Tonestack in BF/SF fenders what values and compostion?builders/modders/discuss

[sidehatch]

Got a question for the builders/modders here. Im thinking about fiddling with the 3 cap tonestack on my pro reverb on the vibrato channel.

Now it has the .1 .047 and .047 setup and its those dark blue caps
These:
http://img.photobucket.com/albums/v334/Audrey81602/my%20pro%20reverb/IMG_8603.jpg

I'm thinking of trying another configuration .and I'd like to know what you amp buiders/modders like. I have read that 3 of the same type(say orange drop) don't sound as good as mixed.

The amp has a lot of bottom end. As it is I run the bass at 2 and the treble at 8. On my other fenders the treble gets ran at 3 or so. The amp is Dark and fat by nature. I like the midrange content and realy dont want to add a mid pot or anything or mess with the mid resistor because I've been down that road before and didnt like it.

So basically, which 3 caps would you use and which makes/comnpositions

Maybe a .1, .022 and a .047? I already have 1 of those paper in oil russian military caps I bought from outahear on the board.

The desired goal is better fender amp tone and maybe lighten up the sound a tad without making it brittle. I hate the bright cab. Maybe I could put a different cap value in there? Is that a .002? I'd have to go look.

Oh Yeah, Speakers I have in there are Emi's red,white and blues and a C rex. I have the original oxfords which I think are terrible,worst speakers ever. I also have some jensens and a celestion G12H30. Im willing to swap one of those out but for now just want to mess with caps. I like the amp as is but think it can be better and want to learn about cap selection and tone.
Thanks

[rmconner80]

check out the tonestack calculator on http://www.duncanamps.com/

If you check schematics, you'll find some variations on the mid / bass caps used in the tone stack of BF amps. Some use 022uFs, maybe it was a super? Don't remember.

Also if you are really adventurous, give a 350K/70K tapped treble pot a whirl like the brownface amps.

[TweeDLX]

I recommend you buy several different types, brands, and values. Your ears will be the judge of what sounds "best". I like silver mica for treble caps, and have been tending towards Mallory's for the rest. Mainly because I have a lot of them. If you're trying to get rid of some bass, modifying the tonestack won't help as much as lowering the value of the cathode bypass caps. Most Fenders use 25uf/25VDC caps, but using a 10uf/25VDC, or even lower values (4.7, 2.2, or 1uf) significantly changes the tone. Again, your ears will be the judge of what sounds "best". I used a .68uf in my Concert II to great advantage. YMMV

Mike

[RedRock]

The standard Fender tonestack is 250pf (treble), .047 (midrange), and .1
(bass). Here are some combinations that have been used:

150pf, .022, .047 (high bass; used by Zinky in Tonemaster and Dual Pro. High bass frequency)
250pf, .022, .047
250pf, .047, .047 (much like a std. Fender but with a little less bass)
250pf, .022, .1 (more bass than std. Fender combination)
250pf, .033, .1 (somewhat more bass than std. Fender)
250pf, .022, .022 (Marshall type, open, airy sound. No heavy bass here.)
470pf, .022, .022 (Marshall type, with a thicker treble)

Try silver mica caps for the pf values. They have a sound that is different
from the ceramics. You may or may not like them more. Traditional Fender
is ceramic.

+1 on lowering the cathode bypass cap values to reduce bass.

You can also reduce the value of coupling caps. Change a .02 to a .01 and
a .1 to .047. You might try changing the phase inverter coupling caps
from .1 to .02.

The nice thing is - if you don't like something, change it back.

[smolder]

On the advice of a couple others (I am learning and not a tech)... I just swapped out the caps in the tone stack on my musicmaster bass (same as the champ I think). Where the 2/25 and 10/25's were I put 25/50... and in place of the 25/25, I put a 50/50. I bought sprague atom caps from Angela in Maryland... to my ears they sound a bit more musical and transparent. They were also a fairly inexpensive.