{"id":6685,"date":"2017-08-20T09:54:15","date_gmt":"2017-08-20T08:54:15","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=6685"},"modified":"2017-08-20T09:54:15","modified_gmt":"2017-08-20T08:54:15","slug":"4p1l-4%d0%bf1%d0%bb-siberian-gen4-in-screen-mode","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2017\/08\/20\/4p1l-4%d0%bf1%d0%bb-siberian-gen4-in-screen-mode\/","title":{"rendered":"4P1L \/ 4\u041f1\u041b Siberian Gen4 in Screen mode"},"content":{"rendered":"

Some time ago, I did some initial experiments with the 4P1L (4\u041f1\u041b) with the screen performing as anode instead<\/a>. Some DIYers claim the improved sound of the mesh type anodes. Kees Brakenhoff kindly sent me some PL519 to test in screen mode. He has done multiple builds with this mode of operation with great results. Unfortunately I’ve not had the chance yet to build such an amp.<\/p>\n

What I could do instead though, was to mod very quickly my 4\u041f1\u041b preamp<\/a> to screen mode. It was a very easy and fast modification. I kept the same heating wiring and just adjusted the screen (anode) current down to 10mA:<\/p>\n

\"\"<\/a><\/p>\n

The 10mA operating point keeps the screen dissipation within its limit. I’d probably use a BF862 here instead of the BSH111BK, but I reused the existing PCB gyrator board<\/a> for simplicity.<\/p>\n

Some measurements<\/h2>\n

Before listening to the preamp, I conducted a series of basic tests on the preamp:<\/p>\n

\"\"<\/a><\/p>\n

Due to its lower quiescent current, the transconductance of the jFET is lower and so it’s it bootstrapping resulting in a slightly worse HF response compared to the 4P1L Siberian preamp. Still is outstanding. You also get a slightly better gain of about 1dB close to 20dB, instead of 19dB. <\/p>\n

Distortion profile is very good:<\/p>\n

\"Distortion<\/a> \"Distortion<\/a><\/p>\n

 <\/p>\n

 <\/p>\n

It has the characteristic harmonic footprint of the 4P1L with a predominant H2 and cascaded H3 and H4. A very low distortion indeed.<\/p>\n

How does it sound?<\/h2>\n

I played it for about a couple of hours yesterday. It sounds as good as the 4P1L I think. Unfortunately I modded my 4P1L preamp for this so can’t do a side by side comparison. <\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Some time ago, I did some initial experiments with the 4P1L (4\u041f1\u041b) with the screen performing as anode instead. Some DIYers claim the improved sound of the mesh type anodes. Kees Brakenhoff kindly sent me some PL519 to test in screen mode. He has done multiple builds with this mode of operation with great results. Unfortunately … Continue reading “4P1L \/ 4\u041f1\u041b Siberian Gen4 in Screen mode”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5],"tags":[782,537,703,319,142,595,215,625,864,903,982,875,1067,1058,1059],"class_list":["post-6685","post","type-post","status-publish","format-standard","hentry","category-valves","tag-4p1l","tag-4p1l-dht","tag-4p1l-dht-line-stage","tag-4p1l-gyrator","tag-4p1l-preamp","tag-4p1l-preamplifier","tag-4p1l-siberian","tag-bartola","tag-bartola-gyrator","tag-bartola-gyrator-pcb","tag-bsh111bk","tag-gyrator-pcb","tag-screen-mode","tag-siberian-gen-3","tag-siberian-gen-4"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-1JP","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/6685","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/comments?post=6685"}],"version-history":[{"count":2,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/6685\/revisions"}],"predecessor-version":[{"id":6691,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/6685\/revisions\/6691"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=6685"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=6685"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=6685"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}