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Subject: Re: External Mic preamp?
From: BlueChip (
Date: 2004-09-08

Why not copy the circuit from the Archos pre-amp and then let some
electronics guru say
"nah, you wanna do it like this"?

At 22:54 07/09/04, you wrote:
>hey... _you_ are limbus :-P
>anyway, i have tried quite a nice, small preamp which seems to be from
>velleman ( which amplifies quite a bit too
>i could try finding or drawing the schematic. It's spec'd to work at 9-27
>volts. But now I'll just sleep :)
>On Tue, 7 Sep 2004 23:25:32 +0200, Manuel Dejonghe <>
>>me too I am currently making some experiments with that.
>>The main problem is, as you already recognised, this is a line in, and
>>not for mics.
>>I bought an electret condenser microphone from sony (ECM-TS125) which
>>already has some kind of preamp. Unfortunately, this preamp is rather
>>a driver for the ecm. A normal ecm without that element would be very
>>weak on a mic in too.
>>I hoped, this element would raise the level high enough to get it
>>working on the line in. And it does, but still not high enough: If I
>>set up the gain to the max (+19,5 db) I still can normalize the
>>recorded file without having to cut out the peaks.
>>There are many preamplifiers, but not so much that are battery
>>powered, which is a not negotiable option for me.
>>There are some within high-professional-range with balanced xlr-plugs
>>as well as a digital breakout, but that's not what I need. Ok, it
>>would be fine, but it makes it not affordable anymore.
>>There are some around 50-100 euro on ebay, even within semi-professional
>>One of the cheapest solutions (30 euro) seems to be to buy the archos
>>microphone, which has a real amplifier and seems to be of a fair
>>quality, see the list for more comments.
>>I'll let you know if I am making progress.
>>One option is to design a small circuit myself. I'm not good with
>>that, but it may be the cheapest solution that meets my needs. I don't
>>specially need high quality.
>>regards, Manuel
>>On Tue, 7 Sep 2004 15:06:40 -0400, Shervin Riahi <>
>>>Hey guys, I have a nice sony stereo microphone, but I notice (with
>>>much dismay) that it barely picks up any sound when I use it to record
>>>via my AJBR (running today's daily build). As a control, I plug my
>>>_headphones_ into the same port (the Line In socket), and voila, the
>>>device receives sound input and I can record (albeit at a very poor
>>>quality level). As such, I guess I need to buy some sort of preamp in
>>>order to boost the incoming signal, right? Any suggestions on an
>>>affordable one?
>>>Thanks in advance!!
>Ronald Teune
>= 1/2 *


Page was last modified "Jan 10 2012" The Rockbox Crew