Vox - Repeat Percussion (V 809)

acidfuzz · Post by **acidfuzz** » 17 Jan 2012, 04:37

Yeah, I've found if you use two MPSA18's instead of the bc108 + 109's that helps reduce the hiss + generally quiet things down. Haven't noticed any difference between carbon film and metal film resistors. What really killed the hiss was putting a 220uf cap across the power supply, using shielded signal cables and definitely keep the 100uf cap on the rate pot to eliminate ticking as well as the 68nf value cap between Q2's base and the UJT's emitter.

Oh and RNFr, I'll send you one to check out if you'd like an maybe you can do a demo of the 3 in one pedal? It's been in various stages of prototype for months. I just met up with Sonic today and had mentioned a couple other mods I hadn't thought of like a toggle to switch around the order of how the effects run in to one another. I also think I' going to have to bite the bullet and just do this one on a etched pcb for the production model, as building it all point to point or even on strip board is a bit of a nightmare.

gigelmargel · Post by **gigelmargel** » 17 Jan 2012, 19:34

RnFR wrote:looking forward to seeing it!

me too...

i like very much this effect, but i don't like his little tweakability...

thank you very much acidfuzz!

gigelmargel · Post by **gigelmargel** » 23 Feb 2012, 04:40

Hello acidfuzz,

Can you post the mods that you mentioned above? I am very interrested about them...

Thank you!

gigelmargel · Post by **gigelmargel** » 28 Feb 2012, 20:14

gigelmargel wrote:Hello acidfuzz,

Can you post the mods that you mentioned above? I am very interrested about them...

Thank you!

gigelmargel · Post by **gigelmargel** » 06 Mar 2012, 14:52

Can you post the mods that you mentioned above? I am very interrested about them...

Thank you!

acidfuzz · Post by **acidfuzz** » 08 Mar 2012, 01:01

This is the version I've been building in to the Sonic Boom 3 in One pedals. It has more than enough tweakability for anything I've ever needed out of this effect. You can dial back the depth and cut pots and get a basic amp like tremolo. Dial the depth back all the way + you get a dry signal with just the gain stage, so you can use it that way as an extra booster. The with the MPSA18's + the 220uf cap the flashing rate LED will not tick at all as long as you ground the filtering section properly via your layout. I usually just ground the 330K resistor off lug 1 of the depth pot to the grounded sleeve of the expression pedal jack. Then I group the grounds from the 68nf/82K/220uf together + run them to that same sleeve.

Sorry for the late reply Gigelmargel. I see you asked for this a few times. If you have any questions just email me at: acidfuzzpedals@gmail.com. I'm never on these forums, so that's much quicker.

-J

poodlebra · Post by **poodlebra** » 08 Mar 2012, 10:09

cheers acidfuzz - been looking forward to an improved version of this one.

gigelmargel · Post by **gigelmargel** » 08 Mar 2012, 11:28

Thank you very much Acidfuzz!! You're very kindly!

I hope to have time tonight to test all the proposed mods...

Best regards,
Radu

bootle · Post by **bootle** » 21 Mar 2012, 18:08

acidfuzz wrote:
This is the version I've been building in to the Sonic Boom 3 in One pedals. It has more than enough tweakability for anything I've ever needed out of this effect. You can dial back the depth and cut pots and get a basic amp like tremolo. Dial the depth back all the way + you get a dry signal with just the gain stage, so you can use it that way as an extra booster. The with the MPSA18's + the 220uf cap the flashing rate LED will not tick at all as long as you ground the filtering section properly via your layout. I usually just ground the 330K resistor off lug 1 of the depth pot to the grounded sleeve of the expression pedal jack. Then I group the grounds from the 68nf/82K/220uf together + run them to that same sleeve.

Sorry for the late reply Gigelmargel. I see you asked for this a few times. If you have any questions just email me at: acidfuzzpedals@gmail.com. I'm never on these forums, so that's much quicker.

-J

cheers for that acidfuzz!
some useful mods there.
but can anyone explain how the grounding works?
if you were doing a vero layout, would you put the 68nf/82K/220uf on one ground rail and ground it to, say, the input jack sleeve?
then how is the rest grounded?
just can't get my head round this.

acidfuzz · Post by **acidfuzz** » 23 May 2012, 08:56

Bootle,

Sorry, just saw this. For a vero layout without using an expression pedal jack on the rate, I would group the grounds from the 68nf/82K/220uf array, to the sleeve of the OUTPUT jack, as well as the ground for the 330K on lug 1 of the depth control. Group the others to the input sleeve.

For a much better "cut" control than the one I had in the hand drawn schematic use a DUAL 50K B/linear pot in place of the B25K "cut" and the A50K "volume". The cut and volume controls I put in the schematic work ok, but the cut is not very effective unless you also adjust the volume in conjunction with the cut. In order to get a much better sweep from subtle to complete chop with just one twist is to simply wire a dual 50k linear pot in place of the "cut" and "vol" controls. Just be sure to put a 3.3K resistor in series with lugs 2 and 3 to ground where the volume pot was so the volume stays even throughout. Move the volume control to the end of the circuit by replacing the 1M resistor at the output with a 500K audio pot. The new versions of the Sonic Boom have this circuit and it still offers plenty of volume with a much more effective cut/choppiness control.

I'll post the revised schematic when I have a minute.

CBBRooklyn · Post by **CBBRooklyn** » 19 Mar 2014, 15:12

Hello everyone. Newbie here. I just acquired a Vox Repeat Percussion. It's not working so I opened it up and noticed two wires disconnected. Can't figure out where they go. Attaching a picture of the dilemma. As you can see it it looks like the wires (esp. that red one) have been re-soldered haphazardly. All other connections look solid and a fresh battery. Hopefully someone can help me or maybe post a pic of the insides of their working pedal so I can use it as a guide. Thanks.

Masuto · Post by **Masuto** » 31 May 2014, 13:03

Hi brothers..
Id like to see Acidfuzz's layout but it seems his image host is down.
Anyways, i just rebuilt the repeat percussion for the xxth time. I always use the same layout and i do not know if this has been pointed out already, but unless you use the 33r resistor, it wont work as it should. You can pretty much change some resistors, caps and transistors. But if you dont use the 33r it wont go as fast as it should.

tabbycat · Post by **tabbycat** » 06 Jun 2014, 00:20

Masuto wrote:Hi brothers..
Id like to see Acidfuzz's layout but it seems his image host is down.
Anyways, i just rebuilt the repeat percussion for the xxth time. I always use the same layout and i do not know if this has been pointed out already, but unless you use the 33r resistor, it wont work as it should. You can pretty much change some resistors, caps and transistors. But if you dont use the 33r it wont go as fast as it should.

@freestomp one and all... would just like to second masuto's wish to see acidfuzz's layout. if anyone out in stompland has a copy they can up big thanks in advance if you are able to post it??

Re: Vox - Repeat Percussion (V 809) Postby acidfuzz » 08 Mar 2012, 02:01
Image (image not working, missing presumed dead)
This is the version I've been building in to the Sonic Boom 3 in One pedals. It has more than enough tweakability for anything I've ever needed out of this effect. You can dial back the depth and cut pots and get a basic amp like tremolo. Dial the depth back all the way + you get a dry signal with just the gain stage, so you can use it that way as an extra booster. The with the MPSA18's + the 220uf cap the flashing rate LED will not tick at all as long as you ground the filtering section properly via your layout. I usually just ground the 330K resistor off lug 1 of the depth pot to the grounded sleeve of the expression pedal jack. Then I group the grounds from the 68nf/82K/220uf together + run them to that same sleeve.

@masuto... which vero layout and values did you use in the end? there are a few bashing around the forum. have been reading up on this one and it seems the ticking and hiss are a bit of a bitch to get rid of. if you could point me in the direction of one you are sure works i would be very grateful. grazie mille!

tabbycat.

tabbycat · Post by **tabbycat** » 03 Jul 2014, 19:35

hey all,

thought i would post some photos of what one of these looks like as a finished vero board ready-to-be-boxed because (maybe i'm weird or a voyeur or something) as a newbie i like to see how schematics and vero layouts translate to vero board, and maybe i'm not the only one. somehow seeing them on vero board ready-to-go makes them seem less complicated. dread of numbers and mystical symbols perhaps.

also thought it might serve as a confidence booster to any would-be builders and fence-sitters out there (of whom i was once one) who think it's all too hellishly complicated and shy away from getting involved.
lots of it is hellishly complicated, but not all. i know practically nothing and i can make something. so if you are thinking about trying, start small and build up. reading probably seemed hellishly complicated to you once but you've read this post this far? you might even enjoy it.

anyway...

vox repeater on vero (sockets ready for transistors) from lvlark's excellent vero at tagboard effects.

rep1.jpg

vox repeater on vero (transistors in their sockets).

rep2.jpg

btw would like to ask again if anyone out there has acidfuzz's layout that was posted on this thread but has died, as i and masuto (above) and maybe others (it originally recieved a handful of thanks clicks) would definitely like to see it?

and if anyone has any sweet mods for this circuit they want to share i'd be very interested.

thanks to all contributors to this thread and to lvlark for the great layout.

tabbycat.[/color]

ringworm · Post by **ringworm** » 04 Jul 2014, 07:37

I don't recall him ever posting a layout. He posted a schematic he'd drawn. His site has all the schematics for the Vox Starstreamer here http://www.acidfuzz.com/voxguitars

tabbycat · Post by **tabbycat** » 05 Jul 2014, 22:55

ringworm wrote:I don't recall him ever posting a layout. He posted a schematic he'd drawn. His site has all the schematics for the Vox Starstreamer here http://www.acidfuzz.com/voxguitars

thanks for the update ringworm. the schematic would be as fine if anyone has it. i could try to work it out from that. i’m a newbie just at that quantum-leap stage of working out how to turn schematics into layouts, so it would be good practice.
i spent more than an hour in bed last night with the superfuzz schematic in one hand and the vero layout in the other, trying to work out how they related to each other. ‘is that a gain stage?’… ‘that must be the clipping stage?’… sometimes it makes sense and then it suddenly doesn’t. i had an expression on my face like a chimp that has found a copy of ‘a brief history of time’ in the woods.

re the starstream onboard effect schematics, thanks for the link. i had come across them before in my quest, but am grateful for your suggestion.

the schematic/layout i was hoping to find is the modded one acidfuzz was building into his ‘sonic boom’ pedal at the time, that he refers to above (8th march 2012);

“This is the version I've been building in to the Sonic Boom 3 in One pedals. It has more than enough tweakability for anything I've ever needed out of this effect. You can dial back the depth and cut pots and get a basic amp like tremolo. Dial the depth back all the way + you get a dry signal with just the gain stage, so you can use it that way as an extra booster. The with the MPSA18's + the 220uf cap the flashing rate LED will not tick at all as long as you ground the filtering section properly via your layout. I usually just ground the 330K resistor off lug 1 of the depth pot to the grounded sleeve of the expression pedal jack. Then I group the grounds from the 68nf/82K/220uf together + run them to that same sleeve”

and referred to in this from the acidfuzz website…

“I’ve enhanced the repeater’s depth and cut properties and bumped up it’s output volume so you can actually get a volume increase when this effect is on. In addition to the stock “rate” control, the three above aspects all have their own control so you can dial in the exact depth, cut, and volume of the effect. As the original repeater also cuts a lot of low end from your signal, which is nice and cutting in its own way, I’ve added a tone voicing switch so you can toggle between this brighter sound or a full tone. I really opened up the speed range of the repeater and in mode 2 it will go in to a full on ring mod effect which you can tune to resonate in a particular key. Last but not least, the repeater has a dedicated LED that flashes in time with the repeater effect, even when bypassed”

with a few more years experience i might be able to rework the starstream repeater schematic sufficiently myself to meet the modded ‘sonic boom’ criteria above, but at present it’s way beyond my (lack of) technical ability so am dependent on schematics and layouts for builds at this stage.

but i’m working at it a bit at a time, shawshank style…

tabbycat.

ringworm · Post by **ringworm** » 06 Jul 2014, 19:22

Here ye go:

tabbycat · Post by **tabbycat** » 06 Jul 2014, 23:55

great research work, ringworm. you nailed that mythical monster!
many thanks for taking the time to dig it out from the depths. i really appreciate it and i hope it wasn't a mission.
btw, did you ever breadboard it or attempt to build it?

am going to try to translate it into a vero layout of some kind and will post it here as soon as i have it. but it will definitely take a little time as it will be my first. but i'm stubborn. 'like an egg stain on a lacoste...' as they say in france!

thanks again for finding it.

tabbycat.

induction · Post by **induction** » 11 Jul 2014, 15:09

I tried both acidfuzz's version and the stock Vox schematic. In the end, I went mostly stock. I increased the input cap to 100 nF, and I made two speed ranges (Rate pot: 100k B, rate resistor: 47k, rate cap: 2u2, switch adds a 4u7 in parallel). I arrived at this arrangement after a lot of trial and error. You want to balance the rate resistors and caps for the best range. To increase the rate you lower the resistance and capacitance. To decrease the rate you do the opposite. But if the resistance is too low the oscillator will lock up at high rates, so you can increase the resistor and reduce the capacitor to get the same rate. The values I used gave me the range I wanted with no lockup. The fastest rate in the slower range is just a little faster than the slowest rate in the faster range, so a continuous range of rates are available with a small amount of redundancy. A 100k C rate pot might work better, but the linear pot works fine for me.

I didn't find the cut and depth controls to be very useful. It was fun to play with them just to get a feel for what they do, but in practical use I kept trying to dial in the stock sound. I have other tremolos for more traditional sounds and the waveform on this circuit doesn't lend itself to subtlety, so I just use this one for percussive trem sounds, which is where it excels.

I used an MU4892 for the UJT and I managed the grounds very carefully (following RG's suggestions) to avoid ticking. My layout should work without modification for 2N2646, but I recommend breadboarding it first to get the rate range how you like it.

tabbycat · Post by **tabbycat** » 19 Jul 2014, 02:29

many thanks for the post, induction.

that is about as in-depth and thorough i could ever have hoped for. even breaking down how you balanced (reciprocal-fashion) resistance and capacitance against speed. i'd never have worked that stuff out on my own in a lifetime, so do appreciate your taking the time to explain how and why as well as what you did to get the result you wanted.
i will give it some thought.

re:

I didn't find the cut and depth controls to be very useful. It was fun to play with them just to get a feel for what they do, but in practical use I kept trying to dial in the stock sound.

that's one i'm always wary of getting seduced into. am getting to the learning stage when i know how and where to add a diode switch or a mid-scoop trimmer etc to a schematic/layout. but am just wise enough to appreciate that each addition is also potentially one step further away from the stock sound that made want to build the pedal in the first place.
just because you can doesn't necessarily mean you should (was it oppenheimer who said that?).

as the photos show above i've built one from mark's layout, but as it's such a small build (and i always socket my transistors) i will build up yours too, to see how they compare.
and have just downloaded 'diylayoutcreator' this evening which may help me come up with a vero for acidfuzz's schematic. but don't hold your breath. i have three different pedals unfinished on my desk as it is. but that's how i roll.
i write music and read books the same way. linear just doesn't seem to be my style.

thanks again for the thorough post and will get back here with a result as soon as i get something finished.

tabbycat.

Vox - Repeat Percussion (V 809) [schematic]