Vibracaster - or "How to turn your Valvecaster into a Tremolo"

[frequencycentral]

That's a really well thought out build Anatoliy, I like the way it all fits together in the enclosure with the tube tucked safely away, and the board mounted pots too - a man after my own heart. Nice.  

[GeorgeM2]

Sanks!

Well, but not ideally, It is a lot of wires, not accurately. Blue caps and 3/4W resistors in oscillator - not very fine. Has made from this that was
And on the right on a board there was а lot of an empty place, may be need add spring reverb?    

This - "his father", ValveCaster, PtP soldered, my previus project.

[station]

Hey guys - Awesome project FC! Thanks for making an awesome pedal even better. I've been playin around with the valvecaster and I've been wanting to build a tremolo circuit for a while. So this one ended up on my breadboard tonight. Great sounds.

One critique I have of the design is the depth pot. People have mentioned that turning the knob down effects the gain of the circuit, and I noticed that too. I also heard a bit of a swishing sound while turning in the middle of the pot, then a bump at the end of its turn. Nothing terrible, but I thought I'd try to tweak it a bit. Here's what I came up with:



I moved the 4.7 resistor to the middle lug of the pot moved the "anti-pop" cap along with it. This seemed to fix the gain problem. smooth levels all the way up and down. And with lug one still shorted to ground, the oscillator still shuts off completely on zero. The bump still happens when the wiper reaches ground - oh will, no biggie.

I also lowered the 47k resistor to 10k to get faster speeds.

(sorry for hacking up your schematic too  I hope you don't mind  )

[frequencycentral]

Hey Station, thats a neat solution. Re. the bump when the wiper reaches ground, if you've still got the circuit on your breadboard try adding a low value resistor between the pot and ground - say 1K or around that value. I've noticed the same thing with my Valvecaster.

Re. the depth pot affecting the gain, I still can't decide if this is 'real' or 'percieved' - a Keeley modded Boss TR-2 for example has an extra volume control to combat the 'percieved' volume loss when the depth is engaged.

Nice work anyway - good to see this project maturing.

[GeorgeM2]

My LED wired stupid,   

Right:

[station]

That's an interesting idea - perceived volume loss. I think perception is reality though. And I like the way the mod makes the output a bit louder at the top of the wave. The pulsing is more balanced at the lower extremes and pronounced at the higher ones. It's kind of like a modulation effect, where you want to set the wave above and below the original, not just dipping down below it.

By the way, I really like the LFO circuit. I noticed you used in the tube vibrato pedal you came up with. Can't wait to try that out when I get some photocells.

I just made a modular version of the LFO on perfboard so that I can easily plug it in into different effects on my breadboard. This could yield some interesting sounds. I'm trying to use it to do a modulated auto wah, but I can't find the right circuit.

[frequencycentral]

I had help from R.G. with the LFO: http://www.diystompboxes.com/smfforum/index.php?topic=70056.0

[station]

awesome! thanks - I'll have to check that out when I can really absorb it.

[w437776]

here's my layout:

..and PCB:

[frequencycentral]

^
Nice looking layout!

Happy birthday to the Vibracaster thread - one year old today!

[GeorgeM2]

HI! I tested "Station mod" - Less pulses in pauses, but too deep depth... deepestissimo... no very good, imho.
and i add One more 100k anode resistor(to sekond triode) consistently in "vibra" mode - It has balanced loudness without more gain.

p.s. Happy birthday! ;-)

p.p.s. to w437776 - i dont undestand, why 4 capacitors 0.47mf ? thanks.

[w437776]

HI! I tested "Station mod" - Less pulses in pauses, but too deep depth... deepestissimo... no very good, imho.
and i add One more 100k anode resistor(to sekond triode) consistently in "vibra" mode - It has balanced loudness without more gain.

p.s. Happy birthday! ;-)

p.p.s. to w437776 - i dont undestand, why 4 capacitors 0.47mf ? thanks.

sorry for the mistake, layout and pcb reuploaded.

[station]

Thanks the feedback on my mod. It's really two mods: one changes the depth limit, the other effects the gain and evens out the wave pulse along the travel of the depth pot. The depth limiting resistor was originally a 47k. I changed it to 10k to get more depth, but you can change it back and not effect the main part of the mod.

[UKToecutter]

Damn,

So many circuit diagrams / mods etc

Can someone point me to the 'final' 12V version circuit diagram please.   



Andy

[frequencycentral]

Damn,

So many circuit diagrams / mods etc

Can someone point me to the 'final' 12V version circuit diagram please.   



Andy

Well. That would depend if you want to do the 6111 submini version or the 12AU7 version. And if you want the tremolo only version or the drive/boost/tremolo version.

I think this is the most common version: http://www.diystompboxes.com/smfforum/index.php?topic=70160.msg566503#msg566503

.....but add the 3.3uF cap as in this version: http://www.diystompboxes.com/smfforum/index.php?topic=70160.msg576174#msg576174

[UKToecutter]

Yep,

Too little information, I know.........

Tremelo only (I'm gonna build a seperate ValveCaster) and 12AU7 tube.

I think I'll incorporate Station's mod on the anti-pop cap location.

I think I got it all.

Guess I'd better get ordering parts

Any suggestions as to the best UK based supplier to use?

Andy

[isildur100]

I just built this vibracaster and I really like it! It's a really cool tremolo! Thanks a lot for making this cool circuit available!

I made some modifications to it, notably a switch for clean/dirty sound and I tweaked the values of the oscillator in order to put a rate led without any audible clicking. I noticed that the choice of transistors really made a difference regarding the oscillator noise and clicking. I also used different values for the rate pot and associated resistor in order to get really fast rates which I was not able to get with the stock version.

I was also wondering, do you think it could be possible to make an all-tube vibracaster? I mean, replacing the 2 trannies of the oscillator with another 12au7 tube?

Maybe this question was already asked but I didn't read the whole 12 pages of this thread...

John

[frequencycentral]

I just built this vibracaster and I really like it! It's a really cool tremolo! Thanks a lot for making this cool circuit available!

I made some modifications to it, notably a switch for clean/dirty sound and I tweaked the values of the oscillator in order to put a rate led without any audible clicking. I noticed that the choice of transistors really made a difference regarding the oscillator noise and clicking. I also used different values for the rate pot and associated resistor in order to get really fast rates which I was not able to get with the stock version.

I was also wondering, do you think it could be possible to make an all-tube vibracaster? I mean, replacing the 2 trannies of the oscillator with another 12au7 tube?

Maybe this question was already asked but I didn't read the whole 12 pages of this thread...

John

Sounds like a redesign to me.    It would be great if you could post a schematic for your version, sounds excellent!

I did a bit of research into tube phase shift oscillators, and it really needs to be a 12AX7 operating at high voltage to do the job. I guess it should be possible to do this with a charge pump or SMPS to get a high voltage. But ultimately I'm not sure that the ear would perceive much difference between a transistor PSO and a tube PSO, it's the same waveform after all.

[isildur100]

Here is what I did. I have tweaked lots of component values to my taste. It is not really a re-design since I followed much of the original design.



First, the diode did not really make a difference except reduce the depth. I tried it with 2N5089's and it did not tick. Trying different trannies, I stumbled on some that ticked a lot. The bc414B was the less noisy of all but I think it may be hard to find. So the 2N5089 is the best choice for most of us. In that case note that you must use a 330k resistor instead of 100k where the speed pot is connected.

Another thing I noticed and that is valid for the valvecaster too is about pin 4 and 5. Notice that I have reversed them (gnd on 5 and V+ on 4). It sounds less harsh like that, to my ears anyways .

The original vibracaster lacked a bit of fast rates and "deep" depth. Using the values in my mods now make it possible to have really fast rates (think about the tremolo in Pink Floyd's Money) and setting the depth at maximum really chops the sound. Anyways, you may want to try the mods, it does not take much time. Tell me if you like it.

Again, thanks for your hard work on this project! I hope my contribution is worth it. 

John

[GeorgeM2]

I was also wondering, do you think it could be possible to make an all-tube vibracaster? I mean, replacing the 2 trannies of the oscillator with another 12au7 tube?

I tried, but to achieve work oscillator at low anode voltage and it has not turned out. If to make high anode voltage - all idea of a pedal is lost.
%-(