Help! No Envelope on a Bassballs Circuit

[Freekmagnet]

I just built my second Bassballs EF from the topopiccione layout found here:

http://topopiccione.atspace.com/PJ08EHBassBalls.html

These are actually my first DIY PCBs. I added a few additional Mark Hammer mods found on the perf layout found here:

http://i1070.photobucket.com/albums/u499/catchascatchcan/bb4_zpsc64bbb6f.gif

I built them both simultaneously. The first one works great and has quickly become my favorite pedal. Funk city.

The second one doesn't seem to have any envelope detection at all. There is definitely a sweep, but it's more of a swirly flangy phasey sound that doesn't respond to touch. The fuzz works OK.

Here's some info:

Source voltage from the wall: 9.28v

IC1:

Pin1: 2.13v
Pin2: 1.92v
Pin3: 0
Pin4: 0
Pin5: 4.52v
Pin6: 4.62v
Pin7: 4.62v
Pin8: 9.28v

IC2:

Pin1: 4.62v
Pin2: 4.62v
Pin3: 4.62v
Pin4: 0
Pin5: 4.62v
Pin6: 4.63v
Pin7: 4.62v
Pin8: 9.27v

At first I was weirded out by the voltage on the first two pins on IC1, but it's consistent with the unit that functions perfectly. Let me know if this should be something different.

Following the steps found here:

http://www.diystompboxes.com/smfforum/index.php?topic=104413.msg936417#msg936417

I measured the AC where R5 and C3 meet and I got about 50mv.
I measured the DC where D1 and R6 meet and I got up to 6v.

I turned off the fuzz and tested the filter pots, and both of the pots have and effect on the sound of the sweep, although the P2 (the upper filter) seems to have less of an effect.

I'm 99% sure transistors are oriented correctly, but I'll double check in a few minutes. Like I said, I built both simultaneously so I was pretty good about comparing them as I built them.

Any help or suggestions are appreciated. Thanks in advance.

Jeremy

[Freekmagnet]

OK. I just confirmed that yes, the transistors are oriented correctly.

[Mark Hammer]

And R6 is definitely 100 ohms, and not 1k or 100k?

From your description, it would seem like you get an audio signal via the fuzz and non-fuzz paths, and the trimpots alter the tone of that audio signal.  Correct?  If so, then the problem lies exclusively in the envelope part of the circuit.  Is Q1 installed correctly?

If all of the above checks out fine, then you need to start checking for unintended shorts and discontinuities.

[Freekmagnet]

And R6 is definitely 100 ohms, and not 1k or 100k?

From your description, it would seem like you get an audio signal via the fuzz and non-fuzz paths, and the trimpots alter the tone of that audio signal.  Correct?  If so, then the problem lies exclusively in the envelope part of the circuit.  Is Q1 installed correctly?

If all of the above checks out fine, then you need to start checking for unintended shorts and discontinuities.

Cool. I'll take a look at R6 and Q1. I'll post some measurements today.

Also, maybe I should reword my previous statement. The upper sweep pot works only a little bit, but I can't tell by ear if it just seems lackadaisical because there is no envelope happening.

BTW, Mark Hammer, thanks for replying. I really like the mods you came up with for this circuit. It really makes the Bassballs a really cool and versatile effect as opposed to the novelty that the stock pedal seems to be.

[Freekmagnet]

And R6 is definitely 100 ohms, and not 1k or 100k?

From your description, it would seem like you get an audio signal via the fuzz and non-fuzz paths, and the trimpots alter the tone of that audio signal.  Correct?  If so, then the problem lies exclusively in the envelope part of the circuit.  Is Q1 installed correctly?

If all of the above checks out fine, then you need to start checking for unintended shorts and discontinuities.

OK. R6 is definitely 100 ohms. Just eyeballing it, the transistor is oriented correctly. I took voltage readings:

C: 9.28
B: 1.874
E: 1.335

Should I start checking my solder joints?

[Mark Hammer]

Should I start checking my solder joints?

Unless the board is huge, always a good thing to be able to check off and say "Nah, that's not it".

I really like the mods you came up with for this circuit. It really makes the Bassballs a really cool and versatile effect as opposed to the novelty that the stock pedal seems to be.

Thanks.  Keep in mind that in the early days, EHX were considered to be ridiculously inexpensive  http://hammer.ampage.org/files/1981_E-H_pricelist.gif.  And one of the ways they kept production costs down was to use the same punched folded-metal chassis for as much as they could, such that machining costs were kept to a minimum.  And if that meant restricting the effect to 1 knob and 1 switch, and forfeiting some flexibility, so be it.

In recent years, they have swung in the other direction, sometimes implementing more controls than the user knew what to do with (e.g. Flanger Hoax), but often implementing a very pleasing increase beyond what long-time EHX customers were used to.

The stock Bassballs certainly had a distinctive sound, compared to other commercial autowahs, but I think it could have gone much farther with an additional control or two.

[Freekmagnet]

Should I start checking my solder joints?

Unless the board is huge, always a good thing to be able to check off and say "Nah, that's not it".

I really like the mods you came up with for this circuit. It really makes the Bassballs a really cool and versatile effect as opposed to the novelty that the stock pedal seems to be.

Thanks.  Keep in mind that in the early days, EHX were considered to be ridiculously inexpensive  http://hammer.ampage.org/files/1981_E-H_pricelist.gif.  And one of the ways they kept production costs down was to use the same punched folded-metal chassis for as much as they could, such that machining costs were kept to a minimum.  And if that meant restricting the effect to 1 knob and 1 switch, and forfeiting some flexibility, so be it.

In recent years, they have swung in the other direction, sometimes implementing more controls than the user knew what to do with (e.g. Flanger Hoax), but often implementing a very pleasing increase beyond what long-time EHX customers were used to.

The stock Bassballs certainly had a distinctive sound, compared to other commercial autowahs, but I think it could have gone much farther with an additional control or two.

Keeping costs down makes sense, I guess. And yes, another control would have helped. The Mix knob is my favorite and gets the most use from me. I can get a lot of different sounds out of it. The variable Decay is pretty handy as well.

[Freekmagnet]

Yay, got the Bassballs up and running!

The lead where R7 attached to the Decay pot broke. Ironically, I'd put a piece of shrink tubing around it, but I guess I must have heated the joint up too much when I used the side of my soldering iron to melt the tubing.

Thanks for you help, Mark Hammer. You totally pointed me in the right direction. Now I kind of have a better idea of where to find the envelop detection part of a circuit.

One last question, if you're still looking at this post: It seems like the upper sweep pot has a really small window of usability. Like maybe 20% is that normal for this circuit?

Thanks again!

[Mark Hammer]

I think its a bit more than that, but you're right in that it's NOT 100%.  Same thing in the Dr. Q.  The trimpot is useful for about 40% of its rotation.