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Subject: RE : my facts on mics
From: Henri David (hdavid_at_mail.com)
Date: 2002-10-21


Well as i said, if you leave the gain to zero while recording, and
instead use an external amp it's ok. I have the feeling that the build
amp amplify more electronic noises than the actual signal...

henri

> -----Original Message-----
> From: owner-rockbox_at_cool.haxx.se
> [mailto:owner-rockbox_at_cool.haxx.se] On Behalf Of Justin Fisher
> Sent: Monday, October 21, 2002 8:57 PM
> To: 'rockbox_at_cool.haxx.se'
> Subject: RE: my facts on mics
>
>
> I think I've noted this before, but I don't imagine everyone
> saw - I rerouted the line-in wires in my recorder through the
> battery compartment, thus shielding them from the archos
> circuitry and HDD (the wires are unshielded and travel the
> length of the case, right up against the circuitry). This
> resulted in the removal of the interference from the archos
> operation and disk spins. Hopefully later model recorders
> have shielded wires now, but if you can hear interference in
> your recordings that corresponds with HDD spins, shielding or
> rerouting the line-in wires seems to be an easy and fairly
> effective fix.
>
> -----Original Message-----
> From: Henri DAVID [mailto:hdavid_at_mail.com]
> Sent: Monday, October 21, 2002 2:04 AM
> To: rockbox_at_cool.haxx.se
> Subject: RE: my facts on mics
>
>
> hello,
>
> I tried the Sony ECM 907 with the archos. you need a preamp.
> I made one using one of those http://www.velleman.be/ kits +
> two 9v batt. http://www.velleman.be/Product.asp?lan=1&id=8982
> I put it in a plastic box with one on/off switch in in and out plugs.
>
> The quality is ok as long as you leave the amplifier level to
> 0 on the archos. (this integrated amp is way to loudy if you
> increase the gain !) you can check the quality of what I get
> there :
> http://www.cs.helsinki.fi/u/tkt_davi/photos/2002-04/13-labas/l
> abas01-LQ.mp3
> http://www.cs.helsinki.fi/u/tkt_davi/photos/2002-04/13-labas/l
> abas02-LQ.mp3
> http://www.cs.helsinki.fi/u/tkt_davi/photos/2002-04/13-labas/
> (I reencoded them in lower quality, for internet purpose, but
> can still get an idea about the quality) don't pay attention
> to the saturation, that was my fault I set the level to and
> didn't reduced it ! (BTW Archos Firmware VU meter are quite
> precise as they showed me the clips !)
>
>
> Hope it helps
>
> henri
>
>
>
>
> > -----Original Message-----
> > From: owner-rockbox_at_cool.haxx.se
> [mailto:owner-rockbox_at_cool.haxx.se]On
> > Behalf Of Uwe Freese
> > Sent: Saturday, October 19, 2002 14:24
> > To: jimg
> > Subject: my facts on mics (was: Microphone)
> >
> >
> > Hello jimg,
> >
> > jimg wrote on Saturday, October 19, 2002, 12:58:07 AM:
> >
> > j> You're mixing apples and oranges here. The battery for the
> > j> microphone provides -phantom power- to drive the
> condensor; It does
> > j> not
> > "amplify"
> > j> the signal coming out of the microphone. This mic is a
> pro-level
> > j> mic,
> >
> > I think this is also wrong. Three possibilities:
> >
> > - dynamic mic, this mic doesn't need power
> > - electret condenser: this capsule has a FET inside and
> needs power
> > (>1,5V). Mony mics of this type exist, and they usually
> have a battery
> > inside. This power is not for amplification!
> > - condenser: this type needs the phantom power (48 V). This
> also is not
> > for amplification.
> >
> > Amplification:
> >
> > - dynamic mic has a greater output volume
> > - both dynamic and condenser mics need an amplifier to
> connect them to
> > the AJB line in, but maybe different types
> >
> > "Mic boxes":
> >
> > - many of them only provide the battery power. No amplifier
> inside. But
> > sold for much money. :(
> > - What I want (for ajb) is a box that
> > - gives the power for an electret condensor capsule / mic
> > - amplifies
> > - needs only a battery (9V)
> > - I soldered this type with a simple operational amplifier
> > and this costs < 5 ?
> > - one can built better boxes with better amplifier ICs
> inside (see the
> > german magazine c't 20/02, page 228, ~ 100 ?)
> > - minidisco.com: I think they are very expensive and I
> don't think that
> > these battery boxes are worth the money
> >
> > Mic types:
> >
> > See
> http://arts.ucsc.edu/EMS/Music/tech_background/TE-20/teces_20.
html
>
> I think the best for recording a concert would be a one-point stereo
> mic with mid-side technique. And the Sony ECM 907 is the cheapest
> I've seen (~ 100 ?).
>
> Bye, Uwe.
>
>



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