I didn\u2019t breadboard this Amp but I did draw out where things would be located, however if I was doing it again I would breadboard it for sure.<\/p>\n
![\"26](\"https:\/\/i0.wp.com\/www.bartola.co.uk\/valves\/wp-content\/uploads\/2013\/08\/Barry-French-1.jpg?w=836&h=836&crop=1&ssl=1\" "\\"Barry")
<\/a> ![\"Inside](\"https:\/\/i0.wp.com\/www.bartola.co.uk\/valves\/wp-content\/uploads\/2013\/08\/Barry-French-2.jpg?w=276&h=276&crop=1&ssl=1\" "\\"Barry")
<\/a> ![\"Inside](\"https:\/\/i0.wp.com\/www.bartola.co.uk\/valves\/wp-content\/uploads\/2013\/08\/Barry-French-4.jpg?w=276&h=276&crop=1&ssl=1\" "\\"Barry")
<\/a> ![\"Preamp](\"https:\/\/i0.wp.com\/www.bartola.co.uk\/valves\/wp-content\/uploads\/2013\/08\/Barry-French-3.jpg?w=276&h=276&crop=1&ssl=1\" "\\"Barry")
<\/a> This design is basically taken from Ale\u2019s design<\/a> with exception to his CCS before the glow Valves, instead I used K&K Audio\u2019s compact types, one for each channel, this can easily be adjusted using the on board pot, I also didn\u2019t use Russian Glow Valves as they proved to be unreliable, as did using 2 Salas Regulators, I am pretty sure that using 2 drops the voltage too low coming from the raw power supply, making it difficult for both the SSHV2\u2019s & the Glow Tubes to spark up properly, so I used just one, which works just fine. I am not running the 26 Valves at full spec, but I have found that running the filaments at 900mA has the best sound & lowest noise\/ micro phonic\u2019s for me, this gives a bias voltage of 9 volts exactly, the plate voltage is 147 Volts, noise is very low & sound is deep, open & detailed, the integration is excellent & up there with the very best at any price. I have owned & heard some very expensive gear & I feel that for my purposes it can\u2019t really be bettered. The one thing I may do in future is modify it so it has 2 independent raw power supplies, which will probably improve it a couple of notches. I built mine slightly differently in that the Coleman Regulators are in the power supply case & as such I will probably separate the wiring for this & run it to the main Pre-amp Separately, to get the noise even lower. The 26 type Valve\u2019s that I\u2019m using are the Globe RCA 226\u2019s which definitely sound better, I have used 4 x 10 ohm Mundorf Resistors in series parallel to spread the load a little on the filament supply, and this gives less drift on the current.<\/p>\n I used the 8 pin plug from Maplin as a supply cable between Power Supply & Pre-amp, which is the same type as used by Cary Audio & Supratek, it seems to be very good & has a screw lock.<\/p>\n Volume Pot is the very good TKD type; I did try a stepped attenuator but felt it wasn\u2019t as good overall. I have also reinforced the cases top to bottom with Maple which gives the Valves a much more solid foundation to sit on, making the whole setup less microphonic & solid sounding top to bottom. All resistors used are either Kiwame or Mills for low noise; Capacitors are Panasonic low ESR type in the Regulator Supply, Mundorf in the B+ Supply & some Russian PIO types elsewhere. I used Hammond Chokes as well. I used good quality wire from Jupiter & Neotech, all is either Copper in Cotton or PTFE for higher voltage, and solder used was Audionote. That\u2019s about it really; it is a working progress project & as such will probably go through one or two other mods as time moves on.<\/p>\n Barry French<\/p>\n You can check the following designs here<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" 26 DHT Preamp (by Barry French) After owning several high quality pre-amps & modifying some of them to some degree or another, I decided to have a go at building a top quality unit, so here goes first I needed to build the power supplies for filaments & B+ in a separate case, I already … Continue reading “Barry French’s 26 DHT 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_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_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":[156,5],"tags":[779,420,787,184,333,334],"class_list":["post-1837","post","type-post","status-publish","format-standard","hentry","category-pre-amplifier-valves","category-valves","tag-779","tag-26-dht-gen2","tag-26-dht-preamp","tag-26-preamp","tag-bartola-26-dht","tag-bartola-valves-26"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/s2r2tK-1837","jetpack_likes_enabled":true,"jetpack-related-posts":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/1837","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=1837"}],"version-history":[{"count":7,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/1837\/revisions"}],"predecessor-version":[{"id":3697,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/posts\/1837\/revisions\/3697"}],"wp:attachment":[{"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/media?parent=1837"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/categories?post=1837"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bartola.co.uk\/valves\/wp-json\/wp\/v2\/tags?post=1837"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Interested in the 26 preamp?<\/h1>\n
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