Besides a bias adjustment, what mod(s) should Fender clones include?

Figaro

Silver Supporting Member
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12,768
All models that have Bass and Treble controls should have a Middle control!
 

VaughnC

Silver Supporting Member
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17,846
I like to install a negative feedback pot or a 2 or 3 position switch so I can dial in the feel of the amp to my liking, or just a 2 position switch to turn the negative feedback on/off. Sometimes I like the openess of no negative feedback, sometimes not.

I also find a 3 position bright switch comes in handy sometimes.

And maybe a switch to turn on/off the cathode bypass capacitor in the first preamp stage...sort of gives the amp a different feel.

And maybe a Presence control for a little control over the power amp.
 
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stevel

Member
Messages
14,655
My late 70s Super Reverb had a "Hum Balance" control which I actually found to be quite useful.

I just read another thread here on looking it up and it turns out the SRRI and TRRI still have it (or did for some period of time) but rather than on the back (where it's easily accessible) it's way up under the chassis in front of the transformer on the Pilot Light side. I've been playing the thing for 12 years or so and didn't realize it was there! I bet a lot of techs don't realize it either...

I'd turn the amp up, adjust the control to minimize as much hum as possible, and then turn it back to usual playing volume. It was extremely quiet idle.

As for the middle control, maybe a switch to bring it in and out so you can have it "authentic" or not (assuming there's not a notch on the middle that is "no middle pot").

I've always wanted verb and trem on both channels...wouldn't actually mind having a different amount of verb on each channel...or have a "dwell" control on the verb. A "shape" knob on the trem would be great - or the option of opto or bias trem, and a switch to toggle between them.

A switch to take V1 out of the circuit without having to pull the tube would be cool.
 

ylo

Member
Messages
748
Anyone else?
Some people like a RAW control as used on Allen amplifiers. This is basically a 25 k or 50 k replacement (or additional control) to the usual 10 k mid control potentiometer, as I understand it. Dialing the RAW way up progressively reduces the effect of the entire tone stack, increasing gain.
 

smolder

Platinum Supporting Member
Messages
14,365
Mid pot or a 12k switch., RAW (NFL) adjust... I like the inverter adjustment (Paul c) in a princeton.
 

Figaro

Silver Supporting Member
Messages
12,768
Some people like a RAW control as used on Allen amplifiers. This is basically a 25 k or 50 k replacement (or additional control) to the usual 10 k mid control potentiometer, as I understand it. Dialing the RAW way up progressively reduces the effect of the entire tone stack, increasing gain.
Yep, a 50K pot for the Middle control works great as a Mid/Raw control. You still have a regular Middle control up to about 3 and then it gradually removes the tone stack for a boost and/or tweed sounds as you turn it up more. Some builders now just wire an on/off footswitch to it. And some even mount the pot on the footswitch so it's closer for adjustments while playing. I don't like the sound with the tone stack completely removed.
 
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swiveltung

Member
Messages
14,493
Yeah, the neg feedback adjustment might be interesting. But I have the feeling it would be like the mid control, you find what you like and don't move it. I've converted amps to have the mid control but usually just remove it as I know what I want.
-Multi tap output tranny is the most useful thing I've found.
-To me it's nice having a non verb channel. it's a thicker sounding channel without all that pre amp crap in it. Sometimes useful.
-But if you don't want a normal channel, make that channel your reverb control... including using 1/4" jacks on the front for the pedal etc, and use the pot chassis holes for the Fender stand alone reverb controls.
 

zenas

Member
Messages
8,757
My late 70s Super Reverb had a "Hum Balance" control which I actually found to be quite useful.

I just read another thread here on looking it up and it turns out the SRRI and TRRI still have it (or did for some period of time) but rather than on the back (where it's easily accessible) it's way up under the chassis in front of the transformer on the Pilot Light side. I've been playing the thing for 12 years or so and didn't realize it was there! I bet a lot of techs don't realize it either...

I'd turn the amp up, adjust the control to minimize as much hum as possible, and then turn it back to usual playing volume. It was extremely quiet idle.

As for the middle control, maybe a switch to bring it in and out so you can have it "authentic" or not (assuming there's not a notch on the middle that is "no middle pot").

I've always wanted verb and trem on both channels...wouldn't actually mind having a different amount of verb on each channel...or have a "dwell" control on the verb. A "shape" knob on the trem would be great - or the option of opto or bias trem, and a switch to toggle between them.

A switch to take V1 out of the circuit without having to pull the tube would be cool.
The hum balance control is in the heater filiments. Basically an adjustable artificial center tap for the heater filiment winding. Normally just done with two 100 ohm resisters.

The pot by the power transformer on a TRRI or SRRI sounds more like a bias pot. Which it should be since they're supposed to be reissues of the blackface circuits.
They put it in an inconvenient spot so people that should be messing with it hopefully don't find it. :)
 




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