PastFx PX-101 Lowpass Filter (Moogerfooger MF-101 Clone)

[rowandg]

I do have one issue, and was wondering if anyone else came across this. Whenever the Level LED turns off, there's a slight crackle to be heard. I took the pedal out of its chain, so no other pedals were active but the issue persists. Tested with three different PSU's.

Does no one else experience this issue? Here's a video:

I've tested with two different amps, three guitars (strat, tele & pbass) and three different power supplies with no other pedals in the chain. I even moved to a new house in the meanwhile. Verlie has been very helpful and even sent me a replacement, but it has the same issue.

EDIT: it's the tubes. Both my guitar amp and bass amp have tubes, when I use the clean channels the problem disappears.

 

[Snaxster]

I do have one issue, and was wondering if anyone else came across this. Whenever the Level LED turns off, there's a slight crackle to be heard. I took the pedal out of its chain, so no other pedals were active but the issue persists. Tested with three different PSU's.

Does no one else experience this issue? Here's a video:

I've tested with two different amps, three guitars (strat, tele & pbass) and three different power supplies with no other pedals in the chain. I even moved to a new house in the meanwhile. Verlie has been very helpful and even sent me a replacement, but it has the same issue.

EDIT: it's the tubes. Both my guitar amp and bass amp have tubes, when I use the clean channels the problem disappears.

Thanks for this report. Today I received my PX-101. My apartment is an electrical torture test for all audio devices. So I was not alarmed when in my first test of the PX-101 I heard the crackle you mentioned.

For me it wasn't tubes (of which I have many), but grounding and gain structure. Specifically, once I dialed in the Drive and Level controls, it corrected both 1. a high noise floor, and 2. the crackle.

So I wonder if in your case the cause was not the tubes, but a grounding or impedance issue instead. In other words, yes the tube channels in your setup revealed the problem, but no the tubes themselves were not necessarily the cause.

In any case, at first blush I like the PX-101 very much. It does the cosmic splat thing authentically, and generally sounds organic in all uses.

 

[sunbeast]

Does no one else experience this issue? Here's a video:

I've tested with two different amps, three guitars (strat, tele & pbass) and three different power supplies with no other pedals in the chain. I even moved to a new house in the meanwhile. Verlie has been very helpful and even sent me a replacement, but it has the same issue.

EDIT: it's the tubes. Both my guitar amp and bass amp have tubes, when I use the clean channels the problem disappears.

So I do hear this in my PX101 as well- it seems to be voltage that triggers that top Gain light is bleeding into the audio signal somehow, not unlike the issue some people were having with the meter lights in the original release of the Empress Bass Compressor. It seems to trigger a light “pop” every time the LED changes states (Red to Orange to green to off). With the Px101 set up with ideal gain structuring though the noise is still present but very quiet (which is how I missed it myself until you pointed it out as I tend to push the Gain quite a bit the way I play mine). In your case compression from the amp might have been exacerbating the relative level of the noise.

Set the Gain so the light is solid red when you dig in and either solid orange or just turning red with normal playing, then turn down the Level to match the bypassed volume. On the Moog MF101 this kind of Gain was necessary to trigger a full envelope sweep and the PX seems the same unless you crank the internal Sensitivity control. The level of the noise seems to be directly tied to the Level setting and only on the filtered side of the Blend.

It does seem like a potential design issue, so I’m going to email Past FX myself to see what their take is. It’s not a deal-killer in my rig by any means (my Moog MF101 is noisier than the PX101 regardless of settings- though not this same LED noise), but still room for improvement and they might be able to design a fix.

 

[sprag]

... not unlike the issue some people were having with the meter lights in the original release of the Empress Bass Compressor.

Did the empress get fixed without any other compromise to tone/audio quality?

I'd been holding off getting one of these waiting for a few more reviews A/B ing it with a Moog - Which have been provided in the last page or two.

However I might hold of a little longer if the crackle can be removed in a new iteration.

 

[sunbeast]

Did the empress get fixed without any other compromise to tone/audio quality?

I'd been holding off getting one of these waiting for a few more reviews A/B ing it with a Moog - Which have been provided in the last page or two.

However I might hold of a little longer if the crackle can be removed in a new iteration.

In the Empress the fix was a new ribbon connector that users could install themselves easily. My understanding is that the issue was simply interference from the LED meter leaking into the audio path, so probably they just rerouted or shielded the path of either the voltage or signal somehow using the ribbon cable. I didn’t have one with the issue, but mine (slightly later revision) is silent and sounds great. Hard to say what the fix might be in the PX101, might depend on whether everything is mounted directly to the circuitboard or not if the noise is due to proximity between LED circuit and some sort of signal amplification. I could probably do without that meter light personally if they can’t offer some fix (or just make do with the noise as it isn’t a big deal to me).
I messaged them and will post their response

 

[GrowlerBox]

I just ordered one of these after pondering a few envelope filters, including offerings from Broughton, Aguilar, MXR, solidgoldfx and one or two others. Hard to beat the old school Moog thing, though.

Anyhow, posting mostly to comment on the speed of service, which others have mentioned. I used Paypal (not the 4 payment option, although that is a new and notable addition), which automatically provides my home address. I prefer these sorts of parcels to go to work, so I emailed Pastfx immediately to get them to change it, only to be advised that it was already sent, along with a photograph of the parcel with my address label on it! Extraordinary. Makes me proud of the old country :sniff:

 

[Kevin Hailey]

I’m really happy with my instruments and amps. Haven’t bought anything in well over a year, then I go and look at this thread…

I’ve had the pedal for a couple of days now.
I love it. I’ve been happily using a seamoon funk machine for the last couple of years but the px101 is really a different animal.
So much depth of control and a really wide range of useable, and probably unusable (but fun) sounds and noises on board.
“Best pedal yet” according to my wife!

 

[Charlie Tuna]

In the Empress the fix was a new ribbon connector that users could install themselves easily. My understanding is that the issue was simply interference from the LED meter leaking into the audio path, so probably they just rerouted or shielded the path of either the voltage or signal somehow using the ribbon cable. I didn’t have one with the issue, but mine (slightly later revision) is silent and sounds great. Hard to say what the fix might be in the PX101, might depend on whether everything is mounted directly to the circuitboard or not if the noise is due to proximity between LED circuit and some sort of signal amplification. I could probably do without that meter light personally if they can’t offer some fix (or just make do with the noise as it isn’t a big deal to me).
I messaged them and will post their response

Did you ever get a response, sunbeast?

 

[sunbeast]

Did you ever get a response, sunbeast?

Thanks for reminding me. I had originally messaged them on Instagram and no reply so I just sent it direct via email. I’ll let you know!

 

[GrowlerBox]

Mine arrived yesterday (extra day due to post redirection of parcel to work which is all of 3 km from my house) and have been able to play with it a bit this afternoon.

No crackling that I have detected so far, and everything seems to work. I’ve never owned a Moog, and have very limited experience with envelope filters, but I’m having a whale of a time with this. The non-linearity of the controls and their interactions (except for mix, I suppose) is a lot of fun, although it might prove difficult recreate a particular setting by ear until I’ve had a lot more time on it.

The Tim Tam is a nice touch. They’re a staple in NZ, so no surprises, but it’s convenient not to have to walk to the kitchen for a blood sugar boost while I figure the pedal out .

 

[el murdoque]

....after having spent a fair amount of time with envelope pedals, I must say that the PX-101 is my favorite.

From the top of my head, I can recall having owned:
-Moog MF-101
-FT Elettronica Meatbox clone
-Dr. Scientist Dusk
-Maxon AF-9
-DOD ... can't recall the name, the green one
-Mu-Tron IV
-Strymon Mobius
-C4

...there have to be more that I forgot.

However, that PX-101 does a lot of the things I loved on the Moog, but does not have that many issues.
It runs on 9V center negative, is not a huge behemoth of a pedal, is not as sensitive to anything that
runs current in the immediate vicinity, has true bypass ....

That four pole filter comes down like an anvil and can even create funky quack when I play a bass with dead flatwounds.

 

[sloppy_phil]

I know the price is kinda LOL, but I think your envelope filter hunt can't be concluded until you give a Xerograph Deluxe a whirl. It's also got a ridiculously juicy four-pole filter, and has a super useful feature set. Very easy to control big spikes and peaks, and gets anywhere from super funky/quacky, to full out subtractive synthesis. I had to pinch myself when someone told me it's a digital pedal, not analog; based on the sound, I'd have never believed it!

Not exactly the same flavour as the MF-101, especially since it doesn't have onboard gain/drive, but it's gotta be in the discussion for the best filters currently around. And that's not even counting the static LPF mode, which is the heaviest reggae bass tone I've ever encountered. Even more dubby than the DOD's party trick, but with tons of control over how wild the low end gets.

Would love to give one of these PX's a whirl, but I find it hard to justify the outlay, given the XD sitting here is unlikely to get dethroned. Plus, y'know, side jacks....

Anybody got any sound samples??

 

[GrowlerBox]

I had a few hours on it today, and it’s the most fun I’ve had with my clothes on for some time. It has something interesting to say to pretty much every other effect or group of effects I paired it with, from dirt to delay and reverb, octave and chorus-vibrato. Even changing my compression settings brought something else out of it. I have no idea if this is true of other envelope filters (my Pigtronix big-box Envelope-Phaser isn’t nearly as flexible or interesting), but this thing is astonishing.

 

[Charlie Tuna]

I know the price is kinda LOL, but I think your envelope filter hunt can't be concluded until you give a Xerograph Deluxe a whirl. It's also got a ridiculously juicy four-pole filter, and has a super useful feature set. Very easy to control big spikes and peaks, and gets anywhere from super funky/quacky, to full out subtractive synthesis. I had to pinch myself when someone told me it's a digital pedal, not analog; based on the sound, I'd have never believed it!

Not exactly the same flavour as the MF-101, especially since it doesn't have onboard gain/drive, but it's gotta be in the discussion for the best filters currently around. And that's not even counting the static LPF mode, which is the heaviest reggae bass tone I've ever encountered. Even more dubby than the DOD's party trick, but with tons of control over how wild the low end gets.

Would love to give one of these PX's a whirl, but I find it hard to justify the outlay, given the XD sitting here is unlikely to get dethroned. Plus, y'know, side jacks....

Anybody got any sound samples??

Phil, I've been doing a little A/B'ing vs the Meatball clone tonight with my OC-2 and Brown Dog clone and I have just a couple peeves with the PX-101, or rather the Moog MF-101 design:
#1: No control over attack or release speed of the envelope without an expression pedal. I've had an XD before and the toggle at least gave two distinct speeds. The Meatball has both Attack and Release speeds so I got spoiled even though the slowest speeds can sweep as slow or as wide as the XD.
#2: When the envelope is used to filter, as resonance increases the lows start to drop out so for me it is a "flatter"/less dynamic experience than with the Meatball clone. I put my Spaceman Equinox afterwards and felt like it helped a bunch in this department.
So for me the Envelope/Triggering side is pretty weak and the achilles heel of the pedal in the octave/fuzz chain. With dry bass I felt the envelope/trigger side fared better but it doesn't compare with the Meatball.
Now where I think the PX-101 shines is as a static filter with its 2- or 4-pole choice. As a static filter it sounds like there are more lows retained and consequently it feels better to play through it as such. It can get deep here. I have to play around with it more but I doubt it would dethrone your XD unless you use an expression pedal all the time, which I still have to test out properly.
[EDIT: 2-pole static filtering on the PX-101 is very, very nice with the OC-2/Brown Dog in front. Very beefy with low-end retention, clarity and warmth. The Meatball gets close but no cigar and I don't thing the XD will be able to match it here either.]

 

[OhulahanBass]

I know the price is kinda LOL, but I think your envelope filter hunt can't be concluded until you give a Xerograph Deluxe a whirl. It's also got a ridiculously juicy four-pole filter, and has a super useful feature set. Very easy to control big spikes and peaks, and gets anywhere from super funky/quacky, to full out subtractive synthesis. I had to pinch myself when someone told me it's a digital pedal, not analog; based on the sound, I'd have never believed it!

Not exactly the same flavour as the MF-101, especially since it doesn't have onboard gain/drive, but it's gotta be in the discussion for the best filters currently around. And that's not even counting the static LPF mode, which is the heaviest reggae bass tone I've ever encountered. Even more dubby than the DOD's party trick, but with tons of control over how wild the low end gets.

Would love to give one of these PX's a whirl, but I find it hard to justify the outlay, given the XD sitting here is unlikely to get dethroned. Plus, y'know, side jacks....

Anybody got any sound samples??

I’m glad I’m not the only one with an allergy for side jacks. It’s silly but those are my main deterrent in not buying this. I’ll probably get it eventually and rehouse if I dig it.

 

[Funkinthetrunk]

I’m glad I’m not the only one with an allergy for side jacks. It’s silly but those are my main deterrent in not buying this. I’ll probably get it eventually and rehouse if I dig it.

Hey Chris, I see you've still got the envelope filter bug.

 

[Luke the Fluke]

Mine arrived today - it’s good

 

[OhulahanBass]

Hey Chris, I see you've still got the envelope filter bug.

Always and forever friend! Got anything new you suggest? I bet you have a few more pedals and basses since the last time we we had a chat.

I’ve been off on synth pedals, they never track or sound as good or satisfying as my synths. Fuzz into a juicy filter or phaser is always awesome though.

 

[sunbeast]

Did the empress get fixed without any other compromise to tone/audio quality?

I'd been holding off getting one of these waiting for a few more reviews A/B ing it with a Moog - Which have been provided in the last page or two.

However I might hold of a little longer if the crackle can be removed in a new iteration.

Did you ever get a response, sunbeast?

To update, I’ve got a new one on the way to see if my current one might be a dud. He wasn’t able to recreate my artifact issue and sent a number of videos trying. Cool guy, and definitely intent to make things right however that needs to go.


For illustrative purposes, the easiest way to hear the noise in my PX101 is to turn the Amount control off, Mix all the way up (so it is acting as a static low-pass filter), turn the Frequency down so the tone is in the sub region, Gain up until you are triggering red LED with every hit, Volume up to match unity gain. On my pedal set like this, there is a fizzy Velcro type artifact any time the Gain LED changes colors- from red to orange, orange to green. The noise increases with the Volume control only and is only present on the filtered side of the Blend control. I was able to replicate it with different power supplies, different instruments, different cables, different amps. It isn’t super loud, but enough to show up in a recording environment.

I’ll update when the replacement arrives. Honestly even with the noise artifact I’ll likely keep the replacement as it is such a good filter

 

[Charlie Tuna]

Anybody got any sound samples??

-- I am taking back my previous comments about the PX101 not serving well in an Octave-Fuzz chain without an expression pedal. I sinned and was not testing it in a mix and ask for forgiveness lol. It is thick and it slays. It's so thick I will have to adjust my playing more and work on my timing a lot more. And I have to still get used to the sensitivity and am coming to realize a little change goes a long way. Anyway, headphones will sound best, I used DT770 Pro 80 ohms. Mistakes aplenty but I tried to incorporate different note durations and runs yada yada. \

Quick recording attached with backing track by:

Jam'in Backing Tracks

For educational purposes only.