Ticking Vox Repeat percussion

[Marbles]

To continue on Vox related things.. ;)

I have built the Vox repeater and it sounds great. The speed isn't there yet, but I will change the caps for that.

I was just wondering about the ticking, cause I found a quote on DIY stompboxes by mr Keen about he ticking issue. It was this:

The tick comes from the sudden discharge of the timing cap through the 33 ohm b1 resistor. If any part of the analog circuit, including the modulator transistor, shares any part of the copper trace between the capacitor negative and the 33 ohm resistor, it will tick, and nothing can be done about it. The fix is to make that current path have one and only one wire back to the power supply negative.  If the tick changes the + power, that will tick as well, but there is already good decoupling on that.

I Used this layout:





To check if I'm correct:

Would it work to make a cut in the bottom row right from the link in the middle? I can then move the 100u cap one position to the right. Then make a cut left from it so it doesn't share the ground with the rest. I can then link the bottom-right groundwire with the row with the Capacitor negative (using the far right column).

Then I can run an extra groundwire somewhere on the bottomrow between depth 1 and the resistors.

This way the copper trace for ground of the Capacitor negative and 33r isn't shared with anything else.

I may have butchered the layout pretty much, but is that what is meant in the comment by mr Keen? Or am I waaaay off? If this does not make sense whatsoever, please let me know! I know I can just try it, but I kinda messed the board up twice now, so I'm glad it's working haha.

[Beaker]

I've not come across this article before, so thanks for posting. I'm having a hard time working out exactly what he means here, but I think you may be right with your work-around. How much difference it will actally make, I have no idea.

I've played Vox guitars with this circuit built in, and they tick - the clue is in the name - Repeat Percussion. Vox turned a "fault" in the circuit into a virtue, and the tick is part of the essential character of the sound.

I've built a couple of these, as well as the EQD Hummingbird, which adds a depth pot. That is a better circuit in my opinion, but it still ticks.

You can do a few things to minimise the ticking:

Try several UJT - some tick worse than others.
Use shielded cable for input and output.
Once you have found one that works best, remove the socket and solder the UJT to the board.
Make sure you have fresh air around the UJT - make sure that it is not touching any other components, or is pressed against the inside of the lid. They are microphonic and will tick louder if touching anything else. Don't believe me? - Try pinching it between your finger and thumb and the ticking gets much louder!

Personally I would try to miminise the ticking, but accept the rest as part of the character of the thing. It never did Spacemen 3 any harm!

[nocentelli]

It's not the 100uF electro that needs isolating from the audio ground (that is for power filtering and might reduce ripple from the ac supply polluting the audio power) but the ground connection from the cap selector switch and the 33 ohm. Both need to be separated from the audio ground, meaning there will be three separate wires to the battery negative. Bear in mind you may find it still ticks a bit even with these changes.

[Marbles]

Thanks guys!

My idea did not change a lot haha. I will try to separate the cap selector and 33R. Should be doable.

I don't get the 3 wires to battery negative though... Do they have to go there? Can't I just ground them at the output?

[nocentelli]

Marbles wrote

I don't get the 3 wires to battery negative though... Do they have to go there? Can't I just ground them at the output?

Yes, as long as the output ground and negative battery terminal are connected somewhere in the circuit.

[Marbles]

You're totally right! Maybe I shouldn't sweat it too much.. Been listening to a lot of Spacemen 3 again after your comment. Thanks for that :)
Hope the distortion booster I'm making comes close to that revolution sound. I'm not sure exactly what was in those Starstreams, but heard Vox recycled their schematics a lot.
The Vox Repeater is exactly that sound to my ears. Love it. Maybe shouldn't tinker with it a lot, though the grounds couldn't do that much damage.

[Marbles]

Oh wow, didn''t know that. I always use stereojacks. I ground everything at the middle lug. The battery negative I always solder to the '3rd' lug by itself.

[Beaker]

The only control for the repeater on those guitars was an on/off switch, and a speed pot. Like I said, Vox made the tick into a virtue with this circuit,

I do suggest you build a Hummingbird as well - much greater speed range and a really effective depth pot. I built one for an ex Spacemen 3 guitarist who loves it (I am friends with a few of those guys).

A Fuzzrite should nail Revolution - that's what he uses!

[nocentelli]

Marbles wrote

 I always use stereojacks. I ground everything at the middle lug. The battery negative I always solder to the '3rd' lug by itself.

That's fine, normal "unplugged = power off" wiring should really have the battery negative to input ring/middle lug, with everything else star grounded to the input ground/lug 3 (so the battery/DC negative is connected to absolutely nothing else with no jack in the socket). The key point with the VRP is that the ground wires that come from the cap and resistor which funnel the discharge of the UJT oscillator need to be separate physical lengths of copper to the ground connection of the audio BJT, not sharing a trace on the board, or being daisy chained to a single path to the connection on the input ground lug.

[Marbles]

You're friends with a few of those guys?! Wow, that's awesome! (any chance they have some vinyl lying around that doesn't cost over 100€ second hand? lol, just kidding).

With the switchable caps I can get the desirable speeds I think (4u7 for slow and 2u2 for fast), the depth pot I haven't played around with a lot. I'll see if it bothers me, thanks!


So it's a Fuzzrite? I really did not know that... I always thought it was the built in fuzz. Awesome.

Which version would that be? GE or Sil?

[Beaker]

I'm not sure if they every used a Fuzzrite to be honest, but it nails it perfectly - and I got that from the horses mouth. It was this layout I used to make one for him, so a Si version.

http://tagboardeffects.blogspot.co.uk/2010/02/mosrite-fuzzrite.html

[Marbles]

Awesome, thanks.

Never used tagboard before.. That should be interesting.. Love the look of it though.

Any preference for transistors? Lots of people seem to have luck with 2N3904s. Can't find 2N2926 anywhere.

[Beaker]

I've built a couple, used 2N3904 or 2N2222A, both sound great. There is a vero version of this layout on the main page. I've built the Ge version too, but to be honest, I like the Si version better.

[Marbles]

I like silicon fuzzes,  so no problem there!
I have built the vero one come to think of it... just didn't have that much output from what I remember... hm. Well, it's simple enough to build it again :)

[rocket88]

The difference in tone between the Ge and Si fuzzrite to my ears really is that the Si one is much more biting. The Ge has more warmth and smoothness to it, as least how I have it set. Both can get that 60's garage psych rock sounds I love. I've built both and I prefer the Ge, naturally the Germaniun deathstar emperor prefers the Ge one. But seriously, both great fuzzes and you can't go wrong with either. My suggestion is build both.

[Beaker]

No, the Fuzzrite is not a loud pedal, but you can always use an LPB-1 to boost the output.

One of my very favourite fuzzes though. Zach is right though, the Ge version has a smoother, rounder sound to it. Normally I prefer Ge versions of pedals too, but this is an exception.

[Marbles]

Build both... ok :D


For this 4 in 1 I will stay with the silicon though.. I have this huge box i didnt use, so I thought: I can fit 4 effects in easily. My initial idea was: Vox Treblebooster -> MidFi Tapefuzz -> Vox distortiion Booster -> Vox Repeat Percussion.

I was listening to a lot of Velvet Underground when deciding haha. But thanks to Beaker I have been listening to nothing but Spacemen 3 this week, so I'm having second thoughts :) I played the fuzzrite I had built before, and it sounds indeed amazing. No modern sound to find in there which is what I like. So I thought Treble Booster -> Tape Fuzz -> Fuzzrite -> Repeater.

Now I received my order of 2N2924s and put those in the Vox Distortion Booster and it sounds pretty rad. A lot different to my ears than te 2n3904s I put in before. It's tame, but very nice. But not nice enough to replace the fuzzrite. So maybe I should ditch the treble booster, which has a low output. It's basically unity gain with everything below a certain frequency cut off. (I could boost that too though). And put the distortion booster there.

But then I would end up with 3 different fuzzy sounds.

Dilemmas hahaha. Why should I bother writing this down? Because my gf is staring at me weirdly when I explain why it's hard to choose :D

[Beaker]

Still seems like a good plan. May I suggest a Naga Viper for your treble booster?

I've just built one, though not finished boxing it yet, and it sounds amazing. I think that would do the trick. Loads of volume, and guaranteed to play nicely with other pedals. I've just tried it in front of my Si Fuzzrite and it sounds awesome!

[Marbles]

That sounds great, unfortunately, I don't have room for a 3 knobber I'm afraid... I feel embarrased to post this, but as you can see it's a bit... crowded hahaha

It works fine so far though.. Though the difference between the tapefuzz and fuzzrite is not that big in this setup strangely enough... I feel that the booster took away some character, but maybe the combination of a jazzmaster in a twin is just too trebly.

https://www.youtube.com/watch?v=8fAJTmNPf9U

[tabbycat]

Marbles wrote

You're totally right! Maybe I shouldn't sweat it too much.. Been listening to a lot of Spacemen 3 again after your comment. Thanks for that :)
Hope the distortion booster I'm making comes close to that revolution sound. I'm not sure exactly what was in those Starstreams, but heard Vox recycled their schematics a lot.
The Vox Repeater is exactly that sound to my ears. Love it. Maybe shouldn't tinker with it a lot, though the grounds couldn't do that much damage.

re "I'm not sure exactly what was in those Starstreams, but heard Vox recycled their schematics a lot."

check this link out. http://www.acidfuzz.com/voxguitars (full schematics for onboard starstream effects).

the repeater was my second maybe third ever build. real newbie times. am a big s3 fan and had been looking for that exact flutter since i was at art college trying to rip off their tone for my own thing. it was one of the small handful of effects that made me decide i had to learn to build or never sound right. i'm very 'hate building but love tone' so compelled to do it.

acidfuzz do an all-in-one starstream effects box which sonic uses to this day. it may be that they collaborated to get it right. that's what i heard, maybe acidfuzz mentioned it at fsb. acidfuzz posted his schematic at fsb too, if it's down due to dead links i have it somewhere.

what else is in your 'selection box'?. looks interesting.
the most i have ever put in a box at once is a pedal and an lpb1 or a selection of clipping diodes on a daughter board. off-board wiring has always been my achillies heel. plus i'm a moody and temperamental cat, so easier to ditch stuff you are out of love with if it is boxed separately than in a multi.