I would try a different amp to be sure it isn't the problem. The triton 2 uses a powered woofer, perhaps there is an issue with them. When I bought my Triton 1, the dealer made 3 trips to my house because one of my speakers was bad, as was the replacement. Third time was a charm though.
PrimaLuna ProLogue Integrated - Help Needed
Hi everyone. I recently made a big upgrade (for me); I traded in all my aging mediocre equipment and purchased a pair of GoldenEar Triton Twos and a PrimaLuna Prologue integrated amp. I'm using Nordost Purple flare speaker cables. No power conditioning at this point.
The problem is this: when I turn up the volume past a certain point (about 95 dB sustained), the amp begins to produce a low-frequency "throb". The throb is of moderate volume, very audible during quiet passages. The throb is about two beats per second, I'd say. It manifests both audibly and visually (in the form of a pulsing blue light from the left channel power tubes).
I've done a lot of work to try to diagnose the issue, but would like your opinion. Has anyone heard of a problem like this? I've had all sorts of suggestions from the dealer and PrimaLuna, from microphonic feedback to bad power. I don't think it's feedback, as I've isolated the amp in a separate room from the speakers and still experience the problem.
I'll shut up and just link a video I made. If you use headphones, you can hear the throb pretty clearly.
https://www.youtube.com/watch?v=Juk1ILtarS8
Thanks for any help!
The problem is this: when I turn up the volume past a certain point (about 95 dB sustained), the amp begins to produce a low-frequency "throb". The throb is of moderate volume, very audible during quiet passages. The throb is about two beats per second, I'd say. It manifests both audibly and visually (in the form of a pulsing blue light from the left channel power tubes).
I've done a lot of work to try to diagnose the issue, but would like your opinion. Has anyone heard of a problem like this? I've had all sorts of suggestions from the dealer and PrimaLuna, from microphonic feedback to bad power. I don't think it's feedback, as I've isolated the amp in a separate room from the speakers and still experience the problem.
I'll shut up and just link a video I made. If you use headphones, you can hear the throb pretty clearly.
https://www.youtube.com/watch?v=Juk1ILtarS8
Thanks for any help!
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- 21 posts total
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 |
- 21 posts total