PrimaLuna ProLogue Integrated - Help Needed

Sorry to hear the problem is still there, Rob. Yes, the Ohmite Audio Gold resistors would be fine choices for this purpose, preferably in the non-inductive version that is indicated as being available. However, I couldn't find them indicated as being available anywhere in the 50W rating I suggested, and I couldn't readily find any other similarly high powered resistors that look suitable.

As you may have already seen, PartsConnexion carries the Audio Gold resistors in a 12 watt rating, in non-inductive form. What I'd suggest is that you purchase two (one for each channel) of the 47 ohm 12 watt 1% non-inductive resistors they carry (listed as "47R/12W, Ohmite-77999"), and on each channel connect one of them between the 4 ohm and common (0 ohm) tap of the amplifier (regardless of which tap you are using for the speakers). That shouldn't result in the resistor ever having to dissipate more than about 4 watts, well within its rating, regardless of what power tubes you may ever use in the amp and even with the amp running at max power continuously.

If you do that and it doesn't help, you could then try connecting the resistor between the 8 ohm and common terminals, which would require it to dissipate about 8 watts when the amp is putting out max power. That would also be reasonable as a long term solution if it solves the problem, although the margin relative to the 12 watt rating is a bit less than I'd ideally prefer to see.

Good luck. Regards,
-- Al

Al, you're a genius!

The resistors fixed the problem, at least as far as I can tell (and that's the important part).

I find it interesting that I'm the first person to experience this issue. I guess I'll attempt to report it to someone who might care. Would be a shame to not publicize this solution.

Thank you very much for your help!

Rob

Al's the man!

Same amp, considering same speakers. How do you connect the resistor between the 8 ohm and common terminals? Are you saying on the back where the speaker terminals are, run an Audio Gold 12 watt? And in one sense it said between the 4 ohm and then it suggested the 8 ohm. Which of those worked and was this where it was attached?

Same amp, considering same speakers. How do you connect the resistor between the 8 ohm and common terminals? Are you saying on the back where the speaker terminals are, run an Audio Gold 12 watt? And in one sense it said between the 4 ohm and then it suggested the 8 ohm. Which of those worked and was this where it was attached?

For each channel, the resistor would preferably be connected between the 4 ohm and common terminals. I had suggested trying the resistor between the 8 ohm terminal and the common terminal only if connecting it between the 4 ohm terminal and the common terminal didn’t resolve the problem. Rob didn’t mention which pair of terminals he ended up using, but I suspect it was the 4 ohm and common terminals.

As I mentioned, using the 4 ohm terminal rather than the 8 ohm terminal is preferable, assuming it resolves the problem, because it would provide greater margin between the amount of power the resistor would be called upon to handle and the maximum amount of power it is rated to be able to handle. Although using the 8 ohm terminal should be ok in that respect as well.

And yes, you would connect the resistors to the binding posts on the rear of the amp, in addition to connecting the speaker cables to those terminals. Although the speaker cables needn’t necessarily be connected to the same terminal (4 or 8 ohm) as the resistor.

... run an Audio Gold 12 watt?

Yes, but be sure to also note the other characteristics I indicated for the resistors, especially the 47 ohm resistance.

Good luck. Regards,
-- Al