40 db is too low for that cart. The MC setting may work perfectly.
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I have to turn the volume up quite high on my linestage to get the right volume.Excellent, that is exactly what you want.. In an ideal world as you turn it up you should hit the ideal loudness just as you have it all the way up. There is no such thing as having the volume knob too high unless it is too loud at that point.
It will not hurt anything to try different loads.
40 db is too low for that cart.How do you figure that? The gain needed is function of the total system gain, not just the phono. If you can't get the system to play loud enough all the way up you need more gain. If you can't turn the volume up very far without it getting too loud you need less gain.
Thanks you for you responses. MY issue is this. I have an Aesthetix Calypso with an 88 step volume control. It starts to get a little noisy at step 50. With some LP I am at the mid to upper 50 level. I think the LP 5.3 is known for being very quite so I thought a little more gain there and a little less in the calypso might be a good combination but did not want to damage anything during the experiment.
Unfortunately you are in a bit of a "no man's land" situation here. Ideally, with that cartridge you'll require about 44 db of gain at the phono stage so you are a bit light and that will compromise you dynamically among other things.
Going to 54 db though is going to, IMO, give you way too much gain probably taking you into overload and resulting in even worse sound quality. You can do it; it's just that it will sound lousy, or at least a lot lousier than if you get your gain right.
If you're committed to the Moon and the Soundsmith (they are supposed to be very good phono stage and cartridge respectively), I'd consider sending the phono stage back to the manufacturer to have them change the gain to 44 db.
I'm going to disagree with HDM. I don't see an extra 4dB in the phono stage doing anything that can't be accomplished by turning up the preamp another 4dB, Gain is gain, it doesn't matter where it comes from.
If you are hearing that kind of noise at that level something is wrong. The prime suspect is tubes in first stages of the Calypso but it could be before that.
Put shorting plugs in the input of the Calypso and see if you still have the noise. If not it's coming from the phono stage.
A good test of the 54db setting would be to listen to a recording that contains high volume cymbal crashes. Those sounds probably represent a worst case in terms of high frequency energy.
Listen for distortion or clipping on those notes. It would probably make sense to do your initial trials at a bit less than normal volume. Whether or not overloading occurs will be independent of volume setting, since the phono stage is ahead of the volume control.
JA's measurements for the LP5.3 indicate overloading occurs, for the 40 and 60db gain settings, at levels that are about 20db less at 20kHz than at mid-frequencies. The manual for the LP5.3 indicates an input overload point for the 54db setting of 11mv, which probably means that the 20kHz overload point will be about 1.1mv. Also, the 20db difference may be suggestive that the overload occurs prior to riaa de-emphasis, meaning that the relevant signal level will contain about 20db more energy at 20kHz than the music actually contains.
All of which leads me to feel that you'll probably be ok with most music, but I'm uncertain if clipping or distortion might occur under worst case conditions of high frequency energy.
I also note that JA's measurements of the Calypso indicated a large amount of what he called "rf breakthrough" (perhaps he really means a low level oscillation) at exactly 519 kHz (which is just below the AM broadcast band). I'm wondering if that might somehow be related to the hiss you hear, although his description seems to indicate that its amplitude is not volume control sensitive. Perhaps it's getting on the grounds and somehow beating down to audible frequencies. If you have a portable am radio that can tune to that frequency, it would be interesting to see if it detects that when brought near the preamp. As would trying Herman's suggestion of seeing if the noise is still present with shorting plugs connected to the inputs of the Calypso in place of the phono stage.