Cartridge gain overload - please explain


I am using a Lyra Delos on a JA Michell tecnodec, a Whest .30R phono stage,
an ARC LS25 linestage, ARC VT100 amp, and Rockport Mira Monitors.

I recently added the Whest to get more gain because the ARC PH3SE with 54dB was not enough, especially because the LS25 gives just 12dB of gain to single ended sources. By switching to the Whest, I was able to get more gain right from the phono stage, and also an additional 6dB from running balanced into the LS25.

Because I was coming in from a under-gain situation, I started with the Whest set to 66dB, thinking a bit more is good, and I could just turn the volume knob lower on the LS25. But there was that record pop / loud static discharge sound which was actually cartridge gain overload. When I changed the gain settings to 60dB, the problem ceased.

My question is, why does this happen? Whats wrong with an extra 6dB from the phonostage and just a little less output from the linestage to compensate? In my mind, that seems like it would work fine.

I would like to know more about this. Perhaps there will be even a benefit if I switch down to 55dB? But that seems counter intuitive, because I was getting too little gain before and I had to really ramp up the volume on the line stage, which caused a lot of noise.

thanks,
Mark
marktomaras

Showing 3 responses by jmcgrogan2

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.
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.
Thank you for the clarification Zd, you are correct, it does seem like the problem lies within the the phono stage. Thank you too Al, your acute awareness of minute details is simply amazing. You are a beam of light for the rest of us taking stabs in the dark. Keep up the good work. :)