{"id":8062,"date":"2019-10-26T22:52:35","date_gmt":"2019-10-26T21:52:35","guid":{"rendered":"https:\/\/www.bartola.co.uk\/valves\/?p=8062"},"modified":"2019-10-26T22:52:40","modified_gmt":"2019-10-26T21:52:40","slug":"6e6p-dr-hp-amp-part-2","status":"publish","type":"post","link":"https:\/\/www.bartola.co.uk\/valves\/2019\/10\/26\/6e6p-dr-hp-amp-part-2\/","title":{"rendered":"6e6p-dr HP amp – part 2"},"content":{"rendered":"

My adventure with the HT SMPS modules continued. Did further testing with higher power modules which worked ok.<\/p>\n

\"\"<\/p>\n

\n
Testing the HP amp<\/figcaption>\n<\/figure>\n\n\n

The headphone stage (HP) has a 1MHz bandwidth, impressive. Here is the circuit breadboarded after the modification of the 2P29L HP amp:<\/p>\n\n\n\n\n\n\n\n

\"\"
6e6P-DR HP Amp
<\/figcaption><\/figure><\/div>\n\n\n\n

The cap multiplier isn’t mandatory as the gyrator PCB has a high PSR so a good well-filtered HT supply will work. I added the cap-multiplier for 2 reasons. I have the PCBs made and also I was looking to improve the supply noise of the SMPS modules. My intension was to power this up with an LT supply module I have based out of 2 variable SMPSs. <\/p>\n\n\n\n

The Chinese 40W HT SMPS modules that can do 450V work fine. They need a good HF filter as well as a proper LC stage to decouple and filter the ripple to make it absolutely dead quiet. <\/p>\n\n\n\n

Here is the variable HT supply I build some time ago which I use for multiple circuits:<\/p>\n\n\n\n

\"\"
The variable HT supply made out of HT SMPS modules<\/figcaption><\/figure><\/div>\n\n\n\n

With this stage I have the choice of swapping the output caps. Either a massive (aka expensive) Mundorf EVO Oil 100uF\/350V for direct coupling of the 300R headphones, or via the Sowter HP output transformer with a smaller cap. <\/p>\n\n\n\n

I personally prefer the OT coupling in this circuit, but both sound extremely well. <\/p>\n\n\n\n

More work and measurements to follow.<\/p>\n","protected":false},"excerpt":{"rendered":"

My adventure with the HT SMPS modules continued. Did further testing with higher power modules which worked ok. Testing the HP amp The headphone stage (HP) has a 1MHz bandwidth, impressive. Here is the circuit breadboarded after the modification of the 2P29L HP amp:<\/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":[33,5],"tags":[605,405,44,31,1236,1176],"class_list":["post-8062","post","type-post","status-publish","format-standard","hentry","category-headphone-amp","category-valves","tag-6e6p-dr","tag-dht-headphone-amp","tag-gyrator","tag-headphone-amplifier","tag-hp-amp","tag-hv-cap-multiplier"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p2r2tK-262","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/8062","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=8062"}],"version-history":[{"count":1,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/8062\/revisions"}],"predecessor-version":[{"id":8065,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/8062\/revisions\/8065"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=8062"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=8062"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=8062"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}