Crate Vintage Club 30 /50 Remove V1 from the dirt channel to reduce gain

[littlericky]

I've been researching various suggestions for mods to the Crate VC30 and 50 to reduce gain in the dirt channel. I found this mod which sounds interesting. It looks to tweak the clean channel and dirt channels separately, without V1 adding an extra gain stage in the dirt channel. Does this sound viable?


Remove the jumper in line with pin 7 of V1 and add a 68k grid stopper.

Remove C2 (.047u) and replace with .022u.

Remove C41.Thats it for the clean side.

Replace R67 (1M) with 68k,

Jumper the end that connects R67 to C41 to the input jack tip (high side of R1). So far we've separated the 2 channels, but driving both input stages simultaneously through their own grid stoppers.

Remove R59 (1M). It won't be needed since the dirty channel's input stage is referenced to R1 so the grid won't want to float.

[Enzo]

Hi little. welcome to the forum

it is good form to provide a link to the schematic you are using so we can know what you are talking about. I am looking at the VC3113 drawing, seems to fit.


You can separate the channels if you like. why not. An easier way to reduce gain in the channel would be to try a lower gain tube in V2 and/or V3. A 5751 for example. Easy to try, immediately reversible if not to taste, and that is a fun tube to have around for various uses.

Look at the test points on the drawing, looks to me like the majority of the dirt comes in the gain stage of V3. Of course that is fed by V2.

other options, change R59 to 220k to further lower levels there. or increase R68. Those are simple voltage divider changes.

You may recognize C11,C12 et al as a tone stack with set resistances. We could add a resistor between C11 and the plate of the preceding tube to lower levels.

[gui_tarzan]

I have a V50 2x12 on my bench right now and I think the gain channel sounds pretty good. What is it about that channel that you don't like? Aside from too much "dirt", of course.

[littlericky]

Thanks. Here is the link to the schematic.

https://drive.google.com/file/d/0Bwz...it?usp=sharing

I do see that v3 seems to be doing the brunt of the "dirty work" and believed that v3 was the 4th stage, V1a>V2a>V2b being the 1st, 2nd, and 3rd


I got the amp for next to nothing and love to learn, experiment. The clean channel isn't that clean or loud and is overly bright and sterile before it quickly gets muddy and notes blur together. The dirty channel becomes to dirty "for me" after the gain is raised to 1 0r 2 . Also Channel 2 is considerably louder as well

[gui_tarzan]

That's odd, the one I'm working on is pretty balanced between the two and is very clean on channel 1. You might want to look at some of your components and voltage readings before you start modding.