{"id":6828,"date":"2017-10-14T20:39:57","date_gmt":"2017-10-14T19:39:57","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=6828"},"modified":"2017-10-14T20:39:57","modified_gmt":"2017-10-14T19:39:57","slug":"ba-german-dht-preamp-here-we-go","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2017\/10\/14\/ba-german-dht-preamp-here-we-go\/","title":{"rendered":"Ba German DHT Preamp, here we go…"},"content":{"rendered":"

Flying around<\/h2>\n

Travelling around Europe on business is paying its toll. I’m away from home every week and pretty exhausted now. I don’t have much time free and whatever is available I spend with my family. Hence, the lack of posts recently. I hope this will change in the future.<\/p>\n

Anyway, what’s up in the DHT world? I listened the Aa\/Ba valves long time ago but never played with them. Mainly due to their higher anode resistance. With the gyrator load and the source follower output, things take a different dimension.<\/p>\n

German precision<\/h2>\n

I have a nice stash of Aa<\/a> from Valvo (globe) and Ba<\/a> from Siemens. Interesting to see that curves are not easy to find, so I submit them both to the mercy of the uTracer.  Nice to see the linear curves with high mu about 14 on the Ba to 30 in the Aa.  <\/p>\n

Here is an example of the Ba loadline:<\/p>\n

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

With a maximum of 230V running it at about 200V\/5mA and -3.4V seems reasonable to provide good headroom. <\/p>\n

A simple but yet effective DHT stage<\/h2>\n

With such a high Ra and low anode current, the marriage with the gyrator<\/a> load and the output source follower<\/a> is ideal. I use this with great success on the UV-201a preamp <\/a>which sounds amazing. <\/p>\n

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

The circuit is dead  simple as I have implemented this before again and again.   If you need like 22dB of gain in your system, then look into this option. I have to implement to see how it sounds, and I guess it would be great. The Ba has a high reputation as well as its predecessor Aa.<\/p>\n

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

Flying around Travelling around Europe on business is paying its toll. I’m away from home every week and pretty exhausted now. I don’t have much time free and whatever is available I spend with my family. Hence, the lack of posts recently. I hope this will change in the future. Anyway, what’s up in the … Continue reading “Ba German DHT Preamp, here we go…”<\/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":[12,911,156,67],"tags":[1068,1073,1070,1069,1074,1071,6,186,1072,44,875,1062],"class_list":["post-6828","post","type-post","status-publish","format-standard","hentry","category-dht-valves","category-gyrator-pcb","category-pre-amplifier-valves","category-thd","tag-aa","tag-aa-preamp","tag-aa-tube","tag-ba","tag-ba-preamp","tag-ba-tube","tag-dht","tag-dht-preamp","tag-german-dht-tubes","tag-gyrator","tag-gyrator-pcb","tag-source-follower-pcb"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-1M8","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/6828","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=6828"}],"version-history":[{"count":1,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/6828\/revisions"}],"predecessor-version":[{"id":6831,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/6828\/revisions\/6831"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=6828"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=6828"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=6828"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}