2. amps-preamps
  3. 186365-1614

Hissing at idle through one amp but not another

So I inherited a wonderful Ayon Crossfire from my uncle and it sounds awesome but I'm having a hissing that must be related to the amp/preamp match but I don't understand why.

With my Lamm preamp and the Ayon with the mute on, the speakers are silent, when I unmute I hear a hiss from the tweeters, just loud enough to hear at the listening position 10 feet away with no music playing and also during quiet passages on very quiet vinyl. It happens equally with any input selected on the Lamm. It's the same level of hiss no matter what the volume is set to. I've swapped the cable from preamp to amp. No change.

And then, when I swap out the Ayon for a vintage Fisher SA-100, there is no hiss anywhere at any time. Completely silent.

This is killing me. What the hell is going on!!!

dhcod
tomcy6's avatar
tomcy6
2,539 posts
 

Tubes can hiss.  It's a common problem.  You can try different tubes one set at a time (preamp tubes, power tubes).  That's where I would start.

tonydennison's avatar
tonydennison
382 posts
 

Yeah. 12AT7's are usually quiet but you can always get one that will hiss 2 or 3 times as the other. Switch the pre tubes left to right and see if the noise travels

dhcod OP
706 posts
 

These are good suggestions but this problem is different. It seems like the hiss is coming from the preamp because I don't hear it when the preamp is muted or off. But if I use a different amp, I don't hear hiss at all. I've swapped tubes. That's not the issue. It seems like something incompatible between the Lamm and the Ayon. I'm going to try another preamp next week.

tomcy6's avatar
tomcy6
2,539 posts
 

Yes trying another preamp should tell if the problem is in the Ayon or the Lamm, or maybe the combination of the two.  Let us know how it goes.

mlsstl
1,390 posts
 

How are you connecting the Lamm preamp -- via the direct in or one of the selectable inputs?  I looked at the specs for the Ayon and they don't say what the input sensitivity is. It could be that it is a mismatch for the Lamm.  If you are using direct in, try switching to one of the selectable inputs and then reduce the volume on the Ayre until the hiss goes away. This will mean that you'll need to turn the volume on the Lamm up higher.

If you are using the selectable inputs on the Ayon, it could mean that the preamp tubes are aging and need to be replaced, or once again, just a mismatch with the Lamm.

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