Opinions on Phase Inverter Cap BF fender [Archive]

claytushaywood

April 14th, 2012, 01:07 PM

I am trying to get a bit more fatness out of my fender pro reverb. It's a little shrill right now. I've read somewhere (i believe on here) that some people like to increase the value of some coupling caps. I've heard increasing the .001uf coupling cap on the phase inverter can help- some people like as high as .01uf here or maybe just .0022uf. anyone try this? will it just give me more bass? I guess I'm looking for more low mids. I do have .022uf caps for my bass and mids tone caps. I like how the bass is lowered and I have more mids and low mids present with this mod. but maybe I should go to .047uf for the bass cap? or maybe .033uf and .047uf for mids and bass respectively?

What about the vibrato channel coupling cap? would increasing this from .02 to .033 or .047 help me a bit?

maybe both of these? I also changed the treble caps to silver mica... while I like detail I kinda feel like the highs are just a bit too sharp or piercing. One dude recommended using a polystyrene material cap here... anyone try this? apparently it's got a bit smoother or softer sound than silver mica. I dont wanna hear any arguments about just changing the material of the capacitor- there is an obvious difference in sound between silver mica and ceramic in the treble tone cap position- that one change will make a tonal difference- I even measured both caps to check tolerance and amazingly both were right at 251pf

Any input is greatly appreciated!!!
Thanks!

Wally

April 17th, 2012, 02:06 PM

Clay, for BF sounds, I like the .1mfd bass cap and the /047mfd mid cap in the vibrato ch. IN these two channel Fender reverb amps, I like to separate the cathodes on V1 and V@....pins 8 are tied together. I use a 1.5K resistor for the vibrato channel for stock gain characteristics. I then build a new bypass circuit for the Norm ch....I use the 820ohm resistor there...hotter gain. I then change the tone caps for more of a tweed thing...and the slope resitor may be changed at this time too.
This way, I have that Vib. Ch stock, and I have a hotter channel in the NOrm Ch. Wtih an A/B swtich, one then has a swtichable two channel amp with soem versatility.

FWiw, I use silver micas in the treble position, too. For that PI, a .01mfd cap does increase themids....it doesn't get too far into the lows. This is a change that that FEnder made in the SF amps, too....to the .01mfd value.


	Telecaster Guitar Forum > The DIY Channel > Shock Brother's DIY Amps > Opinions on Phase Inverter Cap BF fender PDA Opinions on Phase Inverter Cap BF fender claytushaywood April 14th, 2012, 01:07 PM I am trying to get a bit more fatness out of my fender pro reverb. It's a little shrill right now. I've read somewhere (i believe on here) that some people like to increase the value of some coupling caps. I've heard increasing the .001uf coupling cap on the phase inverter can help- some people like as high as .01uf here or maybe just .0022uf. anyone try this? will it just give me more bass? I guess I'm looking for more low mids. I do have .022uf caps for my bass and mids tone caps. I like how the bass is lowered and I have more mids and low mids present with this mod. but maybe I should go to .047uf for the bass cap? or maybe .033uf and .047uf for mids and bass respectively? What about the vibrato channel coupling cap? would increasing this from .02 to .033 or .047 help me a bit? maybe both of these? I also changed the treble caps to silver mica... while I like detail I kinda feel like the highs are just a bit too sharp or piercing. One dude recommended using a polystyrene material cap here... anyone try this? apparently it's got a bit smoother or softer sound than silver mica. I dont wanna hear any arguments about just changing the material of the capacitor- there is an obvious difference in sound between silver mica and ceramic in the treble tone cap position- that one change will make a tonal difference- I even measured both caps to check tolerance and amazingly both were right at 251pf Any input is greatly appreciated!!! Thanks! Wally April 17th, 2012, 02:06 PM Clay, for BF sounds, I like the .1mfd bass cap and the /047mfd mid cap in the vibrato ch. IN these two channel Fender reverb amps, I like to separate the cathodes on V1 and V@....pins 8 are tied together. I use a 1.5K resistor for the vibrato channel for stock gain characteristics. I then build a new bypass circuit for the Norm ch....I use the 820ohm resistor there...hotter gain. I then change the tone caps for more of a tweed thing...and the slope resitor may be changed at this time too. This way, I have that Vib. Ch stock, and I have a hotter channel in the NOrm Ch. Wtih an A/B swtich, one then has a swtichable two channel amp with soem versatility. FWiw, I use silver micas in the treble position, too. For that PI, a .01mfd cap does increase themids....it doesn't get too far into the lows. This is a change that that FEnder made in the SF amps, too....to the .01mfd value.