Audio Research SP3-a1

 ARC does not charge excessively for repairs. What did they say was wrong with it? A unit this old may have a number of issues but ARC will go through it with a fine tooth comb. It is worth the cost.

 Has your unit been "modified"? If so ARC will insist on removing the "modifications" before it can be repaired. This is a classic piece, I would not let just anyone work on it.

My SP3-a1 is a stock unit and they want around $1800.00 to rebuild the power supply., then they were going to look at the audio section.They also offer an up grade to the SP3 for $2900.00 plus tubes (no shipping)!   Maybe I'm just out of touch with things cost today !                                                                                              Thanks

Unless this unit has sentimental value, I’d put it in the closet and look for a clean ARC LS-2B with remote ($1000 to $1500).
BTW, $2900 today was worth $900 in 1980. Also, there are three for sale here as I type.

Don't send your SP3 to ARC! They are just preying on your gullibility! What do you think is wrong with it: distortion in one channel, higher noise level, persistent hum, lack of gain ... ? Most of these problems are simply due to tube aging. Tubes do not last forever! Try to find a competent technician in your area! You can also try contacting Audio Classics in Vestal, NY. I have dealt with them before and have been satisfied with their service! Also check the back page classified ads in Vintage Guitar magazine for contact info on "tube amp repair" services! This might be your best bet for service at an affordable cost.