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ARP Odyssey Oscillators
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funkyfarm



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PostPosted: Mon Sep 01, 2008 9:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

/mr wrote:
(I do have a strong belief that "VCO character" is an overrated thing, that's why I'd like to know!))



((I would say that "VCF character" is an overrated thing.
I got many filters and i can always identify my Oakley vcos behind... Wink ))
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/mr



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PostPosted: Tue Sep 02, 2008 1:35 am    Post subject: Reply with quote  Mark this post and the followings unread

funkyfarm wrote:
((I would say that "VCF character" is an overrated thing.
I got many filters and i can always identify my Oakley vcos behind... Wink ))

Laughing

What I mean is that the very VCO cores must be quite "perfect" in order to work and track properly, and I would say that they can't be very unique. But then a number of other stages can make uniqueness - first the waveforming circuits in the VCO, and then VCFs, VCAs, etc, and the connections between them.
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urbanscallywag



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PostPosted: Tue Sep 02, 2008 8:54 am    Post subject: Reply with quote  Mark this post and the followings unread

I'd describe the ARP VCO as shrill, cutting, piercing, maybe a little bit buzzy.
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Peake



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PostPosted: Tue Sep 02, 2008 10:30 am    Post subject: Reply with quote  Mark this post and the followings unread

urbanscallywag wrote:
I'd describe the ARP VCO as shrill, cutting, piercing, maybe a little bit buzzy.


I'd pretty much second that description of the Odyssey. There's a particular whine when you detune the oscillators that is evident in Ultravox recordings.

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bubblechamber



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PostPosted: Tue Sep 02, 2008 11:36 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks for posting this, we cannot have too many oscillators.
i did some tests a few months ago and based on that i've come to believe that the tempco is far more important than tightly matched trannies in an expo pair. i got almost as good of a result with a random pair of 3906's + tempco as i did with a matched pair, both SSM and 2sa798.
and i'm glad my limited knowledge is useful from time to time.
david

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urbanscallywag



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PostPosted: Tue Sep 02, 2008 11:37 am    Post subject: Reply with quote  Mark this post and the followings unread

The funny thing about the tempco in the Odyssey is that they don't even touch the exponential pair in mine.
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Peake



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PostPosted: Tue Sep 02, 2008 11:46 am    Post subject: Reply with quote  Mark this post and the followings unread

No one has purchased the PN5910s that are up on ebay. No one is interested in building this circuit? The other parts, excepting the Tempco, are hella easy to source and inexpensive. If someone modded it to use 1K or 2K Tempco, it'd be even less expensive. Bridechamber have those for days.
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Peake



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PostPosted: Tue Sep 02, 2008 11:49 am    Post subject: Reply with quote  Mark this post and the followings unread

bubblechamber wrote:
i did some tests a few months ago and based on that i've come to believe that the tempco is far more important than tightly matched trannies in an expo pair.


What about capacitor type in the core? Mylar etc. versus Polycarbonate/Polystyrene?

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Broadwave



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PostPosted: Tue Sep 02, 2008 12:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

Peake wrote:


What about capacitor type in the core? Mylar etc. versus Polycarbonate/Polystyrene?


Use a Silvered Mica or Polystyrene (1000pf should work fine too) - I used WIMA High Quality Polycarbonates because I had a few 680pf in my cap box, and I know from past experience that they work well. I would steer clear of mylars and standard "yellow box" polycarbonates for the timing cap.

I tried a few things this afternoon:

Exchanged the 2N5910 for a 2N3906 - still works and tracks well.

Changed the 1.87k tempco for a 1k tempco and standard 820R MF resistor in series - works, but tracking just a little, tiny bit off, but no worse than the ASM 1 osc (but that could be due to the fact that it was a bit breezy here today, and my windows were open, blowing cool air over the board... tut, tut!!)

Don't forget that the outputs are not the usual 10v PP centered around ground - Square is 0-5v and Saw is 0-6v, which doesn't really bother me, but some purists may want to level shift and amplify the outputs Smile

Andy.

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rjd2



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PostPosted: Tue Sep 02, 2008 1:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

do you think that the 2N5459's are able to be subbed for 2N3904 or 2n3906? i only ask cause i've got a bunch of matched 3904's/6's.
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Peake



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PostPosted: Tue Sep 02, 2008 1:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

AndyR1960 wrote:
Peake wrote:


What about capacitor type in the core? Mylar etc. versus Polycarbonate/Polystyrene?


Use a Silvered Mica or Polystyrene (1000pf should work fine too) - I used WIMA High Quality Polycarbonates because I had a few 680pf in my cap box, and I know from past experience that they work well. I would steer clear of mylars and standard "yellow box" polycarbonates for the timing cap.


I actually meant, does mylar cause drift. The question was to Bubblechamber but if you're swapping parts around...wellll....wanna try? Smile

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ericcoleridge



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PostPosted: Tue Sep 02, 2008 3:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for posting this layout, I'll definitely give it a shot.

I've never owned a 2600, and can't comment on those oscillators-- but I've had a couple Odysseys--Mark II and Mark III, and I've never been able to duplicate their unique sound. I've always attributed it (perhaps in error) to the VCOs. I would agree with the earlier description, "bright and piercing", but would also add sharp and crystaline. They have a very precise, cold sound, but still rich and resonant (unlike later sequential, korg, roland, etc.). Plus the sync and ring mod on these VCOs is fantastic.

So, I'm happy to be able to have access to this circuit, without spending 1500 on an odyssey.
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Tim Servo



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PostPosted: Tue Sep 02, 2008 3:48 pm    Post subject: ARP Odyssey Oscillators Reply with quote  Mark this post and the followings unread

Magic Smoke WILL have Ody VCO boards in about two to three months, for those who can wait (huff, puff, pant). I'm currently testing MKI vs. MKII flavors (huff, pant, wheeze) and we'll have them on a nice blue PCB (pant, gasp, wheeze). Along with some other interesting stuff. I'm just running around (puff, pant gasp) trying to get this and a few other projects going...
Wink

Tim (needs to join a gym or something) Servo
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bubblechamber



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PostPosted: Tue Sep 02, 2008 5:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

i was using a 1000pF Polystyrene for my stability tests.

i tested for stability over time, just let it sit over night
there might be a case for matching here, although they all had about the same results around 1% up or down

1V/oct accuracy - tempco+unmatched= .01% starting around 5V VS. tempco+matched=.001% starting around 5V

heat, used a light bulb to heat things up:
no tempco-frequency goes up, and fast by a lot, maybe 15-25% faster in less than a minute
tempco= a slight drop, maybe 1-3% slower over the same period with the same level of heat.

but to my rather untrained ear i like oscillators being a cent or 2 out of tune with each other...

if I were specing out an oscillator i would probable look to something like the WIMA MKS-2. i like silver mica a lot, but the WIMA stuff is easier to get in quantity and at just about any value, except the 2% 300pF i REALLY needed 6 weeks ago...

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frijitz



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PostPosted: Tue Sep 02, 2008 5:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

urbanscallywag wrote:
I'd describe the ARP VCO as shrill, cutting, piercing, maybe a little bit buzzy.

Could someone post a clean wav file of this "shrill, etc, etc" osc? Just a few seconds of a steady tone. Are we sure this isn't just how an accurate waveform sounds? Thanks!

Ian
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urbanscallywag



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PostPosted: Tue Sep 02, 2008 5:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

It very well may be just an accurate waveform.

But my point is that it sounds different than a lot of VCOs I've heard.

I will try and sample something soon. Smile
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Peake



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PostPosted: Tue Sep 02, 2008 5:58 pm    Post subject: Re: ARP Odyssey Oscillators Reply with quote  Mark this post and the followings unread

Tim Servo wrote:
Magic Smoke WILL have Ody VCO boards in about two to three months


Very cool! Might you have a substitute suggestion for the 2N/PN5910? If Mouser has it, it'll be the one-stop shop...

Quote:
Tim (needs to join a gym or something) Servo


I'll bet that you have Popeye's forearms from all of that stuffing and soldering. Ah gug gug guh gug gug Wink

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Tim Servo



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PostPosted: Tue Sep 02, 2008 9:00 pm    Post subject: ARP Odyssey Oscillators Reply with quote  Mark this post and the followings unread

Well, I have a secret source for some 5910s. We'll see if they come through.

One POSSIBLE sub (looks like it should work on paper but I have not tried this yet), is a 2N5771. They're very close, although the 5771 won't carry quite as much current (IIRC, I don't have the spec sheet in front of me at the moment).

Don't tell anyone though. This was the result of a lot of research.

Oh, wait...

Wink

Tim (possible sub) Servo
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Peake



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PostPosted: Tue Sep 02, 2008 10:17 pm    Post subject: Re: ARP Odyssey Oscillators Reply with quote  Mark this post and the followings unread

Tim Servo wrote:
Well, I have a secret source for some 5910s. We'll see if they come through.


Sweet!

Quote:
One POSSIBLE sub (looks like it should work on paper but I have not tried this yet), is a 2N5771. They're very close, although the 5771 won't carry quite as much current (IIRC, I don't have the spec sheet in front of me at the moment).


2N5771 at Mouser: 512-2N5771, $1.29 up to 9 pieces.

This looks to be a -very- inexpensive project, especially for a -dual- oscillator with sync and a good reputation...bravo!

And I of course won't tell a soul, don't worry Laughing

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Luka



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PostPosted: Tue Sep 02, 2008 10:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

tim will your design have 10Vpp waveshapes or will it be the same as andy's board and range from 5-6
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Tim Servo



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PostPosted: Tue Sep 02, 2008 10:42 pm    Post subject: ARP Odyssey Oscillators Reply with quote  Mark this post and the followings unread

Luka wrote:
tim will your design have 10Vpp waveshapes or will it be the same as andy's board and range from 5-6


Well, both, really. I want this to be compatible with standard modular synth levels, so there will be level shifters added to the outputs for standard 10Vp-p waves, but the "original" waves will also be present as the standard circuity will all be there. You could use either with just a jumper. I could probably tweak the original circuitry to provide hotter outputs, but I'd rather not mess with the original any more than absolutely necessary. Also, the level shifters provide the buffering required in a modular system, so I like having them in there.

Tim (making waves) Servo
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davemoog



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PostPosted: Tue Sep 02, 2008 11:22 pm    Post subject: ARP Odyssey Oscillators
Subject description: substitute for 2n5910
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ARP directly replaced the 2n5910 with a 2n4125 in later version of same circuit...Maybe Quadra? (cheap and available - 12cents each) Works great in my cloned ARP oscillators

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=2N4125-ND
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julianw



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PostPosted: Wed Sep 03, 2008 1:01 am    Post subject: Re: ARP Odyssey Oscillators Reply with quote  Mark this post and the followings unread

That's GREAT news you're putting together a PCB run based on the Odyssey VCO.

Tim Servo wrote:
Well, I have a secret source for some 5910s. We'll see if they come through.


I took a look at the auction Peake mentioned, they sell 6 x PN5910 for $9.90 (+ $17.90 postage to the UK!) = $27.80 Total for myself

However, in the listing it says they sell 100 for $89 and 500 for $228.

You could definitely make some money, and save everyone else money, if you could sell this rare part along with the PCB, it seems like the only obscure component.
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Broadwave



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PostPosted: Wed Sep 03, 2008 1:40 am    Post subject: Reply with quote  Mark this post and the followings unread

rjd2 wrote:
do you think that the 2N5459's are able to be subbed for 2N3904 or 2n3906? i only ask cause i've got a bunch of matched 3904's/6's.


No, the 5459's are FET's, still commonly available.

I'll try and get some audio samples up today.

Andy

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/mr



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PostPosted: Wed Sep 03, 2008 2:53 am    Post subject: Reply with quote  Mark this post and the followings unread

AndyR1960 wrote:
I'll try and get some audio samples up today.

If you can, make a recording of some other separate VCO as well with the same equipment, for a comparison. Smile
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