2. amps-preamps
  3. 1432666396

Pre-amp causing loud hiss from speakers

I have a BAT VK3i with Quicksilver Horn mono-blocks and Klipsch LaScala's. This setup is dead quiet, however when I recently hooked up Rogue Audio M-180 mono-blocks there was a loud hiss coming from the speakers well past the listening spot. This noise was constant even with the volume down to zero and occurred with either balanced or rca connectors.

When I took the BAT out of the equation there was now only a faint hiss coming from speakers but one had to put your ear to it to hear it. After disconnecting all components from the BAT and putting it back in - the noise returns. I tried a Conrad Johnson Classic and there was no noise.

So does anyone have any ideas as to why the BAK and Rogue Audios amps do not play nice together?

Thanks
deadlift
zd542
5,339 posts
 
You shouldn't have a problem. I assume you are using your Rogues balanced. What kind of IC's do you have? You need to make sure they are internally balanced, and not SE with XLR connectors. Also, make sure you try both sets of binding posts on your amps. Pick the ones that sound best.
newbee
4,817 posts
 
Your Rogue amps input sensitivity is 1V (high sensitivity). Your QS input sensitivity is 9V (very low). What this means is that the gain (and it's tube noise) from your pre-amp's tube section will be magnified substantially more with the Rogue and, especially when driving highly efficient speakers such as yours, will result in noise. This is not controllable by using your pre-amps volume control as it is in the circuit before the tube section which is always seen by the amp at it's full output gain.

Your problem could be that the tubes in your pre-amp are not 'low noise' enough for the Rogue Amp when it is amplifying your high efficiency speakers. If low noise tubes are not the problem and you still want to use your pre-amp with this amp/speaker combo you can try using in-line attenuators at the amp inputs to reduce the gain from your pre-amp. This may be inelegant but there is not much down side - it is nothing much more that a fixed value resistor in this kind of attenuator.

Hope that helps a bit.
dweller's avatar
dweller
3,867 posts
 
I purchased a used BAT VK-300SE which had the same problem upon arrival.
I decided to work with the seller and had to return the unit to BAT.
It was fixed and worked flawlessly thereafter.
BAT said it had a bad "voltage regulator".
BAT graciously fixed it under warranty even after we explained that I was the new owner.
Like the late-great HP used to say: "If it works the first time, it's not high end"...
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