Adding Presence Control to Deluxe Reverb

[roberto]

To add visitors to its own site.

[Stevem]

Depending on the pots setting it will add highs, drop gain and make the change over point from clean to clipping faster( ( I.E.) smaller dynamic range if that's what your looking for?

[Stevem]

Depending on the pots setting it will add highs, drop gain and make the change over point from clean to clipping faster( ( I.E.) smaller dynamic range if that's what your looking for?

I would find a music store that has a Vox AC15 and go play it loud before you do this mod since the amp has no feedback circuit, play it and make note of how it goes from clean to dirty.

[martin manning]

To add visitors to its own site.

[pompeiisneaks]

To add visitors to its own site.

robrob is Rob from robrobinette.com, yes he has a simple banner ad at the bottom, but for the massive amounts of great content, I don't think it's hurting anyone. His site and the amount of work he puts into it is pretty great imo. Which is massively different than say people trying to shill sales of DMM's or their new 'not a dumble clone' dumble clone.

~Phil

[SixStringBender]

Unlike the original poster, I want to be able to add bite and pinch to the treble. So I want a presence control on a blackface style amp. I'm not the smartest guy, but Rob's suggestion appears the best to me because it is tried and true in the Bassman.

So in a Deluxe:
The 22K PI tail is reduced by 4.7K to compensate for the new 4.7K NFB tail. So the nearest 1% resistor is 17.4K. This is the new PI tail.
The 47R NFB tail increases by 100 times to 4.7K
The 820R NFB resistor increases by 100 times to 82K
That keeps the same NFB ratio.
The .1uF cap and 25K pot go in series, then in parallel with the 4.7K NFB tail.

Is there any reason this isn't the best method? With the same ratio won't the amp have the same sound as before, but with the ability to tweak the treble after the preamp for a brighter and looser feel?

I added a presence to my Blues Junior, thanks to BillM, and I really like it a lot. It makes adjusting the treble and the feel of the amp a lot more versatile.

So again, any reason Rob's version isn't best?

[Roe]

I added presence control to a twin reverb. I also prefer adjustable negative feedback and a larmar master volume

[SixStringBender]

What method did you use for the presence? I really like Rob's idea. I haven't tried it, but I like his idea and how it compensates for the PI tail too.

[Roe]

What method did you use for the presence? I really like Rob's idea. I haven't tried it, but I like his idea and how it compensates for the PI tail too.

I used a 5k presence pot, connected to a 27k nfb resistor in series with a 220k pot connected to the 16ohms secondary (or a 12-15k resistor in series with a 100k pot connected to the 4 ohms secondary). For tail resistors I use everything from 6k8 to 22k