A Noisey CAT SL1 Reference

[hifiscratch]

I have been offered a second hand Convergent Audio Technology SL1 Reference to buy. I do not know if it is mk. I , II or III. It sounded great but was very hissy, clearly audible from my listening position with the volume turned completly down. This hiss did not seam to increase with any adjustment of the volume control but was completly removed when the mute was switch on. I was told the tubes were on their way out and possibly my power amp's sensitivity 240mv (World Audio Design K5881) was to high. Would these be the reasons? How should I reduce the power amp's sensitivity? Should I buy this preamp if the price is right? He is asking around £1000 UKS/ $1800 USD.

[fdegrove]

Hi,

I was told the tubes were on their way out and possibly my power amp's sensitivity 240mv (World Audio Design K5881) was to high. Would these be the reasons?

I very much doubt it but the high input sensitivity of your amp will of course only accentuate the problem even more.

How should I reduce the power amp's sensitivity?

You can always solder in a voltage divider at the input of the amp, or a potentiometer.

While the asking price isn't really excessive, I still wonder where this hissing comes from.
Even if it's the valves, I still wonder how a preamp can possibly wear them out to this point....

Cheers,

[hifiscratch]

Thanks fdegrove. I have about six weeks before the 'CAT SL1' owner will part with it (he has just ordered, and is waiting for the latest version). I have known this person many years and trust him when he says that he does not have this problem in his system (including Horning horn speakers), though he did have his Border Patrol power amp's sensitivity reduced to give him more control over his CD and tuner volumes. He is friendly with Gary Dews of Border Patrol and is going to ask his advice. If any solutions arise I will post them on this forum in the future.

Thanks again. Rob