Biasing Six Pac help

You can get a PDF manual here:

http://www.sixpacs.com/manual.shtml

Thanks, I already downloaded the manual, but strangely, it does not include biasing instructions.

Call 919-355-0010 and ask for a tech. Gerald Walsh is very helpful. Ask what the bias should be set at. Sometimes it differs a little from the manual. Speakers should be hooked up. How hot do they run? I just traded in a Cary V12R amp (they run very hot) that I really enjoyed on a new Cary 120S amp. I still can't beleive how good it sounds. The bias on the V12R was set at 238 and the 120S is set at 150 and has the meters built in so you just need a screwdriver. Be careful not to turn the screws much. 1 or 2 degrees makes a big change, so call Cary to get the right specks. If the amps are good, you're going to love them. Good luck. polk432

I haven't owned these, but certainly the amp has to be turned on. It's not clear if you need to unhook the speaker cables and/or interconnects. FWIW, the parent company (Cary) suggests disconnecting the amps from speakers and sources before biasing, though on my Cary SLI-80 I have occasionally checked bias with everthing connected. I would caution that many amps require the speakers to be connected while in operation, so I would suggest contacting AES.

FWIW, here are the Cary intructions for their amps.

How do you correctly bias a Cary Audio vacuum tube amplifier?

Disconnect the speaker cables and the input RCA cable or XLR cable from the input jack.
Start with the amplifier warmed up for 5-10 minutes and then turn it off to connect the bias cable.
Connect the provided Bias Cord into the bias connection jack. It has a 1/4 inch mono 'phone plug' on one end and a pair of alligator clips on the other end. Plug the phone plug into the jack on the chassis. The red alligator clip is for positive electrical connections, the black one is for negative electrical connections on the milli ampere (mA) meter.
Set your meter to the milli amperes (mA) reading range. NOT to the Milli Volts (mV) range!
Turn the bias adjustment screw on the chassis all the way counterclockwise so that the meter will read zero when you turn the power on. Now, turn the AC power on. Wait for 60 seconds to warm up the tubes.
SLOWLY turn the bias adjustment screw clockwise while you watch the meter for a mA reading.

Thanks for all the helpful posts. I'll call Cary to ask whether it matters if inputs and speakers are connected or not.

I spoke to Gerald about the very same thing. He said that it's ok to insert/remove the plug into the bias jack while the amp is on....your speakers may not like it, but it shouldn't cause any harm to the amp.

I initially followed the directions in Cruz123's post, but since have had no problems just plugging/unplugging the test jack while the amp is on. I do have my multimeter already turned on and set to the correct range BEFORE I plug in the test leads. The suggested bias point for the Six Pacs is 220mA.

Will it work with speakers disconnected?

Springbok10,

I'm not sure if it will work without the speakers connected as I've never tried. I would ask Gerald at Cary.

Enjoy!

I doubt it would hurt the amp, but it may not bias as accurately. I would ask Cary to be sure.

Roblanger, the multimeter supplied is set by the seller (?factory) to 200mA and reads only up to 10. About half way turned reads 2.3. But shouldn't it be 0.2 (there are only 3 LEDs, 00.0, so the theoretical maximum it reads is 10.0.
So, to read 230 mA, should I read 0.2 or 2.3???
I've asked this of Gerald, too, but I dont know if he followed me! Do you? Mathematically, it should be 0.2, which is 200 mA, but that doesn't seem right, as the bias goes all the way to nearly 10.

Springbok10,

I'm not at all familiar with the multimeter that you have. What is it's maximum range in milliamps? My multimeter only measures up to 500mA and uses a needle to check the reading. Sorry I can't be more helpful.

FWIW, the amp can be biased without speakers and inputs attached. Per bias instructions supplied by Gerald at Cary. I gave up on the useless Multimeter and bought an analog meter which measures up to 500 mA, just as you have.
Problem solved. Thanks again! But I wish I knew how the previous owner biased his amps with the supplied multi-meter.