Small Clone modders?

[Steben]

Hi guys,

Just reverted from a Neo Clone back to a Small Clone. I love the box and old school through hole mount...
The vibrato mod is easy.
Any experience here for other mods? Is it worth adding a Flanger mode?

[Mark Hammer]

I built myself a Tonepad Heladito clone of the EHX pedal with several additional functions.
As you're no doubt aware, there is some overlap between chorus and flangers in the delay times they each achieve.  Even taking that into consideration, transforming a chorus into a flanger entails changing more than the clock. 
- Where flanging effects are audible at very slow sweep speeds, chorus effects are not, so "flangifying" a chorus would also include modifying the LFO.
- Chorus effects never have a feedback loop because feedback sounds annoying and distracting for chorus, even though it enhances flanging effects.
- Some of the most striking commercial flangers retain wide bandwidth, and especially top end, for the wet signal.  When you slow down the clock for chorus, you also have to filter the top-end out to reduce audible clock noise.

HOWEVER, many of us were surprised to learn that when we thought guitarist Andy Summers was using a chorus pedal for many of the Police's biggest tunes, he was actually using an Electric Mistress flanger.  He could do this because there is a sweet spot where the delay range of flanging and chorus overlaps.  It does not require feedback to sound pleasing or obvious, and it does not depend on very slow speeds.  What it does is provide something that many use to emulate slow Leslie swirl.  One can accomplish this on a Small Clone by reducing the value of the cap in the clock-generator.  Normally this is 150pf.  Dropping its value by half bumps the delay range to that sweet spot, although component tolerances for little ceramic disc caps probably means one would have to play around with actual, rather than nominal, values.

Another thing I like to do with chorus is include a bass-cut option for the wet signal.  One of the reasons why some players - especially bass players - don't like chorus is because the pitch wobble is too obvious and distracting.  Chopping/attenuating the bottom end of the wet signal makes the pitch wobble less noticeable, while still preserving all the swirl.

The Small Clone feeds the wet signal to the output/mixing stage via a 1uf cap.  Dropping the value of that cap will attenuate the bass.  I'll suggest replacing it with 100nf.  Keep in mind that it is a shallow rolloff so there will still be a bit of bass in there.  If a person wanted to both cut the bass AND provide some protection against BBD distortion with hot signals, you'd cut the value of the 1uf cap at the beginning of the wet path immediately after the input stage.

As pleasing as a rich chorus tone can sound, sometimes you want a little subtlely.  To do that, one adds series resistance to the 20k that normally mixes wet with dry at the final output stage.  One can use a 100k pot, though I doubt anything useful is achieved with more than 50k, since it makes the total resistance 70k, well below the dry level.  It may also be moot to do more than use a 3-position toggle to bump the wet level down to moderate and low by adding two specific series resistances.

Finally, ALL chorus pedals can be turned into vibrato devices by cancelling/lifting the dry signal at the mixing stage.  It may not be the most pleasing vibrato.  The Boss CE-1 uses a different LFO waveform for vibrato than it uses for chorus.  Vibrato-fying a Small Clone gets you the same LFO for chorus and vibrato.  Still, it's a usable mod.

[Steben]

Something like this, Mark?
I'ld recycle the depth switch and keep it in place. It is DPDT anyway, so why not use it to toggle vibrato AND engage a mix pot. The latter is not useful in vibrato mode.

[Mark Hammer]

Took me a minute to fully understand what you were proposing but I think I get it now.
The 47k variable resistance is only in-circuit in chorus mode.  Switch to vibrato, by lifting the dry path, and you instantly revert to full wet volume.  Smart, smart, smart, and very convenient.  I think I will implement that on mine.  Thanks for the idea!    Normally I just use a SPST toggle to do the dry lift.  But if I happen to have the wet-blend pot turned down to get a subtler chorus sound, vibrato-mode now obliges me to turn the wet level up.  Far better to use a DPDT to switch both the dry and wet paths in the manner you show.

You've earned your pay.  Take the weekend off!

[Steben]

Took me a minute to fully understand what you were proposing but I think I get it now.
The 47k variable resistance is only in-circuit in chorus mode.  Switch to vibrato, by lifting the dry path, and you instantly revert to full wet volume.  Smart, smart, smart, and very convenient.  I think I will implement that on mine.  Thanks for the idea!    Normally I just use a SPST toggle to do the dry lift.  But if I happen to have the wet-blend pot turned down to get a subtler chorus sound, vibrato-mode now obliges me to turn the wet level up.  Far better to use a DPDT to switch both the dry and wet paths in the manner you show.

You've earned your pay.  Take the weekend off!

Mmm. Breakfast during Olympic cycling road race, some small clone drilling, preparing lunch, some more soldering, Pfizer no 2 jab, diner BBQ...

[Steben]

[Mark Hammer]

So, how do you like it?

[Steben]

So, how do you like it?

The most useful mod is depth control. The two fixed ones were greatly chosen. EHX did very well in all of their fixed stuff. Nevertheless I like stepless.
The deepest mod is the vibrato. It does quite well if depth is set low. Has a "timbre" to it. Like subtle rotary. With depth to the max latency / tracking becomes a problem.
The mix mod is very subtle and great for tailoring rhythm work. It was the most labour and wiring karate for the least effect, but I like the fact it's on it now.

But, since BBD delay is what it is, a modded SC is simply the basic module of most BBD circuits and quite good at it.

[Mark Hammer]

The PCB allows for anyone  who wants to tack clock caps on the pads on the copper side and play with delay ranges.  Shorter delay ranges (e.g., using 82pf instead of 150pf) get that in-between-flanging-and-chorus zone that nicely mimics slow Leslie.  The other thing it does is that it reduces the pitch-wobble width in vibrato mode, and might make it more palatable for you.

[taxfree]

I built myself a Tonepad Heladito clone of the EHX pedal with several additional functions.
As you're no doubt aware, there is some overlap between chorus and flangers in the delay times they each achieve.  Even taking that into consideration, transforming a chorus into a flanger entails changing more than the clock. 
- Where flanging effects are audible at very slow sweep speeds, chorus effects are not, so "flangifying" a chorus would also include modifying the LFO.
- Chorus effects never have a feedback loop because feedback sounds annoying and distracting for chorus, even though it enhances flanging effects.
- Some of the most striking commercial flangers retain wide bandwidth, and especially top end, for the wet signal.  When you slow down the clock for chorus, you also have to filter the top-end out to reduce audible clock noise.

HOWEVER, many of us were surprised to learn that when we thought guitarist Andy Summers was using a chorus pedal for many of the Police's biggest tunes, he was actually using an Electric Mistress flanger.  He could do this because there is a sweet spot where the delay range of flanging and chorus overlaps.  It does not require feedback to sound pleasing or obvious, and it does not depend on very slow speeds.  What it does is provide something that many use to emulate slow Leslie swirl.  One can accomplish this on a Small Clone by reducing the value of the cap in the clock-generator.  Normally this is 150pf.  Dropping its value by half bumps the delay range to that sweet spot, although component tolerances for little ceramic disc caps probably means one would have to play around with actual, rather than nominal, values.

Another thing I like to do with chorus is include a bass-cut option for the wet signal.  One of the reasons why some players - especially bass players - don't like chorus is because the pitch wobble is too obvious and distracting.  Chopping/attenuating the bottom end of the wet signal makes the pitch wobble less noticeable, while still preserving all the swirl.

The Small Clone feeds the wet signal to the output/mixing stage via a 1uf cap.  Dropping the value of that cap will attenuate the bass.  I'll suggest replacing it with 100nf.  Keep in mind that it is a shallow rolloff so there will still be a bit of bass in there.  If a person wanted to both cut the bass AND provide some protection against BBD distortion with hot signals, you'd cut the value of the 1uf cap at the beginning of the wet path immediately after the input stage.

As pleasing as a rich chorus tone can sound, sometimes you want a little subtlely.  To do that, one adds series resistance to the 20k that normally mixes wet with dry at the final output stage.  One can use a 100k pot, though I doubt anything useful is achieved with more than 50k, since it makes the total resistance 70k, well below the dry level.  It may also be moot to do more than use a 3-position toggle to bump the wet level down to moderate and low by adding two specific series resistances.

Finally, ALL chorus pedals can be turned into vibrato devices by cancelling/lifting the dry signal at the mixing stage.  It may not be the most pleasing vibrato.  The Boss CE-1 uses a different LFO waveform for vibrato than it uses for chorus.  Vibrato-fying a Small Clone gets you the same LFO for chorus and vibrato.  Still, it's a usable mod.

Mark,


In my case, I wanted to have control over the treble to reduce it and have a little more body and bass in the sound. Is there any way to get it? In place of the 150p capacitor I have a selector switch with 50p central and 100p and 220p on each side. The EHX Bass Clone version has these controls but no schematics are available.

[Mark Hammer]

Mark,

In my case, I wanted to have control over the treble to reduce it and have a little more body and bass in the sound. Is there any way to get it? In place of the 150p capacitor I have a selector switch with 50p central and 100p and 220p on each side. The EHX Bass Clone version has these controls but no schematics are available.

Sometimes, when people want, or a designer aims for, "more bass", what they really do is reduce treble, so that the bass seems more obvious and dominant.  Going by the Bass Clone description on the EHX site, I gather they increase the bass in the input stage (which normally rolls off below 2.3khz) and likely use some means to trim back the bass contet from the wet path, and provide variable bass content in the dry path.

Below is the EHX schematic for the Small Clone (I've shifted a few things around for a more compact image).  To increase the amount of bass content in the overall signal, you would probably want to increase the value of C3 from .01uf to perhaps .039uf.  Now, that only drops the bass rolloff down from 2.3khz to 600hz, but R21/C14 in the output stage roll off treble to restore tonal balance.

Of course, having increased bass content going to the wet path risks overdriving the BBD, so we'll trim back  the wet bass content by dropping C4 from 1uf down to 18-22nf for less bass in the wet path.  The X-over switch in the Bass Clone purportedly reduces the wet bass, such that wet is more trebly and dry is more bass.  I don't know how EHX does this, exactly, but what I describe is one way.

How would one be able to vary the bass-iness of the dry path?  R18 (22k) mixes the dry signal with the wet.  We'll replace that with a 470R, 10k linear pot, and a 10k fixed resistor, in series (and in that order), treating the two outside pot lugs as if it was a 10k fixed resistor (the total resistance comes up to roughly 22k5).  The wiper of that pot will go to a 100nf cap to ground.  Regular folks here will recognize that as a SWTC control - a variable 6db/oct cut whose corner frequency can be moved around.  When it is at one extreme, with only 470R before the wiper, the treble rolloff starts around 3.4khz, which is about as bright as we want.  Rotating the pot, so that the wiper is at the other end of travel, we'll have 10.47k leading up to that cap to ground, resulting in a rolloff starting just over 150hz.  At only 6db/oct, the rolloff is not steep, so you'll still get some treble content, but not very much.  Using a 10k fixed resistor, for a total of roughly 20.5k Possibly less, given component tolerances), we'll have very close to the original wet/dry balance.  The shaving off of treble will make the dry seem less dominant.  If the dry still seems overly noticeable, increase the the value of the 10k fixed resistance a bit.

Does this make sense to you?  Are any alarm bells going off for the more knowledgeable folks here?  Did I overlook anything?