Non-working Bassballs

[Baran Ismen]

I'll have to get back to this tomorrow.

Some quick answers.

5- 0,9V
6- 1,26V
7- 1,41V

With 4 diodes, its 1,76v - 1,92 - 1,92v's consecutively. Its much more responsive, but there's this a bit annoying decay effect when the signal goes to zero, it doesn't naturally fade away, but cuts somehow.

So, what does this mean? Is it about the IC or a faulty layout? Most of the schematics are sending the IC1-5 to ground

There's a few things going on that are all interlinked:
- The first is the *input* needs to be biased in order to stop pin 7 going to a high voltage.
   This might only take one or two diodes but the opamp still might not be quite working correctly.
- The second is the output side DC voltage.
   If you need to add a few diodes to the input side then you might need to add some diodes to the output
   side (in series with D1)  to compensate.  The diode(s) in series with D1 might fix the decay.
- The third is the sound of the distortion output.

For bias four diodes you probably should *also* add two diodes in series with D1.  You might even need three diodes.   You can even experiment to see what works better.   It might help to change the 100k bias diode resistor to 10k, that will increase the voltages a bit.    Once you get start using four diodes it might be more economical to use RED LEDs instead of diodes.

The advantage of the second method I suggested is it might work better.   This method starts with the opamp inputs well within their working range.  You can also play with the R6 resistor value to tune the sound.  Much cleaner than playing with many diodes.  You try one extra diode in series with D1 with this method but you should re-tune the resistor value, a higher resistor value is required.

- do you want new R6 to Vcc or Vref?

It's definitely as shown:
-  pin 5 to Vref to bias the opamp *input* to a working voltage
-  R6 to Vcc to set the output bias voltage.  (Without R6 the opamp would bias at Vref but we want to bias the output round 0V to 2V to mimic the original behaviour of the ckt.)

In theory the second method should use a 220k but given the original circuit is no operating the opamp in a good zone I allowed for some tweaking of R6.    This is where putting the finishing touches comes in.

I understand but there should be an easier solution for this, even in the first, original schematics 1458 is used and pin 5 is grounded. Here it is.. https://github.com/yuvadm/guitar-effects-schematics/blob/master/Filters%20Wahs%20and%20VCFs/Electro%20Harmonix%20Bassballs.pdf

I'll order LM358P, LM1458, LM358L and LF353N for trial. I suppose either one would work eventually  They'll probably arrive on Tuesday and I'll write the results.

[Rob Strand]

I understand but there should be an easier solution for this, even in the first, original schematics 1458 is used and pin 5 is grounded. Here it is.. https://github.com/yuvadm/guitar-effects-schematics/blob/master/Filters%20Wahs%20and%20VCFs/Electro%20Harmonix%20Bassballs.pdf

What you are missing is the original design is flawed.   If you want to make it like the original with pin 5 grounded you have to know exactly what brand LM1458 they used.  If you bought the same brand LM1458 today it still might not work and maybe some other brand will work - because some of these designs change over time.

You could buy a whole heap of different brand LM1458's and try them.

EHX still build this unit.  I think they use SMD versions of the LM1458 MC1458? from ST semiconductor - I'm not 100% sure.

I'll order LM358P, LM1458, LM358L and LF353N for trial. I suppose either one would work eventually  They'll probably arrive on Tuesday and I'll write the results.

The LM358P (and LM358L) will work because LM358 opamps are designed to work with pin 5 grounded.  By work I mean pin 7 will not got to 8V with pin 5 grounded and it will produce an output resembling working.  I can't say the unit will work exactly like the original LM1458 because the LM358 doesn't sound the same as a LM1458 - it also has it's own (different) flaws.  Another difference is the output voltage LM1458 is not the same as the LM358 - that can affect the detector.

I doubt the LF353N will work, pin 7 will go high when pin 5 is grounded.

[Baran Ismen]

I understand but there should be an easier solution for this, even in the first, original schematics 1458 is used and pin 5 is grounded. Here it is.. https://github.com/yuvadm/guitar-effects-schematics/blob/master/Filters%20Wahs%20and%20VCFs/Electro%20Harmonix%20Bassballs.pdf

What you are missing is the original design is flawed.   If you want to make it like the original with pin 5 grounded you have to know exactly what brand LM1458 they used.  If you bought the same brand LM1458 today it still might not work and maybe some other brand will work - because some of these designs change over time.

You could buy a whole heap of different brand LM1458's and try them.

EHX still build this unit.  I think they use SMD versions of the Lm1458's from ST semiconductor - I'm not 100% sure.

I'll order LM358P, LM1458, LM358L and LF353N for trial. I suppose either one would work eventually  They'll probably arrive on Tuesday and I'll write the results.

The LM358P (and LM358L) will work because LM358 opamps are designed to work with pin 5 grounded.  By work I mean pin 7 will not got to 8V with pin 5 grounded and it will produce an output resembling working.  I can't say the unit will work exactly like the original LM1458 because the LM358 doesn't sound the same as a LM1458 - it also has it's own (different) flaws.  Another difference is the output voltage LM1458 is not the same as the LM358 - that can affect the detector.

I doubt the LF353N will work, pin 7 will go high when pin 5 is grounded.

I see. For my 2nd project, i guess i have chosen a really hard one.. I doubt EHX would answer that if i ask lol

[Rob Strand]

I see. For my 2nd project, i guess i have chosen a really hard one.. I doubt EHX would answer that if i ask lol

You might be lucky with another LM1458.   I'm very suspicious of your pin 7 voltage going up to 8V (or so).   TL072's do that type of thing but I don't remember LM1458's doing it.   If you buy parts off untrustworthy supplies you could get remarked TL072's (or some unknown made-in-China opamp).

FYI.  IIRC, these two pedals are based off a different EHX pedal, the DR Q.

The DR Q has the same problem as the Bassballs, no bias on the opamp.
https://www.muzique.com/schem/doctor-q.gif

Dr Quack
https://generalguitargadgets.com/effects-projects/filters-envelope/dr-quack-ehx-doctor-q/
https://www.muzique.com/schem/quack.gif

Nurse Quacky
https://home-wrecker.com/nurse-quacky.html
https://home-wrecker.com/nurse-quacky.png

The points I want to make are:
- the designs bias the + input opamp using an LED
- then they have another LED on the output to compensate
- they do this to make sure the pedal works with more opamps
  and so you don't end-up with the situation you are in.

The use of LEDs instead of series diodes is just a way to get more voltage drop with less parts.

[Baran Ismen]

I see. For my 2nd project, i guess i have chosen a really hard one.. I doubt EHX would answer that if i ask lol

You might be lucky with another LM1458.   I'm very suspicious of your pin 7 voltage going up to 8V (or so).   TL072's do that type of thing but I don't remember LM1458's doing it.   If you buy parts off untrustworthy supplies you could get remarked TL072's (or some unknown made-in-China opamp).

FYI.  IIRC, these two pedals are based off a different EHX pedal, the DR Q.

The DR Q has the same problem as the Bassballs, no bias on the opamp.
https://www.muzique.com/schem/doctor-q.gif

Dr Quack
https://generalguitargadgets.com/effects-projects/filters-envelope/dr-quack-ehx-doctor-q/
https://www.muzique.com/schem/quack.gif

Nurse Quacky
https://home-wrecker.com/nurse-quacky.html
https://home-wrecker.com/nurse-quacky.png

The points I want to make are:
- the designs bias the + input opamp using an LED
- then they have another LED on the output to compensate
- they do this to make sure the pedal works with more opamps
  and so you don't end-up with the situation you are in.

The use of LEDs instead of series diodes is just a way to get more voltage drop with less parts.

Yep, I saw that, actually Dr.Q is on my to-do list as well, maybe I should not 

I actually went with this pedal for being dual-filter unlike others, a rather unique and harsh envelope.

I'll order the parts now and wait for their arrival till tomorrow. Until then, I want to learn further about what I do here, I mean my knowledge about audio circuits are shallow, I want to make it deeper and I'm open to suggestions for any type of source for knowing better what's going on a circuit. I do know that it requires lots of practice and experience,yet everyone starts from somewhere, right? For example, this "bias" term, I don't know about it, or different types of opamps and how&where they're used.. maybe its not the basics, but its something and I want to learn.

[Baran Ismen]

As a side question, is the 1458 working as a non inverting amp in this scenario?

[antonis]

We've dealt with many scenarios here but, as long as signal goes to inverting input, it works as inverting amp..

[Matthew Sanford]

everyone starts from somewhere, right? For example, this "bias" term, I don't know about it, or different types of opamps and how&where they're used.. maybe its not the basics, but its something and I want to learn.

My noob two-cents. (smart people please correct my wrong things!)

Vbias centers the voltage of the input signal - with it at 1/2 Vcc the signal wiggles in the middle, instead of slamming into the negative rail.
Opamps are typically differential amplifiers, meaning they output the difference between their two inputs (I think as +ve - (-ve). So say a ramp up signal from 0v to 5v into the inverting input with positive input tied to vbias...or we'll just say 5v this case, the output starts at -5v (5v-0v) and ends up at 0v (5v-5v). On that I don't have a handle on what's the difference with the comparator set up.

Other thing, search the thing you want here and read through some of the million threads that come up. Likely you aren't the only one with issues, plus you learn tons from the explanations you didn't realize you'd receive!

Datasheets! Read them for each OpAmp! It will tell you things like the TL072 is always -V +1.5v, so the negative rail doesn't go to 0v on a single supply, it goes to about 1.5v, on that end the LM358 has V+(-2v) so though it goes down to 0v it isn't going to hit 9v, more like 7v. This is the inputs going through the opamp, learn and remember that the supply voltages are the positive and negative rails are the limits which you must abide - that took me a while to realize I wasn't going to get a negative output voltage with 0v being the lowest on supply (with out charge pump like MAX1044).

Just know that the learning curve is logarithmic, at first you don't realize you're actually walking up a slight incline, feels more like down hill or at least stepping in pot holes, but after time what you learn correlates in your mind (incorrectly too!) and you slowly feel like you are learning.

You can do it!

[Baran Ismen]

I couldnt write due to maintenance.

Its working now. My new ics have arrived, actually i asked for lm1458 yet they sent Mc1458. At first i was like wtf is this nonsense, as i already have one that doesnt work. But after trying, i was in awe that it worked instantly. So did the lm358, but it was clipping here and there, wasnt as good as this one. I think the Mc1458 i initially have is somehow broken or not even a real 1458 at all.

I want to call this done, as everything is working and responsive, (just couldnt get much response from bass pot, it doesnt feel doing anything) and i want to thank everyone here for their great support.

[Rob Strand]

Good news.

For the Bass pot: it would be easier to hear if the bass pot is doing anything if you temporarily lift one end of R23 to remove the treble signal, then start debugging from there.  R23 is the 2k7 on the Treble ckt and the opamp has 2x4n7 caps. This schematic.

https://docs.pedalpcb.com/project/Lowballer-PedalPCB.pdf

[Baran Ismen]

Here's the finished version!

Designed on Tinkercad (can share with anyone if demanded)
3D-Printed the enclosure,
painted with acrylics w/ Airbrush (perks of being a plastic modeler) then coated with matt varnish,
finally designed the label and printed it on a digital printer with matt lamination.
Fits perfectly!
Pot-heads will be reprinted with a bit more height and hole depth and chemically-treated to eliminate layer lines.

[Mark Hammer]

A 1458 is a 1458 is a 1458.  Maybe they might have differences in quality control, but no single manufacturer has a lock on that chip.

[duck_arse]

slammer88 - your images don't work. they are behind your googoo account. we can't sign in, much as I would like to see your pot heads. smoke-em up.

you can do practice test posts in the testing section.

[Baran Ismen]

There you go, this should work

https://photos.app.goo.gl/WEcQDwwGBysVmLxLA