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DRRI Bright Cap Values

jfhudak

Member
Messages
15
Hey Fellers,

Unlike most people, I LOVE LOVE LOVE the brightness of the Fender reissues. They really complement my Gretsches. To wit, I have a question: has anyone INCREASED the bright cap value in your DRRI? Reason I ask. . .

The 65 Twin has a 120pf bright cap on the Vibrato channel. Sounds incredible. The 65 Deluxe only has a 47pf. Has anyone experimented with values in your DRRI to increase the brightness?

Might be a bit of a pain to get it off of the board, but I wonder how a 120pf would sound.

Just curious. . .
 

Silent Sound

Member
Messages
5,531
Changing the value of the bright cap won't increase the treble, per se. What it will do is effect the frequency at which the bright cap comes into play. So if you raised the value, you should get the same amount of treble, but more upper midrange as well. So the bright cap doesn't add treble to the signal, it just allows some of the treble to bypass volume knob, kinda like a shortcut around the volume knob that's only available to treble frequencies. That's why the cap quits working as you turn the amp up. When you decrease the resistance of going through the volume pot by turning the volume up and allowing more signal through, then that shortcut is no longer such a shortcut for the electrical signal, thus it has less and less of an effect.

In any case, you can experiment with different values for the bright cap, and those ceramic disc capacitors are really cheap, so time and soldering skills would be the only reasons not to. And lowering the frequencies that are able to go through that cap may give you the perception of more treble. And I guess it could theoretically add more treble to the signal to, depending on the slope of the crossover point. I'm not going to math that out today.

Anyway, If you like that amp, but want even more treble and spank out of it, I would recommend you try a different speaker. Those old JBL D120F's will give you all you could ask for. They're pretty bright amps in nature, so the speaker and or guitar would be the first place I'd look to add any more treble.
 

jfhudak

Member
Messages
15
Changing the value of the bright cap won't increase the treble, per se. What it will do is effect the frequency at which the bright cap comes into play. So if you raised the value, you should get the same amount of treble, but more upper midrange as well. So the bright cap doesn't add treble to the signal, it just allows some of the treble to bypass volume knob, kinda like a shortcut around the volume knob that's only available to treble frequencies. That's why the cap quits working as you turn the amp up. When you decrease the resistance of going through the volume pot by turning the volume up and allowing more signal through, then that shortcut is no longer such a shortcut for the electrical signal, thus it has less and less of an effect.

In any case, you can experiment with different values for the bright cap, and those ceramic disc capacitors are really cheap, so time and soldering skills would be the only reasons not to. And lowering the frequencies that are able to go through that cap may give you the perception of more treble. And I guess it could theoretically add more treble to the signal to, depending on the slope of the crossover point. I'm not going to math that out today.

Anyway, If you like that amp, but want even more treble and spank out of it, I would recommend you try a different speaker. Those old JBL D120F's will give you all you could ask for. They're pretty bright amps in nature, so the speaker and or guitar would be the first place I'd look to add any more treble.
Hey man, thanks for the great reply! As a matter of fact, I just upgraded the amp with a new baffle to make it a 2 x 10 combo. . .for just the reason you stated: I want more brightness. I used a pair of Jensen P10R alnicos and it got me 90% of the way there. I could live with it the way it is now and be VERY happy, just thought I'd ask about other options to brighten it up. Still, an RC Booster would probably get me the rest of the way there. Here are a couple pics:











 






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