{"id":3300,"date":"2014-04-13T18:50:44","date_gmt":"2014-04-13T17:50:44","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=3300"},"modified":"2014-04-13T19:10:56","modified_gmt":"2014-04-13T18:10:56","slug":"jfet-riaa-preamp-battery-supply","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2014\/04\/13\/jfet-riaa-preamp-battery-supply\/","title":{"rendered":"JFET RIAA Preamp – battery supply"},"content":{"rendered":"

I built a new pack of 12V+6V lead-acid batteries to provide +\/- 18V for my JFET RIAA MC phono stage<\/a>. Despite the bad reputation of these being noisy, Geoff tried them with great success. The Haze brand are the recommended and the low capacity ones (i.e. 1.3Ah) are very quiet.<\/p>\n

I decided to build and test it. As the proof is in the pudding!<\/p>\n

\"differential <\/a>
differential chokes and OSCON caps <\/div> <\/div> <\/div> <\/div>
\"Battery <\/a>
Battery pack <\/div> <\/div> <\/div>
\"Battery <\/a>
Battery pack completed <\/div> <\/div> <\/div>
\"Measuring <\/a>
Measuring noise <\/div> <\/div> <\/div> <\/div> <\/div>\n

Here is a simple test on my workbench of the 18V battery set with a 20mA load to simulate the RIAA stage consumption. The LC is formed by a 33mH choke in differential mode + 100uF\/20V OSCON capacitor.<\/p>\n

No twisted cable pair, just banana alligator clips. The noise level is really low and is obvious that 3.3\u03bcV 50Hz hum is picked from the workbench. I also listened to it for a while and can hear the difference. I monitor the FFT with no average and lower FFT size and also couldn\u2019t see any spikes due to chemical reactions. They may happen in future though \ud83d\ude42<\/p>\n

\"18V<\/a><\/p>\n

The performance of this battery pack is outstanding, so far so good!<\/p>\n

 <\/p>\n

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

I built a new pack of 12V+6V lead-acid batteries to provide +\/- 18V for my JFET RIAA MC phono stage. Despite the bad reputation of these being noisy, Geoff tried them with great success. The Haze brand are the recommended and the low capacity ones (i.e. 1.3Ah) are very quiet. I decided to build and … Continue reading “JFET RIAA Preamp – battery supply”<\/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":[159,449,448,5],"tags":[590,588,587,589,585,586,789],"class_list":["post-3300","post","type-post","status-publish","format-standard","hentry","category-power-supplies","category-riaa","category-riaa-stages","category-valves","tag-battery-supply","tag-jfet-folded-cascode","tag-jfet-phono","tag-jfet-shunt-cascode","tag-lead-acid-batteries-in-phono-preamps","tag-phono-preamp","tag-riaa"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-Re","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/3300","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=3300"}],"version-history":[{"count":5,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/3300\/revisions"}],"predecessor-version":[{"id":3311,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/3300\/revisions\/3311"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=3300"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=3300"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=3300"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}