Small Clone chorus produces distortion

[Pushtone]

Finished the Small Clone Chorus from Tonepad.com.  Tonepad Heladito Small Clone Chorus with 10k depth pot mod.

I was just about to post a problem report about how the sound is chorused but with an unpleasant distortion ( harsh breakup) when I decided to poke at it one more time before hitting the submit button. Well guess what... The distortion seems to be related to putting pressure on the 100k trim pot.

When I adjust the trim to the point where the chorus can be heard I also get this harsh distortion. If I turn the trim some so the chorus is not heard the distortion goes away but so does the chorus. But get this... If I place the trim to the spot where the chorus is heard and apply a small amount of downward pressure on the trim with the tweaker, the distortion is gone and the chorus works! Remove the tweaker screw driver and the distortion is back! This happens both with the depth pot turned full counter - clockwise (dry sound but distorted) and full clock-wise (chorus sound with distortion).

I did desolder this trimmer from another PCB, but before that it was new. Yes I have tried re-heating the solder points of the trim and the components around it. Of course I don't have a replacement AND it's a long weekend here in CANADA so I won't be able to get another till Tuesday night after work.

I've heard of heat damaging IC and transistors, but trim pots?

In the mean time... anyone have this experience before?

Pushtone

[Mark Hammer]

If you have identified the trimpot setting that provides the optimum bias voltage to the BBD, but can't seem to "hang onto" it, consider replacing the trimpot with either a better quality trimpot or with a pair of fixed resistors that mimic the same values.

From the sounds of it, you have a triompot with intermittent contact on the wiper.  It may be as simple as shpritzing some contact cleaner in there, but chances are it is just a bum trimpot that needs replacing.

[Pushtone]

Got a replacement trim pot and that fixed the problem with the distortion. Small Clone Chorus works well now, but a little noisy.

There is a hiss that pumps with the rate knob. When rate and depth are set at max the hiss turns into a thumping sound.

Is this normal for the Small Clone Chorus?

Pushtone

[Bucksears]

I'll let you know. I'm finishing up with a Small Clone build (#2) that I'm replacing for my cousin when the first one crapped out on him.
From what I remember during the brief period that it was working, it was very quiet.
I'm almost envious when comparing it to my original CS9, but I love the thickness that the Ibanez makes.

- Buck

[Pushtone]

After playing throught The Small Clone (and my other pedals) for a week now I have to say its a little noisy on it's own.

I can get rid of the hiss when I boost the input into the Small Clone with a clean boost pedal and turn down the amp volume to compensate.

Perhaps this unit could use a buffer on it's input to boost up the level and improve it's S/N ratio.

One note about the hiss I'm getting... It's a constant hissssssss that does not change as I turn the Depth pot from full counter clockwise to full clockwise.

[Bucksears]

That's odd; I'm still tweaking my rebuild and my big problem is the fact that the chorus isn't consistent. It's like the effect will pause, then swirl, then pause. I'm going to remove the delay pot I had in there because it's not doing a whole lot for me and I think that might be the problem.

Other than that, this thing is extremely quiet. (no popping when switching like last time)
I probably won't build one for myself, it's a PITA to get it running correctly.

[Bucksears]

UPDATE:
I had ordered a MN3007 replacement (NTE1641) from Mouser and put that back in. I think I fried my MN3007 just enough that it wasn't working 100%; the NTE1641 works fine.
I swapped out a couple of double-resistors (2 together to sum up to one value) for true value singles and replaced the 100k trim.

Sounds great, chorus is working great, the delay is an interesting bonus for some 'out there' flavor. Check your wiring and values of all parts; it's a great sounding chorus.
I'm not sure if others are having this issue or not, but my rate pot doesn't do much until it gets to the last 75-100%.

[Pushtone]

A replacement for the MN3007?!? I got excited too fast, at $9.68 its not a CHEAPER replacement. I'd build another if it weren't for the cost. Total for mine around $68.00 in parts and shipping.

I have mine right here... The rate knob is smooth and even from slow to fast and sounds like a sine wave to me. The depth knob is smooth and even too. I didn't do the delay mod. When both controls are maxed there's a helicopter "chopper" noise of hiss and a thumping sound. But this setting is extreem!

Yes, My Small Clone sounds very good. Great project, Well worth the effort, and fits in a 125B enclosure. More input gain makes my hiss go away and dosen't cause distorion in chorus. Its got good headroom. I'm still playing around with gain stages. For now I boost it's input and turn down amp to compensate and the hiss is virtualy gone.

I wonder if an 18VDC version would have better headroom?

[Pushtone]

Here are some pre-paint photos of my Small Clone. The Tonepad layout fits nicely in the 125B box with GGG style connectors.



Here is the wiring I used for the depth pot mod as best I could figure as per the instructions.



I was just compairing it to a barrowed Digitech RP80. No contest here, Small Clone had character and presence, RP80 processed and one dimensional. Wish I has a EH chorus to compare with.