Bias reading question

[Induktionator]

BTW, about the TAD bias meter, the 4 channels aren't completely independent. If you measure the outside of each of the RCA jacks on the meter, you'll find they are connected together. This is fine for sets of power tubes that all have a common grounded cathode connection. This is the usual arrangement for most push-pull power sections in most amps, and all the kits from TAD, so as long as your amp power section is this type, no problem.

The Mark V 'simul class' arrangement is not compatible with this, since its use would introduce a short that isn't intended to be there. It should give correct readings for the pairs that have common cathode connections, though. With the power level switching, this makes taking readings inconvenient.
On some amps (ENGL) that have the standby switch in series with the cathodes, this can give 50V DC on the front plate of the tool.

If you know this, the TAD Biasmaster is a fine tool, but inappropriate in certain situations. You have to understand the tools you use to get correct and safe measurements.

Did you get any answer from TAD?

 

[bucketbot]

BTW, about the TAD bias meter, the 4 channels aren't completely independent. If you measure the outside of each of the RCA jacks on the meter, you'll find they are connected together. This is fine for sets of power tubes that all have a common grounded cathode connection. This is the usual arrangement for most push-pull power sections in most amps, and all the kits from TAD, so as long as your amp power section is this type, no problem.

The Mark V 'simul class' arrangement is not compatible with this, since its use would introduce a short that isn't intended to be there. It should give correct readings for the pairs that have common cathode connections, though. With the power level switching, this makes taking readings inconvenient.
On some amps (ENGL) that have the standby switch in series with the cathodes, this can give 50V DC on the front plate of the tool.

If you know this, the TAD Biasmaster is a fine tool, but inappropriate in certain situations. You have to understand the tools you use to get correct and safe measurements.

Did you get any answer from TAD?

I take on-board what you are saying but I also tried the TAD gear on my Carvin Amps which i'm pretty sure are compatible with the TAD gear & it clearly has some sort of fault.
Disappointingly I got no response at all from TAD.....but I did get a response from Thomann the online retailer who sold me the gear. They say that one of the probes was faulty but they are also saying that this is not covered by the Warranty & alleging that it was probably damaged by either a fault in the amp or tubes.
If you check my prev findings it's quite clear that there is nothing wrong with either my amps or tubes!! :evil:

They have not even offered to replace the faulty probe but say I can buy a new PAIR (I only need one!) for 59 Euros!!!
Needless to say I will NOT be doing that!!
I told them to just send it all back to me & will revert to using my old GT Bias probe with a multimeter & checking one tube at a time.

So much for Customer service! Rest assured I will not be shopping with Thomann again!

 

[bucketbot]

After my protestations Thomann have now agreed to replace the fualty probe free of charge.......as a good will gesture so they say. :wink:

 

[domct203]

After my protestations Thomann have now agreed to replace the fualty probe free of charge.......as a good will gesture so they say. :wink:

Good to hear, too bad you had to bug them about it.

Dom