Bias adjustment

So it appears that the Cary tech was correct.  Your readings were wrong. I have to say, due to poor communication with the manufacturer you end up proclaiming that you'd never buy a Cary product again if your life depended on it despite the issue was user error as Cary correctly pointed out.  Ugh.

I didn't even think that anyone would consider setting bias with music playing. Yes, you want your speakers connected when you check bias but DO NOT play music while measuring. The whole point is that you're checking the bias while the amp is at idle, and running a signal through the amp is not idle. Depending on how you had the volume knob set you could have easily been running the amp 50mA or more ABOVE idle when you were measuring and hence frying your power tubes. 

I accept your logic.   But wouldn't the VOM have read then 130 mA instead of what it was reading? 80 mA?

I would never buy a Cary product again. I should explain: It's not the product which is bad!  It is that after 1-1/2 years they claim there is no more warranty.  It's also that the techs do not give the customer fair and honest information nor ask the "right" questions to try to solve the issue instead of the need to ship it back to Cary. Without warranty, the cost of shipping round trip [+/- $200.00]  and repair (?) and new tubes was going to come out at close to $1000.00. If the amp cost me $3000 and after 1-1/2 years I have to put in another $1000.00 that is 30% of the value, I might as well buy me a new amp ..... and from someone more honest and transparent, totally regardless of whether I was "wrong or right".

I’ve measured my Cary with, and without, a signal. It was the same. I alway check without. I wanted to see if it could cause the reading you had. Mine was fine, so was your.. You do need to recheck at least a few times, back and forth.
WHY?. In a stereo one side will change the other, until they are both within 5% or so. Go back and forth a few times.

I also checked a pair of older VTLs same, and a Citation II. No change in the bias, I set a high, and low capture on my meter. Never more than 5-7ma from zero volume to 50% volume. All six amps, same.

How do you bias? UNIT OFF, turn the bias down CCW. Insert your 1/4" jack. Power up the unit, warm 10 plus min or so. You can leave the input signal off if you like. Bring up the bias slowly CW. Power down, move your 1/4 inch jack, to the other rail, power up and bias.
TWO or more times. New tubes, recheck see if the new valves are holding a bias...

I just had a bit of a tiff also with Cary. I ask for a schematic, hand written, or partial for the hexfred upgrade. Didn’t ask where it goes, or to hold my hand while someone else does it. I asked TWICE. Just ignored the request.

I’ll buy a plane ticket and knock on a door, no problem for me..I’ll get my schematic. If I have to draw my own, I’ll post it for ALL to see. There will be no secrets then. EVERYONE should be able to get technical information on equipment owned by them..Especially a schematic.. That schematic should reflect the safety or lack there of built into unit. It should reflect upgrades also...

Regards...

Hello oldhvymec. Yours has been probably the best and clearest explanation of all the "advices" I've had. I REALLY thank you for taking the time to explain the bias process.

I've had a similar issue with Cary when my old SLA-70 Signature ran into trouble some years back. They would not supply me with a schematic at all saying it was "obsolete" and they do not keep old schematics. None of this should have happened if they had a bit of honesty and transparency. I'm sure that Dennis Had (?) in his days never had issues like that. It's a shame the company has changed owners. Such is life.
Thanks again for your help. Sincerely, Richard

I just had a bit of a tiff also with Cary. I ask for a schematic, hand written, or partial for the hexfred upgrade. Didn’t ask where it goes, or to hold my hand while someone else does it. I asked TWICE. Just ignored the request.

I bought a case of Coca-Cola and called up there head office and requested the formulae and was also ignored.