Tube maintenance for Audio research sp-16 pre-amp

Thorman, You are correct. Audio Research does not make tubes, but they have the knowledge and equipment for screening tubes to best match their equipment.

Just keep in mind Audio Research does not make tubes..They buy just like all of us..The just have them screened and re-lablelled for them..They can get a bad tube also..By buying yourself,you can get the same tube without the cost of the middle man ( Audio Research )..It requires more work on your part but,can be rewaring if you don't mind the extra work involved......

Mapman, That's exactly why you want to stay with ARC tubes, because you don't want to change the sound of a great sounding preamp.

NEwbee, yes, the noise was in one channel only.

More of a very high frequency whine, like a dentist drill, but very constant in tone, than a "buzz". Not very loud either, you have to mute and unmute the pre-amp to be sure it is there unless you listen right up in front of the tweeter.

Which are the least sensitive tube positions in the sp-16? There are 3 tubes in the pre-amp section and 3 in the phono section. The noise has been associated with any input hence I assume the pre-amp section, not the phono section.

I will likely lean towards Arc for the tubes unless someone can tell me something specific about other tubes that might offer improvement in some way without having major impact on the general sound.

I guess my first answer would be to establish yourself with a good tube surplier..There are a handfull of good reliable sources that many of us use..These tube guys take a lot of time to pair and match tubes with double and triple testing..It may cost a couple bucks more but you can pretty much get the best quiet clean tubes around..

Names I might suggest to start with;
Jim Sautter ( audiogon member )
Andy ...(Vintage tube Services )
Jim McShane ( Jim McShane tubes )
This is at least a good starting point.Good Luck..

Although you didn't make it clear I'm going to assume that the problem only arose in one channel (when it arose). If it occurred in both channels each time this solution wouldn't apply.

I think - you've got a bummer tube, or two. The switching around solved your problem because you positioned the bummer(s) in the least sensitive location. I have identical issues with my SP10. You can stop now and go back to listening to music, but do buy a spare pair anticipating they will fail before the others. Or you can put the new pair of tubes in the most sensitive slots and rotate the tubes after removing/replacing the tubes that buzzed (probably now in the least sensitive slots).

If you have had these tubes a long time just replace them with new tubes now and bear in mind that noisy ones can be rotated into the least sensitive slots and/or just replaced individually or pair at a time when the need arrises. Nothing wrong with keeping your present tubes for spares but weed out the buzzers. What ever makes you comfortable.

Re replacement tubes. It is best to get low noise tubes, that is tubes which have been actually tested for noise. This is not routine so you have to ask for it and you will be charged for it. That is one reason why ARC's tubes typically cost more. But I buy my tubes from other vendors because typically I don't care for the tone of the tubes ARC uses in their amps and pre-amps.

Oh, FWIW, tubes hiss and/or buzz to various levels of amplitude. This may only be a big deal if it bugs you. They may last just as long as a tube that is dead quiet. Tubes that crackle and pop get replaced once I'm certain that its not associated with problems arising from contacts in the sockets.

Hope that helps a bit.

As you already know you will get tons of advice on where to buy, what to buy and how much fun it is rolling tubes. Do yourself a favor and buy your tubes from Audio Research. I have played the tube rolling game many times and tubes provided by the manufacturer always sound the best whether its Audio Research, Quicksilver, Music Reference, CJ or whoever. The manufacturers know what to look for in tubes to compliment their circuits.

Tubes vary from one tube manufacturer to another not only in sound, but also in electrical properties. There is no easy way to adjust bias in a preamp to compensate for differences in tubes.