Colorsound Tremolo

[RLBJR65]

Does anyone have any mods for the Coloraound Tremolo?

It's ok as, but kinda plain.

[StephenGiles]

I think it's a great English tremolo pedal - no point in modding it.
Stephen

[cd]

Schematic?

[StephenGiles]

See what I mean!
Stephen

[gez]

Use the trannie used to do the modulating as the variable resistor in a bridged/twin-T set-up hooked up to the amp to give you an auto-wah? (switch between the two)  Not exactly a 'mod', but could be incorporated into the scheme of things if it's on a breadboard.

Thanks for the schematic Stephen, I agree...leave alone! (well, possibly an input buffer)  

[RLBJR65]

Don't get me wrong, it is a good sounding pedal, but I'd like to get a little more pulse width and maybe a little more speed.

I'll have to compare schematics, I built mine some time ago, don't recall using a trim pot though, at first glance there may be a few other differences.

The 2N5088's worked fine in mine too.

[gez]

but I'd like to get a little more pulse width and maybe a little more speed

For more speed make the 220n caps smaller.  Do you mean more depth when you say 'pulse width'?  You'd have to toy with the resistor chain at the input, but you might get distortion if too much voltage develops across the trannie.

[gez]

Maybe the trim will give you more depth?

[StephenGiles]

........and horrendous thump!

[gez]

Well, I did say maybe...

[RLBJR65]

Guess I was working off of a schem. that some one else had already modded. It's alot different from this one. Got it from Fuzz Central, but it's not posted there any more. I'd scan and post it, but they copyright all the drawings.

I recalled a friend having one of these when we were younger and I loved it then, but wasn't nearly as happy with the one I built.

I'm going to build it with the schem you posted.

Thanks everyone!!

[gez]

For more speed make the 220n caps smaller.

Late night post, wasn't thinking.  The next value down that is available would probably make the LFO run a little too fast.  Unless you want to mess around with parallel caps (or switching the smaller values in and out) it would be easier to see if you can get away with making that 4k7 stop resistor (connected to the junction of two of the 220n caps) slightly smaller.

Likewise, you could probably get a little more depth by making the other 4k7 (connected to the collector of the modulating trannie) slightly smaller...though you might end up having to compensate for changes in volume by tweaking the amp.

[RLBJR65]

I decided to tinker with the first unit to see if I could mod it using the sugestions recieved. It's better. Maybe I'll try to turn it into a robot effect, noticed that when the caps were changed to 0.01uF you get that kind of sound but you also get alot off other bad stuff with it buzzing, squealing etc.

Still think I'll try the schem. Stephen posted, thanks again !!

I wander if the schem. I used was for a reissue or something, seem to recall it was listed as the ColorSound / SolaSound Trem.

Haven't got the hang of Posting images here yet (I'll figure it out one of these days) so I posted a schem. on my web page w / the mods if anyone is interested[/url]

[snk]

Hello
(I know i am necrobumping a very old thread, but i think it's better to post here instead of starting a new one ?)

I built the Colorsound tremolo today, using the tagboard layout : it works fine, but I found that the max and minimum speeds could be... faster and slower.
I changed one 3.3 cap to make the max speed faster, and i increased the RATE pot from 250K to 1M to reach slower minimum speed.
Now i am experiencing a strange behaviour : With the 1M speed pot, everything is fine passed the second half, but since i turn the knob below 12 o clock, the tremolo sound starts vanishing.
I guess it is some kind of warning telling me this unit hasn't been designed for a 1M pot, but i am wondering two things :
1- What is the technical reason of the "tremolo vanishing" ?
2- What can i do to get slower minimum speed than with a 250K or 500K knob ? Can i have the nice slow speed i get with the 1M pot, without having the tremolo "vanishing" ?

(note : i have a "speed indicator led" : when the tremolo vanishes, i can see the led getting weak and then stopping to work too.

[PRR]

> the max and minimum speeds could be... faster and slower.

Tough.

There are three R-C networks in this oscillator. For "good" range of speed you must vary *three* ganged parts. But 3-gang pots are rare. The most common configuration varies one resistor, which naturally gives a very limited range of speeds.

Without total re-design, the best path is probably a 3P switch to change all three capacitors to other values, and using the one pot to vary within that narrow zone.

[snk]

Hi, PRR
Thank youfor your answer. This is what i guessed from the tests i made (I tried half a dozen of resistors, and 4 different knobs values).
The resistor setting up the max speed suits my needs fine (it's faster than the original, while not going too fast).
With a 100KB knob, I felt that the minimum speed was still too fast, and not that much different than the other speeds (if that makes sense). Increasing the pot value gave me a better range of speed, and slightly slower times, but my issue is that a low values of speed pot, the tremolo gets weak and disappear.

There are three R-C networks in this oscillator. For "good" range of speed you must vary *three* ganged parts. But 3-gang pots are rare. The most common configuration varies one resistor, which naturally gives a very limited range of speeds.
Without total re-design, the best path is probably a 3P switch to change all three capacitors to other values, and using the one pot to vary within that narrow zone.

Interesting. I had first tried to put the 3.3K resistor on a switch, but I realized that changing this component alone did not allow me to reach what i am after. This is why i tweaked the pot and resistor values until i find a decent range of sounds, without expecting what a full-featured tremolo (like the Tremulus Lune for instance) could have done.
My goal with this build was not to have a decent basic tremolo, so i am not expecting very fast and ultra slow speeds (and the tweaks i made give me a good speed range), but the trouble is that "weakening" effect.

If I could "just" find why the effect (and led light) disappears in the first third of the speed pot and fix that, I would be happy with the speed range and the orverall performance of that effect 

[duck_arse]

my experience messing w/ the phase shift osc says that 250k is the max knob for speed - any larger and the R//C of the variable leg gets too far from the R//C of the fixed leg/s.

one method is to use larger resistance in the fixed legs [I like to use 4 caps, put the speed knob in the centre leg] and switch resistance out for a faster range - say a 33k and a 68k in series to ground, and switch short the 68k for fast. [needs double pole switch.] there is also a method that uses a centre off dpdt to short resistors for a high range, but add caps for a slower range at the opposite end of the switch.

[snk]

Thank you, DUck-Arse.
It is a bit technical for my understanding, but i will take the time to figure this all out
Nice useful informations here.

[snk]

One question, trying to understand the circuit better : what would happen if i select different cap values (instead of 3 times 470nF) ?

[snk]

Hello,
I replaced the 220nF cap with a 470nF, and the 3x470nF with 1µF (with my 2 Wima and one socketed ceramic i had left... I may replace it later with a new Wima), and changed the Speed pot for a 250K as advised, and now i can get a nice and slow tremolo  :mrgreen:
I also want to add that with these changes, there is no "vanishing modulation" anymore, the tremolo is the same at both slow and high speeds.
So, i now have a nice vintage tremolo with a decent range of modulation (the slow speed is not "ultra slow", and the fast one is not "thunder speed", but i like to have a useful, musical range of RATE).
Thank you all for your great help, and all the technical informations !   

(Still, having my pedal working the way intended did not kill my curiosity : i would be curious to know what to expect sound-wise if do not use the same cap values for the 3 x 470nF caps ?)