ARC Reference 2 MkII Preamp white noise levels


Hi,
Just acquired a Ref2 MII preamp. The level of white noise is much higher than my BAT VK-50SE. It does not change with volume setting and is definitely not the amp noise. By muting and unmuting the preamp, you can discern the difference. The noise is quite audible from the listening position 8 feet away. For those who have this preamp, is the noise characteristic? Could it be the tubes? The difference between the BAT and ARC is remarkable. Thanks- William
classicjazz
My gut reation to you situation is that you have a pre-amp with high gain, and amp with high sensitivity and/or very efficient speakers and you are hearing the noise floor of your pre-amp line stage. I recently got some higher efficiency speakers and had to put in-line attenuators to quiet down the line stage from my ARC SP10. As to whether or not its the tubes themselves - tube "noise" is usually not a steady low level hiss, but takes on a more crackly-spitty sound, however light. Don't know about the BAT but I suspect it may be a matter of its output voltage as seen by the amp. Hope that helps a bit...
I doubt gain differences are the problem. While muted, the difference in the two pre's gain capabilities shouldn't matter.

If the noise level isn't at or near zero when the pre is muted, then it sounds like it could be an impedance mismatch...

The tubes would seem pretty unlikely. When they go south, you will definitely know something is wrong.
Thanks for the insight.

It sounds like the impedance mismatch. I have amps with 10K Ohms input, 1/2 of what ARC recommends for the RE2. I don't have another amp on hand but maybe that's it? My speakers are Genesis 501s, which are 90 dB efficient. Amps are Gryphon Reference One Monoblocks. Is there a way to compensate for the mismatch without changing one or the other component?
Tube preamps really do not like anywhere near that low of impedance. You might try asking your amp manufacturer if the impedance can be increased. Generally, there is an input resistor and you can simply substitute another value.
Most tube pre's are happiest when the impedance is around 50K or higher.
I really can't say for sure if this is responsible for the increase in the noise floor. Some tubes have a higher noise floor than others by a substantial amount. If the pre's tubes have been replaced, it's possible this could be an issue. Might check and see if you have replacements(different from the originals) if you purchased used.
If you purchased new---easy---call ARC. Or, call them anyway. They are really friendly people!