Dreadbox Erebus DIY kit

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, Joe., luketeaford, lisa

Post Reply
thement
Learning to Wiggle
Posts: 6
Joined: Thu May 10, 2018 6:47 am

Post by thement » Tue May 15, 2018 5:12 pm

vertflyer wrote:How do you poly chain without a midi out or thru?

Secret port?
I would guess that the atmega that does MIDI-to-cv runs the same program as on erebus-v2, so the TX pin is configured to do MIDI Out. All you need to do is to solder two resistors and stereo jack on GND/+5V/pin 3 on atmega and you have a MIDI Out to polychain on the next lil erebus.

User avatar
StillNotWorking
Veteran Wiggler
Posts: 654
Joined: Thu Aug 22, 2013 3:29 pm
Contact:

Post by StillNotWorking » Wed May 16, 2018 7:23 am

thement wrote:I would guess that the atmega that does MIDI-to-cv runs the same program as on erebus-v2, so the TX pin is configured to do MIDI Out. All you need to do is to solder two resistors and stereo jack on GND/+5V/pin 3 on atmega and you have a MIDI Out to polychain on the next lil erebus.
This is interesting if it works, — like MI's Shruti-1. Guess the delivered stereo midi jack doesn't have internal switch so we could normalize midi in from previous lil' modules and break the midi chain when needed?

thement
Learning to Wiggle
Posts: 6
Joined: Thu May 10, 2018 6:47 am

Post by thement » Wed May 16, 2018 7:34 am

StillNotWorking wrote:
thement wrote:I would guess that the atmega that does MIDI-to-cv runs the same program as on erebus-v2, so the TX pin is configured to do MIDI Out. All you need to do is to solder two resistors and stereo jack on GND/+5V/pin 3 on atmega and you have a MIDI Out to polychain on the next lil erebus.
This is interesting if it works, — like MI's Shruti-1. Guess the delivered stereo midi jack doesn't have internal switch so we could normalize midi in from previous lil' modules and break the midi chain when needed?
Hmm I just reread it and looked up the Erebus v2 docs and I was talking bollocks. This is not how the polychain works. Erebus doesn't have MIDI Out, just MIDI Through, and the polychain is decided by polyphony, not by what devices in the chain forward to each other.

Thus all you need to do is take the Erebus DIN5-to-jack convertor, put it to audio splitter and send the same signal to each Erebus. (And dip-switch the correct polychain number in each device.)

User avatar
xenosapien
Ultra Wiggler
Posts: 826
Joined: Thu Jul 09, 2015 3:30 am
Location: Frankfurt am Main, Germany

Post by xenosapien » Wed May 16, 2018 9:11 am

... okay, shit.

So who wants to sell me their Lil Erebus DIY Kits? I might need like... 5 more. ;)
may you live in interesting times.

vertflyer
Common Wiggler
Posts: 103
Joined: Mon Nov 21, 2011 3:46 pm

Post by vertflyer » Wed May 16, 2018 10:51 am

Keep in mind that the Erebus V2 chains for paraphony, not true polyphony.

vertflyer
Common Wiggler
Posts: 103
Joined: Mon Nov 21, 2011 3:46 pm

Post by vertflyer » Wed May 16, 2018 10:52 am

xenosapien wrote:... okay, shit.

So who wants to sell me their Lil Erebus DIY Kits? I might need like... 5 more. ;)
Is it a limited run?

csaban
Learning to Wiggle
Posts: 38
Joined: Sun Aug 07, 2016 4:55 pm
Location: Glasgow

Post by csaban » Wed May 16, 2018 1:24 pm

Looking at the schematic, I think the EG is a variation of this one http://electro-music.com/forum/phpbb-files/adsr_160.jpg (from http://electro-music.com/forum/viewtopic.php?t=31473). With my limited knowledge, it seems like the 1M pot for release was replaced with a diode (D10).

mschaika
Learning to Wiggle
Posts: 2
Joined: Wed May 16, 2018 3:32 pm

Post by mschaika » Wed May 16, 2018 3:47 pm

Hey!
First of all thanks for all the great advice in here. This thread has been extremely helpful so far :)

I just finished building my lil erebus and I ended up having two problems and I was hoping one of you might be able to point me in the right direction.

1. I only hear a clicky sound when enabling triangle wave only.

2. I also can't get midi to work. I tried the midi out from the arturia keystep but haven't had luck yet.

I double checked all connection visually but can't see an issue.

This has been my most complex soldering project so far which is why I'm having trouble to identy the right locations on the board when looking at the schematic.
I would be very thankful if you could guide me to the right spot to debug vco1 (triangle).

Here's a video of the vco issue:
https://www.dropbox.com/s/8i65oqk9bhcfk ... e.mp4?dl=0

Thanks a lot in advance!

User avatar
Michiel
Common Wiggler
Posts: 78
Joined: Thu Jan 10, 2013 11:03 am
Location: The Low Countries

Post by Michiel » Wed May 16, 2018 5:28 pm

mschaika wrote:Hey!
2. I also can't get midi to work. I tried the midi out from the arturia keystep but haven't had luck yet.
Regarding this question, are you sure? I also thought my midi didn’t work, but I was switching between CV and midi using the Keystep. The problem I had was that those two outputs were offset by 3 octaves. If you play midi notes 3 octaves below what sounds reasonable with cv, nothing comes out.
Go up three octaves with the + key and that might solve it.

I never liked midi, and while researching this I found out all sorts of stuff that makes me like it even less (different standards for midi over stereo jacks - can’t use the Erebus midi converter cable with my 0-Coast and vice versa, voltage offsets,...).

Good luck - hope you get it to work.

Mmdm
Learning to Wiggle
Posts: 6
Joined: Sat May 12, 2018 5:58 pm

Post by Mmdm » Thu May 17, 2018 1:38 am

Finally mine works ok!! I was reversed two transistors.... I put new ones and works perfectly!!!

For those one with troubles double or triple check the soldering, the polarity of the components etc

I needed like 3 days of debbuging to find the error and it was so obvious...

mschaika
Learning to Wiggle
Posts: 2
Joined: Wed May 16, 2018 3:32 pm

Post by mschaika » Thu May 17, 2018 3:06 am

Michiel wrote:
mschaika wrote:Hey!
2. I also can't get midi to work. I tried the midi out from the arturia keystep but haven't had luck yet.
Regarding this question, are you sure? I also thought my midi didn’t work, but I was switching between CV and midi using the Keystep. The problem I had was that those two outputs were offset by 3 octaves. If you play midi notes 3 octaves below what sounds reasonable with cv, nothing comes out.
Go up three octaves with the + key and that might solve it.

I never liked midi, and while researching this I found out all sorts of stuff that makes me like it even less (different standards for midi over stereo jacks - can’t use the Erebus midi converter cable with my 0-Coast and vice versa, voltage offsets,...).

Good luck - hope you get it to work.
I checked midi in all octaves but as I mentioned haven;t had any luck. I do share your concerns about midi but I need to use it due to the way I set up my recording pipeline.

User avatar
xenosapien
Ultra Wiggler
Posts: 826
Joined: Thu Jul 09, 2015 3:30 am
Location: Frankfurt am Main, Germany

Post by xenosapien » Thu May 17, 2018 4:59 am

vertflyer wrote:
xenosapien wrote:... okay, shit.

So who wants to sell me their Lil Erebus DIY Kits? I might need like... 5 more. ;)
Is it a limited run?
actually, I was joking but now I´m not so sure... it is still available on their website, but if past DIY kits from Dreadbox are any indicator... yes, they probably won´t have that forever.

(compare: HADES DIY Kit is not really available anymore, or only if you source your own resistors etc.)
may you live in interesting times.

vertflyer
Common Wiggler
Posts: 103
Joined: Mon Nov 21, 2011 3:46 pm

Calibration Help Needed

Post by vertflyer » Fri May 18, 2018 4:34 am

Could someone post up some details or hints on proper calibration? I spent a long time last night trying to get this right and it still seems like an inexact science of a procedure. A couple questions.

1) The instructions say that order matters and that seems to be the case, scale 1, scale 2, tune 2, master. But it seems to me that default settings per trim makes a difference. I can’t figure out if it helps to have all the trims starting at fully counter clockwise or fully clockwise or all approximately in the middle? It seems some of these options lead me to run out of trim in one direction if that makes any sense.

2) So there is a master tune trim and then the big tune pot on the front side. Is it ok to move the main tune pot on the front to help with setting scale 1? Or does that just keep making my scale 1 setting change? The reason I ask is cause I’m trying to use a chromatic tuner to help with scale 1 and it helps to start at a correct note. Are you using one octave or two to set this? It seems like no matter where I set scale 1, it’s not exactly right. Which leads to the next question.

3) should I use a tuner to set scale 1, or can I use a meter? If I use a meter, where should I measure the voltage? And how many octaves should I use? Why does it seem like the scale 1 trim knob is so course that I can’t finely turn it enough to get scale 1 set right?

4) It’s all circular, when I can't set scale 1 right, I then wonder if my default starting trim settings on the other trims are wrong, and then wonder if the main pot tune should not be moved, then wonder if I should be using a meter, and I go in circles never getting scale 1 to be right. Help!

5) if I can’t use a meter, using my ears to get the scale 1 in the approximate right place is a trip because the starting and ending note keeps changing and it’s hard to just ballpark an octave when the base frequency keeps changing so then I move the big pot tune knob.... help.

I would like there to be a way to calibrate this synth using nothing but a meter or tuner but it seems I can’t get around using my own ears to at least get the trims in the right ballpark, and then I still can’t find tune anything.

Help! Someone please say there is a foolproof procecedure I’m missing that makes this process easy. What is it??

User avatar
lilakmonoke
Super Deluxe Wiggler
Posts: 2755
Joined: Thu Oct 21, 2010 6:18 am
Location: berlin

Post by lilakmonoke » Fri May 18, 2018 7:31 am

autodafe wrote:
lilakmonoke wrote:can somebody post soundfiles please.
here's a very short demo I made with mine:

https://soundcloud.com/antonio-grazioli/erebus-example
thanks! it sounds damn nice just like its big brother. damn, i cant really afford to spend money on ANOTHER monosynth. but ...

Mmdm
Learning to Wiggle
Posts: 6
Joined: Sat May 12, 2018 5:58 pm

Post by Mmdm » Fri May 18, 2018 11:59 am

Vertflier I tuned it by ear.
I play for example a D note and then same D one octave up. Turn the scale until this sounds good.
Then do the same for the osc2. I tuned orc 2 to be at the same note than 1 when the slider is at the center so you can tune orc2 at least 1 octave up and down versus the osc1.

I did not move the main tune pot in all the process. I left it in the middle position. After this I use the back tuner trimmer to get a white note when the main tuner is at 12:00 so I know when the tuner is at 12:00 it will be tuned with my other instruments. But you can always adjust it.

I did nothing with the click thing :)

It is not perfect tuned but its ok for me, if it sound good to my ears is ok.

Hope it helps.

User avatar
s3nt3nz4
Learning to Wiggle
Posts: 3
Joined: Sun Oct 22, 2017 8:14 am
Location: France
Contact:

Post by s3nt3nz4 » Fri May 18, 2018 3:15 pm

mschaika wrote: 1. I only hear a clicky sound when enabling triangle wave only.
I've got exactly the same problem here with vco2 (square). mschaika, did you find a solution ?
I'm afraid i fried an IC (TL074). Did someone has an idea ?
Thanks for your help.

User avatar
JAO
Common Wiggler
Posts: 231
Joined: Fri Jan 06, 2017 10:03 am
Location: Ireland

Post by JAO » Fri May 18, 2018 3:26 pm

Anyone know what are the estimated current requirements? The MG entry is just using the specs from the optional power supply. Thanks.

User avatar
Morphology
Common Wiggler
Posts: 178
Joined: Wed May 04, 2016 7:31 am
Location: Kent, England

Re: Calibration Help Needed

Post by Morphology » Fri May 18, 2018 5:18 pm

vertflyer wrote:Could someone post up some details or hints on proper calibration? I spent a long time last night trying to get this right and it still seems like an inexact science of a procedure. A couple questions.
I have just tuned mine, and I did the following.

1) On a DAW, set up a MIDI Loop putting out about 2 seconds of C4 and 2 Seconds of C5 - ie an octave apart. Set this to loop continuously.

2) Turn VCO1 level full up, and VCO2 full down

3) Use a frequency meter - I used Pitch lap Pro (free) on my phone

4) Turn the main Tune knob (big one on the front) until the frequency of the lower C4 note is a nice round number (I used 50Hz)

5) Note the Frequency of the C5 note. If it's greater than 100Hz (ie double the C4 note), you'll need to turn the (Scale 1) trimmer clockwise (looking from the component side of the board - ie with the front panel removed). If it's slightly less than 100Hz, you'll need to turn the trimmer anti-clockwise.

6) Turn the trimmer a fraction in the direction you need to go. This will also move the frequency of both notes, so use the master Tune knob (big one on the front) to move the lower note back to 50Hz, note the frequency where this has set the upper (C5) note - it should have moved slightly closer to your target frequency of 2 x C4

7) Repeat 4) to 6) until you can get it to cycle between 50Hz and 100Hz reliably. It takes a while but, with care you can get it pretty accurate.

Repeat this for VCO2 using the Scale 2 trimmer, setting the lower (C4) frequency of VCO2 with the VCO2 pitch slider (left-most) - I started off with it somewhere near its mid-point and used 100Hz and 200Hz as my target frequencies.

To tune the two VCOs together, set the master Tune knob at the Mid Point, and the VCO2 slider to its mid point.

Then adjust the Tune 2 Trimmer until the pitches are identical.

The master Tune knob on the front panel changes the pitch of both VCO1 and VCO2 up and down, and the VCO2 slider sets the pitch of VCO2 relative to VCO1.

So, by tuning them so that they are equal with the VCO2 slider in its mid-point, it seems to offer maximum flexibility, as you can then use the slider to move the pitch of VCO2 +/- around 1 octave relative to VCO1.

This process worked pretty well for me, and playing in MIDI sequences the two VCOs seem to track fairly well.

Obviously I was using MIDI, so my tuning was at the mercy of the accuracy and linearity of the internal MIDI to CV circuitry (Atmega + DAC).

The same process should equally apply using the CV Input rather than MIDI, but I don't have a CV source that I can be 100% certain is outputting voltages exactly 1v apart, so MIDI was simpler.

Edit: Clarified the process I used a little

Morph
Last edited by Morphology on Fri May 18, 2018 11:27 pm, edited 1 time in total.
There are only 10 different types of people: Those who understand binary, and those who don't

vertflyer
Common Wiggler
Posts: 103
Joined: Mon Nov 21, 2011 3:46 pm

Re: Calibration Help Needed

Post by vertflyer » Fri May 18, 2018 5:50 pm

Morphology wrote:
vertflyer wrote:Could someone post up some details or hints on proper calibration? I spent a long time last night trying to get this right and it still seems like an inexact science of a procedure. A couple questions.
I have just tuned mine, and I did the following.

1) On a DAW, set up a MIDI Loop putting out about 2 seconds of C3 and 2 Seconds of C4 - ie an octave apart. Set this to loop continuously.

2) Turn VCO1 level full up, and VCO2 full down

3) Use a pitch meter - I used Pitch lap Pro (free) on my phone

4) Turn the main pitch knob until the frequency of the lower C3 note is a nice round number (I used 50Hz)

5) Note the Frequency of the C4 note. If it's greater than 100Hz (ie double the C3 note), you'll need to turn the (Scale 1) trimmer clockwise (looking from the component side of the board - ie with the front panel removed). If it's slightly less than 100Hz, you'll need to turn the trimmer anti-clockwise.

6) Turn the trimmer a fraction in the direction you need to go. This will also move the frequency of both notes, so use the master tune knob to move the lower note back to 50Hz, note the frequency where this has set the upper note.

7) Repeat 4) to 6) until you can get it to cycle between 50Hz and 100Hz reliably. It takes a while but, with care you can get it pretty accurate.

Repeat this for VCO2 using the Scale 2 trimmer

To tune the two VCOs together, set the master Tune knob at the Mid Point, and the VCO2 slider to its mid point.

Then adjust the Tune 2 Trimmer until the pitches are identical.

The Master Tune knob on the front panel changes the pitch of both VCO1 and VCO2 up and down, and the VCO2 slider sets the pitch of VCO2 relative to VCO1.

So, by tuning them so that they are equal with the VCO2 slider in its mid-point, it seems to offer maximum flexibility, as you can then use the slider to move the pitch of VCO2 +/- around 1 octave relative to VCO1.

This process worked pretty well for me, and playing in MIDI sequences the two VCOs seem to track fairly well.

Obviously I was using MIDI, so my tuning was at the mercy of the accuracy and linearity of the internal MIDI to CV circuitry (Atmega + DAC).

The same process should equally apply using the CV Input rather than MIDI, but I don't have a CV source that I can be 100% certain is outputting voltages exactly 1v apart, so MIDI was simpler.

Morph
Morph, thanks so much!

Just to clarify, step 4, is it the main pitch trimmer or the front pot tune?

User avatar
Morphology
Common Wiggler
Posts: 178
Joined: Wed May 04, 2016 7:31 am
Location: Kent, England

Re: Calibration Help Needed

Post by Morphology » Fri May 18, 2018 11:19 pm

vertflyer wrote:Just to clarify, step 4, is it the main pitch trimmer or the front pot tune?
The big master Tune knob on the front, not the trimmer.

I started with it somewhere in the middle, so I'd be able to nudge it up or down as necessary without reaching either end of its rotation.

I've just checked and I actually used C4 and C5 rather than C3 & C4 - I'll edit my previous post, though it doesn't really matter provided that the MIDI Note is going up and down an Octave, and you are picking a nice round number for the lower frequency with the Tune knob.
There are only 10 different types of people: Those who understand binary, and those who don't

User avatar
bartleby
Ultra Wiggler
Posts: 812
Joined: Wed Oct 20, 2010 2:20 pm
Location: berlin

Post by bartleby » Sat May 19, 2018 3:52 am

i've finished my lil erebus, and everything seems to be working fine. i love that creamy filter and the very playlable delay section.

but the envelope seems to be behaving a little strange in some ways. i'm not sure if these are just some quirks of this envelope design, or if there is something wrong with my particualr build:

1. even with decay set to minimum, there is still some noticeable decay time.

2. with high attack and only slightly lower decay settings, a very short gate signal will often result in the envelope not decaying at all, but staying high until re-triggered with a new gate signal.

3. maximum decay time is much longer (ca 6s) than maximum attack time (ca 2s).

4. the envelope won't retrigger while the decay phase is still lasting.

i suspect that the last item is probably normal. but i'm not sure about the other ones. could anybody with a lil erebus check if their envelopes are showing similar behavior?

(these are best tested with the cutoff set to minimum, env lvl to maximum, and the env output patched into the vca input)
Last edited by bartleby on Sat May 19, 2018 4:00 am, edited 1 time in total.

User avatar
bartleby
Ultra Wiggler
Posts: 812
Joined: Wed Oct 20, 2010 2:20 pm
Location: berlin

Post by bartleby » Sat May 19, 2018 3:56 am

oh and a note on calibration:

this module needs quite some time to warm up before it is stable. interestingly, this seems to affect not just the vco tuning, but also the vca click calibration.

so better make sure to have it running for 15min or so before you start calibrating!

vertflyer
Common Wiggler
Posts: 103
Joined: Mon Nov 21, 2011 3:46 pm

Post by vertflyer » Sat May 19, 2018 6:09 am

bartleby wrote:i've finished my lil erebus, and everything seems to be working fine. i love that creamy filter and the very playlable delay section.

but the envelope seems to be behaving a little strange in some ways. i'm not sure if these are just some quirks of this envelope design, or if there is something wrong with my particualr build:

1. even with decay set to minimum, there is still some noticeable decay time.

2. with high attack and only slightly lower decay settings, a very short gate signal will often result in the envelope not decaying at all, but staying high until re-triggered with a new gate signal.

3. maximum decay time is much longer (ca 6s) than maximum attack time (ca 2s).

4. the envelope won't retrigger while the decay phase is still lasting.

i suspect that the last item is probably normal. but i'm not sure about the other ones. could anybody with a lil erebus check if their envelopes are showing similar behavior?

(these are best tested with the cutoff set to minimum, env lvl to maximum, and the env output patched into the vca input)
Do you have the 3rd optional 470n cap in circuit? There is a * in the manual that says the Erebus v2 behavior is to not have that 3rd cap on.

User avatar
bartleby
Ultra Wiggler
Posts: 812
Joined: Wed Oct 20, 2010 2:20 pm
Location: berlin

Post by bartleby » Sat May 19, 2018 6:11 am

vertflyer wrote: Do you have the 3rd optional 470n cap in circuit? There is a * in the manual that says the Erebus v2 behavior is to not have that 3rd cap on.
no, i left that one unpopulated as suggested in the build guide. (that part wasn't included in my kit, anyway)

so, does the env on your lil erebus behave differently, then?

vertflyer
Common Wiggler
Posts: 103
Joined: Mon Nov 21, 2011 3:46 pm

Post by vertflyer » Sat May 19, 2018 7:52 am

Bartleby,

I’ll investigate your envelope observations a little later today.

For now, I finally realized how to adjust the scale settings right. Like morph says, use a tuner app that show exact pitch frequencies. I found that trying to hit a target like 50-100 didn’t work for me. Here is the key for me. If you are at say 55-112, your instinct is to turn the scale in a way that lowers the pitch to bring the 112 down. That doesn’t work. Raise the pitch to bring the 55 up!

I haven’t tried the method where I keep adjusting the front panel knob, I simply kept moving the scale trim pitching up until I found a frequency that doubles.

Post Reply

Return to “Music Tech DIY”