{"id":50,"date":"2007-10-17T18:22:21","date_gmt":"2007-10-18T00:22:21","guid":{"rendered":"http:\/\/www.muzique.com\/news\/index.php\/?p=50"},"modified":"2016-01-05T13:02:10","modified_gmt":"2016-01-05T19:02:10","slug":"guitar-direct-box","status":"publish","type":"post","link":"http:\/\/www.muzique.com\/news\/guitar-direct-box\/","title":{"rendered":"Guitar Direct Box"},"content":{"rendered":"

Guitar Direct Box<\/strong><\/p>\n

I posted this design for a direct box in an online forum:<\/p>\n

<\/p>\n

Download the schematic here<\/a><\/p>\n

I simplified the design and converted it to run off a single 9v battery. This allows powering it with a typical pedal power supply or a battery, and switching the power on\/off with the input jack as is done in pedals so you don’t need a switch… Want more headroom? Feed it 12v or even 18v.<\/p>\n

I changed a bunch of resistors to 10k because it’s a common value and I have plenty of them around. I deleted the input pulldown resistor since this is a direct box and you are not going to switch it… the input impedance is 1M, which is plenty for guitar and typical of the tube amps that they are usually plugged into. You can parallel R3 with a 10 to 47pF ceramic if RF becomes a problem but likely won’t be needed at these gains in a metal box.<\/p>\n

I’m not that familiar with the op2134 but if it’s a fet then it will be fine. The input impedance of a 5532 is too low for this application. The TL072 will be almost as quiet at these impedances. Put in a socket and try different chips.<\/p>\n

Without some frequency shaping with an EQ, guitars will typically sound a little lifeless and thin when going direct.<\/p>\n

I deleted a bunch of other components for simplicity’s sake, and changed other minor things besides converting to a single 9v supply. I also added the unbalanced output.<\/p>\n

The “GND” point should be isolated from the chassis but Vee can be connected to chassis.<\/p>\n

I have a box almost exactly like this that I’ve used for years. It can be built on the AMZ Multi-Purpose Opamp PCB<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Guitar Direct Box I posted this design for a direct box in an online forum:<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-50","post","type-post","status-publish","format-standard","hentry","category-diy"],"yoast_head":"\nGuitar Direct Box - AMZ-FX Guitar Effects Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.muzique.com\/news\/guitar-direct-box\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Guitar Direct Box - AMZ-FX Guitar Effects Blog\" \/>\n<meta property=\"og:description\" content=\"Guitar Direct Box I posted this design for a direct box in an online forum:\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.muzique.com\/news\/guitar-direct-box\/\" \/>\n<meta property=\"og:site_name\" content=\"AMZ-FX Guitar Effects Blog\" \/>\n<meta property=\"article:published_time\" content=\"2007-10-18T00:22:21+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2016-01-05T19:02:10+00:00\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@AmzFx\" \/>\n<meta name=\"twitter:site\" content=\"@AmzFx\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.muzique.com\\\/news\\\/guitar-direct-box\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.muzique.com\\\/news\\\/guitar-direct-box\\\/\"},\"author\":{\"name\":\"admin\",\"@id\":\"http:\\\/\\\/www.muzique.com\\\/news\\\/#\\\/schema\\\/person\\\/2ff886e309b4cfdd0bc718b43770df73\"},\"headline\":\"Guitar Direct Box\",\"datePublished\":\"2007-10-18T00:22:21+00:00\",\"dateModified\":\"2016-01-05T19:02:10+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.muzique.com\\\/news\\\/guitar-direct-box\\\/\"},\"wordCount\":299,\"articleSection\":[\"DIY\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.muzique.com\\\/news\\\/guitar-direct-box\\\/\",\"url\":\"https:\\\/\\\/www.muzique.com\\\/news\\\/guitar-direct-box\\\/\",\"name\":\"Guitar Direct Box - 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