Fender deluxe Rev normal channel mod

[alien]

Anyone know how to mod this channel for higher gain and marshall voicing without changing the other channel

thanks

[Bruce / Mission Amps]

Anyone know how to mod this channel for higher gain and marshall voicing without changing the other channel

thanks

I do...

[soundmasterg]

Its not all that hard to do since the channels are seperate until they mix right before the phase inverter. I don't have access to a schematic right now so I can't point out anything in particular, but if you study the schematic you should be able to see how to change it the way you would like to.....

Greg

[alien]

Its not all that hard to do since the channels are seperate until they mix right before the phase inverter. I don't have access to a schematic right now so I can't point out anything in particular, but if you study the schematic you should be able to see how to change it the way you would like to.....

Greg

Hey

I have a pic here but Im not sure if it will apply to my amp..below is also a pic of that channel on my FDR





It looks like a slighty different layout. For instance, I dont see where that 3.3m resistor would go
Thanks

[darrellcheng]

looks like between the blue cap (3rd from the left) and the e-lytics to the left of it. I think you should change all your e-lytics first before you do anything and see how you like the tone, if they are all original (those white ones in the pictures are)

btw, where did you get that picture?

[Bruce / Mission Amps]

It's my opinion that in this way, you will never get this amp to sound like a Marshall nor will you get either channel to sound like a Marshall as there is much more to it then a few extremely minor tone tweaks such as changing plate loads or cathode bypass caps, as described above.
I think you are barking up the wrong tree.
You can get the amp to be more ballsy sounding, more driven and less Fendery clean/distorted sounding but without a complete topology rework, including a cathode follower tone stack with Marshellesque values, ... it isn't going to be be what you think you wanted.

[darrellcheng]

Bruce, What would you recommend for a more 'tweedish' sound, if possible, in the normal section?

[Bruce / Mission Amps]

Bruce, What would you recommend for a more 'tweedish' sound, if possible, in the normal section?

Use high quality plastic polyester coupling caps for both channels.
Use .022uF@400v caps for the bass and mids with a 68K to 82K slope resistor and a real silver mica 250pF to 360pF treble cap.... but do it on the vibrato channel instead. You need that little bit more gain the reverb recovery section offers in this channel over the normal channel.
Replace all the electrolytic cathode bypass caps with new ones (I like 10uF here) .... but keep the normal channel values stock.
Make sure the phase inverter section is using black face amp's resistor values and then increase the actual coupling cap from the two 220K mixer resistors to the phase inverter, but use NO MORE then .0047uF@400v.
Remove the .1uF caps in the phase inverter and use no more then .033uF to .047uF caps there.
Lift the ground wire of the vibrato intensity pot and insert a 22K 1/2w resistor in series with the pot's lug to ground.

[alien]

looks like between the blue cap (3rd from the left) and the e-lytics to the left of it. I think you should change all your e-lytics first before you do anything and see how you like the tone, if they are all original (those white ones in the pictures are)

btw, where did you get that picture?

Thanks..I found it on the net somewhere..it may be from a book

My part all all original. I know it wont sound like a marshall but im thinking--that channel nas never been used--ever--why not change it if I can make something with a little more gain to it

My other question would be --would this increase or decrease the value when I sell it. To me personally it would increase it cause I only care about the sound --not the story--but generally is this a devaluing mod?

[Ben N]

Bruce, since you are talking about boosting the Vibrato channel, are you not a fan of replacing the reverb mixing resistor with a lower value, say 2M2, for more gain?

[darrellcheng]

Generally, the highest value of a vintage amp is, if it ain't broke don't fix it. stock specs and only components that are damaged or dying should be replaced

[Bruce / Mission Amps]

Bruce, since you are talking about boosting the Vibrato channel, are you not a fan of replacing the reverb mixing resistor with a lower value, say 2M2, for more gain?

Right... I think screwing with this too much can actually ruin the overall tone and usefulness of the amp... you can mess a little here but not too much.
I suspect Fender spent lots of hours on that little mixing circuit.
********
added
Also, Darrel's comment about changing the cathode bypass caps is spot on... change them all first for a solid reference point when modding these amps.

[Chuck H]

There are a lot of reasons why BF Fender and Marshall amps sound different. The topology, use of a cathode follower to drive the tone stack, different tubes, bigger filters, different speakers and closed back cabinets, the use of a presence control and diode rectifiers are all important. You can't possibly change these things and still have the vibrato channel sound anything like a Fender amp. But...

Risking scourn and humiliation I have a mod to "ruin" your vintage amp that should make the normal channel nice and crunchy with more gain without altering the tone of the vibrato channel. If you are thoughtful in your approach these mods are reversable and I reccommend that you save all your original parts.

The circuit changes are in red.

If the .033 PI decoupling caps alter the tone of the vibrato channel too much you can try .047 but the distortion could start getting muddy. Sometimes you can't have it all.

THIS IS PI AND POWER TUBE DISTORTION. There is some clipping of the last preamp stage but you do need to crank the amp to get distortion with this circuit. Also, If you use dark sounding speakers you may need to use some kind of presence circuit to get the full effect. If you don't have dark speakers you shouldn't need it.

This circuit has worked for me in similar amps but I have never done it with a DR. The schem is an AA763 but all the same info in red applies. I only used the AA763 schem because thats what I had.

Enjoy

Chuck

P.S. Yes, you do have vibrato on both channels now. If you want more gain, don't jumper the 220k R between the .1 and .0022 PI decoupling caps. Instead, increase the value of the new 68k load resistor.