Hello! I recently built the Glasshole and am getting LFO tick, both with the effect on and in bypass.
Does anyone have experience with this? I'm hoping I can just add another cap to the LFO circuit to take care of any transient spikes.
Thanks!
James
I had this also and I fixed mine by moving the 2 jumper wires on the PCB closer to the case and away from the 470nf cap that is close by. That cap does not like those wires close to it.
Hello.
I've got the same problem with mine, but the LFO ticking is only present on the 6 and 8 stage settings, is not something that is made more or less present with higher/lower Depth and Feedback settings, it's not made more or less present with a buffered effect before or after it and also is not bleeding thorough in bypass. Not affected in any way by moving the short flying leads. No more or less present whether it is in the enclosure or out of it. It's simply a very consistent tick that is of a tolerable volume - at least in slow settings (not any less present, just fewer of the ticks trying to tick me off) - but loud enough that it is pretty much unusable at higher rates of speed. It's not louder than the guitar when picking/strumming, but letting a chord die out is going to reveal the problem within seconds (as soon as the guitar level starts to drop).
But it's quiet as a mouse in 2 and 4 stage mode, and fortunately, the higher speed settings are more useful to me with fewer phase stages anyway, so if I can't get this resolved I'm still going to be extremely happy with this build.
What I've done so far:
a) Checked voltages - everything is in line with the published voltages. Grounds at jack are good. Grounds from board are good (or I'd not be phasing, presumably).
b) I've tried moving the two jumpers by C18 as suggested. Mine were originally both very short an on top of the board. I've tried very short ones under the board (without success), then tried longer (2") loop under the board, giving me something that can be moved around. Moving them around makes no difference.
c) I've now disconnected the leads connecting the jack's tip to the board and board to switch and replaced them with shielded straight runs from jack to switch (shielding connected at the jack sleeve lug). Moving them around makes no difference.
Overall, the build seems super stable to me - I guess I'm used to building gain devices where you get all kinds of noise/radio/squelchy stuff with the back plate off, while poking around inside and moving wires (and where I can fix things like this by doing so - I've never resorted to using shielded wire in a build). This thing is completely silent and stable in or out of the box and moving wires or putting my hands on the board don't seem to affect it adversely at all. Other than the tick, it's as clean/clear as anything I've made.
Being that I'm not at all at the level to understand this circuit, I've now exhausted my knowledge on how to fix it. So with brain failing me, I've resorted to using my eyes and I see that:
1) my 470nf cap C18 itself is larger than ideal (both of them, actually). It's a 100v cap and has one leg bent inward/under it to reach the hole and the cap is therefore extended further out toward the light shield than it would be if I'd used a smaller cap, but since moving those jumpers and tipping this cap forward/backward don't show any indication of a change for better or worse, I expect my issue is not here. I'll order a smaller caps anyway and see what happens.
2) I did use the four non-essential/visual-only LEDs for the "stage" indicators, each a different color (all diffused) and I notice that the blue LED used for the 6 stage setting doesn't ramp on/off as smoothly as the rest - it comes on and drops off a little more abruptly and is brighter than the rest. Given that this LED is not on when the ticking is present on the 8 stage mode leads me to believe this is a non-issue.
Regarding components: I used all 1/4 watt resistors standing on end where required. One small ceramic and maybe 15% of the resistors are carbon film. Most of the 6n8 caps were greenies purchased from Jameco on a whim and I've not tested them. Everything else was the normal "good stuff" from Smallbear or the specific items from Mouser listed on the BOM.
Any suggestions would be most appreciated.
So enough of the complaining/troubleshooting for a minute. Let me give a big thanks to Brian and bangerang101 for making this project available. I foolishly sold my own Mutron Phasor II many (many) years ago and this is by far the closest I've come to replacing it and closer than expected. I've been building pedals for years but haven't really advanced my electronics too far. As such, I can still believe in magic when it comes to gear and the Phasor II is a magical thing to me and I expected this build to result in a working phaser that was cool and worth building (as all phasers are), but without any expectation that it would hold a candle to my recollection of how it felt playing the real deal at loud levels with the sound filling the room. Well, it definitely does (hold said candle). The quality of sound of this build is fantastic. I had a chance to A/B it against my brother's Phasor II while tuning mine and found it to be very similar. Not quite as loud and a bit less roomy/spacious sounding as the original - didn't seem to inhale the guitar as much (not quite as much headroom maybe?) - so the feel is different, but the sounds the Glasshole produces are somewhat more clear/refined sounding overall and the richness and smoothness of the sweep plus the (controllable) vowel-y content are beautiful and exactly what I'd hoped it to be. I can now kick myself a little less vehemently for selling my original.
I'll get mine out tomorrow and take another listed to see if I can hear any ticking.
It's not unusual to get some "pulsing" in analog modulation pedals. This is unavoidable since amplitude changes will carry the noise floor of the circuit to the output. However, there should not be any kind of hard transient (like a click) with that and certainly not in bypass. There are some steps to take but let me listen to mine again to see if I can identify a problem.
I just reread my original post and I mentioned that it was a "continual" ticking and should clarify. That is only the case at higher speeds. When at slow speeds I hear two tick/thumps - one at the peak of the sweep (peak of the indicator LED brightness) and once at the bottom of the sweep (well after the indicator LED has turned off).
I've also spent some more time today listening to it with the amp up loud but without a guitar in hand - just listening. The tick/thump is absolutely not present at all on the 2 and 4 stage settings.
The volume of the tick/thump is a little less than what I get when switching between the different stages with the rotary with the effect active (neither are sounds that worry my in terms of speaker health - unlike the pop from engaging either of the Phase 45s I've built, but that's another discussion altogether).
The overall hiss (and its low end content) and the click/pop when engaging the effect are all very negligible. In other words, it is hard to believe that I've miswired something, used an incorrect part value or that I have a bad solder joint as everything really seems to be working as expected other than the tick at the top and bottom of the cycle of stages 6 and 8.
If there is any reason to think that the ICs are to blame I can swap them around but I'd prefer not to pry them out of the socket arbitrarily.
Circling back to this an apologies for taking so long. You are absolutely right there is ticking in bypass. For me, I had to turn my amp to full volume to hear it. The ticking is quiet but it is there and that's not acceptable. Also, I can hear it no matter what stage is selected so this is coming directly from the LFO.
So, I'm going to look for a solution. It might be through using a different IC for the LFO or using shielded wire on the I/O jacks. The extra flashing LEDs could be an issue. I'll work on it today and report back soon.
Okay I think I've identified the problem and solution. It's the proximity of the Rate control to the I/O connections at the top of the board. This was a bad design decision on my part and it became obvious after I realized the issue. So the solution appears to be re-routing the tip connections directly from the jacks to the 3pdt (grounds can be left as they are). I couldn't hear any ticking after doing that.
Unfortunately, while I was messing around with my build my little expression jack contacted the enclosure and I fried the whole goddam LFO somehow (there was smoke). So I need to pull the board out, repair it then put everything back together before I can sign off on the rewiring being the only thing needed (pretty sure that's the case but I won't jump the gun). I'll do that as quickly as possible.
Wow, magic smoke.
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Quote from: jimilee on April 23, 2021, 03:17:40 PM
Wow, magic smoke.
Indeed. I actually did blow up the entire LFO. I had to replace the two diodes, LED and 2n4401! When you start moving hardware around on a powered pedal you are asking for trouble.
Anyway, I have confirmed the solution 100%. It just needs the tip of the Input and Output jacks rewired directly to the 3pdt. No ticking whatsoever now. I will update the doc tomorrow with the correction, make a new wiring diagram and update the build pic.
Quote from: madbean on April 23, 2021, 04:41:55 PM
Quote from: jimilee on April 23, 2021, 03:17:40 PM
Wow, magic smoke.
Indeed. I actually did blow up the entire LFO. I had to replace the two diodes, LED and 2n4401! When you start moving hardware around on a powered pedal you are asking for trouble.
Anyway, I have confirmed the solution 100%. It just needs the tip of the Input and Output jacks rewired directly to the 3pdt. No ticking whatsoever now. I will update the doc tomorrow with the correction, make a new wiring diagram and update the build pic.
Yep, I did that to a GGG phase 100, never did get it working again.
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I took another listen to mine again today and found that with the amp cranked fully (low watt amp) I could indeed hear some clock noise in bypass after all (mine already has straight runs from the tip of the input/output jack straight to the switch with shielded cable) but this was only when it was in the middle of a long chain of DIY effects powered by a single One Spot, two of which have charge pumps in them. Asking a lot from the One Spot for sure. When I took half of the downstream effects out of the picture the clock noise in bypass became very negligible but still there. When I reduced the chain down to where the Glasshole was the only thing being powered by the One Spot and it was the only thing between my guitar and the cranked amp there was no clock noise at all on any of the various "stages" settings (again, in bypass). So in that way I'm good to go.
However, I still do have the issue of the clock noise in non-bypass mode on the 6 and 8 stage settings. Testing for this issue has primarily been done with the Glasshole isolated - alone on the One Spot, no other FX in the chain, but of course it is also present when it was in the chain as well. The clock noise present across multiple amps, multiple guitar cables. Also present when powered by a 9v battery rather than the One Spot I mentioned earlier. I'm sure that some of my tests are no more than shots in the dark and have nothing to do with the actual issue, but I figured that I'd rule out what I could before posting again. Let me know if you have any recommendations of what I should try in order to track it down and lessen or eliminate it.
Bump :)
My tip: IC4 that creates trigger of LFO - block it at power pins 4 and 11 with some little cap 47-100nF against ground. Straight at PCB side, at very pins output.
I would like to know too, if that negative power supply IC5 LT1054 has sufficient current output for those circuits attached there. Maybe is too weak to hold it.
Thanks for the reply Zerro
I tried what you suggested with a pair of 100nf caps and it didn't help, unfortunately.
I also tried a few other things:
a) Disconnected the rate status LEDs from the offending stages (6 and 8). No difference.
b) Replaced my large size C18 with a smaller, lower voltage version of the same (thinking that the large one was acting as an antenna). No difference.
c) Wondering if my plastic light shield's tie-down harness (thin metal wire) was acting as an antenna, I removed it and held the light shield in place. No difference.
d) I then removed the light shield and the ticking stopped. Of course, my swooshing also stopped. I can make it fade in/out by blocking the light that reaches the LDRs and if I do this after first strumming the guitar, the instrument's signal is completely audible, just without any phasing (or ticking) until I start bringing in the light shield.
Also, for what it's worth, I ended up using a diffused green LED for the lamp as it was my closest in value to the 520 nm mentioned in the build doc.
So the ticking is audible only when Phasing is audible. Does that narrow it down to any particular set of components?
And again, my issue in is non-bypass mode only. I clarify that again as it doesn't match the Subject line of this thread. Let me know if it is more appropriate to open a new thread rather than convoluting this one further.
Thanks
I just tried a few more shots in the dark one at a time, all without success.
Repositioned the power lines away from the rate pot temporarily
Tried a different LT1054
Swapped the positions of the TL074s in IC1 and IC4
Re-flowed the solder on the components in the neighborhood of IC1 and IC4 and the LDRs
Played with the trimmers - sweeping these around had no effect on the amount/level/quality of the ticking.
Putting my finger on the Rate pot lug 3 (connects to IC4 pin 1), the quality of the ticking does not go away or even really drop in volume, but it does change in quality (less full-frequencied, cuts some low end out of the signal).
Admittedly, that's some willy nilly troubleshooting and definitely where I draw the line today or I'll end up breaking something irreparably.
Also possibly of note: I used all 1/4 watt metal film resistors, so I have very few resistors lying flat to the board. All of the resistors running alongside IC4 have their tall end up in the air right next to IC4 and the flush-to-board end is therefore on the side by the Depth pot.
Noise gate, that'll fix it. A decimator.
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It is clear, that this tick is VF noise - so,
- at first try heavy duty batteries instead power adaptor, to be sure, that it is not problem of that LT1054 - do substitional power. Put off that LT and connect instead it baterries to +Vc and -Vc points. This will give you picture about power strenght of LT... If weak source from TL, power batteries will show it.
- second, paralelly with R40 (68k) try to connect some capacitor, cca 10-47nF. That caps around IC4, I recommended before, let here anyway. It won't hurt :@)
- third, those caps I recommended to connect to LFO IC4, connect the same way to IC1 now. You can let them here anyway too. Use 47nF or something around, you have now, but ceramic types. As for IC1, as IC4.
Some of this must help. Try all, including that IC4, or only some ot this.
p. s. The best against VF noise from triggers is to use at output wires in machine, ferritic pearls. Several turns around it will shut down most of VF. You can try it too. I will attach picture.
Gotcha - I'll give it all a try at my next opportunity and will report back in a few days.
Many thanks and enjoy your weekend
Update:
Zerro,
I've tried the following but unfortunately there has been no reduction in the ticking (which again is present only when in non-bypass mode and only present on the Six and Eight Stage settings). Granted, I'm using just my ears for this test, not an oscilloscope, but the fact remains that the ticking remains loud enough to be audible after about 4 seconds into the decay of the ringing out of a struck chord played, with no other FX in line and into a non-overdriven amplifier. There is no other unwanted noise - a nice, quiet effect other than the ticking. I still have dead silence (in terms of LFO tick) in the Two and Four Stage settings.
a) Replaced the LT1054 with two 9v batteries. This did not reduce/eliminate the ticking, so I reverted to using the LT1054/OneSpot power supply.
b) Soldered two small-sized 47nf poly caps from pins 4 and 11 to ground on IC4. This did not reduce/eliminate the ticking, so I left this in place and then:
c) Soldered two small-sized 47nf poly caps from pins 4 and 11 to ground on IC1. This did not reduce/eliminate the ticking, so I left this in place and then:
d) Soldered a small-sized 47nf poly cap in parallel with R40. This did not reduce/eliminate the ticking, so I left this in place and then:
e) Harvested a ferrite bead from an old computer keyboard and replaced my shielded output wire (running from switch to output jack) with a longer, non-shielded wire and looped it three times through the bead (the max that the bead's diameter will allow). This did not reduce/eliminate the ticking.
f) I re-flowed the solder on all of the LDRs, this did not reduce/eliminate the ticking, so I then:
g) I went back and double-checked my voltages. Everything still looks good and matches with a few mv to what Brian's build doc specifies with the exception of IC3's pin 7, which he has listed as being -10mv, but in my case, I read +12mv. Is this significant?
Note that I've not tried using ceramic capacitors for this test as you suggested. I can certainly order some if you feel that will be the magic bullet.
Given that none of this has had any audible impact and that (as I understand it) your suggestions are aimed at reducing an induced or indirectly picked up (same thing?) noise, then perhaps the problem is rather something directly injecting it or not filtering out as it is supposed to do? Is there any particular set of components whose job it is to do so? Perhaps I have a bad component or component with incorrect value? Two to four bad LDRs? A bad solder connection? Perhaps an incorrectly oriented polarized component? Given that the thing works and the voltages are all in pretty much in order tell me that the latter is not the case, but at this point I'm open to trying anything and also open to assuming that I could have done with component choices or build/soldering technique could be the culprit. Any further theories are welcome and will be much closer to the mark than what I could come up with, so bring it on!
Thanks again
Hi geetarm@n1, I am sorry, that those enhancements didn't work - my suggestion - raise values of those blocking caps (100n, 470n) but surely try those ceramic caps. It will be about to "fit up" proper timing. It is good to let them there - it can't harm anyway :@) At g) item, 12mV is ok.
Hi freq noise is very tricky, and many etchers trying rid it off, but it was always about penetrating VF ticks to power. Professional machines doesn't do it, so I must admit, that maybe bad PCB concept is here. Generally, it is good to separate tracks of power lines to those problematic parts of machine, from power tracks for audio parts, and separate those LFO tracks (even at grounding side), by some little value resistors 100-47O ohms or little inductions - few turns around ferrit bar, so that sections with VF noise are slightly "floating". Then those blocking caps will work far better. See my pictures. Hapilly, there is only one source of this all - IC4. Or more preciselly, IC4a. If it is possible, maybe prepare to lift up with resistor ground of IC4, too. But then blocking caps at pins of it must be stronger - uF values. Because of stability. But it is last possibility. I hope it will help, otherwise there is none another solution I can offer now.
At real, many years ago, I built mono-phonic guitar synth based on 4046 PLL, and there was non-coherent ring modulation too, by 4011 osc, and even when VCA was closed, under that silent was that VF mod freq clearly at output. I was trying everything to separate all circuits related with it and finally helped this "floating" conception with ceramic caps blocking together - I copied it from my old walkman, where circuit for motor riding was separated at both sides of power line. So, it's noise wasn't almost annoying sound section. I used inductions at ferrite cores instead resistors, and I sucessfully shot down this VF penetration.
Zerro - you rock. Many thanks for the detailed information and know that I appreciate the lessons you're providing.
As for the caps, are you suggessing small MLCC or actual ceramic discs?
Not at all...
Use conds that you have - only respect voltage - minimally cca 16-25V
Got it. I'll reply back in a week or so once I've had time to order what I need. Thanks again.
Hallo, today I was digging in my bearhole and I finally set out this old schematic of phaser with shift 0-720°! Notice down part with LFO modulator. Here I assigned with red circles 2 points coming from power supply. In accompanying text is literally said, that those R-C sets are here to avoid getting trigger clicks to the output signal.
Interesting is double pot riding not only modulation Speed, but Depth too. For low freq, modulation is deeper, and for high is weaker - more like tremolo. Ratio you can additionally set with R37. MOS-FETs was here KF521, which was old czech details. I recommended here 2N4447, but you can try 4448 too. Or another. Chiao.
I finally had some time to sit down with this again and tried what you (Zerro) suggested in your last post.
I lifted the cathode side of D9, attached that to one end of a 120ohm resistor, then attached that where D9's cathode's pad on the board. That connects to the + of C23 and to pin 4 of IC4.
To take care of decoupling and creating a reservoir for IC4's pin 11, I added a second 14 pin socket with the pin 11 section removed on top of my original socket. I soldered a 120 ohm resistor and the (-) leg of a 10uf cap to IC4 pin 11, then soldered the (+) leg of the cap to ground. Then soldered a 1n914's anode to the other end of the resistor and inserted its cathode into the original socket for IC4 pin 11. Looked pretty questionable, but the voltage readings told me that all was well in terms of connectivity.
The result, unfortunately, was the same - tick tock still present at the same volume level it was prior.
I took a last shot at re-calibrating it and doing the chopstick trick (moving around the now shielded Input/Out leads which run from jack to switch) just for grins, but no go. I think I'll keep this thing as a great sounding 2 and 4 stage phaser and maybe try building another and see how that goes.
Many thanks for the suggestions and although I wasn't able to resolve it, I definitely have learned a thing or three in the process. One eye opener was how all of these additional components I've added throughout this process have had so little effect on the core sound - it still sounds just as rich/full as it did originally.
Still look at my post 258, I added before to this thread. Try to do it literally this way. Only resistors and caps to both power branches. Nothing more I suggest :@)
It's the sudden turn on of the op amp forming the square wave in the LFO. I think it's IC4-1 on the Glass Hole schematic. Take a look at the following link:
https://www.scribd.com/document/515633043/Stompboxology-Mo-tremlo
Look at figure 3, drawing 2. The addition of the 33nf cap and 68k resistor will solve the ticking problem of the Glass Hole. I have modded the Glass Hole the way the article describes and mine has no more ticking. Try it, you'll like it!
Zerro - I stripped the new diode out of the equation (the one I tacked on to serve pin 11) leaving just the added 120 ohm resistor and 10uf cap. The other diode D9 is board mounted (and tied to the 120 ohm resistor I added in line) I've not tried removing it, but I did jumper it. Neither of these changes affected the ticking.
danfrank - Thanks for the suggestion. I gave this a try as well on IC4-1 - which I'm taking as being IC4-A (tying a 33n between pins 1 and 2, then a 68K resistor between pins 2 and 5), then unfortunately, this didn't change the behavior.
Given that on this project, IC4-A's pins 2 and 5 are tied to ground, yet the examples shown of this 'soft square' trick from the .pdf you linked don't have these pins grounded, I'm wondering if to implement it here means that I need to lift those pins from ground a bit or something. I tried disconnecting them completely from ground (again, with a stunted row of sockets which allowed me to not make that connection to those pins of the original board-mounted socket) and that "fixed" the tick - by stopping the oscillation altogether :)
Also, here is another link to that PDF which doesn't require an account with scribd.com (it's a good article - thanks for that) - http://www.moosapotamus.net/files/stompboxology-mo-tremlo.pdf
So assuming that you are correct that IC4-A
whoops - I posted before completing my final sentence:
So assuming that you are correct that IC4-A in the Glasshole is actual the target for this fix, it unfortunately didn't work for me.
Yes, IC4-A. Too bad it didn't work for you, it totally got rid of the "tick tick tick" on my Glass hole. See attached pic on how I did it. 68k from ground to pin 2 of LM324 and 33nf between pis 1 & 2. Note that you have to take pin 2 of the TL074 out of the socket so it is no longer connected to ground. Pin 2 is now grounded through the 68k resistor. I also did what Madbean suggested and wire in and out jacks straight to the footswitch. I also shorted the traces on the PCB that originally went to the in and out jacks, since they aren't being used. I figured grounding them wouldn't hurt anything.
One more thing... The article you linked is the same one I was referring to but mine couldn't be downloaded, so thanks for linking it.
Sorry for a hijack here - Dan, did you replace the single turn trimmers on your Glasshole with multi-turn trimmers? Those kind of look like Bourns 3266w? Did you need more precision, or?
Thanks!
Dan -
Ah - I wired it up wrong the first time - never lifted pin 2 out of the socket (among other mistakes with the resistor and at pin 5). Thanks for the explanation and pic - that helped. I connected it up properly and the result is as you expected - the tick tock is now completely gone!! I'm not going to put as many exclamation points as this deserves, but believe me - I am ecstatic. I've been just sitting here listing to it swoosh through a loud amp with the guitar turned off for the last 15 minutes and it's lulled me into a relaxed out state of mind - a sure sign of clean, smooth phasing.
Thanks to all for the help, the lessons and for the project itself Mr. Bean.
Quote from: NorthCoast on September 22, 2021, 02:09:48 PM
Sorry for a hijack here - Dan, did you replace the single turn trimmers on your Glasshole with multi-turn trimmers? Those kind of look like Bourns 3266w? Did you need more precision, or?
Thanks!
Hi!
I used the 10 turn trimmers because that's what I had on hand. This project is pretty easy to dial in. Set the brightness trimmer (1k) about halfway. The offset is the important one... Set the depth pot all the way CW, Feedback CCW and rate fairly slow so you can see the full "sweep" of the LED by the LDRs. Of course this has to be done in close to complete darkness so it helps to have a light on your multimeter. Set the "offset" trimmer (10k) so the LED gets very dim (almost off) but not all the way off. Then you can tweak the two trimmers to taste. I found that adjusting the offset so the LED doesn't turn all the way off is very important.
Quote from: geetarm@n1 on September 22, 2021, 02:36:26 PM
Dan -
Ah - I wired it up wrong the first time - never lifted pin 2 out of the socket (among other mistakes with the resistor and at pin 5). Thanks for the explanation and pic - that helped. I connected it up properly and the result is as you expected - the tick tock is now completely gone!!
One more thing but I think you have already realized this... Pin 5 of the TL074 remains grounded, so it stays as is, no modification to pin 5. Only pin 2 gets lifted off of ground by the 68k resistor.
On that pdf article, I think the referenced drawing is using a single supply where as the Glass Hole uses a split supply. That may cause confusion for some.
Quote from: danfrank on September 22, 2021, 06:15:20 PM
Quote from: NorthCoast on September 22, 2021, 02:09:48 PM
Sorry for a hijack here - Dan, did you replace the single turn trimmers on your Glasshole with multi-turn trimmers? Those kind of look like Bourns 3266w? Did you need more precision, or?
Thanks!
Hi!
I used the 10 turn trimmers because that's what I had on hand. This project is pretty easy to dial in. Set the brightness trimmer (1k) about halfway. The offset is the important one... Set the depth pot all the way CW, Feedback CCW and rate fairly slow so you can see the full "sweep" of the LED by the LDRs. Of course this has to be done in close to complete darkness so it helps to have a light on your multimeter. Set the "offset" trimmer (10k) so the LED gets very dim (almost off) but not all the way off. Then you can tweak the two trimmers to taste. I found that adjusting the offset so the LED doesn't turn all the way off is very important.
Thank you!
Yes - and pin 5 turned out to be an easy place for me to ground that 68K resistor without flying its lead across other circuitry or working under the board. So the cap and the resistor just rest on top of IC4 (whose pin 2 was bent up 45 degrees and then clipped short giving me a flat spot to mount the other side of the 68K and that leg of the capacitor. Ended up looking pretty clean, I'm happy to say.
Thanks again for the tip, Dan
Hey there. I'm yet to fire mine up, but the last few posts here mention lm324, but the BOM lists TL074. Are people using LM324? I have another post asking about substituting MC33074AP in as well.
My mistake, I'll correct it to TLO74, which is what it should be.
LM324 should also work for IC4 but I did use TL074 in mine