Death by Audio - Apocalypse  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Bazzu69
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Post by Bazzu69 »

...try now 2M2 in place of the new 910k resistor. If the signal increase you can try tu put more bigger value resistor till reach the quite signal level. The only problem is the signal/noise ratio, in this way its coming worse, but you can try for reach the good and simple sond withouth any kind of booster or complicated circit design.

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Bazzu69
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Post by Bazzu69 »

Between the two transformers, who the one is better in sound?

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Twilightzoneelec
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Post by Twilightzoneelec »

This thread is totally dead but I wanted to recreate this but create some new modes for this circuit, so I designed a PCB for it.

Note: I had the original pedal by DBA so I remember how each mode sounds, this was a staple pedal for me for years.

The 2 new modes I added work great. One setting is a bumble buzz style circuit, and the other is the HM2 tone stack section. Both work fine and sound amazing.

X1000 works well too. Sounds exactly like the original and functions similar.

Having trouble with the scooped mode as well. Mine gets very compressed and squashed with the tone knob at certain settings, then at other tone knob positions sounds normal, however it is low gain, and low volume. On the original pedal, this mode was much quieter than the rest, but still had quite a bit of gain. Mine has not nearly as much gain, but I don’t have MPSA06 or 05 around. I used 2n5089 and mpsa18 and both sound the same.

Square wave mode on mine is not how it was on the original, on my PCB it is much lower gain and almost sounds like it has a dry blend to it, and the fuzz is more in the background. I checked the schematic and cannot find any errors that would lead to this. Pin 3 and 5 of the 072 are both going to the 10k voltage divider.

The octave mode is flat out strange. There’s a bit of high end hiss, I tried 1n4148 and BAT85s, the Bats sound a bit better, but this version is a lot higher gain and has much more output than on my original apocalypse. On the original pedal, the octave mode had about the same volume drop as the scooped mode. Also, sounded pretty Octavia like. My version had way more output, and is way more noisy, and has somewhat of an octave up sound but it’s more like a very noisy fuzz. Definitely sounds not very much like the original.

I did not do the normal muff mode, so can’t say anything about it.

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thomasbe86
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Post by thomasbe86 »

Hi Twilightzoneelec, can you provide with the schematic of yours, sounds like there could be something in the interactions between the modifications and the original circuit, bumble buzz/super fuzz scoop is intense, the added tone stack and scoop mode may interact together

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Churro Lightyear
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Post by Churro Lightyear »

Twilightzoneelec wrote: 16 Nov 2023, 00:41 This thread is totally dead but I wanted to recreate this but create some new modes for this circuit, so I designed a PCB for it.
Hey, I'm also going to try to revive this a little bit I think it was Johnk's layout I was looking at that I built and tweaked it around mainly on the scoop the square and the twang (I'm pretty sure it's supposed to be like an octave fuzz type deal) I was having trouble getting the clang level and it does sound kind of funny. I like the sounds of the of the apocalypse but I have none of my own and the sweeping bandpass filter is what I really really like about it. All of that's working good, haven't tested the scoop circuit yet and I'm short one IC which I swapped to test out the "x1000" noisey circuit and then just now the "clang" Clang sounds okay but it's the only one that's really low I tried dropping that resistor value from 220k to a much lower value but I realized that made it worse. For the square I swapped out one of the resistors for a 12k much lower value and it's somewhere around the same ballpark.

I used Johnk's layout and made a pcb from JLC (hope that's alright I'm not a distributor or anything) and got a UV printed and drilled unit from tayda. I wanna get a somewhat level and most importantly good sound and leave everything for future folks wanting something relatively close to the apocalypse cause this one took a little digging getting here. I don't have an apocalypse but from what I've seen online it looks like it's all surface mounted components (disregad that it looks like theres a throughhole version literally on this thread lol I saw one on reddit that was clearly not though) with a lot of vias, all pretty much stuff that might make it a little hard to fit into a 1590bb.

I got it to work and I put the clang circuit somewhere on the other side but with that and standoffs, putting the elec caps on the other side of the board and trimming unused legs on my input jacks it fits very tightly. I'm almost 100% certain with a board mounted rotary pot that it all could fit easily in a 1590bb with through holes on a 2 sided pcb. Don't remember if 16mm alpha pots have the same height as a through hole rotary switch or not. I added standoffs holes to the corners of the board and used the tallest ones I had and had 4 holes pre drilled on the enclosure to get the board in there. I had to wire and then bend the rotary pot's legs out (I used a solder lug pretty big switch) On the pcb I took the 0 ohm resistors and just connected those on the back side and made small ground plane between the standoff screw holes and the grounded parts of the pcb. The clang is just on perfboard and is kinda dangling in there right now, need to add some sticky to it.

PCB came out fine, got it done up fast from jlc and everything so far works, just some values need tweaking. Haven't tested the scoop yet and need to work around with some values to bring that clang way way way up. I swapped the 22k i believe for the 910k in the scoop beforehand to see how that works

update***
Got the scoop circuit in with the 910k swap. a tad lower than the fuzz war and square (which I swapped a value to get this up to the fuzz war) clang circuit feels way way off though I used some spare tl002's and the tm002 looks like nearly the same part with a size and the resistances a little different. I played around with the resistances and 220k feels fine I'm pretty sure it's down to the diodes. I put 2 1n34s in parallel with the 4148s and it got louder but I may just swap them out for a different low resistance shottky diode (I dont have bat45s atm) or something and see how that sounds. The octave is kind of there but the whole sound feels way way off.

Update again *** I'm gonna look here on moonn's octave clang https://moonnelectronics.bigcartel.com/ ... the-octave
So with this layout and most other layouts online of just the octave clang, there's a few differences obviously from having their individual pots. The tone/shape knob sweeps between a 10n and a 100n capacitor, the gain knobs max range is 68k ohms from the 741s input to output. 220k feels like a pretty good midpoint and finally the capacitors I see everyone use is 4.7uf electrolytics not ceramics, which I used. (not sure how important that is honestly, could be vital could be nothing) I'm going to play around with the cap values and swap out the ceramic with an elec cap tomorrow. Also I want to find a different diode than 4148s, moonn says try 1n60 so I'll give that a go. I know the bandpass filter stage is before the input but I got a feeling that I might be able to get the higher harmonics to come out by swapping that 100nf cap. And of course to swap my 4u7 cap with an electrolytic one. On the picture in this thread, I'm certain that's where that 3rd electrolytic cap is headed

I'm going to swap the 4.7uf with an electrolytic, switch the 100nf to a 10-47nf, swap the 220k to a 68k, swap the diodes with a 1n60s and hopefully that'll make it come alive. I'll do the 220k to 68k last and then before that try the caps.

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Churro Lightyear
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Post by Churro Lightyear »

Okay so I'm back I swapped the cap with an electrolytic, swapped the 100nf to a 10nf and It sounded too off for me and tried a 33nf. The diodes are probably the biggest blame, could've sworn I had some 1n60s but I just swapped them for just shottkys and it sounds off but it's definitely louder and more present as an octave fuzz. Still, I don't know if it's my pickups or not but It feels the whole drive feels a little off and some things kind of sound like there's the clean tone blended in. The 220k is the best value imo for that resistor, any bigger and it is too noisey and self oscillates and any smaller and the volume drops too far. I feel 1n60s or something close may complete it, the internet tells me to try 1n34as but I didn't like those near as much

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