ARC ref75se bias adjust
 

Hi Guys,
When first got this brand new I adjust the bias as per instruction. My question is how often do I have to adjust the bias or you only do it the first time when the tube is new?

There's no hard and fast rule. Do it as often as you like :thumbsup:

The Ref75 makes it soooo easy that when I had one, I did it every few weeks. I don't plan to do it very often on my Ref150, which takes a lot more effort!

It depends upon how much running time the amp gets, but in general I'd suggest checking the bias again in a couple of weeks and then again in a couple of months as there can be some drift from when new. By that point the tubes and related circuitry should be burned in, so then you can just check them a couple of times a year to verify its bias stability.

Tks for the fast reply guys.
Can I adjust the bias after listening to it after long hours? After switching it on how long should the amp warm up before adjusting the bias?

Bias should stabilize after being on for about 30 minutes with no significant difference after being on for a longer period. Make sure that there is no input signal to the amp when biasing (no active source.)

I know how conservative we get about our equipment to protect it, but ARC equipment is tested to the max here in Minneapolis, I've been to the floor. IMO you could easily be 10 percent off and not here the difference or suffer much shorter tube life. So enjoy it and relax.

Tks , noted.

Will do :music:

You should check and if needed, adjust the bias often when the tubes are new. The bias on new tubes can drift until they settle in. That is why it is important to purchase well matched tubes from someone like ARC. ARC burns their tubes in a bit before the hand match them. Some tube dealers also do this but most don't If the tubes are only (tube) factory match, they will tend to drift a bit more in the beginning. If you are running matched pairs than they can drift in opposite directions and one tube will run hotter than the other. Running tubes too hot can affect tube life.

I bias my tubes at .63ma. I usually check the bias after listening. I mute the preamp and let the amp settle for at least 5 minutes. The first few days with new tube I check the bias often. After that I check the bias about once a month. I also dust the top of the tubes so the have better heat dispersion.

^^ this seems like really good advice and information to me.

I just want to point out (for those that don't have one) that setting bias on a Ref75 is FAR easier than most products. Doing it monthly, or even weekly is very reasonable. It takes like 2 minutes and you don't have to move the amp at all, regardless of how you have your gear arranged. Still probably doesn't need to be done more than once a month at most.:yes: