[Listens2tubes]

I've been using a Cen-Tech P30756 I got from Harbor Freight a while back inthe $3 dollar range. Bias setting is it's only task.

I understand wanting to watch the bias of both channels when one transformer/rectifier are involved. Is there any advantage to seeing both amps bias with my MkIV's?

[trebejo]

Ok, so I stick the red pin into the left socket and the black pin on a screw that is attached to the chassis; then I stick the red pin into the right socket and the black pin still on the same screw attached to the chassis.

Then you guys pine for the chance to measure both simultaneously... what do we measure if we stick the red pin into one of the sockets and the black pin into the other? 

[jtwrace]

I"m going to go to my local H.F. store and purchase the $3 meter.  What is the normal bias reading?

I'm then going to set my desktop power supply up and then take my calibration meter and check the $3 meter against it.  Should be interesting...

[mchuckp]

I've been using the tubes that came in my Ultravalve since I got it earlier this spring.  I just bought a multimeter from Lowe's for $25.  I have yet to check them until now.  My left was around 1.46 and the right about 1.49.  Using the info in Frank's instructions, I adjusted them back and forth until they were each 1.6 (after adequate warm up).

This is my first time biasing (or using a multimeter).  Hopefully I'm doing everything right. 

So I have two questions. 

1. A friend is sending me a quad that he wants me to try out.  Do I need to turn the bias way down before setting them for the first time just in case they are much higher?  Or do I just check it as is and adjust as needed?

2. Given the values I had above (adjustment from roughly 1.46 up to 1.60), should I hear an audible difference in any way or is this considered a minute adjustment?  To my ears, things seem a tad brighter and bass isn't standing out quite as much.  Maybe it is all in my head.  That happens sometimes.

Thanks.

[festuss]

   SAFETY and how a meter handles overloads and mistakes, could be a life changing event.  $3 meters and SAFETY are not usually matched.  If you don't know about different classifications of events and use, the life you fry could be yours.  FLUKE IT what's your life worth?  When your bargain meter explodes in your hands, when you mis apply something, you won't think the cheap Chinese junk was a good deal.  I use only Fluke on the job, in poor situations, same goes for test leads etc.  Ever wonder why those cheap meters are so cheap?    flukecommunity.com/forums/attachment.php?attachmentid=307   

[turkey]

  SAFETY and how a meter handles overloads and mistakes, could be a life changing event.  $3 meters and SAFETY are not usually matched.  If you don't know about different classifications of events and use, the life you fry could be yours.  FLUKE IT what's your life worth?  When your bargain meter explodes in your hands, when you mis apply something, you won't think the cheap Chinese junk was a good deal.  I use only Fluke on the job, in poor situations, same goes for test leads etc.  Ever wonder why those cheap meters are so cheap?    flukecommunity.com/forums/attachment.php?attachmentid=307

Maybe they're cheap because they don't spend as much on advertising or warranty repair as Fluke does?

There is nothing wrong with an inexpensive multimeter for the hobbyist. If you're using a meter to earn your living, then you should probably get a top-shelf meter, but otherwise the cheapies are fine. They may not be as accurate and probably won't last as long, but I have found that they work just fine for me.

Going back to the '50s, my Dad had some Micronta knock-offs of a Simpson multi-meter that he used a lot. The Simpson was a better meter, but the Micronta was a lot cheaper to replace if you dropped it. (He also had much higher-quality test equipment, but it stayed on the bench in his lab and some of it was even rack-mounted.)

[AVnerdguy]

  SAFETY and how a meter handles overloads and mistakes, could be a life changing event.  $3 meters and SAFETY are not usually matched.  If you don't know about different classifications of events and use, the life you fry could be yours.  FLUKE IT what's your life worth?  When your bargain meter explodes in your hands, when you mis apply something, you won't think the cheap Chinese junk was a good deal.  I use only Fluke on the job, in poor situations, same goes for test leads etc.  Ever wonder why those cheap meters are so cheap?    flukecommunity.com/forums/attachment.php?attachmentid=307

I had the same concerns about these cheap meters so i did some tests where I compared them with my Fluke and they passed all the same critieria under normal hobby type use. The fuse blew when it should, none of the leads or connector leads arced over etc.

Obviously, for serious repair work I use my Fluke's (multiple products) exclusively but for a weekend hobbyist that just needs to see if there is a low DC voltage or to check cable continuity they work just fine and as far as i can tell do not pose any safety hazard issues.

[turkey]

I had the same concerns about these cheap meters so i did some tests where I compared them with my Fluke and they passed all the same critieria under normal hobby type use. The fuse blew when it should, none of the leads or connector leads arced over etc.

I kind of wonder whether "good" meters are actually better than cheapos internally these days. They definitely have better cases, better docs, better leads and accessories, and a better warranty. You would think that would be true of the guts too, but...

[AVnerdguy]

I kind of wonder whether "good" meters are actually better than cheapos internally these days. They definitely have better cases, better docs, better leads and accessories, and a better warranty. You would think that would be true of the guts too, but...

I'm sure the quality of the pro meters is much better internally - better chips and board quality but who knows when they all come from a generic offshore factory. But, for simple measurements the cheapies work well.

I also bought a $20 meter from Sears for the junk drawer before I found the $3 Harbor Freight versions and the quality seemed to be a bit higher. I've seen the $3 meters for sale at different prices also - up to $12 (same meter)

[avahifi]

One of the main differences between my good Fluke meters and the $3.00 harbor freight job is that the Flute is much FASTER to give good readings.

This is not important with easy jobs like setting the bias voltage with our Ultravalve amplifier, but makes reading the Harbor Freight meter a pain in the ass while making final bias current adjustments on a Ultra+ hybrid amplifier.

Regards,

Frank Van Alstine

[AVnerdguy]

One of the main differences between my good Fluke meters and the $3.00 harbor freight job is that the Flute is much FASTER to give good readings.

This is not important with easy jobs like setting the bias voltage with our Ultravalve amplifier, but makes reading the Harbor Freight meter a pain in the ass while making final bias current adjustments on a Ultra+ hybrid amplifier.

Regards,

Frank Van Alstine

I definitely agree with that. If you can afford a good meter it's well worth the expense. Not to say everyone needs a $100 meter but something a little further up the chain will be worth it if you use a meter often.

[festuss]

fluke.com/application_notes/electricalpower/1263690.pdf     
add the www cus the forum locks it out?