Author Topic: Fender brownface vibrato in a stomp...does it exist? What about with JFETS?  (Read 40040 times)

skiraly017

I'm just the idea man.  :icon_mrgreen:

I hope it works out. I'm interested in hearing clips.
"Why do things that happen to stupid people keep happening to me?" - Homer Simpson

markm

I too am very interested in this circuit.
What about this one in casey's gallery?
http://aronnelson.com/gallery/Tremolos-and-Vibratos/tube_vibrato


nordine

What about this one in casey's gallery?
http://aronnelson.com/gallery/Tremolos-and-Vibratos/tube_vibrato

hey that's cute,
its like an ancient EA Tremolo  ;D

puretube

I too am very interested in this circuit.
What about this one in casey's gallery?
http://aronnelson.com/gallery/Tremolos-and-Vibratos/tube_vibrato



it`s a Trem...
(similarly working to the one, TTG wrote about a while ago).

R.G.

Quote
Did you by any chance make a PCB?
If enough of you are interested, I can make one.

I actually did two approaches to the same circuit. The one up on the web page is based on the infrastructure of the Phase 90, perverting the phase JFETs to do tremolo. I did another version using the infrastructure of the EA tremolo - two EA trems run out of phase by an enhanced LFO and added filtering.

I'd expect the P90 circuit to work more simply, the EA version to work more tube-i-ly. Whether that makes a difference or not depends on your ears...  :icon_biggrin:
R.G.

Quick IQ Test: If anyone in a governmental position suspected that YOU had top-secret information on YOUR computer, how many minutes would you remain outside a jail cell?

jakenold

  • Guest
Quote
Did you by any chance make a PCB?
If enough of you are interested, I can make one.

I actually did two approaches to the same circuit. The one up on the web page is based on the infrastructure of the Phase 90, perverting the phase JFETs to do tremolo. I did another version using the infrastructure of the EA tremolo - two EA trems run out of phase by an enhanced LFO and added filtering.

I'd expect the P90 circuit to work more simply, the EA version to work more tube-i-ly. Whether that makes a difference or not depends on your ears...  :icon_biggrin:

I take one of each, please! Great work, mr. Keen!  :D

markm

Would love to both hear and see the results RG,
I guess I was thinking this could be easily acheived by using the ROG emulation technology to produce a "simple" JFET circuit that would emulate the Brown Vibrato......from reading this entire thread, I may be VERY wrong huh?!

Ptron

Would there be any way to sneak an intensity control into this circuit? How about a dual-gange 1M pot wired as a rhoestat in place of the 1M bias resistors? I see the 3.3M and 1M resistors forming a 3:1 voltage divider from the lfo output to virtual ground (bias voltage) so a pot halfway down would be a 6:1 and so on... Does that make any sense?

Or perhaps a dry/wet mix pot.

Processaurus

Departing from the emulation of the traditional fender sound, but the voltage controlled bass/trble/panning chip in this threadhttp://www.diystompboxes.com/smfforum/index.php?topic=56630.0 could make an interesting, low parts tremolo!

Ptron

Quote
Would there be any way to sneak an intensity control into this circuit? How about a dual-gange 1M pot wired as a rhoestat in place of the 1M bias resistors? I see the 3.3M and 1M resistors forming a 3:1 voltage divider from the lfo output to virtual ground (bias voltage) so a pot halfway down would be a 6:1 and so on... Does that make any sense?

O.k. Now I see a R.G. Phase90 schematic at GEOfx that does just this. http://www.geofex.com/FX_images/p90ramp.pdf

markm

I found this page with amp trem info......It would be very cool to get a brown-face trem circuit going!  :icon_cool:
How about the Swamp Thang.....anyone know what's going on inside of that one?

skiraly017

I found this page with amp trem info......It would be very cool to get a brown-face trem circuit going!  :icon_cool:
How about the Swamp Thang.....anyone know what's going on inside of that one?

I had one awhile back and don't recall it capturing "that sound" but it's also been quite some time since I played one. I did play the brownface Pro again today. It's really hard not to buy the amp just for the vibrato.
"Why do things that happen to stupid people keep happening to me?" - Homer Simpson

markm

I found this page with amp trem info......It would be very cool to get a brown-face trem circuit going!  :icon_cool:
How about the Swamp Thang.....anyone know what's going on inside of that one?

I had one awhile back and don't recall it capturing "that sound" but it's also been quite some time since I played one. I did play the brownface Pro again today. It's really hard not to buy the amp just for the vibrato.

BUY IT!!  :D
I'd like to know what type of circuit the Swamp Thang is......LDR or FETs?
Anyone looked under the hood?
The clips sound amazing!  8)
If I could build one that sounded like that.....my love affair with the EA would be over.
« Last Edit: April 29, 2007, 10:52:33 PM by markm »

Ghandi

the swamp thang is a modded diaz tremadillo.

markm

the swamp thang is a modded diaz tremadillo.

FET based I assume?

Ghandi

nope, it's based on the NTE123AP silicon npn transitor.
oh and it's called "Texas Tremodillo" instead of tremadillo, whatever! ;D

markm

nope, it's based on the NTE123AP silicon npn transitor.
oh and it's called "Texas Tremodillo" instead of tremadillo, whatever! ;D

Interesting.
I guess that means it's not optical based which was where I was headed with this!
I am in the minority but I dislike Opto-Trems for the most part......the TremLune just really does nothing for me.  :icon_neutral:

nordine

hi there,

well, i breadboarded again the circuit  ;D

RG, this time the oscillator worked perfectly but, sadly, my recording means (a small cam-recorder) are so lo-fi, that the captured sound of the samples doesn't do any justice to whats really sounding -so you could tell it really does the fender thing- ..besides, i did record it on bass, then it's somewhat muddy

anyways, what i can report on the circuit is:

-Vref 15uf cap must be upgraded to 100uf at least, to prevent oscillator thumping
-for a more pronounced effect (depth), i changed both 3.3m resistors for 1.2m resistors
-a LED freq indicator mod suits it really well  ;) (think p45)
-if one takes Q2 out (the fet on the treble path), one get a pleasing bassy-phasing.. pretty cool
-i get the best performance out of the circuit  biasing the fets at 0V (is that a bad thing?)

now,

markm, on the Swamp Thang issue... i did a little research, and got some info that might interest you:

you like the Swamp Thang, right? ..then we know this effect is a modded Diaz Tremodillo (according to Jack Orman, the most noticeable change, is the true bypass conversion)

take a look at this:
http://www.pedaldoctor.com/images/DiazBrd6.jpg

right, thats a tremodillo board

if one looks at it, having in mind its an npn based tremolo, and taking note on the number of electrolytics it has, the resistor values, and number of transistors (besides the number of pots and the 1/2 freq switch), it seems to be none other than this:

http://topopiccione.atspace.com/pjimages/SchallerTremolo.sch.jpg

a schaller tremolo replica ( a very sweet tremolo on its own)

so.. if you clone a Schaller Tremolo, and true bypass it, you might get a very close Swamp Thang  ;D

cheers

markm

if you clone a Schaller Tremolo, and true bypass it, you might get a very close Swamp Thang  ;D

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!

Ghandi

anybody did a pcb for the ersatz fender pro tremolo jet?

@nordine
how would you compare the "ersatz fender trem" to the "schaller trem"?
« Last Edit: May 02, 2007, 05:13:08 PM by Ghandi »