f*^$%$%!!!! bassballs...

[pinkjimiphoton]

hi guys,

i built the "verified" vero layout of this that lars (cathexis) did...

but i got some issues. i used the exact parts and specs specified (other than subbing the 4.7 tant with an electro and the 1.8k resistors with 2k..both were more like 9.54 or so, should be close enough)...

i can't get the fuzz switch to work. that's annoying.

the depth pot does nothing either. more annoying.



but...the thing passes signal, and if i turn the trimmers, the dang circuit is definitely working.

but i can't get the puppy to sweep!

i've gone over the board, tried different opamps (some indeed sound completely different, but i have the stock 1458 in there, have tried 4 of them)
and can't find any bridges. i even looked with my jeweler's loupe to be sure.

took a cutoff wheel on my dremel between the rails of the vero to be sure. reheated all the connections. even tinned the damn rails to be sure there's a good connection.

i've looked at the vero, i've looked at the schematic, and they seem to agree with what i've built. but i can't get this mofo to quack!!

any ideas?

also, should the circuit board be microphonic? that makes me suspect a cold solder joint...but...

any insites appreciated!!!!

[pinkjimiphoton]

it seems to have issues around ic 1 and q1.  i've double/triple checked for solder bridges...but

look at the connection of the diode..it looks to me like 9v b+ SHOULD NOT be connected to pin 8 of opamp 1...the schematic shows it connecting to the c of q1 thru the power supply...or am i mis-reading something?

i tried separating the connection as shown in the vero by cutting the trace between q1 c and ic1 pin 8 and disconnecting the jumper from b+ to ic1 pin 8...and running a jumper to b+  to feed q1 c. doing this, the pedal KINDA works, both sides of the switch and the depth pot work, but the volume is really low.

i DID try subbing a 1n34 for the 4148/914 specc'd... seemed to help the effect somewhat, but wondering if this may be where the volume drop comes from...

with the circuit connected as shown tho, something is definitely wack.







voltages:

ic1
1 4.87
2 4.88
3 4.76
4 0
5 0
6 0
7 9.07
8 9.76

ic2
1 4.86
2 4.85
3 4.84
4 0
5 4.84
6 4.85
7 4.86
8 9.76

q1
e 8.41
b 9.07
c 9.76

q2
e 0
b .42-.65 (trimmer dependent, min to max)
c

q3 same as q3

pix to follow

[Tony Forestiere]

Are you missing a trace cut at pin 5 of IC1? It is being grounded. 

[Mark Hammer]

Pin 5 should be grounded as near as I can tell.

That being said, if there was something amiss with the rectifier section, you would get exactly what you have described; namely no fuzz and no discernible sweep but an ability to audibly adjust the filter sections and hear a filtered output.  That pegs your problem somewhere between R3 and Q1.

Set the sensitivity pot to max, plug in and strum, and take an AC voltage reading at pin 7 of IC1.  If you get no indication of the strum, then your problem lies between R3 and the chip output.  If you do get an AC reading that fluctuates with playing, then perhaps either the diode or Q1 are amiss.

[pinkjimiphoton]

hi tony and mark,

here's some pics of the vero...

mark, i will check that area right now...and post the results, thanks!

[Tony Forestiere]

Sorry, I see that now.  
I am just so used to seeing normal voltages on a dualie op-amp as:

IC X
1 - Vb
2 - Vb
3 - Vb
4 - GND
5 - Vb
6 - Vb
7 - Vb
8 - V+

I will step away from the keyboard and try to learn something from this.

[pinkjimiphoton]

lol!!!

f and a lot of vowels!!

no worries, tony, i don't even understand THAT.



off to check voltages...be back shortly.

[pinkjimiphoton]

checked for voltage on pin 7 of ic 1, got no change.

checked diode, discovered it had blown out!! was reading as shorted with the diode test on my meter, would pass current both ways.

so gonna pop in another diode and hope for the best.

the more i look at the schematic and the vero layout, the more difference i am seeing in that one area of the pedal...on the schematic, the 9v b+ is not connected to ic 1 at all, just the half voltage tap on side a, and side b shows it being tied to 9vb+ thru the filter and diode, am i reading that right?

the vero, c of q1 and pin 8 of ic1 are both on the same rail. i re-connected them after trying to separate them...something here just seems amiss!!

[Mark Hammer]

The "fuzz" output should be available in the absence of the rectifier diode.  Lift one end or remove the diode and see if you get the fuzz sound.  If you don't, then your problem is not confined to the diode.

Incidentally, once you get it working properly, you will find that the "fuzz" sound is more like a gargle than fuzz.  You will also find that turning the sensitivity up affects the sweep, the volume level, and the degree of distortion, simultaneously; a real design weakness AFAIC.

I've replaced that 100k/47k attenuator network where you tap the "fuzz" with a 10k instead of 100k, and a Ge diode pair instead of the 47k.  That solves some of the issues.  It certainly gives you a distorted sound that is harmonically richer, giving a more pronounced filtering effect.  Second, it "clamps" the maximum volume level, so that once you've reached the point where you get a modest sweep, the fuzz volume will not increase much more, even if you turn the sensitivity up higher.

Even with that clamping, the output level from the fuzz signal will be higher than the clean filtered sound, and noticeably louder than bypass.  You may want to turn the 47k terminating resistor on the output to a 50k log pot to set effect volume.

Although there is no end to the possible mods for this beast, the three I will recommend most (over and above the fuzz change and volume pot) are as follows:

1) Swap out the 330k decay-setting resistor for a 47k and 500k pot n series to vary decay time (low resistance = faster decay).  Faster decay time sounds more synthlike.  Alternatively, consider a 3-position toggle to select between 47k, 150k and 470k, for fast/med/slow.

2) Panel-mount the 10k trimpot for the higher filter to set the stagger between upper and lower filters.  You'll get more variation if you panel-mount both 10k pots, but doing just the one is fine.

3) Install a balance control to adjust the relative contribution of each filter section to the overall sound.  You'll see that the two filter outputs are passively mixed 50/50 through a pair of 2k7 resistors.  Replace those 2k7 resistors with 470R-1k resistors feeding the outside lugs of a 10k linear pot, and feed the mixed output from the wiper of that pot to the 1uf output cap.  It won't entirely cancel either filter section but allow you to make one section dominate the other.

You can hear what the whole mess sounds like here: http://www.youtube.com/watch?v=eoAIKHFGOcQ&feature=plcp  Enjoy.

[pinkjimiphoton]

mark, could it be because i used an electro for the tants?

i used ceramic for the rest..

without the diode, still no sound whatsoever when the fuzz is on. stumped!

[Mark Hammer]

I didn't use tants, so it couldn't be that.

[pinkjimiphoton]

hmmm...something must be wrong.

1458 smoked! got hot, now it doesn't do squat.

plugged in another one, if i mess around between the e and f rails, it's suddenly kinda making sounds.... but the diode is out of it, and was cooked (broken) so something's weird here, you used the same schematic i'm looking at...

why won't this puppy sweep?

gonna go mess with it some more...thanks for the help mark!

[pinkjimiphoton]

well, i kept at it, got nowhere.

ended up killing the circuit. finally just now got it working the way it was before.

the whole dang board is microphonic, which makes me suspect cold solder.

sucks. i may have to just re-do the whole damn thing over!! i actually had a couple of the resistors fall out while i was re-flowing it.

my eyes are bugging out. i'll try again tomorrow. thanks for the help and advice!!!

[Ronan]

jimi, triple check pin 6 on IC1. If you have say 9V on pin 7, then you should have about 8.1V on pin 6, but you said you had 0V on pin 6 in your 2nd post. Maybe there is a short to ground on pin 6, or there's a problem with R4 or C3. R4 needs to be 2.2 meg, worth checking too. I've breadboarded that schematic in the past, its fine.

[Ronan]

Any luck with it jimi? I hope so, because sometimes...electronics can be a real PITA when it doesn't do what we want, and all ya feel like doing is burying the project in a hole in the backyard...   But if the problem can be found and fixed, then it becomes something to remember for next time.

Funny that you are working on a bassballs. 2 days ago I hooked up an expression pedal to a EH talking machine, which can do a replica bassballs sound. I like the bassballs pedal, but not enough to build one. But, with an expression pedal (read wah shell plus minor modification of the original bassballs circuit) it could become a completely different animal, IMO, still with similarities, but much more interesting.

Here's a sound clip of the talking machine in bassballs mode with exp pedal.

[pinkjimiphoton]

hi ian,
as you probably guessed, i've been working on this sucker for days...with no success.

it's maddening. but i've learned a lot in the process.

the problem wasn't with my original soldering, or the layout...i figured this out last nite, when i got random fleeting flashes of the unit working.

near as i can figure, here's the problems.

the MAIN, ORIGINAL problem i an POSITIVE was cheap-ass ic sockets. this could have saved me a couple days i think if i had figured that out.

the cheap ones, you really can't run jumpers under them...they don't seat well, and solder isn't glue, so even if you do get them to seat, then nothing will work right, and you'll face eventual failure.

next, i used my cutoff wheel on my dremel to be SURE i had no unwanted solder bridges. this was an EPIC FAIL...all it did was get pcb dust EVERYWHERE...a semi-conductive mix of plastic and solder that gets all over and into everything. you can clean it off, but not ALL of it without a bath in some kind of solvent or something. this makes any solder joint you reheat bad and automatically it will fail, even if working while hot.

"flowing" the solder along the rails is another bad idea...especially combined with the above. makes it impossible to find the bad joints, and makes any "standy-uppy" parts tend to unseat and ruin the connection...as i found while trying to re-heat every connection repeatedly, just to have another fail.

it got to the point the whole vero took a curve to it, and the slots between the rails were deep enough that you could flex the circuit board, leading to occaisonal yelps of the circuit working perfectly...for a split second. i worked on it yesterday for at leas 8 hours, til about 1 am my time anyways.  all newb mistakes.

the COMPONENTS are most likely all good...but the vero was heated up so many times, it's useless. i'm gonna have to remove all the parts, take a dremel to every component lead to make sure there's no solder/plastic on them, and start with a fresh piece of board. there's just too much wrong with this one.

THIS time, i am gonna solder the chips in and put the jumpers for the ic's under the board. maybe i'll use the sockets still if i do that...but if it doesn't work this time, i give up on this one.

i still have the talking pedal i built from the pcb you so kindly sent me, which is very similar as you pointed out

i like the bassballs enough to want to build one, (i bought a black russian one on ebay broken for too much money, and fixed it, but am hoping to sell it to pay for more projects so i figured i'd build one...but the russian circuit is different from this one somewhat). i hope to add a stereo switching jack to it, so i can control as you said, the one 10k trimmer with a treadle.

if you still have the 22k stacked pot from the vocalizer project kicking around, i believe that replacing each of those trimmers with the 2 sides of that pot opposing each other and set to different sweeps should sound amazing...like the talking pedal.

so for the moment, licking my wounds and waking up... then i'm going back, making a new vero, and doing this RIGHT. hopefully. 

[Mark Hammer]

Why don't you just make a PCB?  The layout at topopiccione is compact, nicely done, and works great.

[pinkjimiphoton]

prob is i don't have the resources to make a pcb bro, i live on a paltry disability check (most of my work was always as a musician, so the day job thing didn't net me a large income when i was "retired") and can't afford to buy the stuff i need to do that at this point.

usually gigs keep me afloat, but i have NOTHING this month coming in.

but i DO have a butt-load of vero.

this turned into the same reason i don't do perf...i've found the plastic seems to contaminate the solder joints with perf, and life is too short to endlessly debug something that should work out of the gate.

i HAD it right...other than the sockets being bad...i checked and replaced every single component but them multiple times....when you exhaust all the probabilities, whatever's left is most likely the issue, right?

so...gonna try again this afternoon...nothing better to do!

[Ronan]

OK, good luck this afternoon.

So what do you think of the bassballs clip? Do you think its better with treadle control, worth taking the idea further? Reminds me a bit of the Korg Mr Multi in double wah mode.

[pinkjimiphoton]

hi ian,

frankly, i LOVE the clip...it is reminiscent of the mr. multi...but i think it's got a better growl to it... sounds awesome!!!

greg (govt. lackey) has offered to etch me a board, i'm taking him up on it whether i get this one working or not.

i spent all freakin' day long re-doing the vero. i checked every bloody connection as i went...mounted all the jumpers UNDER the board, on the
rail side...triple checked for bridges /shorts etc with my jewler's loupes to make sure everything was good.

took voltage measurements BEFORE i installed the chips. pin 6 is now a little over 8v on ic1.

put the chips in..

i can HEAR the filters working, both trimmers adjust..

but i can't get any freekin' signal to pass thru the sumbeech!!

so i took more voltages, in hopes someone may be able to help me sort this out...i know i'm close, it's something stupid.

ic 1
1  9.14
2  9.13
3  1.74
4  0.00
5  0.00
6  8.19
7  9.18
8  9.77

ic2
1  5.26
2  5.31
3  5.30
4  0.00
5  5.30
6  5.31
7  5.26
8  9.77

q1

C  9.77
B  9.66
E  9.02

q2

C  0.00
B  .41- .65
E  0.00

q3

C  0.00
B  .41- .65
E  0.00

something on the board is again very microphonic...i think it may just be the nature of the circuit?

stumped...can anyone buy me a clue?