owlexifry
Well-known member
- Build Rating
in this build story you’ll get to hear all about a monumental oversight that nearly ended up being a troubleshoot thread. but after finding the error, it made for probably the strangest troubleshooting experience ive had yet.
chorus is probably my favourite and most useful modulation effect.
have had a CE-2 build on my board since i built one. clean, driven, in front of high gain channels and clean, it all works.
didn't really need another chorus, initially was keen to grab an old chap flanger from lectric fx, but i dropped this karaoke chorus pcb in the cart while i was there.
wasn’t sure what to expect, but yep, this is a very pleasant chorus.
so far i think i like it better than the CE-2.
as everyone says, it is smoother, and somehow feels a little more ‘3-dimensional’.
comparing schematics, other than the obvious differences, including the pre- and de-emphasis filters, it appears CE-2 has 50/50 ratio mix (47K/47K) where CE-1 has a different ratio (20K dry/8K2 wet), maybe... but i have no idea, i guess it would depend on the gain of the wet and dry signals.
as per SOP, here’s a demo, running in front of amp, using normal (clean) and overdrive channels:
i love the sound.
and i never thought i’d like the vibrato. i think it’s awesome. no issues with rates here.
and particularly the vibe mode with dry signal mixed , basically a fast chorus - i’m all about it, sounds delightful.
i guess previously it was never done properly on my CE-2 with a switchable ‘vibe’ mod (just cuts dry signal).
cos after trying this karaoke chorus build, im assuming a sine wave LFO is essential to a smoother vibe (as opposed to triangle wave LFO on chorus)
but there’s one problem with this build.
i didn’t notice it until i used the overdrive channel, as i normally do with the CE-2.
compared to CE-2, sweet merciful crap, there is a concerning amount of idle noise with the effect engaged.
clean channel, it's less noticeable, but on the overdrive channel, it took me by surprise. it just about oscillates when i use middle position. (bridge position doesn't oscillate).
if you listen closely right at the end of the demo above (3:23), you’ll hear the noise.
there’s no noise in bypass, so i assume it’s not the I/O leads picking it up.
looked at the bias trim again, and noticed i could make the noise disappear, but this also made the chorus/vibe effect disappear. (with the trimpot - dialing out the effect proportionally dials out the noise).
i tried swapping in a TL022, but that just made spaceship sounds
so put the LM358 back in, and just letting it be for now. i’ll see how it goes at volume at band practice and decide if it’s bad enough. little bit disappointed with that, but for clean channels it’s far less of an issue.
troubleshoot story time:
so when i first fired it up, only the vibrato and wet modes appeared to function.
chorus mode wasn’t chorusing. the LFO indicator LED was consistent with this, flashing for the vibe and wet modes, and just staying lit for chorus mode.
adjusting the bias wasn’t helping, it would operate for the vibe modes, but nothing was happening for the chorus mode.
i was confounded. wtf.
tried a fresh TL022 in place of the LM358, no change.
attempted to probe the lfo outputs on the LM358 to confirm oscillation action, and didn’t really get far.
looked for errors, looked again, looked some more (and goddamn is it difficult to identify resistors when they’re upright/bentover like this).
i was convinced i had made an error in the LFO section.
so i desoldered and pulled nearly all the resistors from the LFO section to check and confirm i had correctly filled the board.
no errors. wtf.
then checked the reference voltages, and that’s when i was like hold on…..
then checked the supply to the LF353s… ohhhhh…
then the regulator, charge pump, and ohhhhhhhh shit, none of the voltages were right.
so with 8.96v supplied to the jack, LT1054 pin 8 was idling at 8.6v, and then after the x2 5817s, the regulator (78L15) input was seeing about 6.xx volts. output a tad less, around 6.x volts.
so everything was running on about 6 volts
(and reference / bias voltages even less).
holy shit (no wonder it was sounding a bit crap)
i just couldn’t believe that the circuit would be able to run at all like this. what.
and how was it even vibing like that?
so i flipped the board and there it was, spotted immediately, pin 3 of the LT1054 socket was missed. i hadn’t soldered it in.
addressed that, put the LFO resistors back in, and heck yeah, we were in business.
- 8.96V at pin 8 LT1054, 16.7V at regulator input, 15.0V at the output. 14.79V for the audio opamps (LF353). much better.
the moral of this story is to always check the basics first.
after getting that fixed and running, i thought i was done, but then my poor choice of rate LED had to be fixed, i had a UV waterclear in there, way too bright and dazzling, i couldn’t stand it, so i replaced with a standard red, much nicer. honestly im not sure why the 5088 driver for the LED needs a 15v supply, seems excessive.
chorus is probably my favourite and most useful modulation effect.
have had a CE-2 build on my board since i built one. clean, driven, in front of high gain channels and clean, it all works.
didn't really need another chorus, initially was keen to grab an old chap flanger from lectric fx, but i dropped this karaoke chorus pcb in the cart while i was there.
wasn’t sure what to expect, but yep, this is a very pleasant chorus.
so far i think i like it better than the CE-2.
as everyone says, it is smoother, and somehow feels a little more ‘3-dimensional’.
comparing schematics, other than the obvious differences, including the pre- and de-emphasis filters, it appears CE-2 has 50/50 ratio mix (47K/47K) where CE-1 has a different ratio (20K dry/8K2 wet), maybe... but i have no idea, i guess it would depend on the gain of the wet and dry signals.
as per SOP, here’s a demo, running in front of amp, using normal (clean) and overdrive channels:
i love the sound.
and i never thought i’d like the vibrato. i think it’s awesome. no issues with rates here.
and particularly the vibe mode with dry signal mixed , basically a fast chorus - i’m all about it, sounds delightful.
i guess previously it was never done properly on my CE-2 with a switchable ‘vibe’ mod (just cuts dry signal).
cos after trying this karaoke chorus build, im assuming a sine wave LFO is essential to a smoother vibe (as opposed to triangle wave LFO on chorus)
but there’s one problem with this build.
i didn’t notice it until i used the overdrive channel, as i normally do with the CE-2.
compared to CE-2, sweet merciful crap, there is a concerning amount of idle noise with the effect engaged.
clean channel, it's less noticeable, but on the overdrive channel, it took me by surprise. it just about oscillates when i use middle position. (bridge position doesn't oscillate).
if you listen closely right at the end of the demo above (3:23), you’ll hear the noise.
there’s no noise in bypass, so i assume it’s not the I/O leads picking it up.
looked at the bias trim again, and noticed i could make the noise disappear, but this also made the chorus/vibe effect disappear. (with the trimpot - dialing out the effect proportionally dials out the noise).
i tried swapping in a TL022, but that just made spaceship sounds
so put the LM358 back in, and just letting it be for now. i’ll see how it goes at volume at band practice and decide if it’s bad enough. little bit disappointed with that, but for clean channels it’s far less of an issue.
troubleshoot story time:
so when i first fired it up, only the vibrato and wet modes appeared to function.
chorus mode wasn’t chorusing. the LFO indicator LED was consistent with this, flashing for the vibe and wet modes, and just staying lit for chorus mode.
adjusting the bias wasn’t helping, it would operate for the vibe modes, but nothing was happening for the chorus mode.
i was confounded. wtf.
tried a fresh TL022 in place of the LM358, no change.
attempted to probe the lfo outputs on the LM358 to confirm oscillation action, and didn’t really get far.
looked for errors, looked again, looked some more (and goddamn is it difficult to identify resistors when they’re upright/bentover like this).
i was convinced i had made an error in the LFO section.
so i desoldered and pulled nearly all the resistors from the LFO section to check and confirm i had correctly filled the board.
no errors. wtf.
then checked the reference voltages, and that’s when i was like hold on…..
then checked the supply to the LF353s… ohhhhh…
then the regulator, charge pump, and ohhhhhhhh shit, none of the voltages were right.
so with 8.96v supplied to the jack, LT1054 pin 8 was idling at 8.6v, and then after the x2 5817s, the regulator (78L15) input was seeing about 6.xx volts. output a tad less, around 6.x volts.
so everything was running on about 6 volts
(and reference / bias voltages even less).
holy shit (no wonder it was sounding a bit crap)
i just couldn’t believe that the circuit would be able to run at all like this. what.
and how was it even vibing like that?
so i flipped the board and there it was, spotted immediately, pin 3 of the LT1054 socket was missed. i hadn’t soldered it in.
addressed that, put the LFO resistors back in, and heck yeah, we were in business.
- 8.96V at pin 8 LT1054, 16.7V at regulator input, 15.0V at the output. 14.79V for the audio opamps (LF353). much better.
the moral of this story is to always check the basics first.
after getting that fixed and running, i thought i was done, but then my poor choice of rate LED had to be fixed, i had a UV waterclear in there, way too bright and dazzling, i couldn’t stand it, so i replaced with a standard red, much nicer. honestly im not sure why the 5088 driver for the LED needs a 15v supply, seems excessive.
