Customer had spent hours trying to find/fix a noise problem on their expensive microphone (just outside of warranty) so asked me to take a look, from the explained symptoms I suspected preamp valve noise, this microphone has the Abbey Road Studios REDD.47 preamp built in, and uses EF86 and E88CC valves. Repeated the problem (intermittent
Chandler REDD microphone intermittent noise Read More »
Customer brought in a couple of Lux91 300B-based amps, one suddenly stopped working. First off noticed customer had inadvertently managed to remove and reinsert the 300B 4-pin valve rotated 90 degrees (as a ‘diy’ check swapping valves between units) prior to bringing to me which of course failed to fix anything. Thankfully nothing damaged being
Lux91 MonoMax monoblocks one dead Read More »
With the Cary 300SE Monobloc amp in the previous post, turned out the intermittent popping sound was one of the expensive 300B valves! Customer had already considered new valves, so with nothing to lose thought lets just check the connections and after extracting some solder from the pins, found this! One of the wires loose,
300B valve surgery Read More »
A friend reported intermittent issues with loud pops from one of speakers connected to his Cary 300SE monobloc setup. After some diagnosing swapping leads round to rule out the preamp, the issue stayed with one of the monoblocks. Suspected perhaps intermittent shorting of high voltage capacitor plates. Brought them over and found quite a number
Cary 300se Monoblock Amps Read More »
What quite shocking PCB build quality! This small amp came in dead, and whilst looks ok from the outside, the inside leaves a lot to be desired… Everything is… sort of… just all over the place: The soldering is some of, if not the worst I’ve ever seen… Even one transistor leg wasn’t even soldered:
Mini Mofo 15 watt valve amp head Read More »
Customer asked to check state of valves in case they needed replacement and a quick check over everything else, plus a rattle… Very impressed by the build quality: Valves recommended to be replaced after 5000 hours use, am seeing no degradation or need to change at this stage: However a couple of minor issues were
Avalon VT737SP valve compressor checkup/service Read More »
Customer states that TLAudio FatTrack mixer is cutting out after a while, and wanted a valve swap for something better. Found MPSA42 getting extremely hot exceeding 100deg C and breaking down (this is part of the HV circuitry for valves), even with small heatsink attached it was still 86+ and clicking out of service: The
TLA FatTrack mixer cutting out and valve swap Read More »
This THD Univalve came in with a dead HV fuse, was replaced, serviced and tested all ok with the exception that the bias is way too hot for the installed 6L6GC valve. Measuring >110mA and red-plating on Hi-V setting. On Lo-V it was ok of course, but really needed a rebias for using on our
THD Univalve stopped working Read More »
