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Antonio J. wrote:

The builder regards VR1 more like an "offset to 0" adjuster than a bias control for the 6E5P since its working range is quite narrow. He asked me to know from you if along the 6E5P's lifespan it needs further adjustments at VR1 or if a single initial adjustment is enough. He wants to know it in order to make the VR1 easily reachable from the top of the chasis as VR2 should be, and also make the meter able to measure DC offset at VR1 or just making it simpler by forgetting about VR1 once is correctly set. At this point I believe he's drawing the plans to fit the parts into some print board. He's going to use a digital display since it's cheaper and more available than the nice analog meters you sported.

The VR1 has nothing to do with the 6E5P lifespan. The VR1 cancels out DC voltage at input. You will need to adjust it as frequently as you change the gas tubes, means practically one in a few year of even… never. Sometime the DC voltage will be running away within 10mA but it is ability irrelevant and not important. In the Super Milq I put the VR1 under the chassis behind a miniature hole that if I want I would be able to reach by a small screwdriver. Last time I measured my DC at input it was July… I have no needs or motivations to do it again. Pretty much if I you any DC voltage at input then you will be hearing the switching of volume in your preamp. Since the switching in preamp I not auditable then you should not worry about the DC at inputs and you will adjust it one when you bult the preamp and then only if you change the gas tubes.

Antonio J. wrote:

He has been looking at the circuit and believes that in the case some DC offset appeared for whatever reason at that point, it is going to be delivered backwards to the signal source. In your case and mine, the preamp. Have you experienced some problems for that? Does your preamp have any "backwards" protection to avoid any DC coming back from the Melq?

Nope it is not a big deal. Your preamp is capacitance coupled or transformer coupled … my is direct coupled and even so it does not care about the DC at output. Believe me or not but I operated it even without the V1 and it was fine. Sine you set 0 zero Volts at input then you will be juts fine.

Antonio J. wrote:

Just one more question, did you remove R23 from your Melquiades?

It does not mater. Since you have more then triple critical inductance then R23 is not necessary. I believe I do not use it in Milq. In the super Milq where C2 is 5.600uF and C1 and C2 sit on the different chastises I believed I used the R23 to shunt the large caps and to let it to discharge the bi cap. Still, it is has no relation to sound and I have no idea why keep asking me about it. Your technical guy knows very what bleeder resistor does in this case and let his to make this decision.

Rsg,
The Cat

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