fender style opto tremolo circuit in a pedal?

[pinkjimiphoton]

has anyone done this? i tried google searching and the search function which led me to hours of stuff i hope to understand one day, but...

no luck finding what i'm looking for.

i built rob's tiny tremoloooooooooo before, which sounds great, but i need something that's basically the same circuit as the old brown or blonde fenders,
but adapted to use in a simple pedal. gotta run on 9v.

i've seen a lot of trems out there, but i think it's gotta be optical to get *that* sound.

i mean, the fender circuit is pretty minimal...i'm kinda surprised nobody's already done this.

i DID look at RG's geofex article about replacing the trem in a fender amp with mosfets.. i need to do something like that, but in a pedal.

thanks for the advice brothers...drinks are on me .

[mth5044]

You mention geofex has an article about replacing the tubes with mosfets, but he also has a trem pedal version.

Check out his the Ersatz

http://www.geofex.com/FX_images/FakeFenderVib2.pdf

Also, I've heard good things about the swamp thang

I recently built a Baja trem pedal, which I like the feel of much more than circuits like the EA Trem.

[PRR]

> gotta run on 9v

The classic Fender opto I am thinking of (there were several!) uses a Neon lamp. This needs >110V to light-up; as implemented you really need 250V-350V supply.

There are many ways to caress a cat. You could use LED (but it won't be the same). You could jazz-up 9V to 300V (an uphill battle).

[artifus]

how about a grain of wheat (gow) or other small low volt filament lamp? still no neon but typically 6 - 12v so happy in a 9v pedal with a slower response and different light to led,  though life expectancy may not be so great. maybe play with yellow or orange led speed, intensity and its distance from the ldr to fake an incandescent light à la joe meek optical compressors?

[pinkjimiphoton]

YOU GUYS ARE AWESOME!!!

all these years going thru RG's site, and i never saw that one...thank you!!!

i realize the fender is running at a high voltage...but i was thinking could use either a grain of wheat lamp (which i have) or a fender style pilot lamp (incandescent) which i also have.

i realize there's many ways to skin a cat...  i was chatting with chris on fsb, he seems to think it can be done with a dual oa and a vactrol.

i haven't built the ea trem (yet) so don't know what to think of it...so far, all i've built is rob's tiny tremolooooooooo oo oo oo o but it gets overpowered if ya put too much beef into it.

i wanna build something to help a friend going thru a rough patch...and he lusts over the phasey old-school tone of the as he calls it "blonde" fenders...which is basically the same thing as is in my princeton. i figured somebody has to have made a pedal version, and if they haven't, well...

maybe the time is right!

appreciate the replies, and i've got RG's schematic stashed.

i think incandescent may be the way to go...either the GOW or the pilot, both will work on 9v i think, and give it the "sag" it needs to sound authentic.

[PRR]

> the phasey old-school tone of the as he calls it "blonde" fenders...which is basically the same thing as is in my princeton.

Model numbers.

There were several "blondes" and many things badged "Princeton".

IIRC, the opto came after the Blonde era, and optos are not real "phasey"... one of Leo's toys was a complex all-tube (could be FET) 2-band wobbulator, very much like that 'Ersatz', which would be 'phasey'

[pinkjimiphoton]

i think he's trying to describe the simple 2 stage vibrato circuit that's in the brown (not blonde) and black fenders.
the princeton i built years ago, on the chassis of one of the late 70's blackface princeton reverbs with the pull switch on the volume for gain boost IIRC it's just 1 12ax7, two stages.
i gotta get ready for a gig so  will try and find the schem for it and post.

thanks!!

[pinkjimiphoton]

this is the circuit in my amp.....i didn't mess with the tremolo, it's about the only part that's stock.

http://www.el34world.com/charts/Schematics/files/fender/princeton_rev_boostpedal.pdf



as you can see, it's REALLY simple. but very very sweet sounding and extremely organic.

[PRR]

> this is the circuit in my amp.....

That's not an opto trem. It is specific to a push-pull tube output stage. There isn't significant "phasing" but there is a strong clipping (overtone) action when working loud. There's also some interaction with varying speaker impedance versus frequency.

IMHO, the easiest way to get THAT sound is to use that series amplifier. The trem is deeply embedded in the POWER sections. As long as you 'must' build that much, preamp and tone-knobs are trivial.
___________________________________________________________
The AA763 (under several model-badges) is the classic Fender Opto-trem.

http://www.el34world.com/charts/Schematics/files/fender/TREMOLUX_AA763.pdf



It is cheap/easy, but it is not widely loved (simple and soul-less), which is why I was wondering if you really wanted "fender style opto tremolo".

[starekase502]

isn't the demeter tremulator just that?  The fender trem adapted for pedal. baja man over at the other site has a build for it.

[Toney]

 There was some nice work done cooking up the Fender Brownface Vibrato (tremolo) some time back.
Not opto but lovely sounding - could be close to what you are after?

http://www.diystompboxes.com/smfforum/index.php?topic=55129.0

[bhill]

Paul, it is a simple circuit, but "soul less"? I have known a lot of people who chase after the old Blackface and Brownface Fenders both for their tone and the simple effects built into the amp. I am another who really like the Fender tremolo (vibrato), but I have no need to do it with a pedal, just a footswitch. '65 and '67 Bandmasters give me all the tremolo I need.

Bob

[artifus]

there's no accounting for taste 

[Mark Hammer]

1) There are probably two things that accompany optical trem.  One is that the LDR itself can have idiosyncratic, and often asymmetrical resistance-change rates.  That is not so much a property of "optical", so much as some optical.  The other aspect, which IS universal, is that, as completely passive devices LDRs don't clip.  This means you can feed the tremolo just about any sort of signal you want, and if it's designed right, there will be no practical limitations on clean signal handling (unblike what you might find with a 3080 or other OTA--based tremolo).  Feed it a hot output fuzz, and the unit will simply make it louder and softer, without adding anything itself.

2) Though many, if not most, Fender amps have optical tremolo, many of the classic amps have bias-tremolo, which seems to be a bird of a different feather.  And even here we have to differentiate two different varieties: those that provide varying bias to the power tube inputs in Class A/B amps, and other varieties that apply varying bias to preamp or driver-stage tubes.  Myself, I lean towards power-tube bias, and one of the things I like about my Tone Core Tap Tremolo is the Bias Tremolo model.  Whatever you like, do not mistake all Fender amps as having optical tremolo, or inserting the amplitude modulation at the same point in the signal path.

[pinkjimiphoton]

hi guys,
i think some of the confusion comes from MY confusion.

the only part of the princeton i didn't f with was the tremolo, which imho is one of the most organic sounding trems out there. i'd assumed it used an optoisolator like the other fenders i'd worked on,  so i never really looked at the schematic that in-depth. when i built that amp, the only thing i was interested in was where the parts were i needed to swap in and out.

so that's my bad.

also my bad, is that when i said opto i should have been more clear, that i though the sound could maybe be reproduced (at least close enough for rock and roll) with some kind of lamp and a photoresistor.

so...it looks like all the princeton does is the same thing that rob (deadastronaut)'s tiny trem does then...just shorts the signal to ground periodically?

so you'd probably wanna use a quad opamp i'd imagine, so you can have input and output buffering, an oscillator stage and maybe a gain stage to add a little clipping?

thanks for helping me and bearing with me, guys, i'm still a total hack, i learn by blowing stuff up and experimenting, let there be no mistake it's not from any appreciable knowledge.

to me, it's "if it passes audio, and sounds cool, it's good" ...


i saw baja's trem on the other forum, but i'm thinking there's gotta be an easier way with way lower parts count. if the fender is that simple, then this should be able to be done quite simply too, i'd think?

[pinkjimiphoton]

this is absolutely the effect my friend is describing in this post:

http://www.diystompboxes.com/smfforum/index.php?topic=55129.msg423567#msg423567

so it's the "fender harmonic vibrato" that i'm seeking to figure out...and no opto involved.

there's gotta be a way to do it in a pedal form... and to run it on 9v. too much to hope for? 

[Gus]

Simming a circuit idea.  I am working on the linked Princeton schematic type.   9VDC and easy to find parts.

[pinkjimiphoton]

awesome gus,

you sim it, i'll try and vero it!

[tubelectron]

pinkjimiphoton,

If you don't need any photocell/optoisolator kind of tremolo, mine works well and is quite simple :



The version presented above is a double-tremolo, that is to say : you have one switch to engage effect, the other one is to change from "tremolo channel", each channel having its speed and depth controls. Indeed, a single tremolo is derivable. This schematic is a modified version of the SolaSound Tremolo. You can go from subtle slow waving to nearly repeat percussion, and of course you can dial the vintage trem...

There is one issue : the speed pot. You need to find a very progressive reverse log / reverse audio pot, unless - like me - you accept that if you turn the pot to right, the speed decreases... And use then a Log Pot !

A+!

[pinkjimiphoton]

thanks bruno,
it looks good!

i may try and build it up... but it's absolutely the "harmonic vibratto" effect my friend is looking for.

i may try and do a vero layout for this one tho, it looks fun! and i LOVE that repeat percussion style trem.. i was gonna build a kay clone, but this looks like it may be easier
and more versatile.
thanks!