Hall VVR3 and JTM 45

[Ed_Chambley]

I have installed a Hall VVR 3 which has bias tracking.  I have a question about the actual wiring.  On the VVR there is a bias in and a bias out.  I need to break into the bias circuit.  Can I simply use the wiper from the bias pot to the VVR Bias in and from the VVR bias out to where the wiper was connected to the board?  Basically putting the VVR in-between the wiper and the board?

If not here, than where should it be connected.

[FYL]

The VVR should be inserted between the current bias out and 220K resistors. There are may variations around, so it's impossible to give a more precise answer.

[Ed_Chambley]

This is the information I was looking for.  I was wondering if the Hall board had anything too do with the bias circuit other than tracking.  I still don't understand how it can track precisely. The last part I have in the bias circuit before the 220's on the turret board is a 25kl pot.  Of course this will give me a final bias adjustment.  Maxing out the pot on the hall board should bypass this and leave me with the pot I have for adjustment.  Not sure if I will have to change some resistor values in the bias circuit.  I will know soon.  If anyone has experience with installing the Hall Amplification with bias tracking, please I am open to any experience they may have.
Thanks,

[PRR]

...comes complete with detailed instruction manual.

No?

[FYL]

I still don't understand how it can track precisely.

What you've got is ganged 1M pots, a crude form of tracking - OK for most applications but not what I call precise.

The last part I have in the bias circuit before the 220's on the turret board is a 25kl pot.  Of course this will give me a final bias adjustment.  Maxing out the pot on the hall board should bypass this and leave me with the pot I have for adjustment.

Set max bias with the VVR trimmer, use your existing bias pot to adjust it. Don't forget to max the VVR when you set the bias, if you don't you'll overbias.
 

[Ed_Chambley]

...comes complete with detailed instruction manual.

No?

It does come with an instruction manual, but it says in the manual that every amp cannot or type of circuit cannot be covered.  There are different ways of installing and one set of instructions is given for cathode and push/pull.  The problem is the boards are different and the hookup is different if you are controlling the whole amp as opposed to the power tubes alone.  If power tubes alone, the instructions suggest adding a MV.  I understand why a master would be needed and this is no problem.  My concern comes in the bias tracking area and does the board "replace" any of the bias circuit or simply control it via the 1 meg pot.  I assume the latter, but I like to get feedback whenever I have any doubt whatsoever.

[Ed_Chambley]

I still don't understand how it can track precisely.

This is why I am asking the questions.  It seems to me if the bias is set at idle with the VVR full on when reducing the voltage to the power tubes via the VVR the bias cannot track precisely therefore I was wondering if the VVR replaced the bias circuit and if it did how was it possible.

What you've got is ganged 1M pots, a crude form of tracking - OK for most applications but not what I call precise.

The last part I have in the bias circuit before the 220's on the turret board is a 25kl pot.  Of course this will give me a final bias adjustment.  Maxing out the pot on the hall board should bypass this and leave me with the pot I have for adjustment.

Set max bias with the VVR trimmer, use your existing bias pot to adjust it. Don't forget to max the VVR when you set the bias, if you don't you'll overbias.
 

I am thinking it would be a good idea to check the bias in different levels of adjustment of the VVR to verify how closely it does actually track.

[FYL]

I am thinking it would be a good idea to check the bias in different levels of adjustment of the VVR to verify how closely it does actually track.

It doesn't actually. There are two separate sections (VVR and bias) with a common dual-ganged pot. A real tracking system is more complex, cf. the schematic below.