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Hum and Hiss with Tube pre-amp

I recently got a McCormack DNA1 Deluxe and initially used the pre-amp section of my Arcam Alpha 9, and then a Creek OBH 12. No problems, but no excitement!!! I decided to try a tube pre-amp. I have tried a Melos MA 111 and a Cary Ae3 kit that was up-graded in many ways by it builder. Both of these units are reportd to work fine by their owners. When I put them into my system (front end of CAL DX 1 cd and Rotel -entry level- tuner) I get very audible hum (60 cycle) and hiss(like FM hiss). I have tried cheater plugs on both amp and pre-amp to no avail. It was suggested that I disconnect the inputs to the amp and turn it on to check for noise- I did this and there was no noise. This suggests the problem is elsewhere. Since the tube pre-amps worked fine in other systems, they do not seem to be the culprit. But then again, with the ss pre-amps there was no problem, apparently ruling out the front end. But that leaves NOTHING causing the obvious problem!!! Any ideas?? Thanks for any and all help. Rich
drrnc2

Showing 2 responses by 7p62mm

7p62mm
97 posts
 
60 Hz hum is a undereported problem. With your pre-amp connected to your amp try disconnecting the sources to the pre-amp. I had a problem with 60 Hz hum. Trouble shooting determined that the source of the hum was from a cable TV coax (I was taking audio outs from the VCR to my pre-amp).
7p62mm
97 posts
 
I forgot to mention my experience with white noise hiss from tube preamps. My experience is that tube preamps produce a low level white noise hiss that is barely audible (you have to put your ear right up the speaker to hear it). The noise is not noticable to me when music is being played. I have never owned a solid state preamp; but, my solid state amp does not produce any noise when my pre-amp is muted. This suggests to me that the noise floor is lower for solid state devices in gereral. I have read complaints that solid state preamps sound harsh; but,I am not sure if this is true. It sounds like the solid state preamp has worked better for you. Perhaps you should stay with it and not go to tubes. One last comment. The problem may be with the design of the pre-amps that you are using. Maybe they are susceptable to external AC interference. The reason that the other users didn't notice the problem is because the noise level in their listening area is lower than yours.
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