Arion SCH-1 mods? Make it less flanger-esque?

[grolschie]

Hi people.

I scored an old black Arion SCH-1 for next to nothing recently. Sounds only ok to me. Not wonderful. The chorus oscilliates too much when distortion is used - much like a flanger! I believe that flangers and choruses are kinda similar, so I was wondering if there is any mods one can do to make it sound less like a flanger. Also, less detuning/warbling would also be great. :-)

Also, one of the pots is screwy. Soldered onto the PCB and has a long plastic shaft. Are these easy to replace? I haven't seen any that look like this at my local store.

cheers,
grol

A pic uploaded by another person (I presume mine is similar)

[MartyMart]

<<<< MARK HAMMER INFO WARNING >>>>


There's a small "pf" cap near the MN3102, probably C 31, which sets the amount of
pitch wobble for the circuit, usually 47pf.
It should be across pins 5 and 7 ?
It adjusts the delay time, Chorus is around 10 Msec and Flange a bit more like 20/30 Msec
Reduce that for more subtle wobble, perhaps 33pf would do it.



Marty ( Thanks Mark )

[grolschie]

Thanks dude. Might give that a go. Any ideas on pot replacement with these units?

[doug deeper]

cutting out the dry signal might be interesting as well.

[grolschie]

cutting out the dry signal might be interesting as well.

Hmmm.... How to do that??

[Mark Hammer]

<<<< MARK HAMMER INFO WARNING >>>>


There's a small "pf" cap near the MN3102, probably C 31, which sets the amount of
pitch wobble for the circuit, usually 47pf.
It should be across pins 5 and 7 ?
It adjusts the delay time, Chorus is around 10 Msec and Flange a bit more like 20/30 Msec
Reduce that for more subtle wobble, perhaps 33pf would do it.



Marty ( Thanks Mark )

Well....close....but the cigar stays in the wrapper.

C31 is the component in question, but a few corrections:

• Flanging involves shorter time delays (usually between 1 and 12msec) and chorus involves longer ones (between around 6 and 20msec).
• More resonance is usually created at shorter delay times, with the most noticeable ones being at delays around 2-8msec.  At longer delays, any resonances created are so low you don't notice them that much (e.g., a delay of 15msec yields a resonance around 67hz).
• The filtering in the pedal is tailored to the delay range it aims for, so as to provide maximum bandwidth and maximum clock-whine rejection at the same time.  There is usually a margin of error such that longer delays can be tolerated without incurring noticeable increase in audible whine, but only up to a point, after which you have to start changing cap values in the filters.
• Increasing the value of that cap will shift the delay range upward (and resonances downward), so increase its value to around
  30%-50% more than it currently is.  More than that is probably pushing the envelope as far as keeping clock noise low is concerned.
• At longer delays, pitch wobble becomes more apparent AND irritating.  There are two things you can do about it: 1) trim back on the Depth, and maybe stick a fixed resitor in series with the input of that pot to scale back even more, and 2) cut out some of the bass content on the delay signal, as in the method shown in the Tonepad document for the Small Clone.

[doug deeper]

if can find a schematic there should be a resistor that runs in parallel with the delay somewhere along the line (after the input buffer and what have you) that you could pop out.
its also possible that you could diconect the dry signal from the blend pot (if it has one, not familiar with this pedal)
that should give you some interseting vibrato sounds from the chorus side, and some more subtle wobblys from the flange (compared to straight flanging at least)

[doug deeper]

(after the input buffer and what have you) that you could pop out.
its also possible that you could diconect the dry signal from the blend pot (if it has one, not familiar with this pedal)

probably not
im not thinking.

[MartyMart]

RATS !!  Almost had it

MM

[Mark Hammer]

Yeah, but you were REALLY close.  You oughta nail the next one.

[grolschie]

I couldn't locate a schematic for the Arion. Do we have a consensus on whether or not I should change that cap? If so, what value would be best? I don't mind having to turn down the depth knob (or adding a resistor to it).

grol

[MartyMart]

So , it's probably about 47pf increase it to 68pf and see what you think
with the depth rolled back a bit, add a resistor if you need it even less deep.
This will sound more "chorus wobble" than "metalic flange"

My recent CE-2 build has a 68pf in that spot 

MM.

[grolschie]

Many thanks y'all!

Now to figure out that wretch tone pot. It's so worn that the unit cuts out when I wiggle it. :-)

[Mark Hammer]

On a practical note, it is useful to have a small stash of 10-68pf units handy (and ceramic is fine), and simply tack on different values to the solder pads on the copper side of the board, in parallel with the existing cap.  It's less destructive.  Sometimes, you can even just hold the cap leads up to momentarily touch the relevent solder pads and do your ear test that way.  Then, once you have the "right" value identified you can unsolder the stock unit and replace it with a preferred value.

Alternatively, 2 caps in series and a 3-position on-off-on mini-toggle can score you 3 delay ranges of interest.  For instance, if you replaced the stock 47pf cap with a 56pf and 75pf, wired in series, you could have three possible settings/ranges: 32pf (with both caps in series), 56pf (shunting the 75pf cap), and 75pf (shunting the 56pf cap).  This would nail you something a little closer to flanging than stock (great for slow Leslie grind), plus two flavours of "thicker" chorus.

[grolschie]

On a practical note, it is useful to have a small stash of 10-68pf units handy (and ceramic is fine), and simply tack on different values to the solder pads on the copper side of the board, in parallel with the existing cap.  It's less destructive.  Sometimes, you can even just hold the cap leads up to momentarily touch the relevent solder pads and do your ear test that way.  Then, once you have the "right" value identified you can unsolder the stock unit and replace it with a preferred value.

Alternatively, 2 caps in series and a 3-position on-off-on mini-toggle can score you 3 delay ranges of interest.  For instance, if you replaced the stock 47pf cap with a 56pf and 75pf, wired in series, you could have three possible settings/ranges: 32pf (with both caps in series), 56pf (shunting the 75pf cap), and 75pf (shunting the 56pf cap).  This would nail you something a little closer to flanging than stock (great for slow Leslie grind), plus two flavours of "thicker" chorus.

Thanks for that. I am a  bit of a n00b. How would I go about wiring up said switch to have both caps in series in center position, and shunting either cap in the other positions?

[grolschie]

There's a small "pf" cap near the MN3102, probably C 31, which sets the amount of
pitch wobble for the circuit, usually 47pf.

Yup, it's a little ceramic cap with "4.7" written on it. Would that be 4.7pf? Or is that not a decimal point?

[MartyMart]

That's a 47pf
BTW - your circuit board needs a hair cut !   

[grolschie]

That's a 47pf
BTW - your circuit board needs a hair cut !   

Thanks for that!!!! BTW, the other side of the board needs a haircut. It seems that they didn't really trim the legs of the components very short! :-)

I reckon I should try tacking on a ~22pf cap or something in parallel to bring it up to around ~68pf before I start de-soldering.

[MartyMart]

Yup, that's a good idea ... try it and see

MM

[grolschie]

Yup, that's a good idea ... try it and see

MM

Interesting.... I had a spare 33pf cap lying around so I parallelled it with the existing 47pf to make it 80pf. The result is was less flangery. The detuning warble is far less, and the depth is more shallow it would seem. The bad side effect of such an exaggerated tweak is a kind of ticking on each cycle. Not a tick really, but more like the cycle is not longer seamless (if that's a better way of descibing it).

I might go buy a few caps and play it it. Might make it switchable between stock and improved. :-)