Audio Research preamp LS vs SP

What is the difference between ARC preamp LS line and SP line.

Any other specific meaning for the one or two digits after LS and SP. I assume the bigger the digits, the later the model is and more expensive. Any other meaning? For example, Can you distinguish a tube preamp or a solid just by looking the numbers?
Jeromexzh, as far as I can remember, the SP line is an older generation of preamps and they included a phono stage. Some of them are classics (SP10, SP11). The first LS models have appeared around the early 90s. These models are only line preamplifiers (no phono).

You can't distinguish a tube or a solid state preamp just by looking at the numbers. Like you said, for the current line, the bigger the digits, the later the model is and more expensive.

Pay attention if you compare a discontinued model like the LS5 with a new one like the LS12. You may think that the LS12 is better than the LS5 if you just look at the numbers. The LS5 was the high end of his generation while the LS12 is the low end of the current generation.

Cheers. Daniel
Beaudoind is right, the SP series have phono stages, and the LS series are line level preamps only. Most of the SP series do not have remote control capability, whereas the LS products do. As for the model numbers, well, the higher numbers are the most recent but not necessarily the best ARC has/had to offer. Jeff
Not all have remote. The LS-8 MkII which is a current model (entry level product apparently, if you go by the manufacturer's copy, the threshold is simpply quite high for Audio-Research!).
I would guess the LS stands for line stage series and the SP stands for stereo preamp which presumably would have a phono stage. I think all current product is line stage and you need an outboard phono.
According to the nice people at ARC, the current LS models are made to a higher standard and better performance than the LS models - for those reading this posting in the current day period.
There is more of a difference between the SP and LS than just the fact that one has a phono and the other not.

A good reference site is the ARC database site for looking at the history of their products. This site has a strange address and reads "www dot arcdb dot ws"

Here you can look at a history of when products came out and at list prices.

For example, there is a LS16, LS 16MKII, SP16, SP16L. There are similar lineages for the LS17/SP17 and SP17L. In these instances the LS vs. SP differences are a quality and performance based with the LS being considered a higher level product (ie. LS16 vs. SP16L and LS17 vs. SP17L).

Another nice aspect of this site is that you can get true list prices for the components as such prices are often misquoted in ads on Audiogon (obviously to the high side).

For example, the SP16L (without the phono board) had a list price of $1,995 from 2001 through 2006 and a price increase for its last year of production to $2,495 for 2007 year only.

The LS16 had a list price of $2995 when it came out in 1999 and never had a price change. The LS16 MKII was priced at $3,495 and ran from 2001 to 2006 (I believe) and never changed its list price.