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 4 responses by zd542

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.
Sorry if I wasn't clear on my first post. I typed it out really fast this morning as not to be late for work. Its no excuse, of course, but its true. All I really meant to say was that if the phono stage was being overloaded, whatever the cause, and there was audible distortion, you would hear that distortion whatever volume the line stage (LS25) was set to; low or high.

If we look at this piece of the OP:

"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. "

Thats the question I was trying to answer. When I read that, it seems to me that the OP didn't understand why the distortion didn't go away when he turned down the volume on his LS25. Whatever is causing the excess gain issue with his phono preamp, has to be dealt with there. The LS25 has nothing to do with the problem. Actually, any preamp you insert into that system should show the same results. (That is if I'm reading the problem correctly. If not, have no fear. I'm sure Al will chime in and post me back into place.)
Mark,

The one thing I see in your last post that gives me pause is your reference the position of your volume knob. I think you may be focusing too much on that. Given that you can adjust the gain on your phono pre and the LS25, your volume knob can be almost anywhere and not, necessarily be a problem.

If it were me, I would get the phono preamp dialed in first. You ask what you should be looking for sonically. The first thing, of course, is to get your gain set low enough to where there is no distortion. From that point, its up to you. Most people like to try a verity of settings and just pick what sounds best to you.

Once you find a gain setting on your phono that you like, then set the LS25. Just pick a setting that gives you the best control for how you like to listen to music. I wouldn't worry too much about the actual position of the volume knob. Once you take care of the gain issue with the phono, I don't see you having any problems with your LS25. Your phono preamp is a line level source. You can expect the same type of performance you are getting from any of your other sources.
Mark,

Just wondering if you made any progress with your system? If so, what did you do?