Aion FX Xenotron (Lovetone ? Flanger) Build: Weird behavior of ring lift, stereo/mono, and bypass switches.

[puntygr4p3s]

Hi all,

I recently finished a build of Aion FX's Xenotron clone of the Lovetone Flange With No Name. As far as I can tell, the effect seems to be working, good range of sounds out of both the space (tremolo) and time (modulation) circuits. However there seem to be some weird things happening with signal loss depending on the settings of the ring lift and stereo/mono switches. All of the below pertain to using the pedal with only the space/mono output:

Ring lift switch up | stereo/mono switch in any position: Good, strong signal in bypass and with tremolo from the Space circuit. As per design, modulation from the Time circuit is not present in the mono output in this setting.

Ring lift switch down | stereo/mono switch in stereo position: Slightly weaker bypass signal, but pretty good. When only Space is engaged, signal strength is good but modulation is very weak. When Time and Space are engaged, Time signal is good but if "action" is turned towards the center (reducing mix level of the Time circuit), Space signal is very weak.

Ring lift switch down | stereo/mono switch in mono position: Much weaker bypass signal with a lot of missing high and mid frequencies. When only Space is engaged, modulation has decent strength but the overall signal level is much lower than when the ring lift switch is engaged, missing highs and mids. When both Time and Space are engaged, high frequencies come back, but again there seems to be relatively weak modulation from the Space signal as the Time mix is turned down.

I double checked the wiring and checked continuity between the solder pads on all the input/output jacks and haven't found any obvious problems. Wondering if anyone else has had similar issues with this build or has ideas on where to focus troubleshooting. Thanks for having a look! Sorry for the rough picture quality...

The Space/mono out and the Time out jacks are the rightmost in these pictures








Note I have electrical tape on the bottom plate to ensure nothing shorts out against it, since the build was cramped and soldering tabs on the jacks stuck out past the bottom of the enclosure before being bent inwards.

 

[comradehoser]

You can read the other epic Xenotron troubleshooting threads for fun and profit.

There might be some issues in the transition of the signal from the board to the outs and the switching, but given the complexity of the interplay between all the elements and controls here, I'd say if you have a functional board that flanges and trems and goes crazy, then you have a winner. Attenuated highs/lows could be a function of effect overlay from blending in the flange (or even trem, hell). Ring lift and the stereo/mono switch only apply to stereo outs in any case, so I don't mess with them at all. Maybe take a listen to some demos and see if it sounds like yours at similar settings. If it does, I think you're good.

One thing off the bat is that the action/reaction knobs are basically center-0 as opposed to CCW 0. So fully turning CW (even harmonics) *or* CCW (odd harmonics) dimes that part of the effect.

On the function of the ring lift switch, from aion's build docs:

"Ring Lift (toggle switch) disconnects the ring (middle) terminal of the Time jack, which is equivalent to the “C” solution in the user manual under the “Time Out” heading without requiring a specially modified cable. Note that this prevents the Time signal from being mixed to mono when only the Space output is used, so it should only be engaged when both outputs are used and only if you notice a buzz or weak signal from the Time output."

Here's what I figured out about the time/space switch and the special role of the ring switch (on the jack, not the ring lift toggle):

"I had a moment of clarity after reading the manual. The mono-stereo switch only applies to rectify phase of the signal when the delay/modulation is *bypassed* in mono or stereo operations. Otherwise, the modulated signal travels to the time out jack and then to the space out jack if nothing is inserted into the time switch-jack. I am inferring that this happens via the ring switch since the ring switch solder point proceeds from the time out ring switch, and is right next to the space out solder point on the board. The schematic also indicates that "time ring switch" at r26 feeds into to the space out.

So, if I understand this correctly, the modulated signal should be coming in via "ring" on the right of the jack, which is connected to "ring switch" on the left of the jack, which is connected to the space out. When you push the cable into the time out jack, it lifts the tang connecting the ring (right side) to the ring switch (left side) breaking that circuit, at the same time you get the modulated signal fed through the transformer to the tip and sleeve when the cable is inserted, no doubt to give enough juice to the stereo signal or make it proper in some way. The ring conspicuously is not connected through the transformer."

 

[puntygr4p3s]

You can read the other epic Xenotron troubleshooting threads for fun and profit.

There might be some issues in the transition of the signal from the board to the outs and the switching, but given the complexity of the interplay between all the elements and controls here, I'd say if you have a functional board that flanges and trems and goes crazy, then you have a winner. Attenuated highs/lows could be a function of effect overlay from blending in the flange (or even trem, hell). Ring lift and the stereo/mono switch only apply to stereo outs in any case, so I don't mess with them at all. Maybe take a listen to some demos and see if it sounds like yours at similar settings. If it does, I think you're good.

One thing off the bat is that the action/reaction knobs are basically center-0 as opposed to CCW 0. So fully turning CW (even harmonics) *or* CCW (odd harmonics) dimes that part of the effect.

On the function of the ring lift switch, from aion's build docs:

"Ring Lift (toggle switch) disconnects the ring (middle) terminal of the Time jack, which is equivalent to the “C” solution in the user manual under the “Time Out” heading without requiring a specially modified cable. Note that this prevents the Time signal from being mixed to mono when only the Space output is used, so it should only be engaged when both outputs are used and only if you notice a buzz or weak signal from the Time output."

Here's what I figured out about the time/space switch and the special role of the ring switch (on the jack, not the ring lift toggle):

"I had a moment of clarity after reading the manual. The mono-stereo switch only applies to rectify phase of the signal when the delay/modulation is *bypassed* in mono or stereo operations. Otherwise, the modulated signal travels to the time out jack and then to the space out jack if nothing is inserted into the time switch-jack. I am inferring that this happens via the ring switch since the ring switch solder point proceeds from the time out ring switch, and is right next to the space out solder point on the board. The schematic also indicates that "time ring switch" at r26 feeds into to the space out.

So, if I understand this correctly, the modulated signal should be coming in via "ring" on the right of the jack, which is connected to "ring switch" on the left of the jack, which is connected to the space out. When you push the cable into the time out jack, it lifts the tang connecting the ring (right side) to the ring switch (left side) breaking that circuit, at the same time you get the modulated signal fed through the transformer to the tip and sleeve when the cable is inserted, no doubt to give enough juice to the stereo signal or make it proper in some way. The ring conspicuously is not connected through the transformer."

Hey thanks for your reply! Interesting note about the time signal coming into the mono out through the ring switch connection of the time out jack. Makes sense with what I've observed.

It seems like maybe there's some kind of phase cancellation with the time signal being mixed into the space output jack and that's why the mono/stereo switch can fix the bypass signal at the expense of perceived tremolo depth. Maybe that's just how the thing is designed, but I'd be curious to know if others are noticing a big signal drop or muffled tone in bypass when switches are set to mono & ring lift off.

 

[eh là bas ma]

I'd be curious to know if others are noticing a big signal drop or muffled tone in bypass when switches are set to mono & ring lift off.

Using only the Space/Mono main output, i don't notice any change with stereo/mono switch. No volume drop with the Ring switch, but when set upward, the Time modulation is cut off the mix, i only have the clean signal, and the space/tremolo modulation working.

However, using only the Time output (wet flanging signal only) i do notice that the signal is slightly "muffled". I mean there is a very slight volume drop, i'd say around 3 or 5 dB, and some high frequencies are cut off, if i toggle the Ring switch downward.

I am still not really sure if everything works fine on my build :

- it's so difficult to find a good flanging sound, in most settings the sweep doesn't work correctly, the modulation disappears and reappears, with lots of non-modulated zones in the signal. This can be fixed with the Depth control, but at the expense of the width of the sweep. I guess it would take hours to find the best setting with the widest sweep possible, acting on the signal constantly without gaps in the modulation. On my build, the first quarter of rotation on the Depth control is usable, past this point it gets unbalanced with huge gaps in the modulation, also some auto-oscillating sounds start to appear at the ends of the sweep.

- the Manual control is so weirdly calibrated with modulation only in the last quarter of its rotation. In this last quarter, the tiniest variation has a huge impact on the modulation, making it almost impossible to fine-tune. I don't get why they would design the Manual control this way, maybe it's meant to tame some extreme feedback settings ?

- Once we finally manage to dial some kind of flanging effect, with Feedback at noon and the Mix control fully CCW or CW, the clean/wet ratio is a bit weak, lots of clean signal, like 60% i'd say. Wet ratio can only be increased by using the feedback control which will also make the sweep much more invasive, quickly auto-oscillating.

The auto-oscillating noises are interesting but it sounds like that's all the Flanging part can do right... Such a big circuit, and yet so few usable sounds ?

I can't keep myself from wondering if there is an issue somewhere. I built lots of flangers, i love them, this one is the most frustrating, only interesting for some weird experiments with feedback whistlings, and quickly boring (even annoying) by itself. It needs delays, reverbs, all kind of effects in the FX loop to get somewhere. All the delays i tried in the FX loop are pushing the flanger into auto-oscillation turning into white noise. They have to be almost unoticeable (low volume, few repeats) to keep a steady modulation.

The Tremolo/Space function isn't really useful, especially because you can't control its speed, it's only following the Flange speed, i can't see the point of this feature.

I tried to use the Time output. Here, I can only hear the Flanging modulation without the clean signal. I turned the Manual control CCW and i noticed the signal gets dirty in the first quarter of the rotation, it sounds like a bad overdrive. It cleans up when Manual is turned up, around 9 o'clock.

Just to be sure, do you notice the same thing on your build with the Manual control ?

 

[comradehoser]

I can check on some of this when I get home.

I will try to find a useable flanging setting, because I definitely have been able to get solid flanging from it, as well as chorus, and phase. Also some interesting settings that aren't the dimed whompawhompa stuff.

This might also help puntygrapes to see if he or she has a properly operating unit. Maybe I will try to post audio if I can find the time to set up a DAW recording and export. I don't think cell phone audio is adequate and my phone is old and craptastic.

I don't think the trem strictly follows the flange, though. They are correlated because both Flange and Trem are governed by the LFO.

 

[puntygr4p3s]

Using only the Space/Mono main output, i don't notice any change with stereo/mono switch. No volume drop with the Ring switch, but when set upward, the Time modulation is cut off the mix, i only have the clean signal, and the space/tremolo modulation working.

However, using only the Time output (wet flanging signal only) i do notice that the signal is slightly "muffled". I mean there is a very slight volume drop, i'd say around 3 or 5 dB, and some high frequencies are cut off, if i toggle the Ring switch downward.

I am still not really sure if everything works fine on my build :

- it's so difficult to find a good flanging sound, in most settings the sweep doesn't work correctly, the modulation disappears and reappears, with lots of non-modulated zones in the signal. This can be fixed with the Depth control, but at the expense of the width of the sweep. I guess it would take hours to find the best setting with the widest sweep possible, acting on the signal constantly without gaps in the modulation. On my build, the first quarter of rotation on the Depth control is usable, past this point it gets unbalanced with huge gaps in the modulation, also some auto-oscillating sounds start to appear at the ends of the sweep.

- the Manual control is so weirdly calibrated with modulation only in the last quarter of its rotation. In this last quarter, the tiniest variation has a huge impact on the modulation, making it almost impossible to fine-tune. I don't get why they would design the Manual control this way, maybe it's meant to tame some extreme feedback settings ?

- Once we finally manage to dial some kind of flanging effect, with Feedback at noon and the Mix control fully CCW or CW, the clean/wet ratio is a bit weak, lots of clean signal, like 60% i'd say. Wet ratio can only be increased by using the feedback control which will also make the sweep much more invasive, quickly auto-oscillating.

The auto-oscillating noises are interesting but it sounds like that's all the Flanging part can do right... Such a big circuit, and yet so few usable sounds ? What a bad Flanger !

I can't keep myself from wondering if there is an issue somewhere. I built lots of flangers, i love them, this one is the most frustrating, only interesting for some weird experiments with feedback whistlings, and quickly boring (even annoying) by itself. It needs delays, reverbs, all kind of effects in the FX loop to get somewhere. All the delays i tried in the FX loop are pushing the flanger into auto-oscillation turning into white noise. They have to be almost unoticeable (low volume, few repeats) to keep a steady modulation.

The Tremolo/Space function isn't really useful, especially because you can't control its speed, it's only following the Flange speed, i can't see the point of this feature.

I tried to use the Time output. Here, I can only hear the Flanging modulation without the clean signal. I turned the Manual control CCW and i noticed the signal gets dirty in the first quarter of the rotation, it sounds like a bad overdrive. It cleans up when Manual is turned up, around 9 o'clock.

Just to be sure, do you notice the same thing on your build with the Manual control ?

Dialing the ideal sweep is not incredibly easy, but I also don't think I'm having as much trouble with it as you seem to be. I've attached a vid in case it's helpful to compare (apologies for potato image quality and cell phone audio).

 

[eh là bas ma]

Thanks for the demo !

You have modulation with Manual at noon, which tells me something is really wrong on my build....
Your circuit sounds much better than mine.

Congratulations for this difficult build !

 

[puntygr4p3s]

Maybe try revisiting the BBD bias trimmer? Hope it's something simple like that.

 

[eh là bas ma]

Is there a point in the Manual rotation where your modulation fades away ? Or is it supposed to work through the whole rotation ?

 

[puntygr4p3s]

Is there a point in the Manual rotation where your modulation fades away ? Or is it supposed to work through the whole rotation ?

My understanding is that the manual control is setting the center delay time in the modulation sweep, so there should be some discernable modulation with depth turned up at all settings but when you are at the lower range the negative portion of the sweep might not have any effect and when you are at the upper range the positive portion might not. The BBD signal does also seem to get much louder overall past 3:00 on manual on my build, so maybe you are experiencing a weak BBD output and the modulation only becomes noticeable in that final portion of the manual pot's sweep.

(Edit: wrote 9:00 when I meant 3:00)

 

[comradehoser]

3 new items by Rene Hayden

photos.app.goo.gl

I tried to upload direct, but they are too large, so you get a link instead. A flangery thing, a chorusy thing, and some nice overtone thing into the craziness the pedal can do

Ibanez AR in need of a string change on bridge series humbucker setting into my little orange practice amp

 

[comradehoser]

Dialing the ideal sweep is not incredibly easy, but I also don't think I'm having as much trouble with it as you seem to be. I've attached a vid in case it's helpful to compare (apologies for potato image quality and cell phone audio).

Pretty much sounds like mine. I think you're good!

Sometimes it's a mistake, but sometimes it's just the way the pedal sounds

 

[comradehoser]

And that's okay.

 

[eh là bas ma]

I tried to upload direct, but they are too large, so you get a link instead. A flangery thing, a chorusy thing, and some nice overtone thing into the craziness the pedal can do

Thanks a lot for taking the time to record these samples !

I think my build is able to produce some similar sounds. It's probably quite close to total completion.

Now that puntygrapes mentioned it, i guess i can hear something like a delay being modified when i turn the Manual pot within the last quarter of its rotation. The only difference is that it's seems harder to dial the settings on my build, something is wrong somewhere : Manual, and maybe also Depth, aren't responding as they should, compared to your builds.

The BBD trimmer didn't allow me to get a modulation through the whole Manual rotation. I think it's working, the modulation appears between 11' and 15 oclock on the trimmer. I'm having doubts about the BBD led : I built a kit, i took the green led that looked a bit different from the other leds in the kit, with a more transparent glass, it's brighter and not exactly the same shade of green as the usual green led, but maybe it's the wrong kind, i'm not sure. I remember that it has been an issue on an other troubleshooting post.

Is there a way to make sure i have the right BBD led ? Like a diode test with a different value than the usual green leds ? All controls set at noon, on the led pads from the BBD sub-board, i read 2.265 V on diode test. The other leds (LDR1, LDR3) read 1.9 V, still soldered on the pcb. LDR2 reads 1.7 V and doesn't light up on diode test, unlike the others, but it does light up when the power is plugged in, it stays always lit, and pulsate when the tremolo effect is activated.

Do you have similar values by any chance ?

The only way to hear a faint modulated sound with Manual at noon, is by turning up the Feedback to extreme values, this way i can hear some feedback noise at one end of the sweep, but not the sweep itself. It sounds more like a cyclic noise than a modulated signal.

Another lead is the distortion appearing in the first half of the manual rotation, when i use the Time output only. If i understand correctly, there isn't any distortion like this on both your builds, so it could be a big sign pointing in the direction of the issue.

The distortion, or gain, or compression (i'm not sure how to call it) doesn't change the volume, however it's getting more and more distorted as i turn the Manual pot CCW. This distortion disappears around noon, the signal cleans up, and the modulation appears around the last quarter of rotation.

Any idea about what could cause this distortion ?

Using the Time output, the volume is steady, so i'm not sure if it's related to a BBD volume problem, if that's what you meant by "weak BBD output". I guess an audio probe test would be required, but i 'm not sure where would be my test points.

 

[comradehoser]

Definitely, the gain pot should affect the volume.

Redoing biasing and paying extra attention to the protocols might be an easy thing to start with, as it sounds like the two things you are struggling with could be related to bias: distortion/gain issues (BBD bias), and weirdness of the manual knob (Regen bias).

Can check the LED values this evening, but the aion build docs specify 3 regular diffused green LED and one clear. That is also what I used:

"The first three LED/LDR pairs work best with 5mm diffused green LEDs, and these ones from Tayda Electronics have been tested and work perfectly. You can also use other green diffused LEDs, just make sure they’re not the high-brightness or low-current type. There are also some diffused types that have a much higher MCD brightness specification, and these will not work well.

The fourth LED, located on the BBD sub-board, should be a water-clear or semi-transparent highbrightness type. The Kingbright WP7113GT has been tested and works well."

 

[eh là bas ma]

Definitely, the gain pot should affect the volume.

i think i wasn't clear, sry. The Input Gain control does its job, no issue there.

I have distortion appearing during the Manual pot's rotation (1rst half). I noticed it when using only the Time output. On the Mono output, it's there too, but less noticeable because of the wet/clean ratio.

I was saying that turning the Manual knob doesn't impact the volume, even if there are some distortion (in my mind, distortion means that the volume is increased somewhere, that's why i made this precision)

I hope this distortion can help locate the issue somehow.

 

[comradehoser]

Distortion is just a function of a signal exceeding the clean reproduction capacities/bandwidth of an amplification device/circuit, and apparently the delay chipset doesn't have a whole lot of headroom. The manual control along with rate, depth, and the wave shape toggles are all contained in the LFO circuit loop. I don't see any signal ins or outs, only voltage and jack/expression inputs that seem to be governing the behavior of the LED/LDR arrays, whose variable resistance is controlling signal to the delay/trem circuit loops.

From aion (my emphases):

"[With LEDs covered], connect a guitar to the input of the pedal, and connect the Space Out/Mono jack to the amp. Set the amp volume to zero, power it on, and then turn up the volume until the guitar volume is normal when strumming. (With “Input Gain” set fully up, the pedal output will be higher than a normal guitar signal.) Now, listen for distortion, static and clock noise as you adjust the knobs. First turn the “Rate” control down slowly to zero. Then turn “Manual” to 12:00 and turn “Rate” up slowly until you’re back up at full rotation. If at any time you hear any clock ticking, or if you hear distortion, static or hum, make small adjustments to the trimmer until it goes away, and then sweep the [manual and rate] controls again to ensure that it’s been eliminated across the full range. The goal is a complete range of control with no clock ticking and minimal distortion. The BBDs have a fixed amount of headroom, so there will eventually be distortion if the input signal is hot enough, but the “Input Gain” control can compensate for high input levels so the distortion can be dialed out."

Rebias--if the issue persists, maybe it's the Manual pot or [doubtfully, since you have flangey noises] the chipset?