Suggestions for a vintage tremelo pedal.

[Neutral]

I've decided that my virgin project will be a tremelo pedal, because they seem simple to build, and I want one!
I am after a few suggestions to point me towards the right schematic.
I want a basic classic sine wave based amp tremelo.
Knobs I want:
-Depth
-Rate
-Volume (I want PLENTY of volume to boost it louder than the bypassed signal, now that I think of it, if the Depth control was able to compleately flatten the wave, you could use this as a straight volume boost, now that would be cool!)

If there is a circuit that adds a sine to square wave shaper, like the marshal tremelo pedal, then that is a bonus, but not really desired, I want to keep this fairly simple.

I would really appreciate any suggestions and recomendations from you experienced folks!

Thanks.

[axr]

try the 4ms tremulus lune it has vol, depht, speed, wave and spacing knobs, it isnt hard at all it was my first project i'm very pleased with it, right the 4ms page is down, but when they return you should check it, commonsound.com/tremulus.html

[Neutral]

I'm familiar with the 4ms pedal, I've been trying to hit that site for two days now, hope it's back soon.
I'm glad to hear it's a fairly simple build, It's quite a flexible unit it seems.

[PB Wilson]

I'd recommend the EA Tremolo for "vintage" sounds. It was my third build using the pcb from JD Sleep's site. It is pretty straightforward and nice sounding. I haven't tried some of the mods (flashing LED, faster rate, etc.) mainly because it sounded good to my ears and in the music I play. It doesn't get the real choppy sound some people look for, but there are other projects you might try for that option. Do a search in the archives for tons of reading about the EA Trem.

[Paul Marossy]

I'll second on the EA Tremolo. I built one a few weeks ago, and I think it sounds pretty nice. It's got kind of a vintage feel, similar to  a Twin Reverb, but max. speed isn't quite as fast. That can be tweaked by changing a few cap values.

[danngreen]

try the 4ms tremulus lune it has vol, depht, speed, wave and spacing knobs, it isnt hard at all it was my first project i'm very pleased with it, right the 4ms page is down, but when they return you should check it, commonsound.com/tremulus.html

Yep the site's down but should be up in the next few days... we had a major hard drive failure... keep your fingers crossed..

[idlefaction]

yeah man i would also recommend the EA trem.  it has a very cool retro sounding vibe and a TON of boost, actually one of mine distorts and you have to have the volume on about 10% to match the levels.  

i'd be interested in the reverse; figuring it so that there's LESS boost available!  

[gez]

actually one of mine distorts and you have to have the volume on about 10% to match the levels.  

i'd be interested in the reverse; figuring it so that there's LESS boost available!  

I think it was Rob Strand who posted some different resistor values to lessen the gain.  Should be in the archives, or found at his site (I think he has one - will be linked from his profile if so).

One thing I've done in the past is use a MOSFET AC coupled in parallel with the drain resistor of a MOSFET common source circuit to control modulation.  The advantage of doing it this way round is that you attenuate the signal rather than boost it, plus any feedthrough from the FET won't be amplified.

[Paul Marossy]

Look under the EA Tremolo project at GGG. There was some notes about modding it for less gain there.

[Neutral]

Hey thanks guys for all the info.
The EA sounds pretty cool, with plenty of gain too!
Can anyone tell me if the depth control can compeatly flatten the wave to give a straight boost?

[Neutral]

The EA Tremolo parts list asks for:

"2N5457 or J201 or possibly other JFET "

I can't source either from my component suppilers.

Can anyone suggest or verify a working alternative JFET?

Cheers.

[B Tremblay]

Can anyone suggest or verify a working alternative JFET?

The MPF102 worked fine on my breadboard.  You may need to adjust the 560k resistor that precedes the Depth pot, but that's something you might want to do with any FET.

[Neutral]

Great, I can get a MPF102.

You may need to adjust the 560k resistor that precedes the Depth pot, but that's something you might want to do with any FET

Would it's value go up or down?
What problems might I experience if it was not changed?
If you could explain this a little clearer that would be great (I'm new to this game so I'm still in the shallow end with floaties on)
Thanks

[gez]

Would it's value go up or down?
What problems might I experience if it was not changed?
If you could explain this a little clearer that would be great

A full explanation is here:

http://topnet.com.au/~hairbear/page.2.htm

And improved version here:

http://www.generalguitargadgets.com/v2/diagrams/eatrem2_sc.gif

Personally, I'd use the resistor values from the improved version, but replace Q1 with a MOSFET and do away with the input buffer (Q4) as it would be redundant.  To bias the MOSFET use a trim instead of the divider.  Connect a 1M from gate to the wiper of a 100k pot whose outer lugs are connected across the rails and adjust the wiper till you measure about 5V at the drain.  It would be a lot quieter and have nice high input impedance (signal is coupled via a cap directly to gate).

[B Tremblay]

When my EA Trem was on the breadboard, I took the opportunity to try a number of mods.  I used JD Sleep's Improved EA Tremolo schematic, so I'll refer to the components by his reference numbers.

First, I implemented the "pulsing LED" that Rob Strand and Darren described in an earlier thread.  This involves replacing R8 (normally 15k) with a 10k resistor and LED in series (negative lead of LED connects to Q3 collector).  The mod also decreases R7 (normally 560k) to 390k.

Since I'd spent some time with the EA Trem LFO when working on the Phozer, I tried changing the values of R7, R11, and R13 (Depth pot).

Here's what I ended up with:

R11 decreased to 1k - this provides a faster maximum speed.  Not as fast as replacing the 1uF caps with .47uF, but it helps.  Too low of a value will result in no oscillation.

R7 decreased to 120k - for a more percussive maximum Depth

R13 (Depth pot) changed to 250k - gave a more useful range of Depth settings.  The stock 1M pot, when at or below 25% of its rotation, resulted in no tremolo effect.  I wanted the effect to still be present at minimum, so I used the 250k pot and added a 47k resistor between lug 1 and ground.

Unrelated to the actual "effect," I changed R12, the volume pot, from 25k to 100k.  Unity is around 1:00, anything above that is a boost.  I also replaced C9 and C1 with a single 2.2uF cap.

I recommend you breadboard the project and find the values you like best, then build it using the same FET.

Here's the Phozer page, which uses the same LFO: http://runoffgroove.com/phozer.html

[B Tremblay]

Personally, I'd use the resistor values from the improved version, but replace Q1 with a MOSFET and do away with the input buffer (Q4) as it would be redundant.  To bias the MOSFET use a trim instead of the divider.  Connect a 1M from gate to the wiper of a 100k pot whose outer lugs are connected across the rails and adjust the wiper till you measure about 5V at the drain.  It would be a lot quieter and have nice high input impedance (signal is coupled via a cap directly to gate).

Just to be clear, is there a resistor between drain and V+?  Also, does the voltage divider arrangement at the source (previously the emitter of Q1) that feeds the drain of the FET remain the same?

[gez]

Just to be clear, is there a resistor between drain and V+?  Also, does the voltage divider arrangement at the source (previously the emitter of Q1) that feeds the drain of the FET remain the same?

Sorry for any confusion B, I should have been a little clearer (laziness on my part).

Replace Q1 with a n-channel MOSFET, use the 4k7 (R4) for the drain resistor, the 180R (R5) & 1k2 (R6) for the source resistors and the JFET (Q2) connects up just as it did before.  Ditch the 560k (R2) and 150k (R3) divider totally, and replace it with a 100k trimpot across the rails.  Connect the wiper of the trim to the gate of the MOSFET via a 1M resistor.  Adjust the wiper from earth till you measure 4.5 - 5V at the drain.  The input signal couples through directly to the gate by a cap (nothing smaller than 22n).

With this set up you can do away with Q4 and all it's associated circuitry.  Less clutter, but still the high input impedance (higher even).

[gez]

PS Although you know this, for the benefit of others don't forget a pull down resistor at the input (R1).

[B Tremblay]

Is this correct?

(earlier version of schem - see below for final)

Would a BS170 be a good choice for the MOSFET?

[gez]

Is this correct?

It certainly is!  B, you're a star!!  

Would a BS170 be a good choice for the MOSFET?

That's the one I'd go for.