TUBE BIAS, socket to me!

I’ll say this and let it go.. It’s better to stay out of trouble than get out of trouble... Bias is part of maintenance. Very simple.

There are three types of bias adj.

1. The way the factory says to BAIS and WHEN..

2. The way others tell you to or not.

OR

3. NOT at ALL...

The correct answer is what the factory says... Plane and simple.

Yes it changes the sound.. especially if you bais low, it will sound muddy. If you bias HOT the amp will distort sooner (tube break up), and burn valves quicker... Bias is very important...

Bias hot and turn the volume up...LOL.. go ahead... Bias low LISTEN.. muddy as all heck. Especially 60-1500hz.. muddy. YUK...

jjss49, we are on the same page, 4 times a year is good for me.. YUP..

ALWAYS with a valve change..... ALWAYS....

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Billwojo... I just got my New Maxi. It does 4 large valves at a time.
The Mini has been on back order for over 6 months.. They should have started shipping the 15th. There were 16 or 18 before me.. I love um.. A LOT faster a lot more accurate, than the older ones..  My 533 and 39 are OLD... They WORK very well, the 533 for small valves, and 539 for small or large valves.  I use them to compare... I use a couple of known test valves. Pretty good information...

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Last but most important.. OP I’m glad your happy... What else counts..

NOW if your looking for a little nugget..... :-) It may change nothing...

One way to find out..

Regards

https://www.pinoydvd.com/index.php?topic=139769.0

OP check this thread out pretty good, pics in all...

Regards

As tubes age, they lose transconductance.  As they lose transconductance if the grid bias voltage is fixed (not varying with respect to cathode voltage), you gradually run out of oomph (for want of a better term).  The amplifier may begin to sound a bit limp.  But this happens so slowly that the user is often only dimly aware that the sonics are not quite as wonderful as they once were, with fresh tubes.  And eventually, one buys new power tubes.  In this way, I once got 10 years out of a set of power tubes in a Futterman OTL.

However, as the owner of an amplifier with adjustable bias and a built-in method for measuring and correcting bias current when it inevitably goes off, by adjusting grid voltage, I have to say it is a revelation to hear the amplifier restored to normal bias current after a periodic bias adjustment.  By "periodic" I mean once a year or so. If you can adjust bias safely and know what you are doing it for, I highly recommend monitoring it and keeping it up to snuff.  Also, owners of amps with some sort of autobias circuit need not be concerned.
I have a Hickok 533. I use it only to test for transconductance of small signal triodes.  I do not use it to evaluate power tubes because it does not have the capacity to subject such tubes to plate voltage and plate current parameters where such tubes need to operate.

Holy Holidays!

McIntosh tube tuner/preamp MX110Z (1962-1969) / KT88’s

Cayin is A88TC version 1, which has 16 ohm taps for my 16 ohm speakers.

JSE Infinite Slope Model II speakers

@elliottbnewcombjr,

I had no idea...In my ignorance of this thing audio (hifi), I always wondered why some like everything tubes? Period. Now I understand somewhat why.

Could you explain the quality of reproduction of music you get when played on your turntable through the MX110Z preamp with the Cayin is A88TC version 1 and those JSE’s?

I should have bought that Fisher 800C when I had the chance years ago.

Is there any Fisher/Mc and Cayin you can recommend me? Thanks All, for the bias education too.

jjss49

Thanks for the info and link.

In my shop, I’ve got some nice chopsticks, one set hardwood, another set plastic, if I can find them.

And a grinder, and lots of other sharp weapons of destruction.

I know where to make the connections, evicently going for .4 or a bit less.

Multi-meter on what setting????