PrimaLuna ProLogue Integrated - Help Needed
I watched the video, and it appears to be what is referred to as "motorboating". As you'll see in the writeup that can be caused by a number of things, but a frequent cause is a defective or degraded filter capacitor in the power supply of a tube amp. Or if the amp is new, perhaps even a wiring error resulting in a capacitor not being connected properly. I hope that is of some help. Regards, -- Al |
After watching your video, my suggestion is to move ALL AC cables as far away from the speaker cables as possible. Looks like that they are intertwined pretty well. This would include the AC cables to the subs on the speaker and the AC cables from the integrated and source. The Nordost speaker cable doesn't have any shielding, so passing them so close to the AC cables could be causing the problem. |
ZD, I think that if you read this you'll conclude that the problem, or at least its root cause, is unlikely to be related to biasing. And note in the video that the problem can be induced in the power tubes for BOTH channels, if the volume is increased sufficiently. Mofi, your suggestion is very logical, but note that the OP indicated that the same symptom occurred even when he relocated the amp to an adjacent room. My strong suspicion is that the root cause of the problem is a defect in the amp, which is resulting in "motorboating" as I described. Best regards, -- Al |
