I am in my happy place - designing something new. I have several MM cartridges with relatively low to modest output when compared to say a 2M Black at 5 mV.
You see, in the world of solid state phono stages you probably wouldn't notice because the gain of the stages are usually adjustable, but in my world where a tube phono stage has 43dB of gain, and able to handle nearly 20mV of input, I find that cartridges with higher output have more density and slam not to mention blacker backgrounds because you don't have to turn the preamp or amp up as loud, so any noise that is there, is basically unheard.
Even with solid state... just because you have enough or even more than enough gain... doesn't mean you have the ideal gain structure. Let's say we compare a 5mv cartridge against a 3 mv cartridge. The 3 mv cartridge is quieter. We turn up the volume to make the music as loud as it was with the 5 mv cartridge and it sounds more like it. That is until you realize the noise is 3 to 6 dB louder than it was, which basically means the dynamics are reduced by that same amount. The sound is consequently less dense and not as engaging.
So what happens when we select a higher gain on the solid state phono stage? Noise problem solved. Dynamics are improved and everything sounds relatively great. This is where most people quit.
But what would happen if we set the gain on the phono stage back to the lower setting and instead added another gain stage between the cartridge and the phono stage?
Lots.
Firstly, unlike the phono stage, this gain stage is linear. It has no EQ. Dynamics are the same from top to bottom.
Secondly by increasing the gain from the cartridge we also add an additional interconnect. This would normally be a deal breaker. The cable used between the cartridge and phono stage is a very real part of the sound because it has a given capacitance and the cartridge responds to if not depends on it to have the correct frequency balance. But, the game changes when the cable is used to store energy as pressure (voltage) and then release it through an orifice. (input voltage divider staged in front of a given impedance.)
Yes, that's going to need some explaining. So we take a 3mV cartridge and we increase to to 12mv. This travels through the cable to the input of the phono stage that in turn embellishes it like nourishment to the body and now highly energized and full of life it leaves the phono stage at a reference of 5 volts instead of 1 or 2 volts. This in turn causes you to turn down the input control on the amplifier or preamp which then raises the pressure in the cable between the phono stage and the amp or preamp. This tension is reflected back through the entire phono stage, the interconnect, the gain stage driving that, and the tonearm cable and cartridge. That is the reality of it. The result is a profound change in how the cartridge sounds.
Having the linear gain stage between the cartridge and phonostage gives more opportunity to voice things as well as dial it into the matrix. The prototype I am presently using has an adjustable output level which basically means I can adjust the output of a 3mv cartridge anywhere from 0mv. to 12mv or more while I listen to find that magic balance of transparency and power that can only be found this way. It is reserved for the the brave few who are still reading this.
This is the most critical part -- the gain structure that you create for yourself starts here.
The current prototype is battery driven solid state but I am in the process of building a zero feedback design using battery driven tubes, one per channel. This should be so good it makes me wet myself. We will see.
The batteries in both of these designs have a direct effect on the sound signature of the cartridge. Alkaline do not sound the same a Lithium which do not sound the same a carbon. You can voice your cartridge by rolling batteries. Carbon is where it's at if you like vintage tone.
This is taking the performance of the London Decca to a new place. Prior to this experiment, I used a step up cartridge for it that gave me 6dB of gain and it sounds great. That is what I have been using to evaluate that cartridge for the majority of the time I've listened to it. That said, I have not been able to get it as high as I would like to achieve the ideal gain structure and have never gotten it completely black as far as hum goes. Listening to the cartridge by itself without the transformer into a ZP3 is a hum problem because the cartridge is only 3 poles instead of 4. By the time I get the gain on the amp or preamp high enough to start smiling, the hum ruins it. But just before I pull the plug hearing the cartridge with no transformer makes it even faster and accurate.
This is why a gain stage for the Decca and the other MM carts I use makes sense because it can be more neutral or less neutral than a transformer and ultimately have more drive and slam with less noise.
The output level and slam we're trying to achieve is similar at the least to a FR7f with it's 30 to 1 transformer that has some serious slam and a bold presence that makes you look at records like some kind of magic pancake from heaven.
Hope to have something done by spring. The solid state unit I did is so good, I have doubts that it can be topped. But I also realize I might laugh at that statement once I hear the NFB triode model. That would be fun!
What gets me excited is knowing that many people with MM cartridges will feel like they have never heard them once they add this head amp. It will be like taking a $500 cartridge or a $300 cartridge and making it sound like a $1500 cartridge, as well it will be like taking a $5000 cartridge and making it sound like a 15,000 cartridge.
This is all based on the battery driven solid state model I have developed to sound like tubes. As far as I am concerned it can go into production now. However I have to pit it against a worthy contender the NFB battery driven triodes to find out which is actually going to be liked by those who would purchase it.
Hope you're having a great holiday and happy listening!
Steve : )
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New product for MM cartridges (Read 172 times)
