Dreadbox Erebus DIY kit

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ludotex
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Post by ludotex » Sun May 06, 2018 8:01 am

My erebus is 3 octave lower than my other vcos.
I tried also with the mother32 getting CVs from it and mix the signal of the erebus and the mother to verify this.

Anyone know if this is supposed to be the case? A super bassy voice ? :hmm:

If this is the case anyone knows how to change this?

Also the total range of the big tuning knob goes maybe an octave where on the hades it would span several octaves. It acts more as a fine tuning on the erebus?
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Michiel
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Re: Tuning and calibration

Post by Michiel » Sun May 06, 2018 9:14 am

ludotex wrote:For the tuning, play some octave on the CV. Listen to just OSC1 and make sure you hear a real octave between the 2 notes while you tweak scale 1. Then same for OSC2. Once that is done, I matched OSC1 and OSC2 together with the tune 2 (with the "vco2" slider at middle on the panel).

For the click you can turn down both OSC on the panel to hear the click by itself.
most problems sorted - midi still not ok though.

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bagoly
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Post by bagoly » Sun May 06, 2018 11:12 am

Just finished soldering and gave it a quick test, still having mixed feelings about it though.

Positive things first:
It works, it's relatively cheap for what it offers and it actually sounds quite good as a basic mono voice.


"Mono" is the right word here by the way, i don't get why it says "paraphonic" on the front panel. The DAC output is being sent to both VCOs, so its not "duophonic" over midi like the regular erebus is (i think) and while there is a dedicated cv input for the second VCO, it seems to be added to the master pitch cv, so even if you had a polyphonic controller, you could not really play it as a paraphonic (or douphonic) synth.


EDIT: Whoops, as vertflyer pointed out, it is indeed douphonic, see post below. my bad.


Some more details: The VCA is not normalled to the envelope but to the gate signal instead, so without any patch cables in place it acts as a simple on/off switch. Thats why they named the trimmer "click", because it produces a popping noise if the gate signal bleeds into the audio path. I would have at least preferred a switch to route the envelope to the VCA.

The filter will oscillate nicely but won't track pitch very well. Delay sounds allright, pretty lo-fi like your typical pt2399 circuit.


The envelope section does not respond like the envelope generators i'm most used to: if a new gate comes in before the attack/decay cycle is finished, it won't have any effect, so if you feed it with a clock signal and raise the decay slider it will start to "skip" steps, if that makes any sense.
The range seems a bit limited (same goes for the LFO), with the default capacitor in place it's not what you would call a "snappy" envelope.

EDIT 2: By now I think there is something wrong with my envelope section, see the following posts for more details.

Overall the completed module feels pretty cheap to me, the pcb bends around 2mm if i insert a cable into one of the middle jacks. I've never seen this kind of jack before, so i don't know if it comes in a threaded version as well... In combination with the somewhat wobbly pots, the whole thing kind of reminds me of those behringer guitar pedals, to be honest. :sadbanana:

Also, i would not recommend this build to anyone who is stuck with a low wattage soldering iron like i am right now. Tiny pads, very small thermal reliefs and big ground planes on both side of the pcb made it very hard so get good joints on most of the GND pads. I reflowed some sketchy looking ones with a hot air station, even that took pretty long. (The iron in question served me very well for dozens of projects by the way, anything from smt to soldering panel components or even cables, so it's not like it is completely unusable)
I'm sure desoldering stuff will be even worse or next to impossible without ruining traces, so be sure not to skip the additional IC sockets.

Almost feels like they used EAGLEs default design rules to layout the board. The layout is not even very tight in most places, no traces inbetween IC-pins except for the Atmega, so they could have easily allowed for slightly larger pads and bigger thermal relief areas.

I really don't want to discourage anyone who's looking forward to building this kit, if you get it done you'll have a nice standalone voice with a character of it's own, but i can imagine this thread will grow into a pretty big one once everybody gets their kit.. :sadbanana:
Last edited by bagoly on Thu May 10, 2018 12:48 am, edited 3 times in total.

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Post by vertflyer » Sun May 06, 2018 12:16 pm

robin87 wrote: "Mono" is the right word here by the way, i don't get why it says "paraphonic" on the front panel. The DAC output is being sent to both VCOs, so its not "duophonic" over midi like the regular erebus is (i think) and while there is a dedicated cv input for the second VCO, it seems to be added to the master pitch cv, so even if you had a polyphonic controller, you could not really play it as a paraphonic (or douphonic) synth.
I thought dip switch 4 switches the unit from unison to para. Have you tried that switch?

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Post by bagoly » Sun May 06, 2018 12:43 pm

vertflyer wrote:
robin87 wrote: "Mono" is the right word here by the way, i don't get why it says "paraphonic" on the front panel. The DAC output is being sent to both VCOs, so its not "duophonic" over midi like the regular erebus is (i think) and while there is a dedicated cv input for the second VCO, it seems to be added to the master pitch cv, so even if you had a polyphonic controller, you could not really play it as a paraphonic (or douphonic) synth.
I thought dip switch 4 switches the unit from unison to para. Have you tried that switch?
Wow, thanks a lot! i completely missed that, i even used the dip switch for setting the midi channel without noticing! Sorry for the confusion :doh:

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Post by vertflyer » Sun May 06, 2018 12:49 pm

robin87 wrote: Some more details: The VCA is not normalled to the envelope but to the gate signal instead, so without any patch cables in place it acts as a simple on/off switch. Thats why they named the trimmer "click", because it produces a popping noise if the gate signal bleeds into the audio path. I would have at least preferred a switch to route the envelope to the VCA.
Are you sure the VCA is normalled to the gate? Because that would mean no release/decay at all on the VCA. As soon as you note off, the sound cuts hard off?

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Post by ludotex » Sun May 06, 2018 1:37 pm

vertflyer wrote:
robin87 wrote: Some more details: The VCA is not normalled to the envelope but to the gate signal instead, so without any patch cables in place it acts as a simple on/off switch. Thats why they named the trimmer "click", because it produces a popping noise if the gate signal bleeds into the audio path. I would have at least preferred a switch to route the envelope to the VCA.
Are you sure the VCA is normalled to the gate? Because that would mean no release/decay at all on the VCA. As soon as you note off, the sound cuts hard off?
Since its an ADS envelope, it makes sense that there is no release no?
I noticed if you want decay you need to have a long gate, put sustain to zero and have the Decay finishing before the end of the gate (if that makes sense :hmm: )

Btw, where did you get the info about the 4th dip switch function? That's really interesting. Is there a manual somewhere? Could not find any.
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Post by bagoly » Sun May 06, 2018 1:39 pm

vertflyer wrote:
Are you sure the VCA is normalled to the gate? Because that would mean no release/decay at all on the VCA. As soon as you note off, the sound cuts hard off?
Yes, thats exactly how it works on mine. If you patch the envelope out into the vca yoo'll get release, but since the envelope only retriggers when the attack/decay(/release) cycle is finished, it's kind of weird to play it with a keyboard. By now I'm not entirely sure if that is how it's supposed to work or if there is something wrong with my build. Does anyone else experience the same behaviour?

On sequences it's actually quite fun though, sort of like a pulse divider.

Btw. I just tried it with some sequences from my keystep, the duophony makes this thing incredibly more fun! Still, the duophony works best over midi, since the designated CV input for VCO2 gets summed with the master CV.

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Post by vertflyer » Sun May 06, 2018 2:34 pm

ludotex wrote: Since its an ADS envelope, it makes sense that there is no release no?
I noticed if you want decay you need to have a long gate, put sustain to zero and have the Decay finishing before the end of the gate (if that makes sense :hmm: )

Btw, where did you get the info about the 4th dip switch function? That's really interesting. Is there a manual somewhere? Could not find any.
I saw the dip switch setting from a picture of the PCB itself. It says how to set the midi channel and says pin 4 is for unison/para.

I believe most ADS envelopes should be ADSD, so whatever decay time you set, the release time is the same as the decay time. But if the VCA is tied to gate, then there would be no release unless you patch the envelope into the VCA.

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Post by vertflyer » Sun May 06, 2018 2:35 pm

I think its really odd that the envelope doesn't retriever until the envelope cycle is done. That would be a first for me and envelopes.
robin87 wrote:
vertflyer wrote:
Are you sure the VCA is normalled to the gate? Because that would mean no release/decay at all on the VCA. As soon as you note off, the sound cuts hard off?
Yes, thats exactly how it works on mine. If you patch the envelope out into the vca yoo'll get release, but since the envelope only retriggers when the attack/decay(/release) cycle is finished, it's kind of weird to play it with a keyboard. By now I'm not entirely sure if that is how it's supposed to work or if there is something wrong with my build. Does anyone else experience the same behaviour?

On sequences it's actually quite fun though, sort of like a pulse divider.

Btw. I just tried it with some sequences from my keystep, the duophony makes this thing incredibly more fun! Still, the duophony works best over midi, since the designated CV input for VCO2 gets summed with the master CV.

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Post by bagoly » Sun May 06, 2018 2:52 pm

vertflyer wrote:I believe most ADS envelopes should be ADSD, so whatever decay time you set, the release time is the same as the decay time. But if the VCA is tied to gate, then there would be no release unless you patch the envelope into the VCA.
Yes, it works just like that.
vertflyer wrote:I think its really odd that the envelope doesn't retriever until the envelope cycle is done. That would be a first for me and envelopes.
Right, it seems very strange, I expected the envelope to work as on the Minimoog and I'm starting to think it could be an issue with my build. It's not clear from the demo, since he doesn't change the envelope settings throughout the video. I'll have to wait what the other builders have to report.

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Post by Barcode » Tue May 08, 2018 9:32 am

Does anyone have any experience with this style of VCF? I am getting no response from the resonance pot and I hoping to find where to start troubleshooting.

It also seems like I am getting some bleeding through the VCA....

Finally.... a couple more standoffs in the center would help a ton to reduce strain on the PCB when plugging into the middle jacks.

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Post by Monkizzle » Wed May 09, 2018 12:56 am

Also have the Hades, actually building the Erebus. The pcb locked to front panel by four screws ,as opposed to the euro hades, is very disappointing. I find this choice nor aesthetically oriented nor stress free for pots and jacks. Lot of components are clearly from Chinese manufacture but after all this kit seems worth to me. A great surprise is the chance to choose caps to apply short/default/long time cycles to lfo and envelop. It would be extra fun to add a couple of toggles allowing to switch between all possibilities.

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Post by oks2024 » Wed May 09, 2018 4:08 pm

I finished building my Erebus a couple of days ago, and it was quite fun to build. It takes time, but as I usually solder SMT, it's a bit easier.

However I had some issues, the same other mentionned in the thread. The pads are small, most of the time it's ok, but for some reason I had a really hard time to solder some components, even when using a flux pen.

And yes, it's disapointing to see that they did not included sockets for everything. It was also like that on the Hades kit. Sockets are super cheap, but if you only need 1 8pin socket, it's not that easy to source, you will probably need to order 10 sockets, and wait for weeks, etc.
I also don't like the fact that the PCB is bending each time I plug a cable :/. It's too bad, because, unlike the Hades, the panel of the Erebus is really nice and sturdy, but I feel like the Erebus is more likely to break.

But everything was working the first time I connected it.
I quickly tuned the oscillators, and both of them seems to track well over 5 octaves. However I did not touch the "VCA Click" trimmer, as I did not heard the "click". I might come back to those trimmers if I need it, but so far it seems to be good.

As mentionned before, the VCA is normalized to the gate, and the enveloppe is connected to the filter. However I think the enveloppe is re-triggered by a new gate. I will do more test tonight, but that's what I noticed.

Sound wise it's great, the two oscillators are nice, I like the filter, and I also really like playing with the delay. I still need to try some things, like the duophonic mode, or the midi input. I also might change the LFO capacitor, for a "slow" lfo, I think it would be interesting on that synth.

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Post by thement » Thu May 10, 2018 6:52 am

Well, I finished soldering it yesterday. Seemed to be shorted with all ICs in sockets (voltage check with just the TL074s was okay though), so I removed all the ICs and reinserted them one by one and it seems to work now, but the oscillators just give out a high-pitched noise. I wonder if I had by mistake burnt the VCA chip. Also I'm not sure how to proceed now, because I've never debugged analog circuit without schematic (usually just digital and with schematic). Any tips?

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Post by vertflyer » Thu May 10, 2018 4:46 pm

My kit is coming in a couple days. Would super gluing a couple of the jacks to the front panel help the bending issue?

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Post by Monkizzle » Fri May 11, 2018 2:57 am

vertflyer wrote:My kit is coming in a couple days. Would super gluing a couple of the jacks to the front panel help the bending issue?
I don't think so. Rather your're going to damage the whole thing.
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Post by csaban » Fri May 11, 2018 5:42 am

It's interesting that Dreadbox can't/won't release the schematics and they don't provide support either. Feels a bit like a black box when it comes to troubleshooting. :ripbanana:

Could anyone confirm how the expo conversion works on this? I'm assuming it's done with the ATmega and a pair of DACs, since I can't find the 'regular' matched transistor pair with temperature compensation (as it was done on the Hades DIY).

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Post by cane creek » Fri May 11, 2018 12:50 pm

aabbcc wrote: Overall everything from packaging to componenets feels like a random chinese DIY kit
I was expecting cheap $hit, I've opened my Abyss and studied my Emikron PCB so i'm aware they use the cheapest components possible and skip where ever possible with sockets.

I think its the crap components that give Dreadbox their great sound.
Monkizzle wrote:Lot of components are clearly from Chinese manufacture
Do you think the components from Taiwan are better ? :lol: if it wasn't for Taiwan/China you wouldn't be able to build a synth.

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Post by cane creek » Fri May 11, 2018 12:56 pm

Thats mine done......

Changed the crap D shaft Pots for Round shaft Alpha,
Used a Aqua LED which is the same colour as the Font, :tu:
Socketed all the Op-amps.

I wanted to change all the capacitors but feared it may effect the sound.
Those cheap ceramics in my build didn't take to soldering too well they must be very old stock from some damp warehouse.


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Post by Lemmy » Fri May 11, 2018 6:24 pm

Lovely creamy sound on this.
My echo isn't working though. Any one have ideas on troubleshooting? I have +5V at pin 1 of the PT2399
Everything else seems OK.

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Post by cane creek » Fri May 11, 2018 7:17 pm

Lemmy wrote:Lovely creamy sound on this.
My echo isn't working though. Any one have ideas on troubleshooting? I have +5V at pin 1 of the PT2399
Everything else seems OK.
Probably not much help but mine didn't work at all when I first tried it, I got the loupe out and reflowed a few dodgy looking joints and that solved it.

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Post by autodafe » Sat May 12, 2018 4:06 am

I got my unit done and calibrated quite well.
Everything seems to work 100%
only the Resonance Knob seems to have no effect at all...
Can someone post a video/audio of the Resonace knob in action?

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Post by lilakmonoke » Sat May 12, 2018 4:34 am

can somebody post soundfiles please. its all about the sound in the end and im not sure if i should order the kit. does it sound different from a erebus DT?

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Post by autodafe » Sat May 12, 2018 5:11 am

is there a user manual somewhere for the lil erebus?

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