I thought I would post this experience for those who've put off taking the plunge on a tube amp because they're not sure what's involved for maintanence, care, etc.

I got my Jolida 202A tube integrated at the end of November. The manual states that it's biased at the factory, but it suggests biasing out of the box because some adjustment may occur in transit. First, biasing is simply setting the output of the power tubes in your tube amp. For example, the 202 uses EL34 power tubes - 2 per channel. It also uses pairs of 12AX7 preamp tubes and 12AT7 "driver" tubes. Only the power tubes have to be biased. Did I bias my power tubes right out of the box? No. Naturally, I couldn't wait to hear it. It sounded great out of the box, but I knew as the tubes were used and began to settle in, I would have to bias the amp at some point.

Second, with the Jolida, all that's needed is a multimeter and a thin, flat head screw driver. I got a multimeter from Radioshack for Father's Day. To bias the Jolida the amp has to be turned upside down. This is easier than it sounds. It has large, heavy metal rails trimming the transformer cover that are taller than the power tubes. It's weight is proportioned so that it will sit sturdily on the rails when turned upside down. On the bottom are a series of small inserts identified as 78043. These numbers correspond with the positions of the power tubes - the right channel power tube positions are 3 & 4, the left are 7 & 8. The "0" on the bottom series of inserts is the ground insert. Your multimeter will have a pair of leads - one positive (red) and one negative (black). On the bottom under each power tube is a hole with a flat plastic screw head that can be turned to increase or decrease output for each tube. These holes are labeled V3, V4, V7, & V8.

After turning the amp upside down and identifying the inserts for the multimeter leads and the screws for adjusting output, the manual suggests that you turn the screws to the lowest output settings. (I guess you can leave them where they are if you're simply testing the output, but since this was my first time, I turned the settings all the way down.) The screws on one side of the amp are turned one way and the screws on the other side are turned the opposite direction. The manual is very specific and helpful so that you don't get confused as to which 2 have to be turned clockwise for increasing power and which 2 have to be turned counter-clockwise for increasing power. After turning the screws all the way to the lowest output setting, you power up the amp with your speakers connected. (All sources are supposed to be disconnected from the RCA input jacks.) Allow the amp to warm up for a few minutes before you begin.

The black multimeter lead is placed in the "0" insert position and can stay there. The red or positive lead is placed in each corresponding tube position insert. As it's placed in position 3, for example, your multimeter (assuming its set correctly - I set mine on the 2v setting so that its reading would look like - "0.000") will give a 0.000 or 0.001 reading. Then adjust the screw slowly until you reach a point between 0.036 and 0.044. This is the range recommended for the Jolida. I adjusted each tube position to 0.040. And that's it! I let the amp warm up a little longer and got readings again and made minor adjustments. Then I put it back on my shelf. The manual states that biasing is necessary once every one to three years and when you replace the power tubes. I was getting a little noise in one channel as the amp warmed up which prompted me not to wait any longer to bias the amp. After setting the amp back up again and turning it back on, I didn't hear any noise.

Some tube amps are self-biasing. Others allow you to bias with the amp sitting right side up. Still others have built-in meters so you don't have to use a separate multimeter. These features may add a little to the price of the amp, but they may be worth it for some people. If you're on a tight budget, but are somewhat worried about having to bias your amp yourself without convenience features, don't be. As long as you have a little bit of time - say 20 minutes total, a good manual and you get a multimeter with digital readout, you can do this.