Return-Path: X-Spam-DCC: paranoid 1170; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.0 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_RCVD_HELO,PLING_QUERY,RATWARE_GECKO_BUILD autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t55KXJOA027135 for ; Fri, 5 Jun 2015 22:33:19 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Z0yFV-0002Tz-N1 for rs_out_1@blacksheep.org; Fri, 05 Jun 2015 21:29:53 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Z0yFV-0002Tq-49 for rsgb_lf_group@blacksheep.org; Fri, 05 Jun 2015 21:29:53 +0100 Received: from parrot.netcom.co.uk ([217.72.171.49]) by relay1.thorcom.net with esmtp (Exim 4.85) (envelope-from ) id 1Z0yFT-0004mo-1S for rsgb_lf_group@blacksheep.org; Fri, 05 Jun 2015 21:29:51 +0100 Received: from sb.abelian.org (i-194-106-52-83.freedom2surf.net [194.106.52.83]) by parrot.netcom.co.uk (Postfix) with ESMTP id ED9363273F0 for ; Fri, 5 Jun 2015 21:24:53 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id 6630628A079E for ; Fri, 5 Jun 2015 20:29:49 +0000 (UTC) Message-ID: <557206BD.7030103@abelian.org> Date: Fri, 05 Jun 2015 20:29:49 +0000 From: Paul Nicholson User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <20150605090440.Horde.8Mp-oCcE8agOIGl_3aHjYA1@posti.anvianet.fi> <8D26DC7743393A6-F44-3EF5C@webmail-vd004.sysops.aol.com> <25D9436FB040464FBCF2CB75A82278B9@gnat> In-Reply-To: <25D9436FB040464FBCF2CB75A82278B9@gnat> X-Scan-Signature: 046f068074e745d5c60ca47deee9b503 Subject: Re: LF: Re: USB stereo soundcard, CHEAP!? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 3458 Some info on the SD-AUD20101. The chipset is Via Technologies, Envy VT1620A, Datasheet at http://abelian.org/tmp/vt1620a.pdf Sample rates 8k/sec to 96k/sec. Input is stereo, unbalanced, impedance about 4.2k ohms. Full scale at max gain is around 50mV, at minimum gain about 2V. The input carries a DC bias of 3.0 volts with a source impedance of around 4.7k, which you might want to use or decouple. Noise floor at max gain with input open circuit: http://abelian.org/tmp/150605a.gif The humps in the floor move around a bit and vary from specimen to specimen. Cross talk between the two channels is -34dB when fed from a high impedance source but drops to -60dB if the source has low impedance. Most of the cheap USB dongles use a C-Media CM106 which is lower quality with max sample rate 48k. One China supplier was flogging CM106 cards pretending they were SD-AUD20101 but they got rumbled. I would normally recommend an isolating transformer on the input to break any ground loop, but for battery remote operation this may not be necessary. -- Paul Nicholson --