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 Forum index » DIY Hardware and Software
ARP Odyssey Oscillators
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Broadwave



Joined: Feb 16, 2007
Posts: 346
Location: Manchester UK
Audio files: 6

PostPosted: Sun Jul 05, 2015 3:37 pm    Post subject: Re: VCO 1 Audio/LF Switch? Reply with quote  Mark this post and the followings unread

krainov wrote:
Hello!
Could anyone tell me what is VCO 1 Audio/LF Switch on the pcb?


It just switches between audio frequencies (standard VCO operation) or Low Frequency (voltage controlled LFO)

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Kronos 2-88, Kronos 61, Studiologic Sledge V2/SL, Broadwave ARP 2600EX, Broadwave 18U ARP based Eurorack Modular, Broadwave Minimoog Clone, GEM S2 Turbo.

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krainov



Joined: Feb 26, 2015
Posts: 15
Location: Nowhereland

PostPosted: Mon Jul 06, 2015 2:00 pm    Post subject: Dual ARP VCO Scgematics Reply with quote  Mark this post and the followings unread

Thanks Andy!
Will you please check my VCO1 LFO Switch connections in redrawn schematic ? Just to be sure I understand everything correct.
And you have mentioned the (voltage controlled LFO). Is it really voltage controlled in this implementation?


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Last edited by krainov on Sun Jul 19, 2015 10:57 am; edited 1 time in total
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Broadwave



Joined: Feb 16, 2007
Posts: 346
Location: Manchester UK
Audio files: 6

PostPosted: Tue Jul 07, 2015 10:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

@Krainov

The 270k (R102) resistor from the LF/Audio switch needs to go to -12v, not ground as shown Wink

It's voltage controlled to the extent that you can still modulate the low frequency with S&H, ADSR and the "real" LFO.

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krainov



Joined: Feb 26, 2015
Posts: 15
Location: Nowhereland

PostPosted: Tue Jul 07, 2015 11:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

@Andy
Thank you!
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WELLENCOCKTAIL



Joined: Jul 08, 2012
Posts: 3
Location: Germany

PostPosted: Wed Nov 18, 2015 3:00 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello there,
I have the ARP Dual VCO by Andy built. There I have 4 problems:

1) close Unison go the two VCO's in sync.
2) If I tune VCO 2, also the tuning of VCO 1 changes.
3) If I, for example, the FM Fader pull up, short-term changes, the tuning - even if nothing is connected to.
4) The SAW waveform has a small kink in the middle, the PULSE Waveform makes noise, depending on the tuning of the other VCO.
Does anyone have ideas?

The Fader / Jacks have common 0V - but each VCO 1 + 2 is divided and directly at 0V pad connected. With + 15V and -15V voltages at the faders I did the same.
I use to test a Meanwell T60C power supply (62.5W 5V / 5A 15V / 2A 15V / 0.5A)
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elmegil



Joined: Mar 20, 2012
Posts: 2037
Location: Chicago
Audio files: 16

PostPosted: Sat Nov 21, 2015 12:25 am    Post subject: Reply with quote  Mark this post and the followings unread

WELLENCOCKTAIL wrote:
Hello there,
I have the ARP Dual VCO by Andy built. There I have 4 problems:

1) close Unison go the two VCO's in sync.


That sounds like they share an op amp, or have traces running near each other, or grounds that are perhaps too tightly coupled in the cores.

WELLENCOCKTAIL wrote:

2) If I tune VCO 2, also the tuning of VCO 1 changes.
3) If I, for example, the FM Fader pull up, short-term changes, the tuning - even if nothing is connected to.


That sounds like power issues, possibly related to #1 as well

WELLENCOCKTAIL wrote:

4) The SAW waveform has a small kink in the middle, the PULSE Waveform makes noise, depending on the tuning of the other VCO.
Does anyone have ideas?

The Fader / Jacks have common 0V - but each VCO 1 + 2 is divided and directly at 0V pad connected. With + 15V and -15V voltages at the faders I did the same.
I use to test a Meanwell T60C power supply (62.5W 5V / 5A 15V / 2A 15V / 0.5A)


500mA (.5A) seems like it ought to be more than enough. Check your solder joints too.
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WELLENCOCKTAIL



Joined: Jul 08, 2012
Posts: 3
Location: Germany

PostPosted: Sun Nov 22, 2015 4:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you for answering, Elmegil!

1) The "close unison" is better now - I think it was because of the cores Wink

2) and 3) I'll check later with another power (psu) and putting the solder joints of +15 / 0 / -15 v (for sliders / jacks) at the psu-pcb.

4) the knick in the saw & the noise depending on the tuning of the other vco seems to be a kind of "bleed" or something like this of the ring mod (it sounds a little bit like the output of ring mod - near the same modulation between the two vco's).
I use the "HEF4011BP" instead of the "CD4011BE" - I'll change an check after.

...in vco-sync-mode everything is good. Will be GREAT using it with my TTSH Very Happy
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WELLENCOCKTAIL



Joined: Jul 08, 2012
Posts: 3
Location: Germany

PostPosted: Wed Dec 09, 2015 4:44 am    Post subject: Reply with quote  Mark this post and the followings unread

WELLENCOCKTAIL wrote:
Thank you for answering, Elmegil!

1) The "close unison" is better now - I think it was because of the cores Wink

2) and 3) I'll check later with another power (psu) and putting the solder joints of +15 / 0 / -15 v (for sliders / jacks) at the psu-pcb.

4) the knick in the saw & the noise depending on the tuning of the other vco seems to be a kind of "bleed" or something like this of the ring mod (it sounds a little bit like the output of ring mod - near the same modulation between the two vco's).
I use the "HEF4011BP" instead of the "CD4011BE" - I'll change an check after.

...in vco-sync-mode everything is good. Will be GREAT using it with my TTSH Very Happy



...ok, now everything is perfect - it was ONE thing:
I used the "HEF4011BP" instead of the "CD4011BE". That was the problem. With the "CD4011BE" this great ARP VCO is running perfect! Very Happy
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cleaninglady



Joined: Dec 01, 2010
Posts: 12
Location: creeping up behind you...

PostPosted: Sun Jan 10, 2016 5:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

I've finally finished building up a PCB of this and boxing it , wiring it.

It sounds awesome but i haven't calibrated it yet.

Can someone point me at some calibration docs for the VCO ?

PS

I just tried adjusting the 50% Duty cycle trimmers. They seem to have no effects on the duty cycle at all ???
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Syntharo



Joined: Nov 02, 2016
Posts: 1
Location: German

PostPosted: Wed Nov 02, 2016 12:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Hello everybody
I just built this vco and calibrated it.
The sound is powerful and very musical. Super hard sync, but the ring modulator is the hamer.
Thank you ,, Broadwave "for your effort.
However, I had to par with the construction parts, because in Germany are the barely to be seen.
jfets:
2n5459 = j112
transi:
2n5910 = 2n3906
Ca3086 = ca3046
As tempco I used KTY 81-210 2kom ptc, by www.reichelt.de
For clean sound all resistors = must = be properly adapted to the circuit.
Greeting Very Happy
Adam
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Dan Lavin



Joined: Nov 09, 2006
Posts: 644
Location: Spring Lake, Mi, USA
Audio files: 21

PostPosted: Wed Nov 02, 2016 5:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Adam,
you'll probably want to replace that PTC. The KTY81-210 has a temperature Coefficient of +7900ppm (-0.79%/deg C). You really need something in the +3500ppm area.

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ambi-J



Joined: Apr 12, 2007
Posts: 20
Location: belgium

PostPosted: Tue Jul 04, 2017 7:35 am    Post subject: Reply with quote  Mark this post and the followings unread

I have a friend who build this board but it don't work like it should
he asked me why?
I see differences between the original and this board.

can someone tell me what schematics are used for this board?

in de original oddy mk3 oscillator schematic I see one 3086 and 2 4011 ic's
on this board there are 2 3086's and one 4011

cannot work like this or component placement lay-out is wrong
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ambi-J



Joined: Apr 12, 2007
Posts: 20
Location: belgium

PostPosted: Tue Jul 04, 2017 8:04 am    Post subject: Reply with quote  Mark this post and the followings unread

now I see i had the wrong revision
sorry no problem anymore
I found the correct one
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