I have read several threads concerning the Audio Nirvana drive units and Nap140 clone amplifiers. I would like to share my experience. I have built a pair of Audio Nirvana 15 inch ferrites and a pair of Mono Naim Nap 140 clones and this combination is fantastic! this coming from someone who has been listening to an Audio note Oto with type E speakers for the past 20 years. I think some people are concerned with the Audio Nirvanas frequency response of 23 hz-14khz, I am 52 and did an online hearing test before I bought the Nirvana`s and could only hear 12khz if I turned my ear towards the source! Unless you are lucky enough to be a horny adoelesant who can pinpoint the click of a high heal from a 100 yards its unlikely you will miss much above 14 kHz. I have made speakers before but am a novice at amplifier building. The amplifiers work first time by using diagrams I found online. ( I used a dual symmetrical power supply and 22,000 uf 50 volt Keindel Capacitors).
Now I hope someone can help me. ! When I plug a source into the clone amplifiers they work fine, but when I go via the passive preamplifier I just get mains hum (which varies in volume using the volume control) I assume I have an earth loop, The 0v on the clone amps is not connected to earth, but on the passive preamp it is. Any advice would be appreaciated. I am happy to give information to members regarding what I did.
Now I hope someone can help me. ! When I plug a source into the clone amplifiers they work fine, but when I go via the passive preamplifier I just get mains hum (which varies in volume using the volume control) I assume I have an earth loop, The 0v on the clone amps is not connected to earth, but on the passive preamp it is. Any advice would be appreaciated. I am happy to give information to members regarding what I did.