Ive been using the Whammy for couple of months and absolutely love it, but recently its has some very noticeable channel imbalance, the strange thing is when I turn on the amp its usually ok, and after may be 30 mins of listen the left channel suddenly drops in volume significantly, i have tried switching HPs, op amps and poking the wires with a chop stick to see if any loose connections and found ntg so far. Can anyone point me to the right direction to troubleshoot this issue?
Many thanks
Many thanks
Lawil, does it stay like that? Mine does something similar at times: after a few minutes, left speaker goes mute, then back up, then mute, a couple of rinse and repeats and then everything goes fine! It dos not always happen.
On a different option: Did you built yours with pre out? Is this behavior through headphones or speakers? My headphone plug may stay “open” on certain unplugs of the jack as I heated the connector too much when soldering, so a small wiggle of the jacks solves the problem.
Others will have more “technical” suggestions, mine are mostly mechanical at this point.
Best,
Rafa.
On a different option: Did you built yours with pre out? Is this behavior through headphones or speakers? My headphone plug may stay “open” on certain unplugs of the jack as I heated the connector too much when soldering, so a small wiggle of the jacks solves the problem.
Others will have more “technical” suggestions, mine are mostly mechanical at this point.
Best,
Rafa.
Rafa, you are right its not really constant, the sound goes from normal , to small imbalance, and huge imbalance, and sometimes, but not very often cuts out, and comes back, i mean it definitely sounds like a loose connection some where. I didnt build mine with pre out (although i would love to but didnt manage to find the info on it) .
I am not sure what you mean by the headphone plug is staying "open"? so you resolder the headphone jack?
Sorry for my poor explanation. My headphone jack switches the pre outputs on and off. Sometimes when I pull out the headphone plug, the jack leaves the pre left channel loop “open” and no sound flows to the left channel. I have to jerk the headphone plug a bit to make the metal film “snap back” into closed position to get audio on the left channel.
If you didn’t build the pre functionality this is probably not your case.
If you didn’t build the pre functionality this is probably not your case.
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Your problem sounds like the first issue I described. Though this never happens if I let the Whammy warm up a bit. It only happens after very few minutes of starting up but I have never ended up with the imbalance being permanent for a session... it always snaps back to correct balance, so I attributed to some bias dependent upon temps or the opamp “heating up”. It may be a more serious / deep issue?
Check a few things as I had something similar happen:
1) Ensure the OpAmp is seated properly into the DIP8 connector if you are using one. Some of the OpAmps have round pins instead of rectangular ones and don't always slip in tightly. I had things not seated tightly when I first tried the Bursons which are tall and didn't fit super well around the caps and it wiggled loose causing one channel to have less gain.
2) Check your connections with your continuity meter. For example, make sure the connectors (and ground/returns) are tightly seated (or soldered solidly) to the POT, as well as the headphone jack which is easy to mess up the soldering if you are soldering directly onto the little pins. I use blade connectors and when I was assembling my first one I accidentally moved one of the grounds and viola and needed to re-crimp that one. That resulted in a loss/cracking when I moved the connector. Make sure your ground/returns show solid continuity to the star ground point too.
3) One of the top issues people have had are on solder joints. Go over your board and ensure all of your solder joints are sound. Reflow any that are not shiny. Make sure nothing wiggles in the slots that should be soldered. Use a magnifying glass. Also don't just focus on the front-end around the opamp/volume pot/headphone jack; what you describe could be loose joints further towards the MOSFETs or around the opto-couplers which could influence those components. If you still can't figure it out, post some well-lit, high-res pictures of your solder joints if you'd like folks here to put some extra eyes on them.
--Tom
It looks like was a grounding issue of some sort, it keeps make this crackling noise when i poke the white wire attaching the capacitors. Im not sure if I have done this part right, I just made a circle with a piece of wire and solder the earth from IEC and one side of the cap, and sandwich the thing to nut and bolt onto the chassis... I re done that part, the imbalance still kinda there but lessen, just a hum noise which wasnt there before with volume past 1pm now.... am I doing this part correctly?
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I had the same issue.
You can try to replace the opamp socket. Mine had worn with the repeated insertion/removal of opamps. I found the issue by pressing on the opamp when the channel imbalance appeared.
A few things that may (or may not) help much...
Your white wire / insulation is under the washer for your chassis/safety GND. Remove the nut and bolt. Scrape some of the anodization / paint / whatever from under the nut. Remove a bit more insulation from your white wire. Secure the safety GND and your white wire under the nut very well against the bare metal of the chassis. Check for very low resistance between all points intended to be at chassis gnd.
It looks like you've used Cardas (or similar) RCA jacks. From my own experience, those things are a royal B-yatch to solder properly and get a good joint. No disrespect to your technique, and it may be absolutely fine, but I'd give your AGND points a check with the meter and perhaps get your biggest iron tip just-a-scorching and retouch those. Honestly, those Cardas parts are really nice, but given how many bad joints I've made with them... I wonder if they're worth the hassle. I finally committed heresy and just used a tab for the GND vs. attempting to solder to the "notch".
Hope either or both of those may help. Enjoy! 🙂
Edited to add - make your pot shaft is grounded also (if appropriate) - that is a common issue.
Your white wire / insulation is under the washer for your chassis/safety GND. Remove the nut and bolt. Scrape some of the anodization / paint / whatever from under the nut. Remove a bit more insulation from your white wire. Secure the safety GND and your white wire under the nut very well against the bare metal of the chassis. Check for very low resistance between all points intended to be at chassis gnd.
It looks like you've used Cardas (or similar) RCA jacks. From my own experience, those things are a royal B-yatch to solder properly and get a good joint. No disrespect to your technique, and it may be absolutely fine, but I'd give your AGND points a check with the meter and perhaps get your biggest iron tip just-a-scorching and retouch those. Honestly, those Cardas parts are really nice, but given how many bad joints I've made with them... I wonder if they're worth the hassle. I finally committed heresy and just used a tab for the GND vs. attempting to solder to the "notch".
Hope either or both of those may help. Enjoy! 🙂
Edited to add - make your pot shaft is grounded also (if appropriate) - that is a common issue.
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Thanks, I attached a wire between the ground to the nut securing the HP jack , and the hum/mains noise completely gone. is this what u mean by pot shaft grounded?
still has imbalance every now and then i think i will replace the cardas jacks to normal ones with a ground lug so see if that problem goes away . thanks a lot
It looks correctly wired BUT I can see some frayed wires - esp on the positive of one of the inputs. I'd redo all of that and then test.
--Tom
I've found that with those types of jacks that applying a dab of rosin to the inside of the "cup" on the positive and then dipping the stripped end of the wire that is to be connected into the same rosin creates a solid solder joint every time. I then slip shrink-wrap tubing over that which is more to help with the strain relief of the wire than for any insulating purposes.
--Tom