Another thing to check. Try wiggling the unit in the docking cage and see if the noise changes. My MK1 recently developed a similar noise that goes away as I wiggle it in the docking cage. There's something wrong with docking connector (dirty perhaps) and it's causing grounding problems. I need to look into it.

I have had exactly this problem for about the last three months. I have to jiggle the unit very precisely into the sleeve to stop noise pickup and crackling noises that sound as if the differential outputs have no reference ground. Since I also have a two-amp installation, I thought this might have resulted from me only having fitted one of the reference straps. This weekend I fitted the second in the hope that if the connector was breaking contact on the single pin of the connector used for output stage reference, then a second reference earth would minimise this effect. Unfortunately, it has made no difference.

Having looked at the male and female sides of the connector, it appears as if the contacts of the female are compressing unevenly, and remain in their compressed position. This means that not all of the contacts are making proper contact in the connector, with odd results. Not resolved as yet. It does seems to be an audio, rather than feed current grounding problem caused by dodgy contacts - the empeg computer component continues to run regardless of output crackles. Since more than one incidence of this effect has been noted, it should really be reported as a bug relating to possible warranty issues. My warranty expires pretty soon

CJ - firstly, have you DC grounded (not earthed) both amps and the empeg at the same point? Have you checked that relative to the battery contact this point is at 0V? When you power everything on, is it still 0V? What grade of wire have you used to power/ground your amps and the empeg (it should be able to deal with at least twice the maximum current pulled by the device at full power)? Have you used the power filter in line with the empeg power line *only* (it cannot support filtering for all three as the core will saturate making it useless)? Have you checked (with engine off) the positive feed voltage at both amps and empeg? With the engine running, what are the same voltages?



One of the few remaining Mk1 owners... #00015