ARP Odyssey sound enhancements...

[euggie2000]

I'm researching different ways to enhance ARP sound, especially its low end.
There are a few mods, for example this one at CMS:

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AUDIO PATH UPGRADE
This mod replaces critical signal path components with audiophile grade components. Low end response is improved resulting in a more accurate wave shape. This mod used to be called the "Low end wave correction mod" in the early days of CMS. High end response is also Improved.
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Are there any ideas what critical components should be replaced (and where) to achieve the best sound possible? If this is a frequency response correction, is it the filter, which deals with the frequency range, or is this an op-amp (OTA ca3080) that alters the sound the bad way, or are these an oscillator components?
I am not a pro in electronics or a technician, I just want my Ody sound better.

Thanks!

[nofi]

"Low end wave correction mod" makes me suspect they're just increasing the value of decoupling caps to get better bass response.


if you want more bass from your oddy, you could always just turn up the bass knob on your EQ.....

[Reptil]

Originally Posted by nofi

"Low end wave correction mod" makes me suspect they're just increasing the value of decoupling caps to get better bass response.


if you want more bass from your oddy, you could always just turn up the bass knob on your EQ.....

Actually my axxe got refurbished, and has new caps. it helped the low end a lot. It's deeper than my old untouched other axxe. I wouldn't call it a mod, since it didn't change the design.

[nofi]

I'd say it's a mod if you increase the value of the caps. But just a repair if you go for the same value cap, when replacing electrolytics that have decayed.



when I had a micromoog, I got a really impressive result by following the decoupling cap mod here.
MoogManuals/MicroMoog - E-Music DIY

[Reptil]

Originally Posted by nofi

I'd say it's a mod if you increase the value of the caps. But just a repair if you go for the same value cap, when replacing electrolytics that have decayed.



when I had a micromoog, I got a really impressive result by following the decoupling cap mod here.
MoogManuals/MicroMoog - E-Music DIY

I suppose that is technically correct. you could also say that it allows the circuit to funciton as it was intended, by using the right part. in amps that were properly designed (with the right caps) changing the voltage often doesn't mean a notable difference.
semantics I know I know
A synth that old needs new caps anyway
thumbsup

[nofi]

In the case of the micromoog I think it really needs the cap mod, to make it what it should have been. (well, ok, maybe a bit rich of me to claim what it "should" have been - but you'd think that a synth should at least be flat-ish across the range of fundamental frequencies the oscillator can do)

I don't know if there's many other synths where it makes that much of a difference, unless they've decayed and lost lots of capacitance with age... hence my suggestion with the odyssey to just EQ it.

[euggie2000]

Originally Posted by nofi

In the case of the micromoog I think it really needs the cap mod, to make it what it should have been. (well, ok, maybe a bit rich of me to claim what it "should" have been - but you'd think that a synth should at least be flat-ish across the range of fundamental frequencies the oscillator can do)

I don't know if there's many other synths where it makes that much of a difference, unless they've decayed and lost lots of capacitance with age... hence my suggestion with the odyssey to just EQ it.

Actually, as far as can I see, the caps in the filter and everywhere on the boards, are tantalum, which means that they last almost forever. So recapping won't affect the sound imo, except the case when the capacitance is changed intentionally.
I guess the eq is not the best solution since you change overall sound, not only the low end, and moreover these insufficient low frequencies are not consistent, somewhere there are holes in the low frequency range. I hope I could explain my concern.
But what is the decoupling caps? And where are these caps should be changed, in the filter board or the main boards?

[euggie2000]

Originally Posted by Reptil

Actually my axxe got refurbished, and has new caps. it helped the low end a lot. It's deeper than my old untouched other axxe. I wouldn't call it a mod, since it didn't change the design.

Did you replace them by yourself? And all the tantalum caps are replaced? I have read somewhere that these tantalum caps are not that good in audio application. So, there is theoretical possibility to improve the frequency response, if these caps are changed with the better quality electrolytic caps.

But I'm really confused since there are a few film caps on the main board that supposed to be the best suited for audio.
So, ARP engineers used a few good caps and the rest worse ones - may be the latters are not so critical soundwise and recapping them won't bring the whole new sound to the instrument?
Anyway, this is really an pleasant work - the restoration of an old instrument, because the result could be heard.

[Reptil]

no I bought it refurbished. (from the guy who did that)
I wouldn't change tantallum caps, since they are also responsible for the sound. (Neves also got these) too clean is no good.
I'd say change anything electrolytic? Coupling caps, caps in the PSU?

[SighBorg]

If you have an Odyssey with the 4075 filter a popular modification is to increase the filter bandwidth. By default it doesnt open all the way... It's been a long time since I looked but I think it goes to around 9khz or so. The mod is easy and easy to find on the net.

[euggie2000]

Originally Posted by Kelly644

If you have an Odyssey 4075 filter a popular modification is to increase the filter bandwidth. By default it doesnt open all the way... It's been a long time since I looked but I think it goes to around 9khz or so. The mod is easy and easy to find on the net.

I already fixed that filter bandwidth bug. Now trying to add some more bottom end.
I was recently listening to the mini model d, voyager and minimax samples, and found out that the arp filter (fixed) is very close to the mini in terms of nice resonant overtones, more pleasant than the one in voyager imo.
But as i said the low end is not that big as in mini, I guess that some components have to be replaced and then we'll see. So i'm trying to figure out which ones.

[Acid Hazard]

I'd like to know this audio path mod as well. Luckily, my Odyssey has the 4035 "Moog Filter", so i don't need to worry about that.

[chrisso]

I had it done on my grey face Arp2600. I can't remember what the guy did now (we followed the CMS concept though). I think a few very simple components were changed for more modern ones.
We reduced the background noise in the synth, but the bass wasn't noticeably different.
I really don't think you would notice it.
The 2600 became a tiny bit clearer and warmer.....tiny.
I'm surprised you think the Oddy lacks low end.

[RobJB06]

Im having my Mk3 odyssey modified atm by eric van baaren (saint eric)

Saint Eric

He is very good with Arp stuff and offers many mods.

[Secret Friend]

Originally Posted by euggie2000

I already fixed that filter bandwidth bug. Now trying to add some more bottom end.
I was recently listening to the mini model d, voyager and minimax samples, and found out that the arp filter (fixed) is very close to the mini in terms of nice resonant overtones, more pleasant than the one in voyager imo.
But as i said the low end is not that big as in mini, I guess that some components have to be replaced and then we'll see. So i'm trying to figure out which ones.

what's the point of buying an Ody if you want it to sound like a model D?
the fact that ARP synths aren't as bass heavy as Moogs is part of their sonic
character and appeal...

check out some Conny Plank produced D.A.F. for Ody bass and tell me it lacks low end...
not Moog low end, but heavy nevertheless... why not embrace the difference?

[RobJB06]

I agree with that. Love Arp bass, tight and sharp. Mini is juicy round.
Arp is more acid cuts much more..

[euggie2000]

Actually I've made this mod by myself. Changed some caps values on the filter and C boards and removed HP filter (plan to put in a switch). The low end is now something richer and perceptible, even in the higher resonance settings. It is still ody sound but a bit deeper. I really like the sound.
Mini is good, but it is $5000, and now I can challenge it =)