Tubes Asylum: Re: tube rolling... Audio Research SP-3... by anumber1

I have owned my ARC SP3A-1 for 10 years now. I listen to 95% vinyl and have a mostly vintage system consiting of modded Heathkit W-5m amps and Altec Iconic horn speakers.
My SP3 has served me well with very few modifications and upgrades, it still ranks as my favorite preamp. I have had a CJ PV-2, a Threshold FET 3, a Halfler DH 101, a Dyna PAS 2, and a Eico HF-85 in this system at one time or another and the ARC tromps them all for me.
Tubes V1 And V4 are the only tubes that need to be selected for low microphonics in my experience. I find that if I keep tubes with solid, strong electrical characteristics, not neccicarily low microphonic tubes in all the other positions (EI 12AX7s right now), I can tell no difference between modern tubes and NOS in any positions but V1 and V4. The only tubes that actually impart their unique flavor are V1 and V4.
I have been using a 50's Amperex ECC83 in V4 (the linstage) for a few years now and have been very pleased. I have also used 50's RCA and Tele smooth plates in this position and have had pleasing results. It is all a matter of synergy of course but if you use HQ tubes you will be able to find your favorites.
For the Phono Stage (V1), I am using a long plate Mullard ECC83 and I find it absolutly devine with my AT OC9ML/II cartridge and Ortofon T-10 step up transformer (I adjust the load to match the LOMC). prior to the LOMC cartridge I used a smooth plate Tele with a Shure V15VxMR moving magnet cartridge. I find the Tele's to be brighter, detailed and more "forward", Amperex to be "airy" yet well ballanced and a Mullard to have a "darker" character to the sound. for many years I felt the Mullards SUCKED! They had a far to dark and constrained sound with my selecton of MM cartridges (A Grado Signature and the aformentioned Shure). I seem to really enjoy a Mullard in V1 with my OC9ML/II now. It (The Mullard) imparts a very detailed and clear sound that I find non-fatiguing and smooth but with a HUGE soundstage and Razor sharp imaging. Really the best of everything for me! If you can find quiet EI 12AX7s they work and sound very nice. I REALLY disliked JJ 12AX7s. I havent tried the Sovtek, Svetlana or EH 12AX7 tubes.
As I had ARC rebuild the power supply to original specs just a month before they started offering the SP3C-1 mod (promised to bring the SP3 to "modern" specs), I am going to wait until my unit needs service again before I contemplate this "upgrade". I have replaced the volume control and most of the resistors and capacitors in the signal chain with Wimas, Hovlands, Rikkens and Vishays due to the originals going bad or being far out of spec. The SP3 is very easy to work on and has plenty of space on the circuit board for larger than stock audiophile parts.
In your post you mention that the tone controls have been bypassed. What do you mean by that? The tone controls can be switched in or out of the circut by a switch on the front panel. Has the switch been bypassed?
I hope you enjoy your preamp.
Mine will never be for sale for it is is dear to me!
HTH

Alan Gallacher
Born to Tinker!