Fender BF Tremolo Disconnect

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Bombacaototal
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Fender BF Tremolo Disconnect

Post by Bombacaototal »

Hi all, below is a very well known mod to disconnect the tremolo circuit on a Fender BF amp
Here's how it's done:
1. Disconnect the wires from the 50k RA Intensity pot.
2. Remove the pot.
3. Install new 50k RA Intensity pot with SPST switch attached.
4. Solder Brown wire to center lug as before.
5. Solder left lug to pot casing as before.
6. Solder Yellow wire to one side of switch.
7. Solder short length of new wire from other side of switch to right lug.

If you are getting pops when actuating the switch, add a 1 meg resistor inline with the yellow wire in step 6
http://www.regiscoyne.com/tech/tremolo/
I am curious if anyone has found a solution for the volume drop issue (about 30% or so) whenever activating the tremolo circuit back? Ideally would be to have a preamp boost at the same time the tremolo is activated to try to keep the same gain level?
sluckey
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Re: Fender BF Tremolo Disconnect

Post by sluckey »

The sole purpose of that mod is to give you a switchable gain boost. What you ask would defeat the purpose of the mod. If you don't want the volume increase/drop, just use your footswitch to turn the trem on/off.
Bombacaototal
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Re: Fender BF Tremolo Disconnect

Post by Bombacaototal »

sluckey wrote:The sole purpose of that mod is to give you a switchable gain boost. What you ask would defeat the purpose of the mod. If you don't want the volume increase/drop, just use your footswitch to turn the trem on/off.
Thanks for the reply. Yes it makes sense...sorry for the question and thanks for clarifying
pdf64
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Re: Fender BF Tremolo Disconnect

Post by pdf64 »

The 50k trem intensity pot is a very heavy load for a 12AX7 CC stage, reducing the stage gain and, I find, thinning the tone.
Rather than disconnecting it, if a 100k lin pot is used for the trem intensity control then it it all seems to work and sound a lot better, to my ears, apart from the slight drawback of the trem intensity control range being a little squished up into the latter half of control rotation.
Bombacaototal
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Re: Fender BF Tremolo Disconnect

Post by Bombacaototal »

pdf64 wrote:The 50k trem intensity pot is a very heavy load for a 12AX7 CC stage, reducing the stage gain and, I find, thinning the tone.
Rather than disconnecting it, if a 100k lin pot is used for the trem intensity control then it it all seems to work and sound a lot better, to my ears, apart from the slight drawback of the trem intensity control range being a little squished up into the latter half of control rotation.
Thanks a lot for the contribution and for sharing a different idea. It is an interesting approach!
Stevem
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Post by Stevem »

Unfeeling the tremolo kicks up the drive to the output tubes quite a good amount , and as such changes the preamp to output stage distortion ratio!
You need to investigate if this is truly what you want!
Also note added gain does not = better touch / sensivtivity many times out of a Fender as the main thing they need for good solo sound is lees Bass and a bunch more mids!!!

Disconnecting the tremolo mainly surveys to lick up the volume and fatten up the bottom !
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
pdf64
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Re: Fender BF Tremolo Disconnect

Post by pdf64 »

If one experiments with master volumes before and after the LTP, it might be preceived that moving the ratio of distortion away from the pre-amp towards the power amp is a good thing.
The reverb channel of a 2 channel BF Fender sounds awful when it overdrives, as the 1st point of the pre-amp to overdrive is the V3 reverb driver grid, and the signal gets a frequency selective asymmetric diode clip.
SFs with a MV tended to do without the V3 cathode bypass, presumably in an attempt to try and get it sounding a bit better.
In a non-MV amp, the bad sound tends not to be noticeable as the power tube grids are clipping heavily by the time that the signal level gets high enough fot the V3 grid clipper to take effect.
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jjman
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Re: Fender BF Tremolo Disconnect

Post by jjman »

pdf64 wrote:If one experiments with master volumes before and after the LTP, it might be preceived that moving the ratio of distortion away from the pre-amp towards the power amp is a good thing.
The reverb channel of a 2 channel BF Fender sounds awful when it overdrives, as the 1st point of the pre-amp to overdrive is the V3 reverb driver grid, and the signal gets a frequency selective asymmetric diode clip.
SFs with a MV tended to do without the V3 cathode bypass, presumably in an attempt to try and get it sounding a bit better.
In a non-MV amp, the bad sound tends not to be noticeable as the power tube grids are clipping heavily by the time that the signal level gets high enough fot the V3 grid clipper to take effect.
Biasing the reverb driver hotter reduces its (cold) clipping. Fender did this while removing the bypass cap as mentioned. Adding a resistor in line with an original cathode bypass cap then brings the amplification back towards normal. The 12at7 can handle it no problem. The reverb tranny did not change part# so it can handle it too. I did this mod on my '71DR after adding a post PIMV, to curtail clipping in the reverb signal.
Bombacaototal
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Re: Fender BF Tremolo Disconnect

Post by Bombacaototal »

Thanks a lot everyone for sharing your experience and ideas
Bombacaototal
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Re: Fender BF Tremolo Disconnect

Post by Bombacaototal »

I am wondering if anyone can recommend a good 50k ra SPST pot which should disconnect the circuit when intensity=0
Stevem
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Post by Stevem »

I don't think you will find such with a switch!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Bombacaototal
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Joined: Thu Oct 06, 2016 5:53 am

Re: I

Post by Bombacaototal »

Stevem wrote:I don't think you will find such with a switch!
What about the 50k ra SPST pot From weber part # wp503ras? Is it push/pull?
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