Preamp Deal of the Century

I turned off the high gain switch on my just-received Cabernet for the reasons you mention. Mick’s design does draw a fair amount of current in start up, although the manual says the noise is ok, i.e., won’t damage the speakers. I blew a pair of 3.15A SR fuses because of it after merely adding ICs for subs, without the latter even having AC cords attached.

I don’t have a phono stage, so adjusting the dac’s volume has been able to compensate. Likewise, I am getting a 60 Hz buzz, just loud enough to be heard at my listening position when everything else is off. That led me to limit the gain knob adjustment to the 12 o’clock position, vs. the 4 o’clock I previously had with the Chardonnay, even with the dac at roughly half volume (I have a regenerator). I haven’t yet rechecked all the connections and ports used. That might be the best first step. The Cab manual does admit the possibility of hum and tube noise issues in finding the best gain settings. Ggod hunting in finding the culprit.

My Chardonnay 3 may function differently (not sure), but I realized that when the gain knob is active, I get noise/hum between 8am and 4pm on the dial, pretty much the entire spectrum except for the very beginning and very end. Hence, I decided to turn off the gain function and instead reduced output by my Hifi Rose RS150B to 500mv. Quiet as a church mouse now, but still have more than enough gain to play loud music.

I humbly suggest you take a close look at how all your cables are dressed. Where they cross, where they parallel each other, how they are seated in the rca inputs & outputs. That has always been the key to getting my system hum-free.

The Cabernet manual states:

"A gain adjustment knob is provided in case preamp is used with high gain power amps, if noise is an issue adjust gain until noise disappears." The same applies to the Chardonnay.

Adjusting cables is a separate matter. Power cables that cross should do so as close to 90 degrees as possible. I use those cheap rubber-covered foam isolator blocks one finds on eBay to keep cords from touching, and those and bamboo glass coasters held together with wood spindles (Michael's) to keep cables off the carpet.

My 20yo Chenin is quiet, all cords and IC;s have those foam pipe tubes cut to length and separates AC from the signal wires.

All components seperated on their own shelf, I had hum at one time and that seemed to resolve it.