General Asylum: Re: Comment on AR SP3A by Carlos

I agree with my fellow inmates. This is a classic product, it is built like a battleship and plays music, not hi-fi.
I use my Sp3 A-1 as a MM phono stage, cause it sounds way better, more punchy, big and dynamic than my Audible Illusions Modulus phono stage.

I have done the following mods to the SP3:
(If not done yet, convert to SP3 A1: call ARC and buy a copy of the owners manual, it explains the changes).
Alps 100K volume pot; DACT or other stepped attenuator would be even better;
Kimber coupling caps throughout; these are no longer available, I guess Auricap or Hovland would be fine;
Increased (4X) power supply capacitance with Panasonic THSA caps in paralell to original caps;
Implemented automatic mute with a timer/relaý;

last but not least,the SP3 has several wiring problems that muffle its sound:
-the balance pot sucks; just bypass it;
-the stereo/mono/reverse switch will get dirty after a few years and will slightly "rectify" the sound; bypass it with a piece of wire from the selector switch directly to the monitor switch;
-the phono 1 /phono 2 switch is a crime; who would put a switch in series with a 3 mV signal is beyond me; anyway, since I do not have two turntables, I unsoldered the phono 1 input cable from the switch and soldered it directly to the phono input in the main board;
-lastly, horror of horrors, the shielded cable connecting the volume pot to the line stage acts a low pass filter and a blend filter (both channels in one cable); no need to unsolder it, just remove the outer jacket and braid, separate the left and right channel wires by at least one inch.

The above mods do not cost a fortune, do not mess with the original circuit or tube operating points. The end results are a quieter, cleaner, more transparent preamp.
Expect some line stage tube rush, though. Recent preamps with 6dj8 or 6922 tubes have much quieter line stages.
The noise may not be a problem, depending on your amp's gain and speaker efficiency. With my 1 volt sensitivity amp and 86 db speakers, I can barely hear the tube noise.
BTW the SP8 is no competitor, IMO.
Good luck
Carlos