Background noise

Swampwalker, actually there is no loading mismatch, but I think your diagnosis is correct -- noisy tube, exacerbated by being below the minimum input voltage.

I'll look into it and let you know. Thanks.

there is no noise I can hear from the other inputs, even at maximum volume levels. Just to give you a better sense of the loudness of the noise, I just set it at the maximum level, stepped out of my listening room, moved to another room that is approximately 8 meters away from the listening room, and could still hear it.

BTW, I bought the Monbrison 3 months ago from someone who bought it in October. Called Shindo and they told me that the warranty is not transferable...weird policy for a luxury product, if you care about keeping your customers. That said, the Monbrison is just wonderful

I think the hypothesis that this is tube rush is sensible. The gain is ok but not great: I use a MC Sumiko Blackbird through the MM phono section. The Blackbird is 2.5 mV, and the Shindo dealer says the minimum MM should be 3 mV. Despite this slight mismatch, I find the combination to be wonderful...except that I can hear some noise when I turn up the volume level during music reproduction.

I'll find out what tubes are used for the phono stage and see if I can find a replacement. Thanks

Well, in terms of load, I checked the specs of the Sumiko, and there is no problem. So, that is not an issue.

I agree that the load mismatch can exacerbate the problem, but I do not think it is the root cause or the central issue -- the problem is that no matter whether the turntable is connected or not to the preamplifiers, when I turn up the volume I hear a lot of background noise. The underlying problem must be somewhere else...at this point I am convinced it's a tube issue. Thanks.

yes...i'll look into the tubes. Actually, i just opened it, and noticed that the housing of one of the tubes is a bit loose. so, that might be the culprit...or one of the tubes. i'll keep you posted. thanks.