How to pick a COMPATIBLE phono cartridge

hdm 1-1-2018
Unless you are running a very unusual system (passive pre-amplfier, flea type amplifiers with extreme hi-efficiency speakers, etc.), I think you will find it [the KAB calculator] will give you a very accurate read on the type of gain optimization you need to do with the cartridge/phono stage interface.

This is a good point, which emphasizes that an online calculator should not be applied blindly.

Specifically, the KAB calculator indicates the gain that would result in the cartridge’s rated output being boosted to 0.325 volts. As indicated in its description that value was chosen based on what is appropriate for driving a CD recorder. However power amplifiers will typically require inputs in the vicinity of 1 to 2 volts to drive them to full power, for single-ended inputs, and twice that for balanced inputs. Which means that the gain of a typical active line stage, perhaps 6 to 15 db or so, will be required to assure that the phono stage gain specified by the calculator will make it possible to drive the power amp to full power.

On the other hand, like most CJ preamps Randy’s 16LS provides unusually high gain (25 db) for a line stage. So if a gain problem were to arise it would most likely be in the other direction, resulting in the volume control having to be used at undesirably low settings. That is very unlikely to occur with a cartridge/phono stage combination, but is certainly a possibility with a CD player or other digital source depending on the gain of the power amp and the sensitivity of the speakers.

Regards,
-- Al

Great thread and info guys. Al could you expand on this item a little further with another example or two? Maybe a good and bad senario?

"4)The relation between cartridge output and phono stage signal-to-noise ratio is what primarily determines the amount of hiss that will be present when playing a record. Adding gain further downstream will not improve that; it will just result in using the volume control at lower settings."

Robd2, an example of what is likely to be a good scenario would be the combination of a 0.5 mv cartridge with a 60 db phono stage and a 10 db line stage. Those numbers are fairly typical for a system utilizing an LOMC cartridge, and the 60 db phono stage gain can be taken as an indication that the designer intended it for use with such a cartridge. Also, the 70 db total gain that is provided by those components (when the volume control on the line stage is turned all the way up) would boost the 0.5 mv output provided by the cartridge under the standard test conditions (which correspond to a volume that is quite loud but not as loud as the dynamic peaks of some recordings) to about 1.5 volts, which is right in the ballpark of the voltage that is required to drive most power amplifiers to max power.

An example of what is likely to be a bad scenario is the one discussed earlier, involving use of a 0.4 mv cartridge in conjunction with a 52 db phono stage and a 25 db line stage. Even though the total of those gains is more than adequate for use with a 0.4 mv cartridge, the four factors I cited suggest that noise performance is likely to be inadequate.

The reason for my repeated use of the word "likely" is that different phono stages having the same gain can have considerably different levels of internally generated noise. And manufacturer specs on signal-to-noise ratios, when and if provided, should be taken with multiple grains of salt because the input or output signal levels they are based on are often not specified, and the "weighting" they may be based on (such as A-weighting) is also often not specified. If Stereophile has reviewed a particular phono stage, though, John Atkinson’s measurements and his associated commentary about noise performance can often be helpful.

Regards,
-- Al

Dear @rbschauman : Your phono stage is a solid state design a FET design with enough gain for almost any LOMC cartridge.
Been a solid state unit is " weird " its noise level spec, maybe a " finger error by CJ " . Something is not exactly clear/precise down there.

Anyway the Benz low output will works wonderful in your C&J combination.

Your SME 4 is a very good match for it too and the only advise to you is to add the damping SME mechanism for that IV model.

No, you don't need the Benz high output version. As a fact as higher the MC cartridge output as more degradation exist in the cartridge generated signal. This means that the 0.4mv is way superior to the high output version.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

Interesting system.. I use CJ Premier units in two systems - a 15 phono in a heritage system and a 14 and 11a in my main system.

With the 15 I run a Lyra Clavis low output cartridge. The 15 has lower gain than the Vendetta I use in the main system, but it still has enough gain for a low output (0.25 mv), particularly as that is my acoustic music system with inefficient (Martin Logan CLS) speakers.

I see no reason why you can't run a medium or even a low if the output cartridge.  The solid state phone stage you use has higher gain than my tube one does.