lightweight lavalier and fine lead into a standard xlr mic interface. Thru this interface is a balanced xlr and phatom or battery handling.

    That is a standard AT803b.

    However looking at the picture of the SP-BMC-6 on the soundprofessionals page they show the two lavaliers connected together into a single small (3.5 mm) stereo jack !!!

    So I don't think that these are AT803b but the AT803cb which is the AT803 with unterminated lead. Then someone has wired the two AT803cb mics into a single stereo plug.

    So these mikes will need power from somewhere (like most computer sound card electret mics).

    The soundprofessonals site talks about power in its info pages.

    http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?category=binauralinfo
    http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?category=batteryfaq

    But is not specific about power modules, just talks about them. An assumption has been made that the sound card, into which you are plugging this mic, will provide the DC bias voltage on both channels (a sort of pseudo phantom). Certainly the AT803, being a condenser mic, will need power.

    I would suggest that you contact their tech support before you buy, in case your sound cound mic input socket does not provide the right DC bias in the right way for this mic. If not then you may have to consider a battery model that is appropriate for this particular wired model.

    Looking at the page for the single AT803 variant from soundprofessionals

    http://www.soundprofessionals.com/cgi-bin/gold/category.cgi?item=AT803-SP&type=store&template=specifications

    they give a pull down box for power options, and one of them is a 49 dollar battery box. for mono (or maybe stereo). Check with the soundprofessionals tech support.

    regards

    db
     
  3. bowmandj

    bowmandj Guest

    Looking at the ihp spec http://www.iriveramerica.com/images/pdf/iHP-120EngManual.pdf it seems that it uses an internal mic for dictaphone recording and the line jack for external source (whether line input or external mic).

    I don't believe that the same socket can be a line jack AND a mic jack with a DC bias for mic. Normally two seperate sockets are put onto a PC sound card, one for mic and one for line.

    So I think that you will need a power module/pre-amp to make the binaural pair of AT803's work into that system.

    regards

    db
     

Share This Page