OD trimmer on the back wall

[angelodp]

You lost me!!

[Structo]

Doh.... Thanks to Gary for pinting out the obvious!

Use a 50K linear fed by a 270K resistor! I feel dumb... LOL

Gary as in Glaswerks?

Ah, maybe he means instead of the 220K resistor that feeds the trimmer, use a 270K resistor there instead of two resistors in series?
Because you have a 220K and the 68K grid resistor there already.

[angelodp]

I see. And not bother with the ground resistor??

a

[dogears]

Exactly...

220K into 100K trimmer = 270K into 50K trimmer. Difference being better resolution on the 50K trimmer. 25K setting is at noon like I like.

Gary at Glaswerks.... Ya.

[angelodp]

Thanks guys

[exocet]

Can I ask a newbie question here?

I understand that the trimmer setting is key to getting your desired tone. I also understand the concept of making the usable range easier to access by padding the circuit with fixed resistor values.

However, what is the difference between adjusting the signal via the trimmer and simply adjusting the input gain from the main volume control? I'm guessing that it boils down to 'resolution' and usable range but I'm intrigued to know if the same effect can be had by say moving adjusting the 'clean' volume from say 12 O'Clock to 1 O'Clock?

[Structo]

The volume control adjusts the gain of V1.

The OD trimmer fine tunes the gain of V2.

When OD is on, V1 & V2 are cascaded for more drive.
Then the overall gain on OD is adjusted by the Level pot.

[exocet]

The volume control adjusts the gain of V1.

The OD trimmer fine tunes the gain of V2.

When OD is on, V1 & V2 are cascaded for more drive.
Then the overall gain on OD is adjusted by the Level pot.

Thanks for the reply but I still have questions!!

I understand that when in OD, the signal passes through V1 & V2 and that the OD trimmer sets the signal level going into V2, hence the amount of drive. But surely increaing / decreasing the signal level originating from V1 will have a similar effect e.g 6dB more signal from V1 gain stage has similar effect to increasing the signal level going into OD stage by adjusting the trimmer? What sort of gain range is available assuming that the trimmer was 100K?

[dogears]

Not the same as you will clip different sides of the sine wave by changing the gain on the different stages.

The volume control adjusts the gain of V1.

The OD trimmer fine tunes the gain of V2.

When OD is on, V1 & V2 are cascaded for more drive.
Then the overall gain on OD is adjusted by the Level pot.

Thanks for the reply but I still have questions!!

I understand that when in OD, the signal passes through V1 & V2 and that the OD trimmer sets the signal level going into V2, hence the amount of drive. But surely increaing / decreasing the signal level originating from V1 will have a similar effect e.g 6dB more signal from V1 gain stage has similar effect to increasing the signal level going into OD stage by adjusting the trimmer? What sort of gain range is available assuming that the trimmer was 100K?

[angelodp]

Scott, can you give us a rundown of what alternate changes you make using the OD trimmer beyond the 25K and then tweak to taste. Are their specific guitars or tube sets that would cause you alter the trim set.

ange

[Structo]

I can't answer for Scott but I think you just have to use your ears.
One setting for all players is not possible because it is subjective to your tastes and how you hear it.

But, of course different guitars with different styles of pickups may require different trimmer settings.

We all are aware of how sometimes a single coil Fender guitar might not work well with a certain mid cap or trimmer setting while the humbucker equipped guitar can sound awesome.
So you have to make accommodations for that.

I like the idea of moving the trimmer adjustment to the back panel and I may go ahead and do that the next time I open up my amp.

[heisthl]

Why not put it on the front?

[talbany]

Henry
Not to change the subject here.. Always wanted to ask you if you are a fan of the Bluesmaster.. Do you prefer it over the Non HRM/Standard HRM...Personal taste here.. Curious!!.. Thanks!!

Tony

[heisthl]

Henry
Not to change the subject here.. Always wanted to ask you if you are a fan of the Bluesmaster.. Do you prefer it over the Non HRM/Standard HRM...Personal taste here.. Curious!!.. Thanks!!

Tony

I almost hate the Bluesmaster - I don't like the cleans - I don't like the OD. My preference is a modified skyliner (lower plates - more mid choices) with a modified non-HRM section (less low end, smaller snubbers, different bypass caps etc.).

[bluesfendermanblues]

Why not put it on the front?

WHAT? a Red Plate Amp not covered in red tolex?