What are the ramifications of lifting this resistor?

[12AX7]

Theres  a cap (C24) i want to lift to see how it affects the treble in the amp. But it's buried in a place i can't get to w/o pulling the board which i've done and is a major PITA. So i looked at layout which shows that if i lift a 1M resistor that appears to be a feedback resistor on the input stage of the cathodyne PI it will also lift C24 without having to pull the board because they appear to be in series according to the layout. But i'd also be lifting that resistor. So i wanna know what lifting that resistor will do, whether it would be negligable or what. Heres the part of the layout and the schematic.

[nandrewjackson]

According to the schematic,  where that cap and resistor meet is ground.

[12AX7]

I know, but theres something going on there i don't understand like a seperate ground from chassis ground? I dunno, but the layout shows things different from the schematic that i'm not familiar with. But the gist of it is that according to the layout if i lift R67 i'd also be lifting C24. And while i cannot access C24 physically, i CAN get to R67. Thats why i wanna know what lifting R67 would do to the PI

[12AX7]

Ok,i see now. The resistor is the load on the input so it's gotta stay. Brain fart, common issue for me.....

[sluckey]

i wanna know what lifting R67 would do to the PI

Doing so will totally break the PI. R67 (1M according to the schematic) is the grid leak resistor for V3 pin 2 (grid). The bottom side of R67 is connected to ground. Use your ohm meter to verify.

C24 has nothing to do with the PI circuit. C24 is a hi-freq dump located between V2 plate and the tonestack. The only way to take it out of the circuit is to lift one leg of the cap. Doing so will probably make the amp sound brighter.

Would you mind posting the entire Classis 30 II pdf rather than just posting snippets of the schematic/layout drawing? If we can see it all we may be able to offer some more alternatives to temporarily disable C24.

[12AX7]

I did post the schematic in the same post i posted that layout snippet. The entire pdf is too big to post, it won't allow it. Anyways, i HAVE brightened the amp with other changes and so far one works quite well. (470pf to ground after pre pot changed to about 150pf) but i just feel that C24 is a better place to allows highs because it's after the gain stages.
And by the way, i did change the original post to say 1M. I said 2.2M because thats what i remembered but when i looked at something on the schmatic  after i posted i realized it was 1M and also that it;s the grid load which as i stated was just a brain fart. (no shortage of those in my noggin)

[sluckey]

I did post the schematic in the same post i posted that layout snippet. The entire pdf is too big to post, it won't allow it.

What is the file size of the entire pdf? Can you post just the entire board layout?

[12AX7]

Ok, let me try again. I did it once before (saved only the sch) but i don't recall how i did it. If i can save only the sch and layouts i'll post it. There are a bunch of parts pages that make it so big.

[12AX7]

Ok, i was able to save the pdf with just the first 3 pages so lets see if it lets me upload it.
Yes !

[Merlin]

Just snip off C24 with some cutters. You can always put a replacement cap back in, wrapped around and soldered to the remains of the old legs.

[12AX7]

Just snip off C24 with some cutters. You can always put a replacement cap back in, wrapped around and soldered to the remains of the old legs.

The problem is i don't wanna pull the board for the god knows how many'th time. It's tedious and long and i'm done doing that unless i KNOW what i'm gonna do is a result i like. No way to get to it otherwise.

[sluckey]

Show us a hi-rez pic of the actual resistor inside your amp. Some creative mind may offer an alternative that will be easy.