gofar99 Messages: 2048 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi Everyone,Sometimes things work out better than you expected. This phono preamp is one such device. I have built several iterations of it since I first designed it (September 2013). This version is IMO about as good as you can make one without going to extremes. While I usually design tube gear this one is IC based. The first one was cooked up for a temporary need as my main preamp was being modified. It was quiet and sounded quite nice but I never tested it. The new version has been refined a bit, uses battery power and has hand selected parts. Trying to measure its performance put my shop to it limits. The S/N in my shop is usually between -103 and -106 dbv. The IC preamp today measured -100 dbv with a shop noise of -103. Frequency response was ruler flat from 20HZ to 100KHZ. Oddly it rises above 100K so that is 2.5 dbv higher at 1meg HZ. That is the limit of Bode plots I can do. It was -0.5 dbv at 8HZ. There is no provision for rumble filtering so if your turntable has it don’t build this preamp. Contact me via PM for a mod to fix that. Anyway it is a fairly simple project and low cost to boot. Any modern OP amp will work. I tested numerous types. So if you have a preference use it. Depending on the parts you have or need to buy it should be under $200 (US). Oh, please excuse the dust on the preamp. It is everywhere this year.
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