ARC amps, Bias how often between replacing tubes?

It shouldn't need bias reset unless there is a component changed. I have not needed to re-bias my VT 200 except when a tube shorted causing a resistor and the power tube to need replacement along with one of the 6922's.

I believe the replacement cycle recommended is 2500 hours but the amps do not have hour meters so unless you keep track of playing time, it will likely be an estimate anyway. It never hurts to check the bias but be careful to follow safety recommendations and don't do it yourself unless you are trained in electronics.

Follow the owner's manual on recommended maintenance or call ARC. They are very helpful with customer service to ARC owners (or to anyone for that matter).

Don't bias your tubes unless you think something is wrong, ie. if one or more tubes glow incredibly compared to the others or if one channel is fading out. Tubes should last years unless you listen a heck of a lot. You can always take your tubes to get tested (repair shop?).

Before replacing tubes, do some research. Some tubes make a difference in sound quality as well as how long they last. Many of the new tubes out there are very low noise and can keep up with classics like Mullard and Telefunken in sound quality.

Try www.tubesandmore.com or upscaleaudio.com If you can't find anywhere to test your tubes, either send them to one of these stores for testing or send them to me-It only takes a few minutes. All it will cost is shipping.

I only bias mine every 4 months or so. It usually isn't off by much if at all. Make sure you wear gloves and a ground strap, have eye protection, and use rubber encased test leads. There is a LOT of voltage in that amp.

I find that I prefer the Svetlana KT88 tubes to the 6550's, but some people are the reverse. The KT88 is warmer and punches out the midrange. The 6550 is a little more clear and is completely coherent from top to bottom.

If you do buy from a non-ARC source, make sure they match the tubes very closely, and understand that these are for a vt100. Kevin Deal at upscaleaudio is the guy I use - he's a little more expensive, but I feel the quality of expertise is worth it. I understand the vt100 needs to have very closely matched tubes to function properly.

There are quite a few factors determining the tube life:
1. How often you turn the amp on or off
2. The loudness of music
3. Use of a surge protector/dirty electricity,
4. Tube quality to start with.
5. Ventilation of the amp.
6. (most important) the efficiency of your speakers.
If you are running magnepans, you will burn the tubes
up FAST.
7. How hot you run the tubes. I run mine at the recommended settings, but I have heard that you can extend tube life by biasing a little lower.