Dreadbox Erebus DIY kit

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vertflyer
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Post by vertflyer » Sun May 27, 2018 7:36 am

csaban wrote: I think this is relevant form the documentation:

When I patch something to the VCA , i get no sound
-The VCA needs at least 3,5V so as the synth starts producing sound
So does this mean that there is full dynamic range for vca, just that I need to start an envelope at 3.5 and go to 5.0? What’s the easiest way to bias an envelope signal?

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HorseyWindpump
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Post by HorseyWindpump » Sun May 27, 2018 3:57 pm

Just finished building mine, having a lot of trouble getting it to work properly. Having a similar issue to previous users with only one of the oscillators working. The output level also seems extremely quiet - the only 'normal' output level I get is with MIX/FEED turned all the way up, but mix turned down, oscillator output is very quiet.

I've checked for obvious shorts before plugging in (between +ve, -ve and ground power pins) and no problem, so I went ahead and plugged it in.

I think there's something more fundamentally wrong with my handiwork though - doing continuity checks on all of the IC sockets' pins, I'm getting shorts to ground on:

IC10 - pin 3
IC21 - pins 3 and 13
IC26 - pin 12
OK1 - pin 6
IC5 - pin 2
IC1 - pin 7
IC8 - pin

Aside from this the ICs IC26 and IC1 get very hot just being plugged in for a few minutes. All my ICs are socketed. The voltage checks in the manual all pass fine.

Is there anything obviously wrong that means I'm getting these 0v reads? Looking at the schematics, none of the pins I mentioned should go to GND.

Is the only solution for me to desolder the sockets? Bit of a daunting task ... :doh: :doh:

Edit: having gone over the schematics alongside my work in more detail, I'm now fairly certain it's caused by tiny accidental scratches next to the solder pads causing shorts to the ground plane. I blame the stupidly small solder pads ...

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Post by oks2024 » Tue May 29, 2018 10:05 am

I just saw that the schematics are now available, that's great !
Maybe I will try to fix midi on my Erebus. So far I don't really need it, but maybe it's an easy fix, using the schematics.

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Post by Branko » Tue May 29, 2018 12:30 pm

I gotta fiddle with it again and recalibrate, cause I feel like I did something off. It sounds decent but I don't think I followed the steps properly.

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Post by vertflyer » Sat Jun 02, 2018 5:15 am

I just want to summarize some thoughts on the lil Erebus. First, I’m by no means a diy expert. I’d say an average builder with access to my dad, an electronics expert who was able to help trace down each of my four builds’ issues including a bad transistor. And that is exactly my point. I believe I was as careful as possible with each build yet 4 for 4, each build had a problem and if it weren’t for my dad, I’d be sitting on 4 non working units.

The actual build is not hard. It’s the trouble shooting that is hard.

Once it works? I’m disappointed with the way the vca works, it’s just really hard to coax a decent envelope shape response from it. Other than that, the basic sound of the lil Erebus is exactly what I wanted as a former owner of a V2. It really complements my boog well and even puts the boog to shame in terms of having a raw ballsy untamed sound. Compared to the Erebus line, the moog synths feel too clinical and perfect. I think the minimoog sound exists now only to show us what happens when you make a basic perfectly stable synth, you end up with something sort of boring. Maybe because we’ve heard it too much? The Erebus line brings fresh untamed sound to my ears and I’m just drawn to it for some reason.

The lil Erebus gets me that sound in the cheapest most basic way. And it’s worth it’s price as long as you can get it to work.

I should also add that I tried using a white line Erebus filter on my boog oscillators using the boog env outputs to control the vcf and vca (vca was also white line), and it didn’t get me to the sound on the V2 or lil. For a long time I’ve been trying to figure out what gives the Erebus line it’s amazing character. I know now it’s not just the filter. It’s not just the oscillators. I ran the lil Erebus osc into my boog and it sounded boring. It’s just something about the combination of it all. Oscillators into the Erebus vcf with some pretty quirky envelopes. Altogether you get the character. Take one away and the mojo just isn’t the same. I’m still curious about the V3, but for now the lil Erebus is doing all I want.

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Post by MGRL » Sun Jun 03, 2018 9:24 am

vertflyer wrote:
mrcase wrote:I finished my build, all working except VCO2 isn´t doing anything, same issues two other members have. Did anybody solve this?
Swap IC 1 and 2 and see if you still have vco2 missing or vco1 missing.


You mean the two first op-amp starting from left side (labeled IC10 and 21) ? I ask because on schematics, IC1 and 2 are not the same .

https://www.dreadbox-fx.com/wp-content/ ... layout.pdf


I reflowed everything and and still don't get OSC2 ( I get a click for each gate but it doesn't react to cv or vca ; click is always present even with osc level at 0 but it gets louder when i push the fader up )

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Post by vertflyer » Sun Jun 03, 2018 8:54 pm

MGRL wrote:
vertflyer wrote:
mrcase wrote:I finished my build, all working except VCO2 isn´t doing anything, same issues two other members have. Did anybody solve this?
Swap IC 1 and 2 and see if you still have vco2 missing or vco1 missing.


You mean the two first op-amp starting from left side (labeled IC10 and 21) ? I ask because on schematics, IC1 and 2 are not the same .

https://www.dreadbox-fx.com/wp-content/ ... layout.pdf


I reflowed everything and and still don't get OSC2 ( I get a click for each gate but it doesn't react to cv or vca ; click is always present even with osc level at 0 but it gets louder when i push the fader up )
Sorry. I did mean ic10 and ic21.

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Post by Mystery Hole » Mon Jun 04, 2018 2:11 am

So I just finished my build and calibration, everything seems to work, but the LFO is very slightly effecting the pitch of VCO2 which I haven’t heard anyone else mention. I’m no component expert and this is only my second DIY, I’m guessing this is most likely a short? Just wondering if anyone else had this or can suggest another possible cause to check?

In case it matters, my kit was missing one of the 47p capacitors, so I did have to sort out a match from my local electronics store.

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Post by s3nt3nz4 » Tue Jun 05, 2018 6:18 pm

MGRL wrote:
vertflyer wrote:
mrcase wrote:I finished my build, all working except VCO2 isn´t doing anything, same issues two other members have. Did anybody solve this?
Swap IC 1 and 2 and see if you still have vco2 missing or vco1 missing.


You mean the two first op-amp starting from left side (labeled IC10 and 21) ? I ask because on schematics, IC1 and 2 are not the same .

https://www.dreadbox-fx.com/wp-content/ ... layout.pdf


I reflowed everything and and still don't get OSC2 ( I get a click for each gate but it doesn't react to cv or vca ; click is always present even with osc level at 0 but it gets louder when i push the fader up )
Still got the same problem here. I changed ic21, but osc2 is still missing. Tell me i you find something...

vertflyer
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Post by vertflyer » Tue Jun 05, 2018 8:18 pm

s3nt3nz4 wrote:
MGRL wrote:
vertflyer wrote:
mrcase wrote:I finished my build, all working except VCO2 isn´t doing anything, same issues two other members have. Did anybody solve this?
Swap IC 1 and 2 and see if you still have vco2 missing or vco1 missing.


You mean the two first op-amp starting from left side (labeled IC10 and 21) ? I ask because on schematics, IC1 and 2 are not the same .

https://www.dreadbox-fx.com/wp-content/ ... layout.pdf


I reflowed everything and and still don't get OSC2 ( I get a click for each gate but it doesn't react to cv or vca ; click is always present even with osc level at 0 but it gets louder when i push the fader up )
Still got the same problem here. I changed ic21, but osc2 is still missing. Tell me i you find something...
Shot in the dark, but for one of my builds I had to swap out q5 before the osc made sound. You could try replacing q5 and or q10?

My dad measured something and immediately knew q5 was failing. Unfortunately I can’t tell you what he measured.

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Post by HorseyWindpump » Wed Jun 06, 2018 12:22 am

Question on modding the Lil Erebus - to be less of a semi modular and fit in more neatly with the rest of my modules it would be good if either GATE or ENV was normalled to always be high when nothing's plugged in.

This way it's easier to run an input through the Lil Erebus as an effects module without having to worry about patching into GATE or ENV as well.

Does it make sense to do this? Has anyone successfully done this and what's the best way to go about this? Does it make more sense to normal GATE or to normal ENV? Gut feeling is to normal ENV to be high without input but I know very little about this.

mrcase
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Post by mrcase » Thu Jun 07, 2018 6:30 am

vertflyer wrote:
s3nt3nz4 wrote:
MGRL wrote:
vertflyer wrote:
mrcase wrote:I finished my build, all working except VCO2 isn´t doing anything, same issues two other members have. Did anybody solve this?
Swap IC 1 and 2 and see if you still have vco2 missing or vco1 missing.


You mean the two first op-amp starting from left side (labeled IC10 and 21) ? I ask because on schematics, IC1 and 2 are not the same .

https://www.dreadbox-fx.com/wp-content/ ... layout.pdf



I reflowed everything and and still don't get OSC2 ( I get a click for each gate but it doesn't react to cv or vca ; click is always present even with osc level at 0 but it gets louder when i push the fader up )
Still got the same problem here. I changed ic21, but osc2 is still missing. Tell me i you find something...
Shot in the dark, but for one of my builds I had to swap out q5 before the osc made sound. You could try replacing q5 and or q10?

My dad measured something and immediately knew q5 was failing. Unfortunately I can’t tell you what he measured.

I tried all the suggested fixes, still no luck with OSC2 :(
Anybody had success fixing this issue, or could point me to another direction? Running out of ideas...
thanks

MGRL
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Post by MGRL » Thu Jun 07, 2018 9:42 am

mrcase wrote:
vertflyer wrote:
s3nt3nz4 wrote:
MGRL wrote:
vertflyer wrote:
mrcase wrote:I finished my build, all working except VCO2 isn´t doing anything, same issues two other members have. Did anybody solve this?
Swap IC 1 and 2 and see if you still have vco2 missing or vco1 missing.


You mean the two first op-amp starting from left side (labeled IC10 and 21) ? I ask because on schematics, IC1 and 2 are not the same .

https://www.dreadbox-fx.com/wp-content/ ... layout.pdf



I reflowed everything and and still don't get OSC2 ( I get a click for each gate but it doesn't react to cv or vca ; click is always present even with osc level at 0 but it gets louder when i push the fader up )
Still got the same problem here. I changed ic21, but osc2 is still missing. Tell me i you find something...
Shot in the dark, but for one of my builds I had to swap out q5 before the osc made sound. You could try replacing q5 and or q10?

My dad measured something and immediately knew q5 was failing. Unfortunately I can’t tell you what he measured.

I tried all the suggested fixes, still no luck with OSC2 :(
Anybody had success fixing this issue, or could point me to another direction? Running out of ideas...
thanks



i will try to replace transistors soon, and if it fails I guess i will change all component of VCO 2 circuit...

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Post by Morphology » Sat Jun 09, 2018 8:04 am

HorseyWindpump wrote:Question on modding the Lil Erebus - to be less of a semi modular and fit in more neatly with the rest of my modules it would be good if either GATE or ENV was normalled to always be high when nothing's plugged in.

This way it's easier to run an input through the Lil Erebus as an effects module without having to worry about patching into GATE or ENV as well.

Does it make sense to do this? Has anyone successfully done this and what's the best way to go about this? Does it make more sense to normal GATE or to normal ENV? Gut feeling is to normal ENV to be high without input but I know very little about this.

I've just tried this with both the gate input and the ENV input, and it's simple enough - I bridged the switch pin of the gate input (it's the pin closest to the edge of the board on the Gate In socket) to +5v, and there's a handy 5v available on pin 21 on the Atmega 328 / top of C100, which is right next to it.

This pulls the gate high when there's nothing plugged into it, and the gate input works as normal when you plug something into it - in many respects it seems odd they didn't do this?

The ENV Input works much the same - bridge the switch pin on the ENV input to +5v and it'll turn the Envelope level full up, though this seems much less useful, as you can achieve the same by pushing the Sustain and Level sliders full up?

Of the two, Normalising the gate input is much more useful - if you feed Audio in at the envelope stage, you'll get nothing out unless the gate is high, so normalise the gate to +5v, turn the VCO1 & 2 levels to zero, and you can run audio though the envelope & delay. You cannot separately trigger the envelope by doing this, though feeding signals into the 'Cut' input does useful things.

Normalising the gate input means the lil'Erebus can be used as a stand-alone delay with CV-able filter, and that's got to be useful, so I'm going to leave the link connected!

Morph
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Post by JAO » Sat Jun 09, 2018 8:37 am

Tuning procedure video from dreadbox:

[video][/video]

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Post by vertflyer » Sun Jun 10, 2018 4:30 am

So one conclusion I have made is that this unit is great as a mono voice, but probably not the best to use as part of a poly setup. The envelopes are a bit too limited.

I have 4 fully working lil Erebus and think that I need to let 2 of them go. If anyone is interested, pm me, preferably for someone in the US.

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Post by HorseyWindpump » Mon Jun 11, 2018 12:17 pm

Morphology wrote:
HorseyWindpump wrote:Question on modding the Lil Erebus - to be less of a semi modular and fit in more neatly with the rest of my modules it would be good if either GATE or ENV was normalled to always be high when nothing's plugged in.

This way it's easier to run an input through the Lil Erebus as an effects module without having to worry about patching into GATE or ENV as well.

Does it make sense to do this? Has anyone successfully done this and what's the best way to go about this? Does it make more sense to normal GATE or to normal ENV? Gut feeling is to normal ENV to be high without input but I know very little about this.

I've just tried this with both the gate input and the ENV input, and it's simple enough - I bridged the switch pin of the gate input (it's the pin closest to the edge of the board on the Gate In socket) to +5v, and there's a handy 5v available on pin 21 on the Atmega 328 / top of C100, which is right next to it.

This pulls the gate high when there's nothing plugged into it, and the gate input works as normal when you plug something into it - in many respects it seems odd they didn't do this?

(...)

Normalising the gate input means the lil'Erebus can be used as a stand-alone delay with CV-able filter, and that's got to be useful, so I'm going to leave the link connected!

Morph
Thanks so much - soldered in a wire as you suggested, it works a treat! Exactly what I wanted.

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Post by Mystery Hole » Sun Jun 17, 2018 10:53 pm

Can anyone confirm that with their units that VCO2 is not slightly affected by LFO square wave when nothing is patched? Thanks.

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Post by synthi » Mon Jun 18, 2018 9:39 am

Easy build!! We made it togueter with my son. All working perfect at first power up!! :hyper:



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Mystery Hole
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Post by Mystery Hole » Wed Jul 04, 2018 7:23 pm

Mystery Hole wrote:Can anyone confirm that with their units that VCO2 is not slightly affected by LFO square wave when nothing is patched? Thanks.
My resolution on this - I put the Lil Erebus into my Doepfer case and it works perfectly.

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Anothet Midi question

Post by nfip » Tue Jul 17, 2018 1:51 am

So i read all the questions about midi Problems, for me however, the tracking works, but it Just keeps playing forever ... As soon as one of the oscs is turned Up, i hear a Note, that i then can Change with the keystep, but it never stops playing :( some people seemed to have the opposite Problem (Gate but No Tracking), but did anyone find Out how to fix this one?
Thanks! You're all awesome people for helping noobs in the Internet!!!

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Post by TheDegenerateElite » Tue Jul 17, 2018 2:14 am

Built mine up and it works perfectly with no issues. Really simple build, you just have to make sure you verify parts and check again before soldering them.


That said, the sound is a bit drab imo. It seems to have a fairly narrow voice range and I don't like the general lack of control over many things that I guess I take for granted on synths. The number of CV inputs is also severely limited. It seems like sort of waste of euro space given it's limited interfacing.


Maybe it's because I got a Grandmother around the same time and that synth just kills...well most everything that has been released in recent years.

My Lil' Erebus is in it's box for now, maybe I'll dig into it again in the future or just sell it off.

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Post by Fwestivus » Tue Jul 31, 2018 5:51 am

I don't suppose anyone has done any interesting mods yet?
The obvious easy ones are 3 way switches for the LFO and envlope speeds, but other than that, is there a way to get both saw and square outputs from the VCOs? Anyone added in a slew circuit for the vcos?
There looks like a lot of space where the name is printed on the panel - if you mount the components on the other side, and use fairly short jacks there, there coule be a fair amount of room for additions.

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Post by TaTechneta » Thu Aug 02, 2018 6:34 pm

Mystery Hole wrote:Can anyone confirm that with their units that VCO2 is not slightly affected by LFO square wave when nothing is patched? Thanks.
Mystery Hole, I have exactly this issue and it almost drove me nuts just now!

I reflowed the solder on the resistors for the square LFO and the LED CLR, and also I switched places of the two TL3074s that control the two VCOs. After that, it seemed gone, but after I fixed it to the front plate and powered it up again, it had the same issue! It might depend on the temperature, I haven't fully checked that out yet, but the LFO changed VCO2s pitch by up to one quarter tone, which is a bit too much.

Also, when the bleed from the LFO to VCO2 is stronger, it also seems to mess with its timbre on higher frequencies, giving it a bit of really fast vibrato in addition to the ba-bi-ba-bi of the square wave.

I checked the board with a magnifying glass, there's no bridges that I am aware of and all solder joints seem nice to me. Could the tech heads figure out what is the most likely components involved in this bleeding? I re-soldered the three resistors on the LFO square schematics, but no joy.

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Post by TaTechneta » Tue Aug 07, 2018 12:05 pm

Quick update: re-flowing the LED resistors (R10, R11) and the sockets for IC 21 (after removing the chip) did the trick for the square LFO bleeding into VCO2‘s tuning! Although I can‘t say for sure, my best bet is on the LFO resistors not having grounded it fully, but I‘ll never know. Now VCO2 is stable as can be.

ALSO to anyone mildly interested in this synth, there is a summer sale on it right now. 110 bucks, that almost convinced me to get a second one :lol: .

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