Audio Research LS15 vs. SP14

A point to be aware of is that as with many ARC preamps and line stages, the LS15 and SP14 have output impedance characteristics that may make them unsuitable for use with some solid state power amps having lowish input impedances.  Specifically, according to the information at www.arcdb.ws:

LS15:  "40K ohms minimum load and 1000pF maximum capacitance"

SP14:   "Recommended load 60K - 100K ohms and 100pF. (20K ohms minimum and 1000pF maximum)"

The load capacitance recommendation (as opposed to the load resistance recommendation) probably won't be an issue unless the length of the cable to the power amp is particularly long.

Regards,
-- Al
 

P.S: Stereophile’s measurements of the output impedance of the Audible Illusions Modulus 3A was around 1800 ohms, presumably at a mid-range frequency and therefore probably higher at some other frequencies. If the Modulus 3 was similar in that respect it would also raise concern about impedance compatibility with some and probably many solid state power amps.

Regards,
-- Al

I had the SP-14 in the system for a number of years before moving up to the REF-3.   The SP-14 is a fine preamp with an excellent phono stage.  I ran it with a number of amps, including an ARC Classic 60, Atmosphere OTL 60 watt mono blocks and even two of Frank Van Alstine's biggest stereo amps bridged.  For the money they bring these days on the used market, I'd consider the SP-14 to be a good choice, especially considering the excellent phono stage that comes with it.

I had an LS-15 for years, then upgraded to an LS-25.  The -15 was a good amp for the price, if not a little sterile and on the cooler side.  It did eat tubes, though, as did my PH-3 Plus.  Annual replacements were a must.

Someone mentioned having an LS15/PH3 combo and that they burned thru tubes at a rapid clip.  I had the same combo for years and never experienced this.