Cartridge gain overload - please explain

Mark,

There are quite a few A-gon members like Almarg with a tremendous wealth of technical knowledge who will hopefully respond with an in-depth explanation to your query. From my experience and understanding, the voltage gain on the phono pre should "match" the voltage output of the cartridge for optimal performance. Tools like the KAB calculator http://www.kabusa.com/frameset.htm?/ are useful to determining the gain your cart needs to perform well. It's just an approximation, but from my experience it's actually quite accurate. According to the calculation, the Delos needs 55 dB of gain. It has certainly worked in my systems.

As I wrote in the thread you referred to, too much gain results in a sound that's shrill, harsh, and overall unpleasant. I'd think it's the excessive voltage that amplifies the signal and generates spikes in amplitude that is responsible for the harshness and edgy sound I get with excessive gain on my phono pre. It's not distortion, but edginess that is immediately audible and unbearable. I've never experienced pops or static discharge as a result of excessive gain, but it certainly does not surprise me. For what it's worth, I've also found that increasing the gain on the line stage (if it allows it) to compensate for insufficient volume works better than increasing the gain on the phono preamp. Might be a bit noisier, especially if it's a tube line stage, but does not make the sound edgy or shrill.

Mark, according to the specs at ARCDB your LS 25 has selectable gain for each input with settings of 6, 12 or 18 db. So it seems like you could still run your PH3SE and just increase the gain in your LS 25 from 12 to 18 db of gain. That should be plenty of gain.

The reason for the problem is that you are talking about 2 separate things. The volume/gain on your linestage has nothing to do with your phono stage. If you have a gain problem with your phono stage, it exists at all volumes, it really doesn't matter what setting the volume is on the LS. Until you reduce the gain on your phono, the problem will remain; at at whatever volume you have your LS set to.

Zd542, they are seperate issues, but they can be worked on together. His ARC PH3SE had a gain of 54 db which he said is not enough for the Delos with his LS 25 set to 12 dB of gain. Then he got a Whest with 66 db of gain and set it to max out, and found out that 66 dB of gain overloaded the LS25 input. When he reduced it to 60 dB of gain the overload problem went away.

I'm saying that it doesn't matter whether he uses his ARC PH3SE at 54 dB of gain and changes his LS25 to 18 dB of gain OR he has his Whest set to 60 DB of gain and his LS 25 set to 12 dB of gain. Either way he is getting 72 dB of gain, which should be more than enough gain for a 0.6 mV output cartridge.