Return-Path: Received: (qmail 2953 invoked from network); 22 Oct 2002 14:22:09 -0000 Received: from murphys.services.quay.plus.net (212.159.14.225) by mailstore with SMTP; 22 Oct 2002 14:22:09 -0000 Received: (qmail 4100 invoked from network); 22 Oct 2002 14:21:23 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by murphys.services.quay.plus.net with SMTP; 22 Oct 2002 14:21:23 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.10) id 183ztP-0007Zh-00 for rsgb_lf_group-outgoing@blacksheep.org; Tue, 22 Oct 2002 15:20:23 +0100 Received: from [165.212.11.110] (helo=cmsoutbound.mx.net) by post.thorcom.com with smtp (Exim 4.10) id 183ztP-0007ZY-00 for rsgb_lf_group@blacksheep.org; Tue, 22 Oct 2002 15:20:23 +0100 Received: from uadvg129.cms.usa.net (HELO cmsoutbound.mx.net) (165.212.11.129) by cmsoutbound.mx.net with SMTP; 22 Oct 2002 14:20:20 -0000 Received: from usa.net [213.217.169.248] by uadvg129.cms.usa.net (ASMTP/dibene@usa.net) via mtad (CM.1201.1.04A) with ESMTP id 242gJVouR0227M29; Tue, 22 Oct 2002 14:20:18 GMT Message-ID: <3DB55E79.50901@usa.net> Date: Tue, 22 Oct 2002 16:19:37 +0200 From: "Alberto di Bene" User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 X-Accept-Language: en-us, en MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <3DB0C203.A90691A6@verizon.net> <000801c279ad$b339adc0$f530f7c2@a7j7r2> Subject: LF: Re: Vacuum tubes on Motherboards... Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-2.9 required=5.0tests=EMAIL_ATTRIBUTION,REFERENCES,SPAM_PHRASE_01_02,USER_AGENT, USER_AGENT_MOZILLA_UA,X_ACCEPT_LANGversion=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group John Rabson wrote: >A few years ago, I was restoring an ancient Hallicrafters receiver and >noticed the crisp quality of the audio compared with that of a 1960s >transistorised communications receiver. I spoke to one of the experts at BT >Labs, who suggested that the output transformer might have something to do >with it. Also, the characteristics of a bipolar transistor audio output >stage are _not_ identical to those of a pentode or beam tetrode. > > > IMHO, the main reason for the more pleasant sound is the IF filter...supposing the '60s receiver uses a crystal filter, while the Hallicrafters not. Crystal filters are wonderful in the frequency domain, but terrible performer in the time domain, while LC filter just the opposite... 73 Alberto I2PHD