LarMar PPIMV on Liverpool

[bandade]

For those of you using a LarMar type PPIMV on a Liverpool, do you have a layout or schematic you are using?

What resistor values are you using; the standard 2.2M's? I can get the dual pot locally but I'm hoping I can use resistors I already have because I dont have the 2.2M and would have to order them.

I tried a homebuilt VVR which worked ok, but It wasn't really what I was looking for. It seemed to lose some drive when the voltage was dropped.

Thanks!

[paulster]

You want to use 2M2 resistors because the point of them is that they bring the overall pot value down to 220K, the value of the grid reference resistors you are replacing when you substitute in the PPIMV.

You could get by with using a pair of 1M resistors in series if you really don't want to place an order (see https://tubeamparchive.com/viewtopic.ph ... ht=#158517) or you could place an order which includes both the pot and the resistors (you can get the complete kit from Metro for $10).

In terms of layout it's exactly the same as doing it on a Marshall (http://metroamp.com/wiki/index.php/Lar/Mar_PPI-MV) with the exception that the junction of the 2 220K resistors that carries the bias voltage in a Marshall is actually at ground in a Liverpool, so you can run a wire from this point to the pots, or to a more convenient ground point depending on where you are installing the pot.

[bandade]

I installed a PPIMV on the amp last night and it works great. I didn't need to use shielded cable. I just twisted my cables and dont have any additional noise. I may add the VVR to the back of the amp as well.

Thanks for the help!

[daz]

In terms of layout it's exactly the same as doing it on a Marshall (http://metroamp.com/wiki/index.php/Lar/Mar_PPI-MV) with the exception that the junction of the 2 220K resistors that carries the bias voltage in a Marshall is actually at ground in a Liverpool, so you can run a wire from this point to the pots, or to a more convenient ground point depending on where you are installing the pot.

I doing something similar on my cathode bias amp.
Does that mean you wire up exactly as the marshall diagram? Because it appears on the diagram the 220k resistor junction is wired to the ground (shield point) on the pots?

EDIT: Sorry just realised you wire that shield point on the pots to ground.

[ampmike]

Hey Guys,While we are on the Liverpool topic Im going to be starting one next week.I had great results with the rocket and the express.Is a master vol something most of you guys do on Liverpool builds?.What I mean is,Is this something Im going to need down the road.I figure I may as well do it from the getgo.The express and the rocket I dont feel really need them.Following TAG layouts these amps are fantastic.Thanx Guys,Mikey