Sorry again for the lengthy delay in responding.
We haven't decided if there will be a single-layer coil version of our latest cartridges designs or not. Design-wise there are zero obstacles to doing so, but from a business perspective, sales of the Helikon SL have not been strong enough to justify keeping it in our lineup. I am told by some of our distributors that most Helikon SL sales occur when the standard-output version happens to be out of stock, and the customer is willing to accept an SL version instead. IOW, keeping an SL model doesn't appear to have increased our sales of the Helikon series - it looks to exist in more of an either-or situation with the standard output version.
Our SL models use a different coil/cantilever assembly system from the standard Helikon, likewise the voicing is also accomplished differently, and for this reason building these do not happen alongside the standard versions. Cartridges at and below the Helikon's price bracket are made in batches, and we set aside a distinct production batch and schedule for the SL versions when they need to be made. So in terms of production efficiency and making effective use of our builder's time and labor, keeping an SL model in our lineup is a detriment rather than an advantage.
Cartridges at, say, the Titan's price bracket are built in smaller groups, and more time is spent over each cartridge, making it easier to justify an SL variant for this class of cartridge.
I tend to agree with you regarding the situation with current-day phono stages and phono preamps, but I will add that I do not consider S/N ratio as the be-all and end-all of high-performance phono stage design. My experience has been that reduction of intermodulation distortion and maintaining good in-circuit bandwidth (and therefore good phase response) is a higher priority than pure S/N ratio. For example, it is relatively easy to design a phono stage with a good S/N ratio by using multiple input devices in parallel, and there also exist semiconductor devices which tout extra-low noise levels. The problem is, both of these approaches tend to increase non-linear capacitances in the input stage, and my hands-on experience is that I have not particularly liked the type of sound that such a circuit delivers. There is nothing wrong with designing for as good an S/N ratio as possible, but at least in my opinion, this should not come at the cost of increased non-linear input capacitances, intermodulation distortion, or in-circuit bandwidth.
It is far easier to design a good-sounding MM-level phono stage than it is a stellar MC-level phono stage - implementing the extra 30-some dB gain required at a high level of quality does not come easily nor cheaply. My experience is that this is why folks may get better sonic results with a high output high-impedance fixed-coil cartridge (MM or MI) into a low-gain phono stage than a low-output low-impedance cartridge (MC) into many MC-compatible high-gain phono stages. Although the higher inductance of fixed-coil cartridges practically guarantees that the electrical phase response within the audible bandwidth will be messed up, in many cases the sonic penalty for this is less than the sonic penalty imposed if a low-inductance low-output cartridge is used with a phono stage that has noticeably insufficient S/N ratio, marked non-linearities in the RF region, or increased non-linear input capacitances. And the lower the output voltage from the cartridge, the more capable the phono stage needs to be.
But I don't mean to be overly critical of most phono stage designers - to design a world-class phono stage that can do justice to low-output cartridges is not a trivial accomplishment. And the reality is that if we cartridge designers want our products to sell, it is prudent to take the capabilities of contemporary phono stage into consideration, and emphasize cartridge designs that have a good chance of working well with commercially available phono amplification.
To take the SL/low-output cartridge example yet further, the ideal moving-coil cartridge would be one possessing only one coil turn. The electrical bandwidth and phase response in particular would be awesome. But the extremely low output voltage would also mean that such a cartridge would be an utter beast that practically no real-world phono stage would be able to accommodate.
Due to the constraints of real-world phono amplification, cartridge designs which are less than perfect when viewed from a theoretical, idealistic perspective will in many cases deliver more optimal sonic results than a more extreme, "better" cartridge. Conversely, better phono stages are able to extract more of the performance potential of the cartridge, thereby allowing cartridge manufacturers to come up with more idealized, extreme cartridge designs, and users to have a better chance of fully accommodating and enjoying such capable yet demanding cartridges.
Incidentally, we were finally able to start shipments of the Kleos. Because it is a new design that involves new material choices, new surface processing and new building methods that entail a lot of work during the preparation and assembly stages, initial production quantities remain quite low (the first shipment consisted of a grand total of 15 cartridges). Gradually, as we learn how to deal with all of the new design decisions in a time and labor-effective manner, our production rate should go up, and we will be able to deliver Kleos' to more markets.
I think that the Kleos is the most natural-sounding Lyra cartridge yet, but that's just my opinion. I will be quite interested in hearing the impressions of those who get a chance to hear or use it.
As was the case with the Delos, I've done a fair amount of work regarding the effects of phono stage loading, and this information is summarized in the Kleos' instruction manual. Electrically, the Kleos is very similar to the Helikon, Skala and Titan (but not the SL or Mono models), so the loading analysis for the Kleos should be useful also for Helikon, Skala and Titan owners. Please feel free to let me know if if you use one of these cartridges and would like to have this information, and depending on the level of interest I will either send out email replies, or post the information here.
cheers to all, jonathan