{"id":5622,"date":"2016-06-12T20:22:09","date_gmt":"2016-06-12T19:22:09","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=5622"},"modified":"2016-06-12T20:22:09","modified_gmt":"2016-06-12T19:22:09","slug":"2p29l-preamp-and-driver-for-4p1l-pse-amp","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2016\/06\/12\/2p29l-preamp-and-driver-for-4p1l-pse-amp\/","title":{"rendered":"2P29L – Preamp and driver for 4P1L PSE Amp"},"content":{"rendered":"

A very interesting Russian directly-heated pentode related to 4P1L is the 2P29L. It has a similar mu (\u03bc=9), much higher anode resistance 2.8-3K\u03a9 and transconductance of 3mA\/V when triode-strapped. The filament requirements are much lower at 120mA. I picked one valve from my collection to submit it to the mercy of the curve tracer:<\/p>\n

\"2P29L<\/a>
2P29L test point (pentode)<\/figcaption><\/figure>\n

The triode curves are really nice:<\/p>\n

\"2P29L<\/a>
2P29L triode curves and model<\/figcaption><\/figure>\n

This valve is as linear as the 4P1L (hooray). As a preamp it can be easily implemented like the 4P1L Gen2 preamp using a gyrator PCB<\/a> which simplifies the building process:<\/p>\n

\"2P29L<\/a>
2P29L preamp<\/figcaption><\/figure>\n

Running it at 15mA and slightly above the recommended 160V achieve its lowest distortion.<\/p>\n

We could also use this valve as a driver for a 4P1L preamp, which comes very handy for filament bias:<\/p>\n

\"2P29L-4P1L<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

A very interesting Russian directly-heated pentode related to 4P1L is the 2P29L. It has a similar mu (\u03bc=9), much higher anode resistance 2.8-3K\u03a9 and transconductance of 3mA\/V when triode-strapped. The filament requirements are much lower at 120mA. I picked one valve from my collection to submit it to the mercy of the curve tracer: The … Continue reading “2P29L – Preamp and driver for 4P1L PSE Amp”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_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},"jetpack_post_was_ever_published":false},"categories":[835,156,158,67],"tags":[918,919,782,216,6,47,44,875],"class_list":["post-5622","post","type-post","status-publish","format-standard","hentry","category-4p1l-pse-amp","category-pre-amplifier-valves","category-se-designs","category-thd","tag-2p29l","tag-2p29l-triode-strapped","tag-4p1l","tag-4p1l-pse","tag-dht","tag-dht-preamplifier","tag-gyrator","tag-gyrator-pcb"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-1sG","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5622","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=5622"}],"version-history":[{"count":1,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5622\/revisions"}],"predecessor-version":[{"id":5627,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5622\/revisions\/5627"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=5622"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=5622"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=5622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}