My bassballs only works with tlc2262, but why ?!

[Gabriel Simoes]

Hello all,
First I'd like to thank you guys who have helped me from the beggining of my project till now, including zero and the topopiccione info, very helpfull material....
But continuing my sensitivity problem, I will try the germanium diode, a mod for choosing germanium (1n60) or silicon (1n4148), and see if it improves the sensitivity problem ...
But since the beggining one thing is still in my mind, and I think thats the cause of all my trouble .... the only opamp that makes my bassballs clone works is tlc2262, in the gain/fuzz stage (not filter).
I've tried to replace it with rc4559, rc4580, tl072 and NONE of them work, in the first half opamp everythink is completly fine, but in the second half, just before the diode, the signal gets in the opamp (leg 6, 2in-), but do not get out (leg 7, 2out) so I get no sweep or fuzz sound! and this way I still can use the filters, but the sensitivity control has no effect .... I even got no sound trying to direct replace it using a tle2142.
Since the pinouts are the same I have no ideia of what it could be, and that happened with my 2 boards, one from topopiccione (I'm not using since it's the first one and because of this problem I thought it would have any problem but not) and one from the fixed clone wars layout (that I'm using now).
I've built this with bc549C transistors, and since the effect is kind of usable with the tlc2262 I don't think I'm facing any voltage problem of inverted transistor problem at all .... (transistors where soldered inverted to match the pins) ...
Anybody have an ideia of why the signal get into the opamps and never gets out ? maybe thats my problem, and thats why I need to play that hard to get the sweep from my bassballs clone ....
I love this pedal, so I want it to work right, and not only when I play really hard.
Thanks for your attention and help
Gabriel

[Zero the hero]

Gabriel, this pedal is surronded by something mysterious, I'll definitely update my page with Mark suggestions and your impressions in making this circuit...
And definitely, this is NOT a beginner project!
The bassball caused me a lot of op-amp headaches. Unfortunately I have not found the reason of its freaky behaviour, so I actually don't know how to solve this issue.
There are lots of parameters in op-amp datasheet, and I recenlty found that each op-amp has its own behaviour. They are not as interchangable as they are supposed to be, and the Bassball is a perfect example.
I hope that in the near future someone tells us which is the way!
By the time, I'll read all previous post about Dr. Q and Dr. Quack...

[Gabriel Simoes]

Hey zero,

Wich opamp did you use in your project for the gain stage before the diode ?
Do you still have you project in hands ?? did you use sockets maybe you could try to change this ic and see if a tl072 of rc4559 would work, and if so, than the problem is mine hehehehe and all mine heehehe.
The problem is not your project and I'm sure about it because I made 2 boards, one from the topopiccione pcb and one from the fixed clonewars and both gave me the same trouble to solve ....
I will try to use the ge diode and then I think the sensitivity trouble will be solved (less imput, so lets rectify it will less voltage hehe)..

But I still have this doubt .... how could a signal get to the negative in of an optamp, positive in conected to ground, power is alright (because the other half of the opamp is working like a charm) .... and NO SIGNAL FLOW FROM THE OUT PIN (pin number 7) ..... I'm getting crazy with this one...
Once again thanks zero, and if I'm able to solve this I will tell you.. and maybe that info could help you and your site ..
Gabriel

[Gabriel Simoes]

Hey all...
Maybe I found the beggining of my problem!
I got the voltage from all the pins in my circuit today ... here it is

1 - 4.36
2 - 4.36
3 - 3.5
4 - 0
5 - 0
6 - 0
7 - 0
8 - 8.74

and the schematic is



I'm using the tlc2262 to substitute 1458... and in this place I cant get any sweep of fuzz with tl072, rc 3559, rc4580 or tle2142
So, the voltage should be higher on pin 6, shouldn't it ? am I right ?
I will try to read it at all points between pin 1 and pin 6 and discover where it go away ...
Thanks for your help untill now ...
Gabriel

[StephenGiles]

NO, almost any dual opamp could be used in this circuit so something is wrong with your build I think.
Stephen

[gez]

NO, almost any dual opamp could be used in this circuit so something is wrong with your build I think.
Stephen

So all opamps are fine with having their inputs pulled to ground?!

[Gabriel Simoes]

Since the signal get in the opamp (second half 5,6,7)  and never get out with other opamps, I thougth the signal in was too low, and then it's 0....
I dont know if I could fry a tantalum cap with heat .... is that possible ?
If it helps, when I change the opamp, the filters work rigth, and the sensitivity and fuzz have no effect .. so I get no sweep but the filters act at any note with any amplitude ....
I still cannot understand how could the signal be 0v at the negative in ...
Thanks,
Gabriel

[gez]

I still cannot understand how could the signal be 0v at the negative in ...

If only there was a way to consolidate your two threads Gabriel, this is getting ridiculous!  

The + input of the amp used for rectifying duties is referenced to ground.   The amp's output will do whatever it needs to do to make the inverting (-) input 0V too so it biases at 0V (assuming the amp can swing that low - can't remember the specs for this amp).

[Gabriel Simoes]

If you think it is ridiculous I'm so sorry, .... but comments like this, ... you could keep for yourself ...
I  really dont think its ridiculous since some people could do it, could make it work with a bunch of opamps that I cannot, including tl072, but ok ... maybe I should redo redo and redo the board and maybe someday I will figure out what it is ....
Thanks gez for helping the ridiculous ..
Gabriel

[gez]

Gabriel, you've misunderstood me.  I don't think you or your posts are ridiculous, it's just a bit of a headache when replies are spread over two threads at once!  If you look at my last post I included a smiley to indicate that I was just joking, it wasn't my intention to offend you.  :wink:

Perhaps you do have a problem with your layout, I couldn't tell, but it's always best to use the specified components first before you start subbing in stuff.  Unless you do that it's difficult to know whether you have another problem.

[gez]

I  really dont think its ridiculous since some people could do it, could make it work with a bunch of opamps that I cannot, including tl072,

Although the codes may be the same, amps may differ from manufacturer to manufacturer.  It's possible for one maker's product to work fine in a circuit and that from another maker to fail.  Usually, subbing in a part isn't such a big deal and the majority of the time these swaps will work, but with this circuit what you choose for the envelope part of it requires a little thought.

Perhaps I have this wrong, but my impression is that the filter part of your circuit works (though it isn't being swept) and the envelope part doesn't?  If this is the case then try to track down the proper amp (1458).  If you have problems with the rest of the circuit then perhaps it is a layout thing...