Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-md05.r1000.mx.aol.com (Internet Inbound) with ESMTP id D731538000085; Sat, 28 Jan 2012 05:01:05 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Rr54V-0006J8-Km for rs_out_1@blacksheep.org; Sat, 28 Jan 2012 09:59:47 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Rr54V-0006Iz-3O for rsgb_lf_group@blacksheep.org; Sat, 28 Jan 2012 09:59:47 +0000 Received: from out1.ip04ir2.opaltelecom.net ([62.24.128.240]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Rr54T-0002oX-Mg for rsgb_lf_group@blacksheep.org; Sat, 28 Jan 2012 09:59:47 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AhwFAOnGI09cHYLj/2dsb2JhbABDmU4DjGoBiBaBBoFtBQEBBQgBAQNJAiwBAQMFAgEDBA0EAQEKJRQBBBoGFggGEwoBAgIBAYdtBrhFiScLJyEBAYNeNwcGBQEnAheDHASCW4UxhTeSWYdL X-IronPort-AV: E=Sophos;i="4.71,584,1320624000"; d="scan'208,217";a="359339760" Received: from host-92-29-130-227.as13285.net (HELO xphd97xgq27nyf) ([92.29.130.227]) by out1.ip04ir2.opaltelecom.net with SMTP; 28 Jan 2012 09:59:39 +0000 Message-ID: <004501ccdda3$89947f40$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Sat, 28 Jan 2012 09:59:33 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: OT: Headphones Content-Type: multipart/alternative; boundary="----=_NextPart_000_0042_01CCDDA3.89483400" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNSAFE,HTML_MESSAGE autolearn=no version=2.63 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-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:480430944:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d60594f23c7615c20 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0042_01CCDDA3.89483400 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Roger There are plenty of old ex Marine es Military headphones about that are = suitable. 2000 ohms was a common imp for the older headphones. S G BROWN = was a common make in the past plus a variety of others. Old GPO ear = pieces would also suit your requirements.=20 More recent communications headphones are around 600 ohms. Old Crystal sets with a good set of high Z headphones and a decent = antenna like an inv L produced good results, plenty of volume on MF es = LF mal/g3kev =20 ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Friday, January 27, 2012 10:29 PM Subject: LF: OT: Headphones Slightly OT but people like Mal and Jim may have an answer.=20 Is there a "modern" (i.e. can you buy it new today?) headphone set = that is extremely sensitive in the same way that the old DLR5 headsets = were in terms of efficiency converting AF to sound pressure in the ear? = I believe Jim M0BMU claimed 2uV audio power could be heard using DLR5 = headsets in his passive mechanical SAQ receiver. As DLR5s are more = difficult to find these days I was wondering if there is anything as = sensitive, or more so, around "new". 73s Roger G3XBM --=20 http://qss2.blogspot.com/ http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk https://sites.google.com/site/sub9khz/ ------=_NextPart_000_0042_01CCDDA3.89483400 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Roger
There are plenty of old ex Marine es Military = headphones=20 about that are suitable. 2000 ohms was a common imp for the older = headphones. S=20 G BROWN was a common make in the past plus a variety of others. Old GPO = ear=20 pieces would also suit your requirements. 
More recent communications headphones are around = 600=20 ohms.
Old Crystal sets with a good set of high Z = headphones=20 and a decent antenna like an inv L produced good results, plenty of = volume=20 on MF es LF
mal/g3kev
 
----- Original Message -----
From:=20 Roger=20 Lapthorn
Sent: Friday, January 27, 2012 = 10:29=20 PM
Subject: LF: OT: = Headphones

Slightly OT but people like Mal and Jim may have an = answer.=20

Is there a "modern" (i.e. can you buy it new today?) headphone = set=20 that is extremely sensitive in the same way that the old DLR5 = headsets=20 were in terms of efficiency converting AF to sound pressure in the = ear? =20

I believe Jim M0BMU claimed 2uV audio power could be heard = using DLR5=20 headsets in his passive mechanical SAQ receiver. As DLR5s are more = difficult=20 to find these days I was wondering if there is anything as sensitive, = or more=20 so, around "new".

73s
Roger G3XBM

-- =
http://qss2.blogspot.com/
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
https://sites.google.com/site/sub9khz/

=
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