{"id":3232,"date":"2014-03-29T18:30:46","date_gmt":"2014-03-29T18:30:46","guid":{"rendered":"http:\/\/www.bartola.co.uk\/valves\/?p=3232"},"modified":"2014-03-29T19:00:29","modified_gmt":"2014-03-29T19:00:29","slug":"riaa-phono-stage-completed","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2014\/03\/29\/riaa-phono-stage-completed\/","title":{"rendered":"RIAA phono stage completed"},"content":{"rendered":"

FET RIAA Phono Stage<\/h1>\n

Finally completed today. It seems impossible from me to get a project finally boxed properly. I’ve done it this time with the RIAA phono stage<\/a> built recently thanks to the help and guidance from Rod Coleman. This MC stage has a gain of about 70dB for MC cartridges and currently running my DL103a with a 200\u03a9 input load. The beauty of the folded cascode (or shunt cascode as Rod refers it to) is that Miller capacitance is not a problem thanks to the fixed voltage at the drain of the FET input stage. This helps us to have a low input capacitance stage. The second stage is op amp OPA637.<\/p>\n

I need to take final measurements of this Phono stage but this is how it looked when I was initially testing it on the bench:<\/p>\n

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

Nice RIAA compliance to +\/- 0.1dB. LF noise and gain levels made it difficult to capture the LF response below 100Hz.<\/p>\n

The distortion is also really nice with less than 0.025% @ 1kHz and nice harmonic distribution thanks to the CCS at the output which is forcing the\u00a0operational\u00a0amplifier to operate in class A:<\/p>\n

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

This stage was well received at the recent London Audio Circle Meeting<\/a>. It has \u00a0a nice clean and detail sound. I tried it with\u00a0multiple\u00a0MC and even low MM cartridges and has a nice response across the whole bandwidth. Great bass and delicate treble.<\/p>\n

I think it is a very quiet phono stage given its high gain. I really like the overall sound and response and I guess that the negative side of it is the 18V battery pack made up of PP3 rechargeable batteries. It needs charge every two weeks and may be a pain in the back. I will try a DC supply, but will have to be really quiet to\u00a0substitute\u00a0my battery pack.<\/p>\n

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FET RIAA Phono Stage Finally completed today. It seems impossible from me to get a project finally boxed properly. I’ve done it this time with the RIAA phono stage built recently thanks to the help and guidance from Rod Coleman. This MC stage has a gain of about 70dB for MC cartridges and currently running … Continue reading “RIAA phono stage completed”<\/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":[449,448,5],"tags":[571,502,450,451,789,570,572],"class_list":["post-3232","post","type-post","status-publish","format-standard","hentry","category-riaa","category-riaa-stages","category-valves","tag-dl103a","tag-folded-cascode","tag-jfet-riaa","tag-jfet-riaa-shunt-cascode","tag-riaa","tag-riaa-phono-stage","tag-shunt-cascode"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-Q8","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/3232","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=3232"}],"version-history":[{"count":3,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/3232\/revisions"}],"predecessor-version":[{"id":3238,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/3232\/revisions\/3238"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=3232"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=3232"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=3232"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}