{"id":5718,"date":"2016-08-27T21:05:19","date_gmt":"2016-08-27T20:05:19","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=5718"},"modified":"2016-08-27T21:07:42","modified_gmt":"2016-08-27T20:07:42","slug":"tonys-01a-preamp","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2016\/08\/27\/tonys-01a-preamp\/","title":{"rendered":"Tony’s 01a Preamp"},"content":{"rendered":"

\"IMG_3291\"<\/a>I went to see my friend Tony today and helped him to fix his 01a preamp<\/a> implementation. Time ago Tony used a prototype version of my gyrator PCB <\/a>to build the Gen2 preamp with the addition of an output follower to address the slew rate <\/a>limitations he had on his system due to the larger capacitive load.<\/p>\n

Luckily we found the fault easily and it was a bad solder in one of the smoothing HT chokes. Once fault was rectified, we proceeded to take some measurements of this preamp.<\/p>\n

<\/p>\n

The preamp circuit diagram is below. Is the classic 01a preamp Gen2 with the addition of a basic source follower to drive Tony’s amp:<\/p>\n

\"Tony's<\/a>
Tony’s 01a preamp implementation<\/figcaption><\/figure>\n

Looking at the frequency sweep the preamp shows about a gain of x8 (18dB) flat from 3Hz up to about 180kHz. This is impressive and is thanks to the bootstrapped input capacitance of the MOSFET which provides a gentle load to the 01a:<\/p>\n

\"FR<\/a>
FR of Tony’s preamp<\/figcaption><\/figure>\n

I don’t think you can get better than this \ud83d\ude42<\/p>\n

Here is a plot of the harmonics and THD at a signal level of 2Vrms. Distortion is extremely low and with a double output at 4Vrms increases only to 0.008%:<\/p>\n

\"2Vrms<\/a>The build is really neat. The LT supply is on a separate chassis and HT is on same preamp chassis (see TXs on the right). The pair of sockets has rubber suspensions, the Rod Coleman boards are at the bottom and you can see the output caps at the top as well as the volume control and input selector on the left:<\/p>\n

\"Testing<\/a>
Testing the preamp<\/figcaption><\/figure>\n

Least to say: his system sounds impressive. This is one of the best 01a preamps I’ve heard myself. Well done Tony!<\/p>\n

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

I went to see my friend Tony today and helped him to fix his 01a preamp implementation. Time ago Tony used a prototype version of my gyrator PCB to build the Gen2 preamp with the addition of an output follower to address the slew rate limitations he had on his system due to the larger … Continue reading “Tony’s 01a Preamp”<\/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":[12,911,156,162,67,5],"tags":[854,10,249,853,653,697,864,186,47,875,275],"class_list":["post-5718","post","type-post","status-publish","format-standard","hentry","category-dht-valves","category-gyrator-pcb","category-pre-amplifier-valves","category-source","category-thd","category-valves","tag-01-preamp","tag-01a","tag-01a-dht","tag-01a-gyrator","tag-01a-preamp-gen2","tag-2sk170","tag-bartola-gyrator","tag-dht-preamp","tag-dht-preamplifier","tag-gyrator-pcb","tag-rod-coleman"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-1ue","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5718","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=5718"}],"version-history":[{"count":3,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5718\/revisions"}],"predecessor-version":[{"id":5727,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/5718\/revisions\/5727"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=5718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=5718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=5718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}