You may want to read the recent review on the SG-220 Strain Gauge by Jack Roberts of Dagogo, and almost more importantly, the comments from both an owner, and an early developer. Fascinating.
With that in mind, please understand that there is a long history of SG cartridges, ALL of which have varying response curves. There is a great review on the web showing the numerous models of Panasonic units, all of which varied between each other, not to mention between themselves. SG designs are far more sensitive than MC to variations, therefore, are far more difficult to build.
Somce have asked why no total RIAA is needed - and I came up with a very different way of explaining this, and did so first to Micheal Fremer, the explanation of which he used in his review. Simply, when you CUT with RIAA, (boosting the highs and cutting the lows with a roughly 6dB curve) you are essentially cutting a CONSTANT DISPLACMENT groove, BECAUSE you are cutting it with a magnetic cutting head, whose diplacement is normally a function of frequency. You see, when you input a flat volume/amplitude signal to a magnetic head, it cuts wide displacement groove for low frequencies, and less wide as the frequency goes up. With RIAA, you affecting that, and cutting, as said above, a nearly constant DISPLACEMENT groove. If you play that back with a diplacement sensitive device, you get an essentially flat playback response. If desired, VERY little EQ is needed to flatten it completely so you are in complete agreement with RIAA.
When we first introduced ours many years ago, we did not use any EQ to achieve a maximally flat response. This was the same as was done with the RAM design I worked on almost 40 years ago, as well as Matsushita. There were different philosophies regarding any use of slight EQ; some did, some did not. John Iverson, Jeff Rowland, and others did. RAM did not. I did not in the very early Soundsmith designs, but changed my mind early on. I think our website may not reflect that.
I have also made very significant improvements and changes to the cart design over the many years, as well as having included very slight EQ to totally flatten the response - this was done WITHOUT adding any additional active circuitry, which I am totally against.
I have experimented with two TUBE based systems, each designed by my close friends, Jim Fosgate and Richard Majestic (of RAM), both of whom as some of the finest audio engineers in the world. The FOsgate design was +/- 1/8dB (1/4 db total variation) RIAA from 20-20KHZ. Although interesting, they did not compare well with the solid state highly linear design I make. There were NO transformers used in their designs, for which I am glad, as it is a totally unnecessary component, proposed by someone else as a method for the requirede reversing the phase of one channel of a displacement sensitive design. In magnetic designs, they reverse one channel fo the cartridge wiring internally. Why? The groove walls of a stereo record are cut out of phase.
Again, I am totally against adding such a component (transformer) where it is simply not needed at all. There are far more linear and elegant ways to achieve the channel reversal needed for displacement type cartridges, WITHOUT adding unnecessary, non-linear and frequency limiting circuit components.
Considering the real world considerable variation of the Panasonic cartridges, and the efforts I have made over these many years to achieve uniformity of manufacture and specification of my cartridges, I am glad that they have been well received by so many owners. They are a very different system of vinyl replay, and while certainly not for everyone, they have made their place in the homes of many "believers".
This gives me no small amount of satisfaction.
Peter Ledermann/President/Soundsmith
