Author Topic: Fender brownface vibrato in a stomp...does it exist? What about with JFETS?  (Read 40521 times)


Its me or the Ersatz Tremolo doesn't have any depth pot?
I'm sorry but my English sucks!

Freaking with real fuzz boxes...


No Kiddin'!
That's tremendous news nordine......a great Big Thank You for that tid bit of info and the pic is really a great shot too!
I have been looking over the Schaller schem which I printed out a couple of weeks ago but have yet to do anything with it.
Maybe it's time to do something about it.
I didn't think the Schaller was as smooth as the Diaz or Swamp Thang.
Who knew?!!  :icon_lol:
Again, THANK YOU my friend!

hey man, thats a lot of happiness!  ;D
well i'm pretty glad this info served you, i expect the circuit fulfills your expectatives as well.. good luck on that! ..let us informed on how it comes out

ghandi, the ersatz has obviously different sound from the schaller, because the first one uses phase shifting plus AM, and the other one only amplitude modulation.. ... now, the oscillator in the schaller is sweeter (asymmetrical sine wave i think) than the ersatz, which is a square wave at all lights

momiel, right it doesn't have a depth pot, but you can set the depth with the bias pot (not the best way to do it, but it works)



a sound sample of the ersatz tremolo,

notice, again, that in bass and at that recording quality, the effect maybe is not much apreciable, but it gives an idea (also have in count that i subbed the 3.3M resistors, so it's sounding deeper/squarer than intended.. did that for experimenting purposes)

John Blund

This thing sounds great. after reading through the post I even tried to set up a kinda faux version on the computer with plugins based on R.G. instructions, and well I don't know how well these plugins simulate the real deal, but after listening to the youtube sample I'd say I wasn't to far off, this is a must build, just gonna get a bredboard and some opamps. what kind is recommended?



Hi, I just made a version of this as an add on to an existing panning EA tremolo, and had a problem.  What I did was feed the two panning outputs to the two filters (one side to the series 470K and one to the series 220K).  The low pass filter side (with the series 470K and the .05uF to ground) doesn't make sound.  This makes sense now, looking at the schematic, as that RC filter combination gives a frequency rolloff of 6.8Hz.  As is it sounds like a normal, albeit bassless tremolo.

I took a peek at a better resolution Fender 6G5 schematic referenced before here, the filter part RG emulated is right in the middle.  Ah ha, its a .005, not .05! :icon_wink:

Edit:  With the right cap it sounds really cool!  Even tasteful perhaps (a rarity for pedals I build :icon_biggrin:).  Like people said, it has something reminiscent of a univibe or phaser, but not as identifiable.  It also sounds very cool and subtle with the depth of the panning turned down some, to add a slight watery sounding shiftiness. 

Darn it anyway, for it to be perfect, it needs a knob to blend in the brownness with the normal trem, rather than a switch.  But the enclosure is drilled, and its pretty cozy inside, with this new daughter board...  the box is drilled, dude...
« Last Edit: May 06, 2007, 12:28:29 AM by Processaurus »


Oops - sorry about copying that value wrong.

It's interesting that you reworked this on the EA trem body. Shortly after I did the P90 based one, I did an EA trem based version that I sent Mark a print of to try. Convergent evolution is powerful!

I'll put that one up on at GEO if there's enough interest. Mine had the filters before the modulators, like the Fender circuit, but it works either way.

Good work!

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.


Would love to take a look at the EA based version RG, please post it!
Thank you.


yeah, me too!
please post it!


Interesting... I've been toying with the idea of making an EA trem based version too. Only on paper so far thogh...


I had never heard this type of vibrato before, just read about. Found a sound file of a tube-based circuit:

This is the Ted Weber ReVibe - basically a cross between the old stand-alone reverb and the three-tube vibrato.

After hearing this, I realized that Neil Young sounds like he was playing through this type of vibrato on the live album with Crazy Horse from 1970 that came out late last year. Anyone know what amp he was using?

Anyway, it is a great sound, and it would be cool to have in a pedal. Maybe the Spin Semi FV-1 would be a good candidate in the emulation? (might be able to shoehorn a spring reverb simulaton as well...)

Sean Costello


Wow, sweet sound!  Thanks for the clip Sean.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

Ben N

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Anyone know what amp he was using?

I read a (pretty cool actually) article on his crazy setup, he uses a few amps, mixed together, one of them is a Magnatone.

The modulation I'm getting seems similar to that revibe sample, I'll try to record something when its all boxed up.

I'm going to work in the knob to blend in the brownness (the normal trem on one end, fender pro style on the other), it just sounds too cool in the in between settings, to add some mysterious character to the basic tremolo sound.  I'm using a simple pan like is in the Geofex "Panning for Fun" article,  using a 10K pot, the only thing that's weird is I used extra resistance on the trem side of the pan circuit, because it is louder than the pro side, which makes sense, because of inevitable losses in the previous filter part.  R=15K on the pro side, R=30K on the trem side.  I tried the two polarities of the trem to blend in, and preferred the trem in sync with the treble, rather than the bass.  Though the other way wasn't terrible exactly, it just sounded less tremolo like.  Only problem with this panning arrangement is there is a little volume boost in the middle of the pan knob, because when the knob is centered, the two sides are at ~.707x their voltage, rather than 1/2, one could use a dual pot wired as alternating volume controls, but whatever, the EA has a volume control.

Bang Bang


  yeah it's probably that magnatone amp neil is using, those are supposed to be the only amps that ever had true pitch shifting vibrato.  I think he uses one of those old magnatones and also a fender tweed deluxe together. 


A little closer translation brings me to this.
Only thing you need is a well-leveled modulation signal (simple oscillator like ROG phoser?) "A" with inverted "B".
And, yes, a lot of trimming...  ::)
Fet's could be matched ones like sold for Ph45 or Ph90.

Rules apply only for those who are not allowed to break them


That looks interesting...... 8)


A little closer translation brings me to this:

That schematic is real purty. What software did you use?

Sean Costello

Ben N

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Looks nice. Just a suggestion: Why not include a simple one-tranny phase inverter, like in a transformerless octave, so that you have only a single LFO input?
« Last Edit: May 09, 2007, 01:11:48 PM by Ben N »


Actually, that comes pretty close to the EA Trem version, which is here:

Differences are
- JFETs biased for bigger signals without distortion
- Modulation circuit shown; you'd need something like the LFO to make the A and B signals
- Modulation applied to source instead of gate, which seems to be less touchy

Edit: looking at it on line I notice that there's a drafting bug. The place where the signal out of Q1 crosses ground going to the 220K resistor should have a cross-over bump, and does not.

A note about my schemo drafting conventions:
- One wire which meets another at a right angle connects.
- There should never be a four-wire crossover; if there is, it does not connect. There should be a crossover hump just to make this blindingly clear, but sometimes I miss them.

« Last Edit: May 09, 2007, 01:13:36 PM by R.G. »

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.


That looks interesting...... 8)

Thank you RG.  ;)