Quad 405 Mods/problem [Archive] - Audio & Video Forums


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05-21-2005, 03:26 AM
Hi guys

I have a lovely old Quad 405/405 Mrk 2 amps which I had biamped with an Audiolab 8000C I wanted to upgrade so bought 2 of their upgrade kits containing capcitors and new opamps, etc, the Quad 405/2 works like a dream, although not technically minded, if shown where and how to solder and replace its not a problem. Dare i say that this problem is nothing to do with Net AUdio. The guy has been very helpful with me and very patient. But on first power up. It wailed very loudly in the right speaker, coughed , spluttered and died. So I sent the whole boards back this time to Dave at Net Audio, and he fixed for a minimum price. I got the boards back yesterday and fitted them back into the chassis connected to the heatsink, all correct and seated properly The boards were checked by Dave and so no problems there.
He has told me to check the ohm readings with a multimeter to the negative and positive teminals on the speakers. The right side reads, 3.12 ohms, and the left side 0.9ohms. The DC voltage on either side left and right, into the boards from the transformer is 105 volts, so no probs. But Since the wailing was down to my wrong placement of some Capacitors i knew that the first time it wailed it was my fault. But I think to add into the equation, that the right sided speaker terminals are shorting themselves?? . Might that account for the different readings , left and right. It is an old 405 with those spring clip terminals, so if a short peice of wire has somehow jammed inside the housing snd is causing a problem, would this reading of 3.12 ohms, be an indication of that?

I hope i havent confused anyone, lol

Thanks for any comments, Daves away for the weekend so im pretty much on my own with this!