Little VOODOO VIBE project by Kaputepalla

Post by **modman** » 18 Sep 2007, 08:43

KT66 wrote:hey alessandro

thanks for those layouts

could you please tell me the dimentions of the little voodoo vibe pcb.

i was going to make a hires version and fill in the white space.

thanks
kt

And that, contrary to the KOT, you ARE going to share?

KT66 · Post by **KT66** » 18 Sep 2007, 09:14

yeah i make it 11.75cmx10.25cm

everyone else make it the same dimentions?

i WILL make a hires (1200dpi) version of this layout and i WILL share it with everyone.

cheers
kt

alessandro · Post by **alessandro** » 18 Sep 2007, 12:28

There 're empty solder parts 'cause i've omitted a transistor and some components of the OVERLOAD LED INDICATOR(i did't build this section in my device)!If tou want to build this part you can easily make it by the original schematic!CIAO

tuemmueh · Post by **tuemmueh** » 18 Sep 2007, 12:59

Ah, okay. That makes sense.

Thanks for the great layout!

KT66 · Post by **KT66** » 18 Sep 2007, 14:40

ok guys

here is the pcb i will be using to create mine. enjoy.

edit: im modifying it slightly to include space for bourne trim pots

- will upload shortly.

kt!

Bernardduur · Post by **Bernardduur** » 18 Sep 2007, 17:00

Hey Bajaman!

I tried the values as suggested

And man........ HUGE improvement. Thanks for the great improvement!

bajaman · Post by **bajaman** » 18 Sep 2007, 21:50

Hi KT
yes, mine came out that size too. - it just fits nicely on the base plate of an NSC1790 case (pedal parts plus or smallbear electronics).
I had a long play through mine earlier tonight - love it, now that I've got the capacitor values sorted out. All the controls are very useful for getting a wide variety of bubbly sounds. In fact, alot of recordings that I thought were guitar played through leslie cabinet, were more likely played through one of these - or it's ancestor - the Unicord Univibe 905/915

bajaman

bajaman · Post by **bajaman** » 19 Sep 2007, 08:11

Sorry if my last post seems cryptic - somehow the two kaputella threads have got tangled up a bit - i have advised modman, and hopefully he will untangle then delete this message soon - in the meantime read the other thread ( deluxe memory man)
cheers
bajaman

KT66 · Post by **KT66** » 19 Sep 2007, 14:01

hey bajaman,

if you graph out RM's (greenfuz) vibe caps you can see he has taken the high and the dip out of the univox curve by lowering the value of the second cap and raising the value of the third cap. this gives us a much more even curve, but still with some nice swing.

this is prob becasue he wanted an even swing becasue the led circuit is so flexible - no need to ramp the caps as much as the univibe.

if you put in the green-fuz suggested caps, set your led to sine wave with even symmetry, set the mode to vibe, you should get a very even swing.

i graphed out your caps also 470pf 3n9 30n 240n - it did not look like an even repeating curve - and with the trem on the first cap - the trem prob wouldnt sound right using your caps.

i will order the required IC's and post once i have built it.

kt!

KT66 · Post by **KT66** » 19 Sep 2007, 14:25

alessandro wrote:There 're empty solder parts 'cause i've omitted a transistor and some components of the OVERLOAD LED INDICATOR(i did't build this section in my device)!If tou want to build this part you can easily make it by the original schematic!CIAO

im not sure why so many of the threads are mixed up. i think there may be somethign wrong with the database. posts i made in one thread are now in other threads..

could you please tell me whether there are parts missing from the little voodoovibe or the memoryman project??

you said in another post that the greenfuzz schem was wrong, did you just mean some part values were incorrect, or that parts were missing?

cheers
kt!

Post by **modman** » 19 Sep 2007, 19:30

KT66 wrote:
alessandro wrote:There 're empty solder parts 'cause i've omitted a transistor and some components of the OVERLOAD LED INDICATOR(i did't build this section in my device)!If tou want to build this part you can easily make it by the original schematic!CIAO
im not sure why so many of the threads are mixed up. i think there may be somethign wrong with the database. posts i made in one thread are now in other threads..

Because I moved them.

KT66 wrote: could you please tell me whether there are parts missing from the little voodoovibe or the memoryman project??

you said in another post that the greenfuzz schem was wrong, did you just mean some part values were incorrect, or that parts were missing?

cheers
kt!

Somebody posts a complete project and you start working off an unverified schematic? Check the first message in THIS thread.

bajaman · Post by **bajaman** » 19 Sep 2007, 21:08

Hi KT66
All I know is that when I built the little voodoo vibe with the suggested capacitors - 15n, 100n, 47n, 4n7 - in thais order, I was less than impressed by the vibrato and chorus settings, and there was no way I could get the symmetry, bias, or intensity controls to work properly for a smooth bubbly underwater sound. The tremelo, by the way, is one of the best I have heard and may become the subject of a future stand alone project from me (when I get time)

After changing the last two capacitors to 2n7 and 470p in that order, the sound improved noticeably. Bernardduur has used these values and notes a HUGE improvement (his words). I would not go any lower in capacitance than the 15n after the first section though - you could insert the 100n here and then the 15n followed by the 2n7 and 470p in that order. I have not tried this yet, but should work fine.
Some other values worth considering in this order would be
(x 6.66)

100n 15n 2n2 330p
(x 5.97) 100n 17n 2n8 470p
(x8.15) 220n 27n 3n3 407p
(x7.77) 220n 28n 3n7 470p

cheers
bajaman

KT66 · Post by **KT66** » 19 Sep 2007, 23:57

hey bajaman

just a thought.. becasue the phase shifting stage is virtually identical to the univibe i really do think that the cap values are correct.

so why would yours not sound right with these values?

the only thing i can think of is the LDR/LED combination. your cap values give a big peak which may be compensating for the lack of swing in the led/ldr section.

the ldr's should be around 30k. what are yours?

the brightness of the leds should give a flat linear decay of the ldr. ie, led brightness at 50%, LDR value 15k.. now with 150R resistors on hibrite leds, those suckers are not going to dip in brightness anywhere near a linear scale.. and they are going to be way to bright.. and from my personal experience with LDR based circuits, hibrite leds never give a linear response when used with LDR's.. the yellow wavelength in a hibrite led is a completly different wavelength than the yellow wavelength the LDR was designed for..

i suggest you get try with 4 normal yellow 5mm $0.10c leds and 4 30k LDR's.. then stick in the original cap values..

just something to try.

cheers
kt! woot!

bajaman · Post by **bajaman** » 20 Sep 2007, 00:37

Hi KT66

Schematic values:
Univox 915: 15n, 220n, 470p, 4n7
Shinei RT-18: 4n7, 3n3, 2n2, 1n
Jax Vibrachorus: 15n, 100n?, 500p, 47n?
Companion SVC-1: 15n?, 100n?, 470p?, ???

Look at the values for the Univox 915 - they are the same as the voodoo vibe

- no

Look at the Jax Vibrachorus - they are closer to the voodoo vibe values,
but why is the 3rd capacitor always 470 - 500pf (except the shinei) i suspect whoever traced the voodoo vibe schem mistook the 470p for a 4n7 capacitor. One thing in common though - they all use a 15n for the first stage(except the shinei again).
at the risk of repeating myself - the unit sounded a lot better with a 470pf capacitor in position three

bajaman

KT66 · Post by **KT66** » 20 Sep 2007, 01:02

at the risk of repeating myself i think RM intentionally smoothed out the phase curve by lowering the second cap and raising the third cap to give a smoother phase curve becasue there is so much flexibility in the LED section. i could be wrong. but from my charts it looks like a very smart move.

try it with standard yellow 5mm $0.10c non-hibrite leds and 30k ldrs. i think you will find it will make a world of difference. then again i could be wrong again.. i will build it and see.

another suggestion i have is to try 3mm hibrite leds.. maybe this is what RM used? from the pics i have seen, it looks like they could be 3mm. did you use 5mm or 3mm leds. do you know the mcd value of the leds you used?

if the cap values were incorrect that would mean that both the original drawer of the schem and the person who corrected the schem at a later date were both wrong. i just think this is unlikely.

didnt mean to step on your toes.

kt!

bajaman · Post by **bajaman** » 20 Sep 2007, 01:23

I used 3mm hi brite transparent lens yellow leds and the ldrs have a off value of several megohms. On value is in the low 10 ohm region.
What did you use to draw the phase curves?
I think Roger lowered the 220n to 100n to lessen the bass phase frequency, in an attempt to make it less boomy for guitar signal - the unit was originally designed for organs was it not? Incidentally if you use 4n7 as the lowest value capacitor and multiply it by 3.19 you get the following sequence - 4n7, 15n, 47n, 150n, so it may be interesting to change the 100n to 150n in the little voodoo vibe circuit and see what that sounds like

I think you will see and hear what I mean when you build it - let us all know then. In the meantime, does anyone own a genuine Roger Mayer Voodoo Vibe or Voodoo vibe Jr? If so, please confirm these capacitor values used
cheers
Steve

KT66 · Post by **KT66** » 20 Sep 2007, 02:32

bajaman wrote:I used 3mm hi brite transparent lens yellow leds and the ldrs have a off value of several megohms. On value is in the low 10 ohm region.
What did you use to draw the phase curves?

hey steve - did you measure the LDR's with your finger over them? usually a rating of 1mohm will only come about after a long time in the dark. typically ldrs come in immediate darkness values say from 1k to 50k with 500k to 10mohm complete darkness resistance (overnight without light).

im just thinking that if your ldr's have a low immediate darkness resistance, say 5k then the phase shifting stage may not be sweeping (cutting off) correctly. with a complete darkness rating of 1m, your immediate darkness rating is prob only about 5k.

again, not trying to step on your toes, just offering a suggestion.

re: the graph i used to chart the curve: i just drew it out on a piece of paper. capacitance on the y axis, cap 1, 2, 3, 4, 1 on the x axis. the phase sweep moves through the caps in order and then from 4 back to 1 continuously. if you chart out rm's cap values you will see it is a very smooth continuous wave as opposed to the original univibe values with had a peak and drop in the middle of the curve.

cheers
kt!

EDIT: i just checked you guys have jaycar in NZ. RD-3480 is quite a good LDR with an immediate darkness resistance of 48k. they cost $2.50AUD so prob about $3NZ. cheers

bajaman · Post by **bajaman** » 20 Sep 2007, 03:36

Hi KT66
I enclose the leds and ldrs in a piece of black poythene pipe (garden watering system riser) then , I seal the ends with black magic toughned superglue - but black rtv would work as well - just takes longer to solidify

Then when i measure across the ldr, i get a very high resistance in the megohms region - when i connect a 9v battery in series with a 4k7 resistor across the led , the ldr now measures somewhere near 200 ohms or less.
The ldrs are the common typoe available from Jaycar, Dick Smith etc - nothing fancy - just the small ones.

re: the graph i used to chart the curve: i just drew it out on a piece of paper. capacitance on the y axis, cap 1, 2, 3, 4, 1 on the x axis. the phase sweep moves through the caps in order and then from 4 back to 1 continuously. if you chart out rm's cap values you will see it is a very smooth continuous wave as opposed to the original univibe values with had a peak and drop in the middle of the curve.

Please explain more clearly - if possible post a picture - the caps on the y axis then 12341 on x axis - is it linear graph or logarithmic? - excuse my ignorance - i simply do not understand what exactly you are plotting here.
Please explain

I arrived at my values by using a logarithmic x axis graph paper and inserting 470pf and 100n as the low and high values, then i simply divided the space linearly between the two extremes into 3 spaces - this gave me the remaining two capacitor values - crude but it sounds wonderful - build it and you will see what i am talking about, or ask Bernardduur - he has built one too.
Don't worry - you are not stepping on my toes - I am interested to learn too. Many thanks for your input - now if i can understand your graph I will be even happier
Cheers
bajaman

KT66 · Post by **KT66** » 20 Sep 2007, 04:10

hey bajaman

i have drawn out the graph so you can see what i have done.

although the y axis is not to scale, it does show you the difference in the curves even though they are not exactly proportional.

you can see rm's curve is very symmetrical, the univibe has some ramping in the middle, and yours is just one big ramp.

i think rm reshaped the curve to give a very even sweep given all the settings are set to 12o'clock. you can then shape with the leds.

let me know your thoughts.

re:your LDR's. when an LDR goes from bright source (100ohms or there about) to immediate darkness it should then measure its immediate darkeness resistance (between 1 and 50k on average). it will then very slowly (overnight depending on the ldr) increase its resistance to its maximum darkness resistance (1m-10m) as the now slightly charged electrons drop from the conduction band.

i suggest you turn on the led, measure the ldr, then turn off the led and measure the ldr again. it should show your immediate darkness resistance. this immediate darkness resistance should be 30k for this circuit. if it is less than 30k then i suspect that your phasing sweep is not being cut correctly with a lack of high enough resistance.

cheers
kt!

greenskull · Post by **greenskull** » 20 Sep 2007, 05:48

Very interesting to see the stage caps graph!!
I wonder if it would be easier to find a suitable photocoupler than rolling my own. Something tells me my build will be packed with sockets!!
Good to see these latest discussions, gentlemen.

Little VOODOO VIBE project by Kaputepalla [documentation]